WorldWideScience

Sample records for bolometric light curve

  1. Type Ia supernova bolometric light curves and ejected mass estimates from the Nearby Supernova Factory

    CERN Document Server

    Scalzo, R; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Cellier-Holzem, F; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Guy, J; Kim, A; Kowalski, M; Kromer, M; Nordin, J; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Saunders, C; Sim, S A; Smadja, G; Tao, C; Taubenberger, S; Thomas, R C; Weaver, B A

    2014-01-01

    We present a sample of normal type Ia supernovae from the Nearby Supernova Factory dataset with spectrophotometry at sufficiently late phases to estimate the ejected mass using the bolometric light curve. We measure $^{56}$Ni masses from the peak bolometric luminosity, then compare the luminosity in the $^{56}$Co-decay tail to the expected rate of radioactive energy re- lease from ejecta of a given mass. We infer the ejected mass in a Bayesian context using a semi-analytic model of the ejecta, incorporating constraints from contemporary numerical models as priors on the density structure and distribution of $^{56}$Ni throughout the ejecta. We find a strong correlation between ejected mass and light curve decline rate, and consequently $^{56}$Ni mass, with ejected masses in our data ranging from 0.9-1.4 $M_\\odot$. Most fast-declining (SALT2 $x_1 < -1$) normal SNe Ia have significantly sub-Chandrasekhar ejected masses in our fiducial analysis.

  2. The bolometric light curves and physical parameters of stripped-envelope supernovae

    Science.gov (United States)

    Prentice, S. J.; Mazzali, P. A.; Pian, E.; Gal-Yam, A.; Kulkarni, S. R.; Rubin, A.; Corsi, A.; Fremling, C.; Sollerman, J.; Yaron, O.; Arcavi, I.; Zheng, W.; Kasliwal, M. M.; Filippenko, A. V.; Cenko, S. B.; Cao, Y.; Nugent, P. E.

    2016-05-01

    The optical and optical/near-infrared pseudo-bolometric light curves of 85 stripped-envelope supernovae (SNe) are constructed using a consistent method and a standard cosmology. The light curves are analysed to derive temporal characteristics and peak luminosity Lp, enabling the construction of a luminosity function. Subsequently, the mass of 56Ni synthesized in the explosion, along with the ratio of ejecta mass to ejecta kinetic energy, are found. Analysis shows that host-galaxy extinction is an important factor in accurately determining luminosity values as it is significantly greater than Galactic extinction in most cases. It is found that broad-lined SNe Ic (SNe Ic-BL) and gamma-ray burst SNe are the most luminous subtypes with a combined median Lp, in erg s-1, of log(Lp) = 43.00 compared to 42.51 for SNe Ic, 42.50 for SNe Ib, and 42.36 for SNe IIb. It is also found that SNe Ic-BL synthesize approximately twice the amount of 56Ni compared with SNe Ic, Ib, and IIb, with median MNi = 0.34, 0.16, 0.14, and 0.11 M⊙, respectively. SNe Ic-BL, and to a lesser extent SNe Ic, typically rise from Lp/2 to Lp more quickly than SNe Ib/IIb; consequently, their light curves are not as broad.

  3. The bolometric light curves and physical parameters of stripped-envelope supernovae

    CERN Document Server

    Prentice, S J; Pian, E; Gal-Yam, A; Kulkarni, S R; Rubin, A; Corsi, A; Fremling, C; Sollerman, J; Yaron, O; Arcavi, I; Zheng, W; Kasliwal, M M; Filippenko, V V; Cenko, S B; Cao, Y; Nugent, P

    2016-01-01

    The optical and optical/near-infrared pseudobolometric light curves of 84 stripped-envelope supernovae (SNe) are constructed using a consistent method and a standard cosmology. The light curves are analysed to derive temporal characteristics and peak luminosity $L_{\\mathrm{p}}$, enabling the construction of a luminosity function. Subsequently, the mass of $^{56}$Ni synthesised in the explosion, along with the ratio of ejecta mass to ejecta kinetic energy, are found. Analysis shows that host-galaxy extinction is an important factor in accurately determining luminosity values as it is significantly greater than Galactic extinction in most cases. It is found that broad-lined SNe Ic (SNe Ic-BL) and gamma-ray burst SNe are the most luminous subtypes with a combined median $L_{\\mathrm{p}}$, in erg s$^{-1}$, of log($L_{\\mathrm{p}})=42.99$ compared to $42.51$ for SNe Ic, $42.50$ for SNe Ib, and $42.36$ for SNe IIb. It is also found that SNe Ic-BL synthesise approximately twice the amount of $^{56}$Ni compared with SN...

  4. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  5. Type II supernovae Early Light Curves

    CERN Document Server

    Shussman, Tomer; Nakar, Ehud

    2016-01-01

    Observations of type II supernova early light, from breakout until recombination, can be used to constrain the explosion energy and progenitor properties. Currently available for this purpose are purely analytic models, which are accurate only to within an order of magnitude, and detailed numerical simulations, which are more accurate but are applied to any event separately. In this paper we derive an analytic model that is calibrated by numerical simulations. This model is much more accurate than previous analytic models, yet it is as simple to use. To derive the model we analyze simulated light curves from numerical explosion of $124$ red supergiant progenitors, calculated using the stellar evolution code MESA. We find that although the structure of the progenitors we consider varies, the resulting light curves can be described rather well based only on the explosion energy, ejecta mass and progenitor radius. Our calibrated analytic model, which is based on these three parameters, reproduces the bolometric ...

  6. Analytical Expressions For Light-Curves Of Ordinary And Superluminous Supernovae Type Ia

    OpenAIRE

    Dado, Shlomo; Dar, Arnon

    2013-01-01

    Supernovae of type Ia (SNeIa) can be produced by the explosion of slowly-rotating carbon-oxygen white dwarfs whose mass increases beyond a critical value by mass accretion. Collision with circumstellar material during their photospheric and early nebular phase can enhance the bolometric luminosity of otherwise ordinary SNeIa to become superluminous. A few simplifying assumptions lead to a simple analytic master formula, which describes quite well the bolometric light-curves of ordinary SNeIa ...

  7. PSD analysis of optical QSO light curves

    Science.gov (United States)

    Simm, Torben; Salvato, M.; Saglia, R.; Ponti, G.; Lanzuisi, G.; Trakhtenbrot, B.; Nandra, K.; Bender, R.

    2016-08-01

    One of the elementary properties of quasar activity is continuous variability in the UV/optical bands. The power spectral density (PSD) potentially contains information about the underlying processes connected to variability. We applied a novel method based on continuous-time autoregressive moving average (CARMA) models (Kelly et al. 2014) to derive the PSD even for irregularly sampled light curves. Using a sample of ~100 X-ray selected non-local QSOs from the XMM-COSMOS catalog and optical light curves provided by the Pan-STARRS1 MDF survey we find that the PSD resembles a broken power-law with a high-frequency slope significantly steeper than observed in X-ray studies. The PSD normalization is observed to scale inversely with bolometric luminosity and Eddington ratio, whereas there is no correlation between the characteristic bend timescale and black hole mass. We find a weak tendency for QSOs with higher black hole mass to have steeper high-frequency PSD slopes. In an ongoing work we extend these studies employing a sample of ~700 variable broad-line QSOs with high-quality black hole mass estimates and well-sampled light curves from the SDSS-RM project.

  8. Ultraviolet Light Curves of Supernovae with Swift Uvot

    CERN Document Server

    Brown, Peter J; Immler, Stefan; Milne, Peter; Roming, Peter W A; Gehrels, Neil; Nousek, John; Panagia, Nino; Still, Martin; Berk, Daniel Vanden

    2008-01-01

    We present ultravioliet (UV) observations of supernovae (SNe) obtained with the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is the largest sample of UV light curves from any single instrument and covers all major SN types and most subtypes. The UV light curves of SNe Ia are fairly homogenous while SNe Ib/c and IIP show more variety in their light curve shapes. The UV-optical colors clearly differentiate SNe Ia and IIP, particularly at early times. The color evolution of SNe IIP, however, makes their colors similar to SNe Ia at about 20 days after explosion. SNe Ib/c are shown to have varied UV-optical colors. The use of UV colors to help type SNe will be important for high redshift SNe discovered in optical observations. These data can be added to ground based optical and near infrared data to create bolometric light curves of individual objects and as checks on generic bolometric corrections used in the absence of UV data. This sample can also be compared with rest-frame UV obser...

  9. Light on curved backgrounds

    CERN Document Server

    Batic, D; Nowakowski, M

    2014-01-01

    We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other, a general relativistic Dark Matter metric, a dirty Black Hole and a Worm Hole metric, the last two inspired by non-commutative geometry. The lensing in a Holographic Screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behaviour in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases we improve the accuracy of the lensing results for the weak and strong regime.

  10. Light on curved backgrounds

    Science.gov (United States)

    Batic, D.; Nelson, S.; Nowakowski, M.

    2015-05-01

    We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other items, a general relativistic dark matter metric, a dirty black hole, and a worm hole metric, the last two inspired by noncommutative geometry. The lensing in a holographic screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behavior in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases, we improve the accuracy of the lensing results for the weak and strong regimes.

  11. The light curve in supernova modeled by a continuous radioactive decay of $^{56}$Ni

    CERN Document Server

    Zaninetti, L

    2014-01-01

    The UVOIR bolometric light curves are usually modeled by the radioactive decay. In order to model more precisely the absolute/apparent magnitude versus time relationship the continuous production of radioactive isotopes is introduced. A differential equation of the first order with separable variables is solved.

  12. Analysis of Exoplanet Light Curves

    Science.gov (United States)

    Erdem, A.; Budding, E.; Rhodes, M. D.; Püsküllü, Ç.; Soydugan, F.; Soydugan, E.; Tüysüz, M.; Demircan, O.

    2015-07-01

    We have applied the close binary system analysis package WINFITTER to a variety of exoplanet transiting light curves taken both from the NASA Exoplanet Archive and our own ground-based observations. WINFitter has parameter options for a realistic physical model, including gravity brightening and structural parameters derived from Kopal's applications of the relevant Radau equation, and it includes appropriate tests for determinacy and adequacy of its best fitting parameter sets. We discuss a number of issues related to empirical checking of models for stellar limb darkening, surface maculation, Doppler beaming, microvariability, and transit time variation (TTV) effects. The Radau coefficients used in the light curve modeling, in principle, allow structural models of the component stars to be tested.

  13. A two-component model for fitting light-curves of core-collapse supernovae

    CERN Document Server

    Nagy, Andrea P

    2016-01-01

    We present an improved version of a light curve model, which is able to estimate the physical properties of different types of core-collapse supernovae having double-peaked light curves, in a quick and efficient way. The model is based on a two-component configuration consisting of a dense, inner region and an extended, low-mass envelope. Using this configuration, we estimate the initial parameters of the progenitor via fitting the shape of the quasi-bolometric light curves of 10 SNe, including Type IIP and IIb events, with model light curves. In each case we compare the fitting results with available hydrodynamic calculations, and also match the derived expansion velocities with the observed ones. Furthermore, we also compare our calculations with hydrodynamic models derived by the SNEC code, and examine the uncertainties of the estimated physical parameters caused by the assumption of constant opacity and the inaccurate knowledge of the moment of explosion.

  14. DELightcurveSimulation: Light curve simulation code

    Science.gov (United States)

    Connolly, Samuel D.

    2016-02-01

    DELightcurveSimulation simulates light curves with any given power spectral density and any probability density function, following the algorithm described in Emmanoulopoulos et al. (2013). The simulated products have exactly the same variability and statistical properties as the observed light curves. The code is a Python implementation of the Mathematica code provided by Emmanoulopoulos et al.

  15. Scintillation Caustics in Planetary Occultation Light Curves

    CERN Document Server

    Cooray, A R; Cooray, Asantha R.

    2003-01-01

    We revisit the GSC5249-01240 light curve obtained during its occultation by Saturn's North polar region. In addition to refractive scintillations, the power spectrum of intensity fluctuations shows an enhancement of power between refractive and diffractive regimes. We identify this excess power as due to high amplitude spikes in the light curve and suggest that these spikes are due to caustics associated with ray crossing situations. The flux variation in individual spikes follows the expected caustic behavior, including diffraction fringes which we have observed for the first time in a planetary occultation light curve. The presence of caustics in scintillation light curves require an inner scale cut off to the power spectrum of underlying density fluctuations associated with turbulence. Another possibility is the presence of gravity waves in the atmosphere. While occultation light curves previously showed the existence of refractive scintillations, a combination of small projected stellar size and a low rel...

  16. Light extraction block with curved surface

    Energy Technology Data Exchange (ETDEWEB)

    Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

    2016-03-22

    Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

  17. Classification of ASKAP Vast Radio Light Curves

    Science.gov (United States)

    Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.

    2012-01-01

    The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.

  18. Modeling Type IIn Supernova Light Curves

    Science.gov (United States)

    De La Rosa, Janie; Roming, Peter; Fryer, Chris

    2016-01-01

    We present near-by Type IIn supernovae observed with Swift's Ultraviolet/Optical Telescope (UVOT). Based on the diversity of optical light curve properties, this Type II subclass is commonly referred to as heterogeneous. At the time of discovery, our IIn sample is ~ 2 magnitudes brighter at ultraviolet wavelengths than at optical wavelengths, and ultraviolet brightness decays faster than the optical brightness. We use a semi-analytical supernova (SN) model to better understand our IIn observations, and focus on matching specific observed light curves features, i.e peak luminosity and decay rate. The SN models are used to study the effects of initial SN conditions on early light curves, and to show the extent of the "uniqueness" problem in SN light curves. We gratefully acknowledge the contributions from members of the Swift UVOT team, the NASA astrophysics archival data analysis program, and the NASA Swift guest investigator program.

  19. KAIT Fermi AGN Light-Curve Reservoir

    Data.gov (United States)

    National Aeronautics and Space Administration — This web page shows the light curves of a total of 163 AGNs that are monitored by KAIT with average cadence of 3 days. These are unfiltered observations; in...

  20. Light curves from rapidly rotating neutron stars

    OpenAIRE

    Numata, Kazutoshi; Lee, Umin

    2010-01-01

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitu...

  1. High accuracy & long timescale light curves

    OpenAIRE

    Hodgkin S.; Mislis D.

    2013-01-01

    We present a theoretical analysis of the optical light curves (LCs) for short-period high-mass transiting extrasolar planet systems. Our method considers the primary transit, the secondary eclipse, and the overall phase shape of the LC between the occultations. Phase variations arise from (i) reflected and thermally emitted light by the planet, (ii) the ellipsoidal shape of the star due to the gravitational pull of the planet, and (iii) the Doppler shift of the stellar light as the star orbit...

  2. A new approach of analyzing GRB light curves

    OpenAIRE

    Varga, B.; Horváth, I.; Balázs, L. G.

    2006-01-01

    We estimated the Txx quantiles of the cumulative GRB light curves using our recalculated background. The basic information of the light curves was extracted by multivariate statistical methods. The possible classes of the light curves are also briefly discussed.

  3. High accuracy & long timescale light curves

    Directory of Open Access Journals (Sweden)

    Hodgkin S.

    2013-04-01

    Full Text Available We present a theoretical analysis of the optical light curves (LCs for short-period high-mass transiting extrasolar planet systems. Our method considers the primary transit, the secondary eclipse, and the overall phase shape of the LC between the occultations. Phase variations arise from (i reflected and thermally emitted light by the planet, (ii the ellipsoidal shape of the star due to the gravitational pull of the planet, and (iii the Doppler shift of the stellar light as the star orbits the center of mass of the system. Our full model of the out-of-eclipse variations contains information about the planetary mass, orbital eccentricity, the orientation of periastron and the planet's albedo. For a range of hypothetical systems we demonstrate that the ellipsoidal variations (ii. can be large enough to be distinguished from the remaining components and that this effect can be used to constrain the planet's mass. As an example we presend KOI-13b (candidate exoplanet system included in the September 2011 Kepler data release. The Kepler light curve shows both primary and secondary eclipses, as well as significant out-of-eclipse light curve variations. We model the relative contributions from (i thermal emission from the companion, (ii planetary reflected light, (iii doppler beaming, and (iv ellipsoidal variations in the host-star arising from the tidal distortion of the host star by its companion. Our analysis, based on the light curve alone, enables us to constrain the mass of the KOI-13.01 companion to be MC = 8.3 ± 1.25 MJ and thus demonstrates that the transiting companion is a planet. The teqnique is useful for current and future space missions such as Kepler and PLATO.

  4. SPOTTED STAR LIGHT CURVES WITH ENHANCED PRECISION

    International Nuclear Information System (INIS)

    The nearly continuous timewise coverage of recent photometric surveys is free of the large gaps that compromise attempts to follow starspot growth and decay as well as motions, thereby giving incentive to improve computational precision for modeled spots. Due to the wide variety of star systems in the surveys, such improvement should apply to light/velocity curve models that accurately include all the main phenomena of close binaries and rotating single stars. The vector fractional area (VFA) algorithm that is introduced here represents surface elements by small sets of position vectors so as to allow accurate computation of circle-triangle overlap by spherical geometry. When computed by VFA, spots introduce essentially no noticeable scatter in light curves at the level of one part in 10,000. VFA has been put into the Wilson-Devinney light/velocity curve program and all logic and mathematics are given so as to facilitate entry into other such programs. Advantages of precise spot computation include improved statistics of spot motions and aging, reduced computation time (intrinsic precision relaxes needs for grid fineness), noise-free illustration of spot effects in figures, and help in guarding against false positives in exoplanet searches, where spots could approximately mimic transiting planets in unusual circumstances. A simple spot growth and decay template quantifies time profiles, and specifics of its utilization in differential corrections solutions are given. Computational strategies are discussed, the overall process is tested in simulations via solutions of synthetic light curve data, and essential simulation results are described. An efficient time smearing facility by Gaussian quadrature can deal with Kepler mission data that are in 30 minute time bins.

  5. Analysis of light curve of LP Camelopardalis

    Science.gov (United States)

    Prudil, Z.; Skarka, M.; Zejda, M.

    2016-05-01

    We present photometric analysis of the RRab type pulsating star LP Cam. The star was observed at Brno Observatory and Planetarium during nine nights. Measurements were calibrated to the Johnson photometric system. Four captured and thirteen previously published maxima timings allowed us to refine the pulsation period and the zero epoch. The light curve was Fourier decomposed to estimate physical parameters using empirical relations. Our results suggest that LP Cam is a common RR Lyrae star with high, almost solar metallicity.

  6. Supernova Light Curves Powered by Fallback Accretion

    OpenAIRE

    Dexter, Jason; Kasen, Daniel

    2012-01-01

    Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time (> days) power associated with the accretion of this "fallback" material may significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of pro...

  7. X-Ray Nova Light Curves

    Science.gov (United States)

    Shrader, Chris; Titarchuk, Lev

    2002-04-01

    We describe recent work in which we revisit the database of historical X-Ray nova (XRN) light curves compiled by Chen, Shrader & Livio (1997, ApJ 491, 312), augmented by subsequent events recorded by RXTE, in an attempt to gain a better understanding of the outburst phenomenon. Previously, we demonstrated that, given the occurrence of an instability in the mass transfer rate from the secondary, a model based on viscous diffusion of matter through the disk (Wood et al, 2001, astro-ph/0108189) we could reproduce a large number of fast-rise exponential decay (FRED) type XRN light curves. We augment this effort by considering deviations from the FRED form, such as plateaus and power-law decay forms are also considered within this framework. More complex structures are, in a number of instances, successfully modeled as a superposition of mass- injection, diffusive propagation events. In addition, for a large number of cases, we perform a joint analysis of optical light curve data. In particular, we will attempt to characterize empirical characteristics such as possible tie lags, and relative decay time scales, and then interpret such effects withing the context of diffusive propagation in the disk.

  8. A GLOBAL MODEL OF THE LIGHT CURVES AND EXPANSION VELOCITIES OF TYPE II-PLATEAU SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Pejcha, Ondřej [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08540 (United States); Prieto, Jose L., E-mail: pejcha@astro.princeton.edu [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441 Santiago (Chile)

    2015-02-01

    We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of Type II-Plateau supernovae based on their expansion velocities and photometric measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and velocities. We simultaneously fit ∼230 velocity and ∼6800 mag measurements distributed over 21 photometric passbands spanning wavelengths from 0.19 to 2.2 μm. The light-curve differences among the Type II-Plateau supernovae are well modeled by assuming different rates of photospheric radius expansion, which we explain as different density profiles of the ejecta, and we argue that steeper density profiles result in flatter plateaus, if everything else remains unchanged. The steep luminosity decline of Type II-Linear supernovae is due to fast evolution of the photospheric temperature, which we verify with a successful fit of SN 1980K. Eliminating the need for theoretical supernova atmosphere models, we obtain self-consistent relative distances, reddenings, and nickel masses fully accounting for all internal model uncertainties and covariances. We use our global fit to estimate the time evolution of any missing band tailored specifically for each supernova, and we construct spectral energy distributions and bolometric light curves. We produce bolometric corrections for all filter combinations in our sample. We compare our model to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard R{sub V}∼3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.

  9. Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

    CERN Document Server

    Hounsell, R; Hick, P P; Buffington, A; Jackson, B V; Clover, J M; Shafter, A W; Darnley, M J; Mawson, N R; Steele, I A; Evans, A; Eyres, S P S; O'Brien, T J

    2010-01-01

    We present light curves of three classical novae (KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete sky-map coverage with precision visible-light photometry at 102-minute cadence. The light curves derived from these sky maps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the nova eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass and object distance. For KT Eri, Liverpool Telescop...

  10. Light curves from rapidly rotating neutron stars

    CERN Document Server

    Numata, Kazutoshi

    2010-01-01

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitudes to disturb the spot. For a $l'=m$ core $r$-mode, the oscillation frequency $\\omega\\approx2m\\Omega/[l'(l'+1)]$ defined in the co-rotating frame of the star will be detected by a distant observer, where $l'$ and $m$ are respectively the spherical harmonic degree and the azimuthal wave number of the mode, and $\\Omega$ is the spin frequency of the star. In a linear theory of oscillation, using a parameter $A$ we parametrize the mode amplitudes such that ${\\rm max}\\left(|\\xi_\\theta|,|\\xi_\\phi|\\right)/R=A$ at the surface, w...

  11. Light Curve Analysis of Neon Novae

    CERN Document Server

    Hachisu, Izumi

    2015-01-01

    We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free-free and photospheric emission. For QU Vul, we obtained a distance of d~2.4 kpc, reddening of E(B-V)~0.55, and WD mass of M_WD=0.82-0.96 M_sun. This suggests that an oxygen-neon WD lost a mass of more than ~0.1 M_sun since its birth. For V351 Pup, we obtained d~5.5 kpc, E(B-V)~0.45, and M_WD=0.98-1.1 M_sun. For V382 Vel, we obtained d~1.6 kpc, E(B-V)~0.15, and M_WD=1.13-1.28 M_sun. For V693 CrA, we obtained d~7.1 kpc, E(B-V)~0.05, and M_WD=1.15-1.25 M_sun. For V1974 Cyg, we obtained d~1.8 kpc, E(B-V)~0.30, and M_WD=0.95-1.1 M_sun. For comparison, we added the carbon-oxygen nova V1668 Cyg to our analysis and obtained d~5.4 kpc, E(B-V)~0.30, and M_WD=0.98-1.1 M_sun. In QU Vul, photospheric emission contributes 0.4-0.8 mag at most to the optical light curve compared with free-free emission only....

  12. "Atlas of Secular Light Curves of Comets"

    CERN Document Server

    Ferrin, Ignacio

    2009-01-01

    In this work we have compiled 37,692 observations of 27 periodic and non-periodic comets to create the secular light curves (SLCs), using 2 plots per comet. The data has been reduced homogeneously. Our overriding goal is to learn the properties of the ensemble of comets. More than 30 parameters are listed, of which over ~20 are new and measured from the plots. We define two ages for a comet using activity as a proxy, the photometric age P-AGE, and the time-age, T-AGE. It is shown that these two parameters are robust, implying that the input data can have significant errors but P-AGE and T-AGE come out with small errors. This is due to their mathematical definition. It is shown that P-AGE classifies comets by shape of their light curve. The value of this Atlas is twofold: The SLCs not only show what we know, but also show what we do not know, thus pointing the way to meaningful observations. Besides their scientific value, these plots are useful for planning observations. The SLCs have not been modeled, and th...

  13. HYDRODYNAMICAL MODELS OF TYPE II-P SUPERNOVA LIGHT CURVES

    Directory of Open Access Journals (Sweden)

    M. C. Bersten

    2009-01-01

    Full Text Available We present progress in light curve models of type II-P supernovae (SNe II-P obtained using a newly devel- oped, one-dimensional hydrodynamic code. Using simple initial models (polytropes, we reproduced the global behavior of the observed light curves and we analyzed the sensitivity of the light curves to the variation of free parameters.

  14. Analysis of the early spectra and light curve of SN 1987A

    Science.gov (United States)

    Hauschildt, Peter H.; Ensman, Lisa M.

    1994-01-01

    Numerical modeling of supernova spectra, light curves, and hydrodynamics requires physical inputs, numerical techniques, approximations, and assumptions which must be thoroughly understood in order to study the details of supernova explosions. Here, we discuss some of these in the context of the early evolution of supernova 1987A. Gray radiation-hydrodynamics is used to calculate the bolometric light curve and the hydrodynamic evolution of the supernova. Synthetic spectra are then obtained for the resulting density and velocity structure. The spectrum calculations are performed using a special-relativistic treatment of the radiative transfer equation in the comoving frame, line blanketing by about 10(exp 5) spectral lines, and departures from local thermodynamic equilibrium (LTE) for H I, He I, Mg II, and Ca II. We find that we are able to simultaneously fit the early light curve and spectra reasonably well, using a progenitor model from Arnett (1991a), without fine-tuning the free parameters. Temperature structures and radiative equilibrium, non-LTE effects, homologous expansion, and mean opacities are discussed.

  15. SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. Q.; Wang, L. J.; Dai, Z. G. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2015-01-20

    Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required.

  16. SUPERNOVA LIGHT CURVES POWERED BY FALLBACK ACCRETION

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, Jason; Kasen, Daniel, E-mail: jdexter@berkeley.edu [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

    2013-07-20

    Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time ({approx}>days) power potentially associated with the accretion of this 'fallback' material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as M-dot {proportional_to}t{sup -5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous ({approx}> 10{sup 44} erg s{sup -1}) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.

  17. Supernova Light Curves Powered by Fallback Accretion

    Science.gov (United States)

    Dexter, Jason; Kasen, Daniel

    2013-07-01

    Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time (gsimdays) power potentially associated with the accretion of this "fallback" material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as \\dot{M} \\propto t^{-5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous (gsim 1044 erg s-1) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.

  18. Supernova Light Curves Powered by Fallback Accretion

    CERN Document Server

    Dexter, Jason

    2012-01-01

    Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time (> days) power associated with the accretion of this "fallback" material may significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as Mdot ~ t^-5/3 at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse o...

  19. SN 2011ht: Confirming a Class of Interacting Supernovae with Plateau Light Curves (Type IIn-P)

    CERN Document Server

    Mauerhan, Jon C; Silverman, Jeffrey M; Filippenko, Alexei V; Morgan, Adam N; Cenko, S Bradley; Ganeshalingam, Mohan; Clubb, Kelsey I; Matheson, Thomas

    2012-01-01

    We present photometry and spectroscopy of the Type IIn supernova (SN) 2011ht, identified previously as a SN impostor. The light curve exhibits an abrupt transition from a well-defined ~120 day plateau to a steep bolometric decline. Leading up to peak brightness, a hot emission-line spectrum exhibits signs of interaction with circumstellar material (CSM), in the form of relatively narrow P-Cygni features of H I and He I superimposed on broad Lorentzian wings. For the remainder of the plateau phase the spectrum exhibits strengthening P-Cygni profiles of Fe II, Ca II, and H-alpha. By day 147, after the plateau has ended, the SN entered the nebular phase, heralded by the appearance of forbidden transitions of [O I], [O II], and [Ca II] over a weak continuum. At this stage, the light curve exhibits a low luminosity that is comparable to that sub-luminous Type II-P supernovae, and a relatively fast visual-wavelength decline that is significantly steeper than the Co-56 decay rate. However, the total bolometric decli...

  20. The Ultimate Light Curve of SN 1998bw/GRB 980425

    CERN Document Server

    Clocchiatti, Alejandro; Covarrubias, Ricardo; Candia, Pablo

    2011-01-01

    We present multicolor light curves of SN 1998bw which appeared in ESO184-G82 in close temporal and spacial association with GRB 980425. They are based on observations done at Cerro Tololo Inter-American Observatory and data from the literature. The CTIO photometry reaches ~86 days after the GRB in $U$ and ~160 days after the GRB in BV(RI)_C. The observations in U extend by about 30 days the previously known coverage, and determine the slope of the early exponential tail. We calibrate a large set of local standards in common with those of previous studies and use them to transform published observations of the SN to our realization of the standard photometric system. We show that the photometry from different sources merges smoothly and provide a unified set of 300 observations of the SN in five bands. Using the extensive set of spectra in public domain we compute extinction and K corrections, and build quasi-bolometric unreddened rest frame light curves. We provide low degree piecewise spline fits to these li...

  1. Chaotic Feature in the Light Curve of 3C 273

    Institute of Scientific and Technical Information of China (English)

    Lei Liu

    2006-01-01

    Some nonlinear dynamical techniques, including state-space reconstruction and correlation integral, are used to analyze the light curve of 3C 273. The result is compared with a chaotic model. The similarities between them suggest there is a low-dimension chaotic attractor in the light curve of 3C 273.

  2. Do the Kepler AGN Light Curves Need Re-processing?

    CERN Document Server

    Kasliwal, Vishal P; Richards, Gordon T; Williams, Joshua; Carini, Michael T

    2015-01-01

    We gauge the impact of spacecraft-induced effects on the inferred variability properties of the light curve of the Seyfert 1 AGN Zw 229-15 observed by \\Kepler. We compare the light curve of Zw 229-15 obtained from the Kepler MAST database with a re-processed light curve constructed from raw pixel data (Williams & Carini, 2015). We use the first-order structure function, $SF(\\delta t)$, to fit both light curves to the damped power-law PSD of Kasliwal, Vogeley & Richards, 2015. On short timescales, we find a steeper log-PSD slope ($\\gamma = 2.90$ to within $10$ percent) for the re-processed light curve as compared to the light curve found on MAST ($\\gamma = 2.65$ to within $10$ percent)---both inconsistent with a damped random walk which requires $\\gamma = 2$. The log-PSD slope inferred for the re-processed light curve is consistent with previous results (Carini & Ryle, 2012, Williams & Carini, 2015) that study the same re-processed light curve. The turnover timescale is almost identical for bot...

  3. Spitzer Space Telescope Mid-IR Light Curves of Neptune

    CERN Document Server

    Stauffer, J R; Gizis, J E; Rebull, L M; Carey, S J; Krick, J; Ingalls, J G; Lowrance, P; Glaccum, W; Kirkpatrick, J D; Simon, A A; Wong, M H

    2016-01-01

    We have used the Spitzer Space Telescope in February 2016 to obtain high cadence, high signal-to-noise, 17-hour duration light curves of Neptune at 3.6 and 4.5 $\\mu$m. The light curve duration was chosen to correspond to the rotation period of Neptune. Both light curves are slowly varying with time, with full amplitudes of 1.1 mag at 3.6 $\\mu$m and 0.6 mag at 4.5 $\\mu$m. We have also extracted sparsely sampled 18-hour light curves of Neptune at W1 (3.4 $\\mu$m) and W2 (4.6 $\\mu$m) from the WISE/NEOWISE archive at six epochs in 2010-2015. These light curves all show similar shapes and amplitudes compared to the Spitzer light curves but with considerable variation from epoch to epoch. These amplitudes are much larger than those observed with Kepler/K2 in the visible (amplitude $\\sim$0.02 mag) or at 845 nm with the Hubble Space Telescope in 2015 and at 763 nm in 2016 (amplitude $\\sim$ 0.2 mag). We interpret the Spitzer and WISE light curves as arising entirely from reflected solar photons, from higher levels in N...

  4. Asteroid Shape and Spin Axis Modeling Via Light Curve Inversion

    Science.gov (United States)

    Friz, Paul; Gokhale, V.

    2013-01-01

    We present light curves and shape and spin axis models for the five asteroids: 291 Alice, 281 Lucretia, 321 Florentina, 714 Ulula, and 3169 Ostro. These models were obtained using data taken from the Truman Observatory, the Asteroid Photometric Catalogue, and the Minor Planet Center. Knowledge of individual asteroids shapes and spin axes is vital to understanding the solar system. However, currently only 213 out of the 500,000 asteroids with known orbits have been modeled. By taking many light curves of asteroids over several apparitions it is possible to determine their shapes and spin axes by a process known as light curve inversion.

  5. Automatic classification of eclipsing binaries light curves using neural networks

    CERN Document Server

    Sarro, L M; Giménez, A

    2005-01-01

    In this work we present a system for the automatic classification of the light curves of eclipsing binaries. This system is based on a classification scheme that aims to separate eclipsing binary sistems according to their geometrical configuration in a modified version of the traditional classification scheme. The classification is performed by a Bayesian ensemble of neural networks trained with {\\em Hipparcos} data of seven different categories including eccentric binary systems and two types of pulsating light curve morphologies.

  6. A Degeneracy in DRW Modelling of AGN Light Curves

    CERN Document Server

    Kozlowski, Szymon

    2016-01-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power $\\beta=1$. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes ($0.5\\leq\\beta\\leq 1.5$ and $\\beta\

  7. EVEREST: Pixel Level Decorrelation of K2 Light Curves

    Science.gov (United States)

    Luger, Rodrigo; Agol, Eric; Kruse, Ethan; Barnes, Rory; Becker, Andrew; Foreman-Mackey, Daniel; Deming, Drake

    2016-10-01

    We present EPIC Variability Extraction and Removal for Exoplanet Science Targets (EVEREST), an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation to remove systematics introduced by the spacecraft’s pointing error and a Gaussian process to capture astrophysical variability. We apply EVEREST to all K2 targets in campaigns 0–7, yielding light curves with precision comparable to that of the original Kepler mission for stars brighter than {K}p≈ 13, and within a factor of two of the Kepler precision for fainter targets. We perform cross-validation and transit injection and recovery tests to validate the pipeline, and compare our light curves to the other de-trended light curves available for download at the MAST High Level Science Products archive. We find that EVEREST achieves the highest average precision of any of these pipelines for unsaturated K2 stars. The improved precision of these light curves will aid in exoplanet detection and characterization, investigations of stellar variability, asteroseismology, and other photometric studies. The EVEREST pipeline can also easily be applied to future surveys, such as the TESS mission, to correct for instrumental systematics and enable the detection of low signal-to-noise transiting exoplanets. The EVEREST light curves and the source code used to generate them are freely available online.

  8. SN 2011fu: A type IIb Supernova with a luminous double-peaked light curve

    CERN Document Server

    Morales-Garoffolo, A; Bersten, M; Jerkstrand, A; Taubenberger, S; Benetti, S; Cappellaro, E; Kotak, R; Pastorello, A; Bufano, F; Domínguez, R M; Ergon, M; Fraser, M; Gao, X; García, E; Howell, D A; Isern, J; Smartt, S J; Tomasella, L; Valenti, S

    2015-01-01

    We present optical and near infrared observations of the type IIb supernova (SN) 2011fu from a few days to $\\sim300$ d after explosion. The SN presents a double-peaked light curve (LC) similar to that of SN 1993J, although more luminous and with a longer cooling phase after the primary peak. The spectral evolution is also similar to SN 1993J's, with hydrogen dominating the spectra to $\\sim40$ d, then helium gaining strength, and nebular emission lines appearing from $\\sim60$ d post-explosion. The velocities derived from the P-Cygni absorptions are overall similar to those of other type IIb SNe. We have found a strong similarity between the oxygen and magnesium line profiles at late times, which suggests that these lines are forming at the same location within the ejecta. The hydrodynamical modelling of the pseudo-bolometric LC and the observed photospheric velocities suggest that SN 2011fu was the explosion of an extended star ($\\rm R\\sim450$ R$_\\odot$), in which 1.3 $\\times 10^{51}$ erg of kinetic energy wer...

  9. The Chaotic Light Curves of Accreting Black Holes

    Science.gov (United States)

    Kazanas, Demosthenes

    2007-01-01

    We present model light curves for accreting Black Hole Candidates (BHC) based on a recently developed model of these sources. According to this model, the observed light curves and aperiodic variability of BHC are due to a series of soft photon injections at random (Poisson) intervals and the stochastic nature of the Comptonization process in converting these soft photons to the observed high energy radiation. The additional assumption of our model is that the Comptonization process takes place in an extended but non-uniform hot plasma corona surrounding the compact object. We compute the corresponding Power Spectral Densities (PSD), autocorrelation functions, time skewness of the light curves and time lags between the light curves of the sources at different photon energies and compare our results to observation. Our model reproduces the observed light curves well, in that it provides good fits to their overall morphology (as manifest by the autocorrelation and time skewness) and also to their PSDs and time lags, by producing most of the variability power at time scales 2 a few seconds, while at the same time allowing for shots of a few msec in duration, in accordance with observation. We suggest that refinement of this type of model along with spectral and phase lag information can be used to probe the structure of this class of high energy sources.

  10. EVEREST: Pixel Level Decorrelation of K2 Light curves

    CERN Document Server

    Luger, Rodrigo; Kruse, Ethan; Barnes, Rory; Becker, Andrew; Foreman-Mackey, Daniel; Deming, Drake

    2016-01-01

    We present EVEREST, an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation (PLD) to remove systematics introduced by the spacecraft's pointing error and a Gaussian process (GP) to capture astrophysical variability. We apply EVEREST to all K2 targets in campaigns 0-7, yielding light curves with precision comparable to that of the original Kepler mission for stars brighter than $K_p \\approx 13$, and within a factor of two of the Kepler precision for fainter targets. We perform cross-validation and transit injection and recovery tests to validate the pipeline, and compare our light curves to the other de-trended light curves available for download at the MAST High Level Science Products archive. We find that EVEREST achieves the highest average precision of any of these pipelines for unsaturated K2 stars. The improved precision of these light curves will aid in exoplanet detection and characterization, investigations of stellar variabi...

  11. Spatial Reasoning Training Through Light Curves Of Model Asteroids

    Science.gov (United States)

    Ziffer, Julie; Nakroshis, Paul A.; Rudnick, Benjamin T.; Brautigam, Maxwell J.; Nelson, Tyler W.

    2015-11-01

    Recent research has demonstrated that spatial reasoning skills, long known to be crucial to math and science success, are teachable. Even short stints of training can improve spatial reasoning skills among students who lack them (Sorby et al., 2006). Teaching spatial reasoning is particularly valuable to women and minorities who, through societal pressure, often doubt their spatial reasoning skill (Hill et al., 2010). We have designed a hands on asteroid rotation lab that provides practice in spatial reasoning tasks while building the student’s understanding of photometry. For our tool, we mount a model asteroid, with any shape of our choosing, on a slowly rotating motor shaft, whose speed is controlled by the experimenter. To mimic an asteroid light curve, we place the model asteroid in a dark box, shine a movable light source upon our asteroid, and record the light reflected onto a moveable camera. Students may then observe changes in the light curve that result from varying a) the speed of rotation, b) the model asteroid’s orientation with respect to the motor axis, c) the model asteroid’s shape or albedo, and d) the phase angle. After practicing with our tool, students are asked to pair new objects to their corresponding light curves. To correctly pair objects to their light curves, students must imagine how light scattering off of a three dimensional rotating object is imaged on a ccd sensor plane, and then reduced to a series of points on a light curve plot. Through the use of our model asteroid, the student develops confidence in spatial reasoning skills.

  12. A Late-Time Flattening of Afterglow Light Curves

    CERN Document Server

    Frail, D A; Berger, E; Kulkarni, S R; Yost, S A

    2004-01-01

    We present a sample of radio afterglow light curves with measured decay slopes which show evidence for a flattening at late times compared to optical and X-ray decay indices. The simplest origin for this behavior is that the change in slope is due to a jet-like outflow making a transition to sub-relativistic expansion. This can explain the late-time radio light curves for many but not all of the bursts in the sample. We investigate several possible modifications to the standard fireball model which can flatten late-time light curves. Changes to the shock microphysics which govern particle acceleration, or energy injection to the shock (either radially or azimuthally) can reproduce the observed behavior. Distinguishing between these different possibilities will require simultaneous optical/radio monitoring of afterglows at late times.

  13. GRBs Light Curves - Another Clue on the Inner Engine

    CERN Document Server

    Piran, E N T

    2002-01-01

    The nature of the `inner engine' that accelerate and collimate the relativistic flow at the cores of GRBs is the most interesting current puzzle concerning GRBs. Numerical simulations have shown that the internal shocks' light curve reflects the activity of this inner engine. Using a simple analytic toy model we clarify the relations between the observed $ \\gamma $-rays light curve and the inner engine's activity and the dependence of the light curves on the inner engine's parameters. This simple model also explains the observed similarity between the observed distributions of pulses widths and the intervals between pulses and the correlation between the width of a pulse and the length of the preceding interval. Our analysis suggests that the variability in the wind's Lorentz factors arises due to a modulation of the mass injected into a constant energy flow.

  14. Afterglow Light Curves and Broken Power Laws: A Statistical Study

    CERN Document Server

    J'ohannesson, G; Gudmundsson, E H; J\\'ohannesson, Gudlaugur; Bj\\"ornsson, Gunnlaugur; Gudmundsson, Einar H.

    2006-01-01

    In gamma-ray burst research it is quite common to fit the afterglow light curves with a broken power law to interpret the data. We apply this method to a computer simulated population of afterglows and find systematic differences between the known model parameters of the population and the ones derived from the power law fits. In general, the slope of the electron energy distribution is overestimated from the pre-break light curve slope while being underestimated from the post-break slope. We also find that the jet opening angle derived from the fits is overestimated in narrow jets and underestimated in wider ones. Results from fitting afterglow light curves with broken power laws must therefore be interpreted with caution since the uncertainties in the derived parameters might be larger than estimated from the fit. This may have implications for Hubble diagrams constructed using gamma-ray burst data.

  15. On classical meteor light curves and utilitarian model atmospheres

    Science.gov (United States)

    Beech, M.; Hargrove, M.

    2005-01-01

    We present a series of classical meteor light curve profiles based upon a set of simplified analytic atmospheric models. The model atmospheres specifically express the density variation as a power law in atmospheric height, and are derived under a variety of assumptions relating to the atmospheric temperature profile and the variation of the acceleration due to gravity. We find that the light curve profiles show only small differences with respect to any variation in the temperature profile and the geometry imposed upon the atmospheres.

  16. Preliminary Analysis of ULPC Light Curves Using Fourier Decomposition Technique

    CERN Document Server

    Ngeow, Chow-Choong; Kanbur, Shashi; Barrett, Brittany; Lin, Bin

    2013-01-01

    Recent work on Ultra Long Period Cepheids (ULPCs) has suggested their usefulness as a distance indicator, but has not commented on their relationship as compared with other types of variable stars. In this work, we use Fourier analysis to quantify the structure of ULPC light curves and compare them to Classical Cepheids and Mira variables. Our preliminary results suggest that the low order Fourier parameters of ULPCs show a continuous trend defined by Classical Cepheids after the resonance around 10 days. However their Fourier parameters also overlapped with those from Miras, which make the classification of long period variable stars difficult based on the light curves information alone.

  17. Supernovae with two peaks in the optical light curve and the signature of progenitors with low-mass extended envelopes

    International Nuclear Information System (INIS)

    Early observations of supernova light curves are powerful tools for shedding light on the pre-explosion structures of their progenitors and their mass-loss histories just prior to explosion. Some core-collapse supernovae that are detected during the first days after the explosion prominently show two peaks in the optical bands, including the R and I bands, where the first peak appears to be powered by the cooling of shocked surface material and the second peak is clearly powered by radioactive decay. Such light curves have been explored in detail theoretically for SN 1993J and 2011dh, where it was found that they may be explained by progenitors with extended, low-mass envelopes. Here, we generalize these results. We first explore whether any double-peaked light curve of this type can be generated by a progenitor with a 'standard' density profile, such as a red supergiant or a Wolf-Rayet star. We show that a standard progenitor (1) cannot produce a double-peaked light curve in the R and I bands and (2) cannot exhibit a fast drop in the bolometric luminosity as is seen after the first peak. We then explore the signature of a progenitor with a compact core surrounded by extended, low-mass material. This may be a hydrostatic low-mass envelope or material ejected just prior to the explosion. We show that it naturally produces both of these features. We use this result to provide simple formulae to estimate (1) the mass of the extended material from the time of the first peak, (2) the extended material radius from the luminosity of the first peak, and (3) an upper limit on the core radius from the luminosity minimum between the two peaks.

  18. New NIR light-curve templates for classical Cepheids

    CERN Document Server

    Inno, L; Romaniello, M; Bono, G; Monson, A; Ferraro, I; Iannicola, G; Persson, E; Buonanno, R; Freedman, W; Gieren, W; Groenewegen, M A T; Ita, Y; Laney, C D; Lemasle, B; Madore, B F; Nagayama, T; Nakada, Y; Nonino, M; Pietrzynski, G; Primas, F; Scowcroft, V; Soszynski, I; Tanabe, T; Udalski, A

    2014-01-01

    We present new near-infrared (NIR) light-curve templates for fundamental (FU, JHK) and first overtone (FO, J) Cepheids. The new templates together with PL and PW relations provide Cepheid distances from single-epoch observations with a precision only limited by the intrinsic accuracy of the method adopted. The templates rely on a very large set of Galactic and Magellanic Clouds (MCs) Cepheids (FU,~600; FO,~200) with well sampled NIR (IRSF data) and optical (V,I; OGLE data) light curves. To properly trace the change in the shape of the light curve as a function of period, we split the sample of calibrating Cepheids into 10 different period bins. The templates for the first time cover FO Cepheids and the FU short-period Cepheids (P<5 days). Moreover, the zero-point phase is anchored to the phase of the mean magnitude along the rising branch. The new approach has several advantages in sampling the light curve of bump Cepheids when compared with the phase of maximum light. We also provide new estimates of the ...

  19. On Correlated-noise Analyses Applied To Exoplanet Light Curves

    CERN Document Server

    Cubillos, Patricio; Loredo, Thomas J; Lust, Nate B; Blecic, Jasmina; Stemm, Madison

    2016-01-01

    Time-correlated noise is a significant source of uncertainty when modeling exoplanet light-curve data. A correct assessment of correlated noise is fundamental to determine the true statistical significance of our findings. Here we review three of the most widely used correlated-noise estimators in the exoplanet field, the time-averaging, residual-permutation, and wavelet-likelihood methods. We argue that the residual-permutation method is unsound in estimating the uncertainty of parameter estimates. We thus recommend to refrain from this method altogether. We characterize the behavior of the time averaging's rms-vs.-bin-size curves at bin sizes similar to the total observation duration, which may lead to underestimated uncertainties. For the wavelet-likelihood method, we note errors in the published equations and provide a list of corrections. We further assess the performance of these techniques by injecting and retrieving eclipse signals into synthetic and real Spitzer light curves, analyzing the results in...

  20. New NIR light-curve templates for classical Cepheids

    NARCIS (Netherlands)

    L. Inno; N. Matsunaga; M. Romaniello; G. Bono; A. Monson; I. Ferraro; G. Iannicola; E. Persson; R. Buonanno; W. Freedman; W. Gieren; M.A.T. Groenewegen; Y. Ita; C.D. Laney; B. Lemasle; B.F. Madore; T. Nagayama; Y. Nakada; M. Nonino; G. Pietrzyński; F. Primas; V. Scowcroft; I. Soszyński; T. Tanabé; A. Udalski

    2015-01-01

    Aims. We present new near-infrared (NIR) light-curve templates for fundamental (FU, J, H, KS) and first overtone (FO, J) classical Cepheids. The new templates together with period-luminosity and period-Wesenheit (PW) relations provide Cepheid distances from single-epoch observations with a precision

  1. UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, N. E.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Betancourt, M., E-mail: nsanders@cfa.harvard.edu [Department of Statistics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-02-10

    Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.

  2. Light curve and period study of V Trianguli

    Science.gov (United States)

    Gürol, B.; Müyesseroğlu, Z.; Özdemir, T.

    2006-08-01

    New BVR light curves and times of minimum light for the short period β Lyrae system V Tri were analyzed to derive the physical parameters of the system. The light curves were obtained at Ankara University Observatory and at the TÜBİTAK National Observatory during 5 nights in 2001 and 2002. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson-Devinney 2003 code. The present solution reveals that V Tri is a near-contact system with a mass ratio near 0.5. The absolute radii and masses estimated for the components, based on our photometric solution, are R1=1.94 Rsun, R2=1.44 Rsun, M1=2.68 Msun, M2=1.36 Msun, respectively, for the primary and secondary components. The period variation of the system can be attributed to the light-time effect. With the assumption of a coplanar orbit of the third body its revealed mass is m3=0.17 Msun.

  3. First light curve and period study of LO Andromedae

    Science.gov (United States)

    Gürol, B.; Müyesseroğlu, Z.

    2005-01-01

    New BV light curves and times of minimum light for the short period W UMa system LO And were analyzed to derive the preliminary physical parameters of the system. The light curves were obtained at Ankara University Observatory during 5 nights in 2003. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson-Devinney 2003 code. The present solution reveals that LO And has a photometric mass ratio q = 0.371 and is an A-type contact binary. The period of the system is still increasing, which can be attributed to light-time effect and mass transfer between the components. With the assumption of coplanar orbit of the third body the revealed mass is M3 = 0.21M. If the period change dP/dt = 0.0212 sec/yr is caused only by the mass transfer between components (from the lighter component to the heavier) the calculated mass transfer rate is dm/dt = 1.682 10-7M/yr. The absolute radii and masses estimated for the components, based on our photometric solution and the absolute parameters of the systems which have nearly same period are R1 = 1.30R, R2 = 0.85R, M1 = 1.31M, M2 = 0.49M respectively for the primary and secondary components.

  4. Orbital Signatures from Observed Light Curves of Blazars

    Indian Academy of Sciences (India)

    A. Mangalam; P. Mohan

    2014-09-01

    Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical models based on this view. These models include general relativistic effects such as light bending, aberration effects, gravitational and Doppler redshifts. The novel aspects relate to the treatment of helical flow in cylindrical and conical geometries in the vicinity of a Schwarzschild black hole that leads to amplitude and frequency modulations of simulated light curves as well as the inclusion of beaming effects in these idealized geometries. We then present a suite of time series analysis techniques applicable to data with varied properties which can extract detailed information for their use in theoretical models.

  5. Orbital signatures from observed light curves of blazars

    CERN Document Server

    Mangalam, A

    2014-01-01

    Variability in active galactic nuclei is observed in ultraviolet to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical models which build on this view. These models include general relativistic effects such as light bending, aberration effects, gravitational and Doppler redshifts. The novel aspects relate to the treatment of helical flow in cylindrical and conical geometries in the vicinity of a Schwarzschild black hole that leads to amplitude and frequency modulations of simulated light curves as well as the inclusion of beaming effects in these idealized geometries. We then present a suite of time series analysis techniques applicable to data with varied properties which can extract detailed information from them for their use in theoretical models.

  6. Orbital Signatures from Observed Light Curves of Blazars

    Science.gov (United States)

    Mangalam, A.; Mohan, P.

    2014-09-01

    Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical models based on this view. These models include general relativistic effects such as light bending, aberration effects, gravitational and Doppler redshifts. The novel aspects relate to the treatment of helical flow in cylindrical and conical geometries in the vicinity of a Schwarzschild black hole that leads to amplitude and frequency modulations of simulated light curves as well as the inclusion of beaming effects in these idealized geometries. We then present a suite of time series analysis techniques applicable to data with varied properties which can extract detailed information from them for their use in theoretical models.

  7. Bolometric Flux Estimation for Cool Evolved Stars

    CERN Document Server

    van Belle, Gerard T; Ruiz-Velasco, Alma

    2016-01-01

    Estimation of bolometric fluxes (F_BOL) is an essential component of stellar effective temperature determination with optical and near-infrared interferometry. Reliable estimation of F_BOL simply from broad-band K-band photometry data is a useful tool in those cases were contemporaneous and/or wide-range photometry is unavailable for a detailed spectral energy distribution (SED) fit, as was demonstrated in Dyck et al. (1974). Recalibrating the intrinsic F_BOL versus observed F_2.2um relationship of that study with modern SED fitting routines, which incorporate the significantly non-blackbody, empirical spectral templates of the INGS spectral library (an update of the library in Pickles 1998) and estimation of reddening, serves to greatly improve the accuracy and observational utility of this relationship. We find that F_BOL values predicted are roughly 11% less than the corresponding values predicted in Dyck et al. (1974), indicating the effects of SED absorption features across bolometric flux curves.

  8. Unsupervised clustering of Type II supernova light curves

    CERN Document Server

    Rubin, Adam

    2016-01-01

    As new facilities come online, the astronomical community will be provided with extremely large datasets of well-sampled light curves (LCs) of transient objects. This motivates systematic studies of the light curves of supernovae (SNe) of all types, including the early rising phase. We performed unsupervised k-means clustering on a sample of 59 R-band Type II SN light curves and find that our sample can be divided into three classes: slowly-rising (II-S), fast-rise/slow-decline (II-FS), and fast-rise/fast-decline (II-FF). We also identify three outliers based on the algorithm. We find that performing clustering on the first two components of a principle component analysis gives equivalent results to the analysis using the full LC morphologies. This may indicate that Type II LCs could possibly be reduced to two parameters. We present several important caveats to the technique, and find that the division into these classes is not fully robust and is sensitive to the uncertainty on the time of first light. Moreo...

  9. The Effect of Lunar-like Satellites on the Orbital Infrared Light Curves of Earth-analog Planets

    CERN Document Server

    Moskovitz, Nicholas A; Williams, Darren

    2008-01-01

    We investigate the influence of lunar-like satellites on the infrared orbital light curves of Earth-analog extra-solar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet. We use an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of the Earth while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g. via spectroscopy or visible-wavelength detection of specular glint from a surface ocean) only the largest (approximately Mars-siz...

  10. Modelling the light curves of Fermi LAT millisecond pulsars

    CERN Document Server

    Venter, C; Harding, AK; Grove, JE

    2014-01-01

    We modelled the radio and gamma-ray light curves of millisecond pulsars using outer gap, two-pole caustic, low-altitude slot gap, and pair-starved polar cap geometric models, combined with a semi-empirical conal radio model. We find that no model fits all cases, with the outer gap and two-pole caustic models providing best fits for comparable numbers of millisecond pulsar light curves. We find a broad distribution of best-fit inclination angles as well as a clustering at large observer angles. The outer gap model furthermore seems to require relatively larger inclination angles, while the two-pole caustic model hints at an inverse trend between inclination angle and pulsar spin-down luminosity.

  11. Unsupervised Transient Light Curve Analysis Via Hierarchical Bayesian Inference

    CERN Document Server

    Sanders, Nathan; Soderberg, Alicia

    2014-01-01

    Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometr...

  12. Describing Blazhko light curves with almost periodic functions

    Science.gov (United States)

    Benko, J. M.; Szabo, R.

    2016-05-01

    Recent results of photometric space missions such as CoRoT and Kepler showed that the cycle-to-cycle variations of the Blazhko modulation is very frequent. These variations have either multiperiodic or irregular (chaotic/stochastic) nature. We present a mathematical framework in which all of these variations can be handled. We applied the theory of band-limited almost periodic functions to the modulated RR Lyrae light curves. It yields several interesting results: e.g. the harmonics in the Fourier representation of these functions are not exact multiplets of the base frequency or the modulation function depends on the harmonics. Such phenomena are reported for observed RR Lyrae stars as well showing that the almost periodic functions are promising in the mathematical description of the Blazhko RR Lyrae light curves.

  13. Explosion models, light curves, spectra and H$_{0}$

    CERN Document Server

    Höflich, P; Wheeler, J C; Nomoto, K; Thielemann, F K

    1996-01-01

    From the spectra and light curves it is clear that SNIa are thermonuclear explosions of white dwarfs. However, details of the explosion are highly under debate. Here, we present detailed models which are consistent with respect to the explosion mechanism, the optical and infrared light curves (LC), and the spectral evolution. This leaves the description of the burning front and the structure of the white dwarf as the only free parameters. The explosions are calculated using one-dimensional Lagrangian codes including nuclear networks. Subsequently, optical and IR-LCs are constructed. Detailed NLTE-spectra are computed for several instants of time using the density, chemical and luminosity structure resulting from the LCs. The general methods and critical tests are presented (sect. 2). Different models for the thermonuclear explosion are discussed including detonations deflagrations, delayed detonations, pulsating delayed detonations (PDD) and helium detonations (sect.3). Comparisons between theoretical and obs...

  14. Simulated Performance of Timescale Metrics for Aperiodic Light Curves

    CERN Document Server

    Findeisen, Krzysztof; Hillenbrand, Lynne

    2014-01-01

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy -- {\\Delta}m-{\\Delta}t plots, peak-finding, and Gaussian process regression -- and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that {\\Delta}m-{\\Delta}t plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out ana...

  15. Preparation of Kepler light curves for asteroseismic analyses

    OpenAIRE

    García, R. A.; Hekker, S.; Stello, D.; Gutiérrez-Soto, J.; Handberg, R.; Huber, D.(Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany); Karoff, C.; Uytterhoeven, K; Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; Mathur, S; Ballot, J.; Christensen-Dalsgaard, J.; Gilliland, R. L.

    2011-01-01

    The Kepler mission is providing photometric data of exquisite quality for the asteroseismic study of different classes of pulsating stars. These analyses place particular demands on the pre-processing of the data, over a range of timescales from minutes to months. Here, we describe processing procedures developed by the Kepler Asteroseismic Science Consortium (KASC) to prepare light curves that are optimized for the asteroseismic study of solar-like oscillating stars in which outliers, jumps ...

  16. Fractal dimension and thermodynamic fluctuation properties of IDV light curves

    Institute of Scientific and Technical Information of China (English)

    Chun-Sing Leung; Jian-Yan Wei; Zoltan Kovács; Tiberiu Harko

    2011-01-01

    Fractals are a basic tool for phenomenologically describing natural objects having a high degree of temporal or spatial variability.From a physical point of view the fractal properties of natural systems can also be interpreted by using the standard formalism of thermodynamical fluctuations.We introduce and analyze the fractal dimension of the Intra-Day-Variability (IDV) light-curves of BL Lac objects,in the optical,radio and X-ray bands.A general description of the fluctuation spectrum of these systems based on general thermodynamical principles is also proposed.Based on the general fractal properties of a given physical system,we also introduce the predictability index for the IDV light curves.We have explicitly determined the fractal dimension for the R-band observations of five blazars,as well as for the radio band observations of the compact extragalactic radio source J 1128±5925 and of several X-ray sources.Our results show that the fractal dimension of the optical and X-ray observations indicates an almost pure "Brownian noise" (random walk) spectrum,with a very low predictability index,while in the radio band the predictability index is much higher.We have also studied the spectral properties of the IDV light curves and we have shown that their spectral index is very closely correlated with the corresponding fractal dimension.

  17. A degeneracy in DRW modelling of AGN light curves

    Science.gov (United States)

    Kozłowski, Szymon

    2016-07-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time-scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light-curve modelling.

  18. New Horizons approach photometry of Pluto and Charon: light curves and Solar phase curves

    Science.gov (United States)

    Zangari, A. M.; Buie, M. W.; Buratti, B. J.; Verbiscer, A.; Howett, C.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; Young, L. A.; Stern, S. A.

    2015-12-01

    While the most captivating images of Pluto and Charon were shot by NASA's New Horizons probe on July 14, 2015, the spacecraft also imaged Pluto with its LOng Range Reconnaissance Imager ("LORRI") during its Annual Checkouts and Approach Phases, with campaigns in July 2013, July 2014, January 2015, March 2015, April 2015, May 2015 and June 2015. All but the first campaign provided full coverage of Pluto's 6.4 day rotation. Even though many of these images were taken when surface features on Pluto and Charon were unresolved, these data provide a unique opportunity to study Pluto over a timescale of several months. Earth-based data from an entire apparition must be combined to create a single light curve, as Pluto is never otherwise continuously available for observing due to daylight, weather and scheduling. From the spacecraft, Pluto's sub-observer latitude remained constant to within 0.05 degrees of 43.15 degrees, comparable to a week's worth of change as seen from Earth near opposition. During the July 2013 to June 2015 period, Pluto's solar phase curve increased from 11 degrees to 15 degrees, a small range, but large compared to Earth's 2 degree limit. The slope of the solar phase curve hints at properties such as surface roughness. Using PSF photometry that takes into account the ever-increasing sizes of Pluto and Charon as seen from New Horizons, as well as surface features discovered at closest approach, we present rotational light curves and solar phase curves of Pluto and Charon. We will connect these observations to previous measurements of the system from Earth.

  19. Light Curves of Core-Collapse Supernovae with Substantial Mass Loss using the New Open-Source SuperNova Explosion Code (SNEC)

    CERN Document Server

    Morozova, V; Renzo, M; Ott, C D; Clausen, D; Couch, S M; Ellis, J; Roberts, L F

    2015-01-01

    We present the SuperNova Explosion Code SNEC, an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different wavelength bands assuming black body emission. As a first application of SNEC, we consider the explosions of a grid of 15 Msun (at zero-age main sequence) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ~20-100 days if >~1.5-2 Msun of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. The shorter plateau lengths are unlike the Type IIP supernova light curves typically observed in nature. This suggests that, at least for zero-age main sequence masses <~ 20 Msun, hydrogen mass l...

  20. Focusing Light with Curved Guided-Mode Resonance Reflectors

    Directory of Open Access Journals (Sweden)

    Robert Magnusson

    2011-04-01

    Full Text Available Employing numerical simulations, we investigate the possibility of using curved guided-mode resonance (GMR elements to focus light in reflection. We treat GMR reflectors with a parabolic shape and show that they are capable of focusing light effectively across wavelength bands that extend several hundred nanometers. The spatially infinite reflector model is simulated with a finite-element method, whereas the spatially finite reflector is treated with a finite-difference-time-domain method. The numerical results demonstrate that light intensity at the focal point is 8.6 dB stronger than the incident intensity when the GMR reflector’s size is on the order of 10 wavelengths. The results indicate potential applicability of wideband-focusing devices in electromagnetics and photonics using compact resonance elements.

  1. UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de; Moraga, Tania; González-Gaitán, Santiago; Gutiérrez, Claudia P. [Millennium Institute of Astrophysics, Universidad de Chile (Chile); Phillips, Mark M.; Morrell, Nidia I.; Thomas-Osip, Joanna [Carnegie Observatories, Las Campanas Observatory, Casilla 60, La Serena (Chile); Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Maza, José; González, Luis; Antezana, Roberto; Wishnjewski, Marina [Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile); Krisciunas, Kevin [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); McCarthy, Patrick [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Anderson, Joseph P. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University (Denmark); Folatelli, Gastón, E-mail: lgalbany@das.uchile.cl [Instituto de Astrofísica de La Plata (IALP, CONICET) (Argentina); and others

    2016-02-15

    We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.

  2. UBVRIz Light Curves of 51 Type II Supernovae

    CERN Document Server

    Galbany, Lluís; Phillips, Mark M; Suntzeff, Nicholas B; Maza, José; de Jaeger, Thomas; Moraga, Tania; González-Gaitán, Santiago; Krisciunas, Kevin; Morrell, Nidia I; Thomas-Osip, Joanna; Krzeminski, Wojtek; González, Luis; Antezana, Roberto; Wischnjewski, Marina; McCarthy, Patrick; Anderson, Joseph P; Gutiérrez, Claudia P; Stritzinger, Maximilian; Folatelli, Gastón; Anguita, Claudio; Galaz, Gaspar; Green, Elisabeth M; Impey, Chris; Kim, Yong-Cheol; Kirhakos, Sofia; Malkan, Mathew A; Mulchaey, John S; Phillips, Andrew C; Pizzella, Alessandro; Prosser, Charles F; Schmidt, Brian P; Schommer, Robert A; Sherry, William; Strolger, Louis-Gregory; Wells, Lisa A; Williger, Gerard M

    2015-01-01

    We present a compilation of UBV RIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986 to 2003: the Cerro Tololo Supernova Survey, the Calan/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being thus shorter (longer) for larger (smaller) s values.

  3. Light-Curve Survey of Jupiter Trojan Asteroids

    Science.gov (United States)

    Duffard, R.; Melita, M.; Ortiz, J. L.; Licandro, J.; Williams, I. P.; Jones, D.

    2008-09-01

    Trojan asteroids are an interesting population of minor bodies due to their dynamical characteristics, their physical properties and that they are relatively isolated located at the snow-line The main hypotheses about the origin of the Jupiter Trojans assumed that they formed either during the final stages of the planetary formation (Marzari & Scholl 1998), or during the epoch of planetary migration (Morbidelli et al. 2005), in any case more than 3.8 Gy. ago. The dynamical configuration kept the Trojans isolated from the asteroid Main Belt throughout the history of the Solar System. In spite of eventual interactions with other populations of minor bodies like the Hildas, the Jupiter family comets, and the Centaurs, their collisional evolution has been dictated mostly by the intrapopulation collisions (Marzari et al. 1996, 1997). Therefore, the Jupiter Trojans may be considered primordial bodies, whose dynamical and physical properties can provide important clues about the environment of planetary formation. The available sample of Jupiter Trojans light-curves is small and mainly restricted to the largest objects. According to the MPC-website (updated last in March 2006), the present sample of rotation periods and light-curve-amplitudes of the Jupiter Trojan asteroids is composed by 25 objects with some information about their periods and by 10 of them with only an amplitude estimation. A survey of contact binary Trojan asteroids has been done by Mann et al. 2007, where they have recorded more than 100 amplitudes from sparse-sampled light-curves and very-wellresolved rotational periods. More than 2000 Trojan asteroids have been discovered up to date, so, there is an urgent need to enlarge the sample of intrinsic rotation periods and accurate light-curve amplitudes and to extend it to smaller sizes. Results and Discusions We requested 26 nights of observation in the second semester of 2007, to begin with the survey. They were scheduled for the following instruments

  4. Transit light curves with finite integration time: Fisher information analysis

    Energy Technology Data Exchange (ETDEWEB)

    Price, Ellen M. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Rogers, Leslie A. [California Institute of Technology, MC249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

    2014-10-10

    Kepler has revolutionized the study of transiting planets with its unprecedented photometric precision on more than 150,000 target stars. Most of the transiting planet candidates detected by Kepler have been observed as long-cadence targets with 30 minute integration times, and the upcoming Transiting Exoplanet Survey Satellite will record full frame images with a similar integration time. Integrations of 30 minutes affect the transit shape, particularly for small planets and in cases of low signal to noise. Using the Fisher information matrix technique, we derive analytic approximations for the variances and covariances on the transit parameters obtained from fitting light curve photometry collected with a finite integration time. We find that binning the light curve can significantly increase the uncertainties and covariances on the inferred parameters when comparing scenarios with constant total signal to noise (constant total integration time in the absence of read noise). Uncertainties on the transit ingress/egress time increase by a factor of 34 for Earth-size planets and 3.4 for Jupiter-size planets around Sun-like stars for integration times of 30 minutes compared to instantaneously sampled light curves. Similarly, uncertainties on the mid-transit time for Earth and Jupiter-size planets increase by factors of 3.9 and 1.4. Uncertainties on the transit depth are largely unaffected by finite integration times. While correlations among the transit depth, ingress duration, and transit duration all increase in magnitude with longer integration times, the mid-transit time remains uncorrelated with the other parameters. We provide code in Python and Mathematica for predicting the variances and covariances at www.its.caltech.edu/∼eprice.

  5. Nonlinear Time Series Analysis of White Dwarf Light Curves

    Science.gov (United States)

    Jevtic, N.; Zelechoski, S.; Feldman, H.; Peterson, C.; Schweitzer, J.

    2001-12-01

    We use nonlinear time series analysis methods to examine the light intensity curves of white dwarf PG1351+489 obtained by the Whole Earth Telescope (WET). Though these methods were originally introduced to study chaotic systems, when a clear signature of determinism is found for the process generating an observable and it couples the active degrees of freedom of the system, then the notion of phase space provides a framework for exploring the system dynamics of nonlinear systems in general. With a pronounced single frequency, its harmonics and other frequencies of lower amplitude on a broadband background, the PG1351 light curve lends itself to the use of time delay coordinates. Our phase space reconstruction yields a triangular, toroidal three-dimensional shape. This differs from earlier results of a circular toroidal representation. We find a morphological similarity to a magnetic dynamo model developed for fast rotators that yields a union of both results: the circular phase space structure for the ascending portion of the cycle, and the triangular structure for the declining portion. The rise and fall of the dynamo cycle yield both different phase space representations and different correlation dimensions. Since PG1351 is known to have no significant fields, these results may stimulate the observation of light curves of known magnetic white dwarfs for comparison. Using other data obtained by the WET, we compare the phase space reconstruction of DB white dwarf PG1351 with that of GD 358 which has a more complex power spectrum. We also compare these results with those for PG1159. There is some general similarity between the results of the phase space reconstruction for the DB white dwarfs. As expected, the difference between the results for the DB white dwarfs and PG1159 is great.

  6. Dependence on supernovae light-curve processing in void models

    Energy Technology Data Exchange (ETDEWEB)

    Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); De Rossi, Maria E., E-mail: derossi@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2014-06-02

    In this work, we show that when supernova Ia (SN Ia) data sets are used to put constraints on the free parameters of inhomogeneous models, certain extra information regarding the light-curve fitter used in the supernovae Ia luminosity fluxes processing should be taken into account. We found that the size of the void as well as other parameters of these models might be suffering extra degenerations or additional systematic errors due to the fitter. A recent proposal to relieve the tension between the results from Planck satellite and SNe Ia is re-analyzed in the framework of these subjects.

  7. Light curve solutions of the ultrashort-period $Kepler$ binaries

    CERN Document Server

    Kjurkchieva, Diana

    2015-01-01

    We carried out light curve solutions of the ultrashort-period binaries with MS components observed by $Kepler$. All six targets turned out almost in thermal contact with contact or slightly overcontact configurations. Two of them, KID 4921906 and KID 6309193, are not eclipsing but reveal ellipsoidal and spot variability. One of the components of KID 8108785 exhibits inherent, quasi-sinusoidal, small-amplitude variability. KID 12055255 turned out a very rare case of ultrashort-period overcontact binary consisting of two M dwarfs. Our modeling indicated that the variability of KID 9532219 is due to eclipses but not to $\\delta$ Sct pulsations as it was previously supposed.

  8. On the Analysis of Light Curves in Asteroseismology

    Indian Academy of Sciences (India)

    David L. Mary

    2005-06-01

    We provide a detailed introduction to the main problems arising when analyzing light curves in asteroseismology. Attention is first paid to the signal model delivered by the pulsating stars and to the noise sources corrupting this model in photometric observations. The main pitfalls and ambiguities occurring in Fourier analysis are summarized and illustrated. Someclassical, Least Squares (LS) based methods for spectrum analysis are analyzed and commented on from the point of view of ill-posed problems. The insight that can be gained from such analyses is discussed.

  9. A new approach to the analysis of Mira light curves

    Science.gov (United States)

    Mennessier, M. O.; Barthes, D.; Mattei, J. A.

    1990-01-01

    Two different but complementary methods for predicting Mira luminosities are presented. One method is derived from a Fourier analysis, it requires performing deconvolution, and its results are not certain due to the inherent instability of deconvolution problems. The other method is a learning method utilizing artificial intelligence techniques where a light curve is presented as an ordered sequence of pseudocycles, and rules are learned by linking the characteristics of several consecutive pseudocycles to one characteristic of the future cycle. It is observed that agreement between these methods is obtainable when it is possible to eliminate similar false frequencies from the preliminary power spectrum and to improve the degree of confidence in the rules.

  10. Broadband turbulent spectra in gamma-ray burst light curves

    Energy Technology Data Exchange (ETDEWEB)

    Van Putten, Maurice H. P. M. [Astronomy and Space Science, Sejong University, 98 Gunja-Dong Gwangin-gu, Seoul 143-747 (Korea, Republic of); Guidorzi, Cristiano; Frontera, Filippo, E-mail: mvp@sejong.ac.kr [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  11. Unifying Type II Supernova Light Curves with Dense Circumstellar Material

    CERN Document Server

    Morozova, Viktoriya; Valenti, Stefano

    2016-01-01

    A longstanding problem in the study of supernovae (SNe) has been the relationship between the Type IIP and Type IIL subclasses. Whether they come from distinct progenitors or they are from similar stars with some property that smoothly transitions from one class to another has been the subject of much debate. Here we show using one-dimensional radiation-hydrodynamic SN models that the multi-band light curves of SNe IIL are well fit by ordinary red supergiants surrounded by dense circumstellar material (CSM). The inferred extent of this material, coupled with a typical wind velocity of ~10-100 km/s, suggests enhanced activity by these stars during the last ~months to ~years of their lives, which may be connected with advanced stages of nuclear burning. Furthermore, we find that even for more plateau-like SNe that dense CSM provides a better fit to the first ~20 days of their light curves, indicating that the presence of such material may be more widespread than previously appreciated. Here we choose to model t...

  12. The light curve of a transient X-ray source

    Science.gov (United States)

    Kaluzienski, L. J.; Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Eadie, G.; Pounds, K. A.; Ricketts, M. J.; Watson, M.

    1975-01-01

    The Ariel-5 satellite has monitored the X-ray light curve of A1524-62 almost continuously from 40 days prior to maximum light until its disappearance below the effective experimental sensitivity. The source exhibited maximum light on Dec. 4, 1974, at a level of 0.9 the apparent magnitude of the Crab Nebula in the energy band 3-6 keV. Although similar to previously reported transient sources with a decay time constant of about 2 months, the source exhibited an extended, variable preflare on-state of about 1 month at a level of greater than 0.1 maximum light. The four bright (greater than 0.2 of the Crab Nebula) transient sources observed during the first half-year of Ariel-5 operation are indicative of a galactic disk distribution, a luminosity at maximum in excess of 10 to the 37-th power ergs/sec, a frequency of occurrence which may be as high as 100/yr, and a median decay time which is less than 1 month.

  13. The Rising Light Curves of Type Ia Supernovae

    CERN Document Server

    Firth, R E; Gal-Yam, A; Howell, D A; Maguire, K; Nugent, P; Piro, A L; Baltay, C; Feindt, U; Hadjiyksta, E; McKinnon, R; Ofek, E; Rabinowitz, D; Walker, E S

    2014-01-01

    We present an analysis of the early, rising light curves of 18 Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF) and the La Silla-QUEST variability survey (LSQ). We fit these early data flux using a simple power-law $(f(t) = {\\alpha\\times t^n})$ to determine the time of first light $({t_0})$, and hence the rise-time $({t_{rise}})$ from first light to peak luminosity, and the exponent of the power-law rise ($n$). We find a mean uncorrected rise time of $18.98 {\\pm} 0.54$ days, with individual SN rise-times ranging from $15.98$ to $24.7$ days. The exponent n shows significant departures from the simple 'fireball model' of $n = 2$ (or ${f(t) \\propto t^2}$) usually assumed in the literature. With a mean value of $n = 2.44 {\\pm} 0.13$, our data also show significant diversity from event to event. This deviation has implications for the distribution of 56Ni throughout the SN ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The range of n found also confirms that the...

  14. VizieR Online Data Catalog: V346 Cen multiwavelength light curves (Mayer+, 2016)

    Science.gov (United States)

    Mayer, P.; Harmanec, P.; Wolf, M.; Nemravova, J.; Prsa, A.; Fremat, Y.; Zejda, M.; Liska, J.; Jurysek, J.; Honkova, K.; Masek, M.

    2016-06-01

    We present photographic light curves from O'Connell (1939, Publications of the Riverview College Observatory, 2, 5), uvby light curves from Gimenez et al. (1986A&AS...66...45G), BVR light curves from 0.6 m reflector with a CCD camera, Mt. John, New Zealand, green light curve from Sonnar 4/135mm telephoto lens with a CCD ATIK16IC camera, Sutherland, South Africa and BVRI light curves from 0.3m Meade Schmidt-Cassegrain reflector with a CCD camera. (5 data files).

  15. High Order Harmonics in Light Curves of Kepler Planets

    CERN Document Server

    Armstrong, Caden

    2015-01-01

    The Kepler mission was launched in 2009 and has discovered thousands of planet candidates. In a recent paper, Esteves et al. (2013) found a periodic signal in the light curves of KOI-13 and HAT-P-7, with a frequency triple the orbital frequency of a transiting planet. We found similar harmonics in many systems with a high occurrence rate. At this time, the origins of the signal are not entirely certain. We look carefully at the possibility of errors being introduced through our data processing routines but conclude that the signal is real. The harmonics on multiples of the orbital frequency are a result of non-sinusoidal periodic signals. We speculate on their origin and generally caution that these harmonics could lead to wrong estimates of planet albedos, beaming mass estimates, and ellipsoidal variations.

  16. Disk-averaged Spectra & light-curves of Earth

    CERN Document Server

    Tinetti, G; Crisp, D; Fong, W; Kiang, N; Fishbein, E; Velusamy, T; Bosc, E; Turnbull, M

    2005-01-01

    We are using computer models to explore the observational sensitivity to changes in atmospheric and surface properties, and the detectability of biosignatures, in the globally averaged spectra and light-curves of the Earth. Using AIRS (Atmospheric Infrared Sounder) data, as input for atmospheric and surface properties, we have generated spatially resolved high-resolution synthetic spectra using the SMART radiative transfer model, for a variety of conditions, from the UV to the far-IR (beyond the range of current Earth-based satellite data). We have then averaged over the visible disk for a number of different viewing geometries to quantify the sensitivity to surface types and atmospheric features as a function of viewing geometry, and spatial and spectral resolution. These results have been processed with an instrument simulator to improve our understanding of the detectable characteristics of Earth-like planets as viewed by the first generation extrasolar terrestrial planet detection and characterization mis...

  17. Multifrequency light curves of low-frequency variable radio sources

    Science.gov (United States)

    Altschuler, D. R.; Broderick, J. J.; Dennison, B.; Mitchell, K. J.; Odell, S. L.; Condon, J. J.; Payne, H. E.

    1984-01-01

    Light curves for the low-frequency variable sources AO 0235 + 16, NRAO 140, PKS 1117 + 14, DA 406, CTA 102, and 3C 454.3, obtained in monthly observations at 318, 430, and 606 MHz using the 305-m telescope at Arecibo and in bimonthly observations at 880 MHz and 1.4 GHz using the 91-m Green Bank transit telescope during 1980-1983, are presented and analyzed. AO 0235 + 16 is found to have basically canonical variability which is attributed to relativistically moving evolving synchrotron components; but in the other sources, strong simultaneous variations at 318, 430, and 606 MHz are observed to be greatly diminished in amplitude at 880 MHz and 1.4 GHz, confirming the existence of the intermediate-frequency gap at about 1 GHz proposed by Spangler and Cotton (1981). The possibility that a second variability mechanism is active in these sources is explored.

  18. Secondary eclipses in the CoRoT light curves

    Directory of Open Access Journals (Sweden)

    Belmonte Juan Antonio

    2013-04-01

    Full Text Available We identify and characterize secondary eclipses in the original light curves of published CoRoT planets using uniform detection and evaluation criteria. Our analysis is based on a Bayesian statistics: the eclipse search is carried out using Bayesian model selection, and the characterization of the plausible eclipse candidates using Bayesian parameter estimation. We discover statistically significant eclipse events for two planets, CoRoT-6b and CoRoT-11b, and for one brown dwarf, CoRoT-15b. We also find marginally significant eclipse events passing our plausibility criteria for CoRoT-3b, 13b, 18b, and 21b, and confirm the previously published CoRoT-1b and CoRoT-2b eclipses.

  19. Periodic Relativity: Deflection of Light, Acceleration, Rotation Curves

    Directory of Open Access Journals (Sweden)

    Zaveri V. H.

    2015-01-01

    Full Text Available Vectorial analysis relating to derivation of deflection of light is presented. Curvilinear acceleration is distinguished from the Newtonian polar conic acceleration. The dif- ference between the two is due to the curvature term. Lorentz invariant expression for acceleration is derived. A physical theory of rotation curves of galaxies based on second solution to Einstein’s field equation is presented. Theory is applied to Milky Way, M31, NGC3198 and Solar system. Modified Kepler’s third law yields correct orbital periods of stars in a galaxy. Deviation factor in the line element of t he theory happens to be the ratio of the Newtonian gravitational acceleration to th e measured acceleration of the star in the galaxy. Therefore this deviation factor can replace the MOND function.

  20. Analysis of selected Kepler Mission planetary light curves

    CERN Document Server

    Rhodes, M D

    2014-01-01

    We have modified the graphical user interfaced close binary system analysis program CurveFit to the form WinKepler and applied it to 16 representative planetary candidate light curves found in the NASA Exoplanet Archive (NEA) at the Caltech website http://exoplanetarchive.ipac.caltech.edu, with an aim to compare different analytical approaches. WinKepler has parameter options for a realistic physical model, including gravity-brightening and structural parameters derived from the relevant Radau equation. We tested our best-fitting parameter-sets for formal determinacy and adequacy. A primary aim is to compare our parameters with those listed in the NEA. Although there are trends of agreement, small differences in the main parameter values are found in some cases, and there may be some relative bias towards a 90 degrees value for the NEA inclinations. These are assessed against realistic error estimates. Photometric variability from causes other than planetary transits affects at least 6 of the data-sets studie...

  1. Analysis of selected Kepler Mission planetary light curves

    Science.gov (United States)

    Rhodes, M. D.; Budding, E.

    2014-06-01

    We have modified the graphical user interfaced close binary system analysis program CurveFit to the form WinKepler and applied it to 16 representative planetary candidate light curves found in the NASA Exoplanet Archive (NEA) at the Caltech website http://exoplanetarchive.ipac.caltech.edu, with an aim to compare different analytical approaches. WinKepler has parameter options for a realistic physical model, including gravity-brightening and structural parameters derived from the relevant Radau equation. We tested our best-fitting parameter-sets for formal determinacy and adequacy. A primary aim is to compare our parameters with those listed in the NEA. Although there are trends of agreement, small differences in the main parameter values are found in some cases, and there may be some relative bias towards a 90∘ value for the NEA inclinations. These are assessed against realistic error estimates. Photometric variability from causes other than planetary transits affects at least 6 of the data-sets studied; with small pulsational behaviour found in 3 of those. For the false positive KOI 4.01, we found that the eclipses could be modelled by a faint background classical Algol as effectively as by a transiting exoplanet. Our empirical checks of limb-darkening, in the cases of KOI 1.01 and 12.01, revealed that the assigned stellar temperatures are probably incorrect. For KOI 13.01, our empirical mass-ratio differs by about 7 % from that of Mislis and Hodgkin (Mon. Not. R. Astron. Soc. 422:1512, 2012), who neglected structural effects and higher order terms in the tidal distortion. Such detailed parameter evaluation, additional to the usual main geometric ones, provides an additional objective for this work.

  2. Supervised detection of anomalous light curves in massive astronomical catalogs

    Energy Technology Data Exchange (ETDEWEB)

    Nun, Isadora; Pichara, Karim [Computer Science Department, Pontificia Universidad Católica de Chile, Santiago (Chile); Protopapas, Pavlos [Institute for Applied Computational Science, Harvard University, Cambridge, MA (United States); Kim, Dae-Won [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-09-20

    The development of synoptic sky surveys has led to a massive amount of data for which resources needed for analysis are beyond human capabilities. In order to process this information and to extract all possible knowledge, machine learning techniques become necessary. Here we present a new methodology to automatically discover unknown variable objects in large astronomical catalogs. With the aim of taking full advantage of all information we have about known objects, our method is based on a supervised algorithm. In particular, we train a random forest classifier using known variability classes of objects and obtain votes for each of the objects in the training set. We then model this voting distribution with a Bayesian network and obtain the joint voting distribution among the training objects. Consequently, an unknown object is considered as an outlier insofar it has a low joint probability. By leaving out one of the classes on the training set, we perform a validity test and show that when the random forest classifier attempts to classify unknown light curves (the class left out), it votes with an unusual distribution among the classes. This rare voting is detected by the Bayesian network and expressed as a low joint probability. Our method is suitable for exploring massive data sets given that the training process is performed offline. We tested our algorithm on 20 million light curves from the MACHO catalog and generated a list of anomalous candidates. After analysis, we divided the candidates into two main classes of outliers: artifacts and intrinsic outliers. Artifacts were principally due to air mass variation, seasonal variation, bad calibration, or instrumental errors and were consequently removed from our outlier list and added to the training set. After retraining, we selected about 4000 objects, which we passed to a post-analysis stage by performing a cross-match with all publicly available catalogs. Within these candidates we identified certain known

  3. Predicting Fundamental Stellar Parameters From Photometric Light Curves

    Science.gov (United States)

    Miller, Adam; Richards, J.; Bloom, J. S.; a larger Team

    2014-01-01

    We present a new machine-learning-based framework for the prediction of the fundamental stellar parameters, Teff, log g, and [Fe/H], based on the photometric light curves of variable stellar sources. The method was developed following a systematic spectroscopic survey of stellar variability. Variable sources were selected from repeated Sloan Digital Sky Survey (SDSS) observations of Stripe 82, and spectroscopic observations were obtained with Hectospec on the 6.5-m Multi-Mirror Telescope. In sum, spectra were obtained for ~9000 stellar variables (including ~3000 from the SDSS archive), for which we measured Teff, log g, and [Fe/H] using the Segue Stellar Parameters Pipeline (SSPP). Examining the full sample of ~67k variables in Stripe 82, we show that the vast majority of photometric variables are consistent with main-sequence stars, even after restricting the search to high galactic latitudes. From the spectroscopic sample we confirm that most of these stellar variables are G and K dwarfs, though there is a bias in the output of the SSPP that prevents the identification of M type variables. We are unable to identify the dominant source of variability for these stars, but eclipsing systems and/or star spots are the most likely explanation. We develop a machine-learning model that can determine Teff, log g, and [Fe/H] without obtaining a spectrum. Instead, the random-forest-regression model uses SDSS color information and light-curve features to infer stellar properties. We detail how the feature set is pruned and the model is optimized to produce final predictions of Teff, log g, and [Fe/H] with a typical scatter of 165 K, 0.42 dex, and 0.33 dex, respectively. We further show that for the subset of variables with at least 50 observations in the g band the typical scatter reduces to 75 K, 0.19 dex, and 0.16 dex, respectively. We consider these results an important step on the path to the efficient and optimal extraction of information from future time

  4. The anatomy of $\\gamma$-ray pulsar light curves

    CERN Document Server

    Seyffert, A S; Johnson, T J; Harding, A K

    2015-01-01

    We previously obtained constraints on the viewing geometries of 6 Fermi LAT pulsars using a multiwavelength approach (Seyffert et al., 2011). To obtain these constraints we compared the observed radio and $\\gamma$-ray light curves (LCs) for those 6 pulsars by eye to LCs predicted by geometric models detailing the location and extent of emission regions in a pulsar magnetosphere. As a precursor to obtaining these constraints, a parameter study was conducted to reinforce our qualitative understanding of how the underlying model parameters effect the LCs produced by the geometric models. Extracting useful trends from the $\\gamma$-ray model LCs proved difficult though due to the increased complexity of the geometric models for the $\\gamma$-ray emission relative to those for the radio emission. In this paper we explore a second approach to investigating the interplay between the model parameters and the LC atlas. This approach does not attempt to understand how the set of model parameters influences the LC shapes ...

  5. GRB afterglow light curves from realistic density profiles

    CERN Document Server

    Mimica, Petar

    2011-01-01

    The afterglow emission that follows gamma-ray bursts (GRBs) contains valuable information about the circumburst medium and, therefore, about the GRB progenitor. Theoretical studies of GRB blast waves, however, are often limited to simple density profiles for the external medium (mostly constant density and power-law R^{-k} ones). We argue that a large fraction of long-duration GRBs should take place in massive stellar clusters where the circumburst medium is much more complicated. As a case study, we simulate the propagation of a GRB blast wave in a medium shaped by the collision of the winds of O and Wolf-Rayet stars, the typical distance of which is d /sim 0.1 - 1 pc. Assuming a spherical blast wave, the afterglow light curve shows a flattening followed by a shallow break on a timescale from hours up to a week after the burst, which is a result of the propagation of the blast wave through the shocked wind region. If the blast wave is collimated, the jet break may, in some cases, become very pronounced with ...

  6. The detailed optical light curve of GRB 030329

    CERN Document Server

    Lipkin, Yu M; Gal-Yam, A; Leibowitz, E M; Poznanski, D; Kaspi, S; Polishook, D; Kulkarni, S R; Fox, D W; Berger, E; Mirabal, N; Halpern, J; Bureau, M; Fathi, K; Price, P A; Peterson, B A; Frebel, A; Schmidt, B; Orosz, J A; Fitzgerald, J B; Bloom, J S; Van Dokkum, P G; Bailyn, C D; Buxton, M M; Barsony, M

    2004-01-01

    (Abridged) We present densely sampled BVRI light curves of the optical transient associated with the gamma-ray burst GRB 030329, the result of a coordinated observing campaign conducted at five observatories. Augmented with published observations of this GRB, the compiled optical dataset contains 2687 photometric measurements, obtained between 78 minutes and 79 days after the burst. We show that the underlying supernova 2003dh evolved faster than, and was probably somewhat fainter than the type Ic SN 1998bw, associated with GRB 980425. We find that our data can be described by a broken power-law decay perturbed by a complex variable component. The early- and late-time decay slopes are determined to be ~1.1 and ~2, respectively. Assuming this single power-law model, we constrain the break to lie between ~3 and ~8 days after the burst. This simple, singly-broken power-law model, derived only from the analysis of our optical observations, may also account for available multi-band data, provided that the break ha...

  7. Properties of GRB light curves from magnetic reconnection

    Science.gov (United States)

    Beniamini, Paz; Granot, Jonathan

    2016-07-01

    The energy dissipation mechanism within gamma-ray burst (GRB) outflows, driving their extremely luminous prompt γ-ray emission is still uncertain. The leading candidates are internal shocks and magnetic reconnection. While the emission from internal shocks has been extensively studied, that from reconnection still has few quantitative predictions. We study the expected prompt-GRB emission from magnetic reconnection and compare its temporal and spectral properties to observations. The main difference from internal shocks is that for reconnection one expects relativistic bulk motions with Lorentz factors Γ'≳ a few in the jet's bulk frame. We consider such motions of the emitting material in two antiparallel directions (e.g. of the reconnecting magnetic-field lines) within an ultrarelativistic (with Γ ≫ 1) thin spherical reconnection layer. The emission's relativistic beaming in the jet's frame greatly affects the light curves. For emission at radii R0 tracking (for Γ' > 2). However, the relativistic turbulence mode is more likely to be relevant for the prompt sub-MeV emission and can naturally account also for the peak luminosity - peak frequency correlation.

  8. NON-RELATIVISTIC RADIATION MEDIATED SHOCK BREAKOUTS. II. BOLOMETRIC PROPERTIES OF SUPERNOVA SHOCK BREAKOUT

    International Nuclear Information System (INIS)

    Exact bolometric light curves of supernova shock breakouts are derived based on the universal, non-relativistic, planar breakout solutions, assuming spherical symmetry, constant Thomson scattering opacity, κ, and angular intensity corresponding to the steady-state planar limit. These approximations are accurate for progenitors with a scale height much smaller than the radius. The light curves are insensitive to the density profile and are determined by the progenitor radius R, and the breakout velocity and density, v0 and ρ0, respectively, and κ. The total breakout energy, EBO, and the maximal ejecta velocity, vmax, are shown to be EBO = 8.0πR2κ–1 cv0 and vmax = 2.0v0, respectively, to an accuracy of about 10%. The calculated light curves are valid up to the time of transition to spherical expansion, tsph ≈ R/4v0. Approximate analytic expressions for the light curves are provided for breakouts in which the shock crossing time at breakout, t0 = c/κρ0 v20, is 14 cm). Modifications of the flux angular intensity distribution and differences in shock arrival times to the surface, Δtasym, due to moderately asymmetric explosions, affect the early light curve but do not affect vmax and EBO. For 4v0 –4/3 at max (Δtasym, R/c) sph and R may be accurately estimated from R ≈ 2 × 1013(L/1043 erg s–1)2/5(t/1 hr)8/15.

  9. GERLUMPH Data Release 2: 2.5 billion simulated microlensing light curves

    CERN Document Server

    Vernardos, Georgios; Bate, Nicholas F; Croton, Darren; Vohl, Dany

    2015-01-01

    In the upcoming synoptic all--sky survey era of astronomy, thousands of new multiply imaged quasars are expected to be discovered and monitored regularly. Light curves from the images of gravitationally lensed quasars are further affected by superimposed variability due to microlensing. In order to disentangle the microlensing from the intrinsic variability of the light curves, the time delays between the multiple images have to be accurately measured. The resulting microlensing light curves can then be analyzed to reveal information about the background source, such as the size of the quasar accretion disc. In this paper we present the most extensive and coherent collection of simulated microlensing light curves; we have generated $>2.5$ billion light curves using the GERLUMPH high resolution microlensing magnification maps. Our simulations can be used to: train algorithms to measure lensed quasar time delays, plan future monitoring campaigns, and study light curve properties throughout parameter space. Our ...

  10. GENERALIZED SEMI-ANALYTICAL MODELS OF SUPERNOVA LIGHT CURVES

    International Nuclear Information System (INIS)

    We present generalized supernova (SN) light curve (LC) models for a variety of power inputs including the previously proposed ideas of radioactive decay of 56Ni and 56Co and magnetar spin-down. We extend those solutions to include finite progenitor radius and stationary photospheres as might be the case for SN that are powered by interaction of the ejecta with circumstellar matter (CSM). We provide an expression for the power input that is produced by self-similar forward and reverse shocks that efficiently convert their kinetic energy into radiation. We find that this ejecta-CSM interaction luminosity that we derive is in agreement with results from multi-dimensional radiation hydrodynamics simulations in the case of an optically thin CSM. We develop a semi-analytical model for the case of an optically thick CSM by invoking an approximation for the effects of radiative diffusion similar to that adopted by Arnett for SN II and compare this model to the results of numerical radiation hydrodynamics models. This model can give complex LCs, but for monotonically declining shock input, the LCs have a smooth rise, peak, and decline. In the context of this model, we provide predictions of the shock breakout of the forward shock from the optically thick part of the CSM envelope. We also introduce a hybrid LC model that incorporates ejecta-CSM interaction plus 56Ni and 56Co radioactive decay input. We fit this hybrid model to the LC of the super-luminous supernova (SLSN) 2006gy. We find that shock heating produced by ejecta-CSM interaction plus some contribution from radioactive decay provides a better fit to the LC of this event than previously presented models. We also address the relation between SN IIL and SN IIn with ejecta-CSM interaction models. The faster decline of SN IIL can be reproduced by the diffusion of previously deposited shock power if the shock power input to the diffusive component vanishes when the reverse shock sweeps up the whole ejecta and/or the

  11. Methodology of light response curves: application of chlorophyll fluorescence to microphytobenthic biofilms

    NARCIS (Netherlands)

    Herlory, O.; Richard, P.; Blanchard, G.F.

    2007-01-01

    The light response curve methodology for microphytobenthic biofilms was studied by comparing the two most usual approaches used in pulse amplitude modulated (PAM) fluorometry. The non-sequential light curve (N-SLC) method is characterized by independent measures of the photosynthetic activity across

  12. appaloosa: Python-based flare finding code for Kepler light curves

    Science.gov (United States)

    Davenport, James R. A.

    2016-08-01

    The appaloosa suite automates flare-finding in every Kepler light curves. It builds quiescent light curve models that include long- and short-cadence data through iterative de-trending and includes completeness estimates via artificial flare injection and recovery tests.

  13. Application of Geodetic VLBI Data to Obtaining Long-Term Light Curves for Astrophysics

    Science.gov (United States)

    Kijima, Masachika

    2010-01-01

    The long-term light curve is important to research on binary black holes and disk instability in AGNs. The light curves have been drawn mainly using single dish data provided by the University of Michigan Radio Observatory and the Metsahovi Radio Observatory. Hence, thus far, we have to research on limited sources. I attempt to draw light curves using VLBI data for those sources that have not been monitored by any observatories with single dish. I developed software, analyzed all geodetic VLBI data available at the IVS Data Centers, and drew the light curves at 8 GHz. In this report, I show the tentative results for two AGNs. I compared two light curves of 4C39.25, which were drawn based on single dish data and on VLBI data. I confirmed that the two light curves were consistent. Furthermore, I succeeded in drawing the light curve of 0454-234 with VLBI data, which has not been monitored by any observatory with single dish. In this report, I suggest that the geodetic VLBI archive data is useful to obtain the long-term light curves at radio bands for astrophysics.

  14. GAMMA-RAY LIGHT CURVE AND PHASE-RESOLVED SPECTRA FROM GEMINGA PULSAR

    Institute of Scientific and Technical Information of China (English)

    ZHANG LI; BIAN XIA; MEI DONG-CHENG

    2001-01-01

    We calculate the light curve and phase-resolved spectra of Geminga in a three-dimensional pulsar magnetosphere model. The light curve of gamma-rays is consistent with that observed if the magnetic inclination and viewing angle are~50° and~86° respectively. We also model the phase-resolved spectra of the Geminga pulsar.

  15. Type Ia Supernova Light Curve Inference: Hierarchical Bayesian Analysis in the Near Infrared

    CERN Document Server

    Mandel, Kaisey S; Friedman, Andrew S; Kirshner, Robert P

    2009-01-01

    We present a comprehensive statistical analysis of the properties of Type Ia SN light curves in the near infrared using recent data from PAIRITEL and the literature. We construct a hierarchical Bayesian framework, incorporating several uncertainties including photometric error, peculiar velocities, dust extinction and intrinsic variations, for coherent statistical inference. SN Ia light curve inferences are drawn from the global posterior probability of parameters describing both individual supernovae and the population conditioned on the entire SN Ia NIR dataset. The logical structure of the hierarchical Bayesian model is represented by a directed acyclic graph. Fully Bayesian analysis of the model and data is enabled by an efficient MCMC algorithm exploiting the conditional structure using Gibbs sampling. We apply this framework to the JHK_s SN Ia light curve data. A new light curve model captures the observed J-band light curve shape variations. The intrinsic variances in peak absolute magnitudes are: sigm...

  16. CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH STOCHASTICALLY VARYING LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Rebull, Luisa; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cody, Ann Marie [NASA Ames Research Center, Kepler Science Office, Mountain View, CA 94035 (United States); Hillenbrand, Lynne A.; Carpenter, John [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, Maria [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, P.O. BOX 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Alencar, Silvia H. P.; McGinnis, Pauline; Sousa, Alana [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Bouvier, Jerome; Venuti, Laura [Université de Grenoble, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble (France); Hartmann, Lee; Calvet, Nuria [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI:48105 (United States); Micela, Giusi; Flaccomio, Ettore [INAF—Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States); Gutermuth, Rob, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); and others

    2016-03-15

    We provide CoRoT and Spitzer light curves and other supporting data for 17 classical T Tauri stars in NGC 2264 whose CoRoT light curves exemplify the “stochastic” light curve class as defined in 2014 by Cody et al. The most probable physical mechanism to explain the optical variability within this light curve class is time-dependent mass accretion onto the stellar photosphere, producing transient hot spots. Where we have appropriate spectral data, we show that the veiling variability in these stars is consistent in both amplitude and timescale with the optical light curve morphology. The veiling variability is also well-correlated with the strength of the He i 6678 Å emission line, predicted by models to arise in accretion shocks on or near the stellar photosphere. Stars with accretion burst light curve morphology also have variable mass accretion. The stochastic and accretion burst light curves can both be explained by a simple model of randomly occurring flux bursts, with the stochastic light curve class having a higher frequency of lower amplitude events. Members of the stochastic light curve class have only moderate mass accretion rates. Their Hα profiles usually have blueshifted absorption features, probably originating in a disk wind. The lack of periodic signatures in the light curves suggests that little of the variability is due to long-lived hot spots rotating into or out of our line of sight; instead, the primary driver of the observed photometric variability is likely to be instabilities in the inner disk that lead to variable mass accretion.

  17. Microlensing light curve of a source on the other side of a wormhole

    CERN Document Server

    Tsukamoto, Naoki

    2016-01-01

    The observation of microlensing is a good probe into the topological structure of dark gravitating celestial objects. In this paper, we study the microlensing light curves due to light rays emitted by a source on the other side of a traversable wormhole. The present method will apply for general spherically symmetric traversable wormholes. Based on the obtained light curves, we discuss a possibility to observationally distinguish traversable wormholes with nontrivial topology from usual positive masses and other exotic objects without nontrivial topology.

  18. Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?

    CERN Document Server

    Kasliwal, Vishal P; Richards, Gordon T

    2015-01-01

    We test the consistency of active galactic nuclei (AGN) optical flux variability with the \\textit{damped random walk} (DRW) model. Our sample consists of 20 multi-quarter \\textit{Kepler} AGN light curves including both Type 1 and 2 Seyferts, radio-loud and -quiet AGN, quasars, and blazars. \\textit{Kepler} observations of AGN light curves offer a unique insight into the variability properties of AGN light curves because of the very rapid ($11.6-28.6$ min) and highly uniform rest-frame sampling combined with a photometric precision of $1$ part in $10^{5}$ over a period of 3.5 yr. We categorize the light curves of all 20 objects based on visual similarities and find that the light curves fall into 5 broad categories. We measure the first order structure function of these light curves and model the observed light curve with a general broken power-law PSD characterized by a short-timescale power-law index $\\gamma$ and turnover timescale $\\tau$. We find that less than half the objects are consistent with a DRW and ...

  19. Light Curve Properties of Supernovae Associated With Gamma-ray Bursts

    CERN Document Server

    Li, Xue

    2014-01-01

    Little is known about the diversity in the light curves of GRB-SNe, including whether the light curve of SN 1998bw can be used as a representative template or whether there is a luminosity-decline rate relation akin to that of SNe Ia. In this paper, we aim to obtain well-constrained light curves of GRB-SNe without the assumption of empirical or parametric templates and to investigate whether the peak brightness correlates with other parameters such as the light curve shape or the time of peak. We select eight SNe in the redshift range 0.0085 to 0.606, which are firmly associated with GRBs. The light curves of these GRB-SNe are well sampled across the peak. Afterglow and host galaxy contributions are subtracted and dust reddening is corrected for. Low-order polynomial functions are fitted to the light curves. A K-correction is applied to transform the light curves into the rest frame V band. GRB-SNe follow a luminosity-decline rate relation similar to the Phillips relation for SNe Ia, with $M_{V,peak} = 1.59^{...

  20. Gamma-Ray Light Curves from Pulsar Magnetospheres with Finite Conductivity

    Science.gov (United States)

    Harding, A. K.; Kalapotharakos, C.; Kazanas, D.; Contopoulos, I.

    2012-01-01

    The Fermi Large Area Telescope has provided an unprecedented database for pulsar emission studies that includes gamma-ray light curves for over 100 pulsars. Modeling these light curves can reveal and constrain the geometry of the particle accelerator, as well as the pulsar magnetic field structure. We have constructed 3D magnetosphere models with finite conductivity, that bridge the extreme vacuum and force-free solutions used in previous light curves modeling. We are investigating the shapes of pulsar gamma-ray light curves using these dissipative solutions with two different approaches: (l) assuming geometric emission patterns of the slot gap and outer gap, and (2) using the parallel electric field provided by the resistive models to compute the trajectories and . emission of the radiating particles. The light curves using geometric emission patterns show a systematic increase in gamma-ray peak phase with increasing conductivity, introducing a new diagnostic of these solutions. The light curves using the model electric fields are very sensitive to the conductivity but do not resemble the observed Fermi light curves, suggesting that some screening of the parallel electric field, by pair cascades not included in the models, is necessary

  1. Dust in Intermediate Polars: Light Curves from the Spitzer Space Telescope

    Science.gov (United States)

    Belle, Kunegunda E.; Hoard, D. W.; Howell, S. B.

    2010-12-01

    Here we present Spitzer 4.5 μm light curves of two intermediate polars (IPs)-DQ Her and EX Hya-obtained with Cycle 6 observations. Our initial evaluation of the light curves of DQ Her and EX Hya shows that these two IPs exhibit similar behavior as that seen in non-magnetic systems (specifically WZ Sge). The binary eclipses seen in the Spitzer light curves of DQ Her and EX Hya are about three times longer than their optical counterparts, indicating that a reservoir of dust extends beyond the outer edge of the optically visible accretion disk.

  2. MBI: Millimetre-wave bolometric interferometer

    Science.gov (United States)

    Ali, S.; Rossinot, P.; Piccirillo, L.; Gear, W. K.; Mauskopf, P.; Ade, P.; Haynes, V.; Timbie, P.

    2002-05-01

    We present the design of the prototype of a millimeter-wave bolometric interferometer (MBI). This interferometer uses two arrays bolometers as detectors. The combination of high sensitivity bolometers and interferometric imaging appears to be well suited for precision measurements in observational cosmology. .

  3. Light waves guided by a single curved metallic surface.

    Science.gov (United States)

    Krammer, H

    1978-01-15

    Propagation of TE-waves along a single curved metallic surface with radius of curvature much larger than wavelength is investigated both theoretically and experimentally. Approximate analytic expressions for the field configuration yield that power concentrates in a small region near the metal. The attenuation constant per unit angle of bend (radian) is given by the real part of the inverse of the refractive index, independent of the radius of curvature and of the mode number. In agreement with theory experiments with 10-microm radiation showed that low loss guiding can be realized.

  4. Light propagation on quantum curved spacetime and back reaction effects

    Energy Technology Data Exchange (ETDEWEB)

    Kozameh, Carlos; Parisi, Florencia [FaMAF, Universidad Nacional de Cordoba, 5000 Cordoba (Argentina)

    2007-09-07

    We study the electromagnetic field equations on an arbitrary quantum curved background in the semiclassical approximation of loop quantum gravity. The effective interaction Hamiltonian for the Maxwell and gravitational fields is obtained and the corresponding field equations, which can be expressed as a modified wave equation for the Maxwell potential, are derived. We use these results to analyze electromagnetic wave propagation on a quantum Robertson-Walker spacetime and show that Lorentz invariance is not preserved. The formalism developed can be applied to the case where back reaction effects on the metric due to the electromagnetic field are taken into account, leading to non-covariant field equations.

  5. Wavelet-based filter methods to detect small transiting planets in stellar light curves

    CERN Document Server

    Grziwa, Sascha

    2016-01-01

    Strong variations of any kind and causes within a stellar light curve may prohibit the detection of transits, particularly of faint or shallow transits caused by small planets passing in front of the stellar disk. The success of future space telescopes with the goal for finding small planets will be based on proper filtering, analysis and detection of transits in perturbed stellar light curves. The wavelet-based filter methods VARLET and PHALET, developed by RIU-PF, in combination with the transit detection software package EXOTRANS allow the extraction of (i) strong stellar variations, (ii) instrument caused spikes and singularities within a stellar light curve, (iii) already detected planetary or stellar binary transits in order to be able to search for further planets or planets about binary stars. Once the light curve is filtered, EXOTRANS is able to search efficiently, effectively and precisely for transits, in particular for faint transits.

  6. Determination of Cepheid parameters by light-curve template-fitting

    CERN Document Server

    Tanvir, N R; Watkins, A; Kanbur, S M; Berdnikov, L N; Ngeow, C C

    2005-01-01

    Determining the parameters (periods, mean magnitudes etc.) of periodic variable stars is a frequently met problem in astronomy. Here we describe techniques to characterise the light-curves of regular variables by applying principal component analysis (PCA) to a training set of high quality data, and to fit the resulting light-curve templates to sparse and noisy photometry. The PCA approach allows us to efficiently represent the multi-band light-curve shapes of each variable, and hence quantitatively describe the average behaviour of the sample as a smoothly varying function of period, and also the range of variation around this average. In this paper we focus particularly on the utility of such methods for analysing HST Cepheid photometry, and present simulations which illustrate the advantages of our PCA template-fitting approach. These are: accurate parameter determination, including light-curve shape information; simultaneous fitting to multiple passbands; quantitative error analysis; objective rejection o...

  7. Neptune's Dynamic Atmosphere from Kepler K2 Observations: Implications for Brown Dwarf Light Curve Analyses

    CERN Document Server

    Simon, Amy A; Gaulme, Patrick; Hammel, Heidi B; Casewell, Sarah L; Fortney, Jonathan J; Gizis, John E; Lissauer, Jack J; Morales-Juberias, Raul; Orton, Glenn S; Wong, Michael H; Marley, Mark S

    2015-01-01

    Observations of Neptune with the Kepler Space Telescope yield a 49-day light curve with 98% coverage at a 1-minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-meter telescope at 1.65 microns and Hubble Space Telescope visible imaging acquired 9 months later. This direct comparison validates the feature latitudes assigned to the K2 light curve periods based on Neptune's zonal wind profile, and confirms observed cloud feature variability. Although Neptune's clouds vary in location and intensity on short and long time scales, a single large discrete storm seen in Keck imaging dominates the K2 and Hubble light curves; smaller or fainter clouds likely contribute to short-term brightness variability. The K2 Neptune light curve, in conjunction with our imaging data, provides context for the interpretation of current and future brown dwarf and extras...

  8. Observable fractions of core-collapse supernova light curves brightened by binary companions

    CERN Document Server

    Moriya, Takashi J; Izzard, Robert G

    2015-01-01

    Many core-collapse supernova progenitors are presumed to be in binary systems. If a star explodes in a binary system, the early supernova light curve can be brightened by the collision of the supernova ejecta with the companion star. The early brightening can be observed when the observer is in the direction of the hole created by the collision. Based on a population synthesis model, we estimate the fractions of core-collapse supernovae in which the light-curve brightening by the collision can be observed. We find that 0.19% of core-collapse supernova light curves can be observed with the collisional brightening. Type Ibc supernova light curves are more likely to be brightened by the collision (0.53%) because of the high fraction of the progenitors being in binary systems and their proximity to the companion stars. Type II and IIb supernova light curves are less affected (~1e-3% and ~1e-2%, respectively). Although the early, slow light-curve declines of some Type IIb and Ibc supernovae are argued to be caused...

  9. Light curves, Spherical and Bond albedos of Jupiter, Saturn, and exoplanets.

    Science.gov (United States)

    Dyudina, U.

    2015-12-01

    We estimate how the light curve and stellar light reflection of a planet depends on forward and backward scattering, which was observed on Jupiter and Saturn. We fit analytical scattering phase function to Pioneer 10 and 11 spacecraft observations of Jupiter at 0.64 μm and Saturn at 0.64 and 0.44 μm and to Cassini spacecraft observations of Jupiter at 0.938 μm atmospheric window, 0.889 μm CH4 absorption band, and 0.258 μm UV filter. Using scattering ray-tracing model of a planet by Dyudina et al. (2005)*, the images of the planets with different scattering properties are simulated to calculate the reflected luminosity as it varies with scattering phase to produce full-orbit light curves. We compare the light curve shapes and total reflection integrated in all directions (spherical albedos) for Jupiter and Saturn with the ones for planets with Lambertian and semi-infinite Rayleigh-scattering atmosphere. Saturn-like and especially Jupiter-like atmosphere produces light curves that are several times fainter at half-phase than does a Lambertian planet, given the same brightness at transit. The spherical albedo (and hence the wavelengh-integrated Bond albedo) is lower than for a Lambertian planet. Corresponding absorption of the stellar light and planet's heating rate would be higher than estimated for Lambertian planets, especially for bright planets. In extreme case of Jupiter-like scattering at 0.64 μm Lambertian assumption can overestimate spherical albedo by a factor of ˜1.5. We will discuss how the light curves and absorption for planets covered by atmospheres would differ from the light curves of rocky planet without atmosphere. * Dyudina, U. A., et al., Phase Light Curves for Extrasolar Jupiters and Saturns. ApJ, 618, 973-986, 2005

  10. Reflected Light Curves, Spherical and Bond Albedos of Jupiter- and Saturn-like Exoplanets

    Science.gov (United States)

    Dyudina, Ulyana A.; Zhang, Xi; Li, Liming; Kopparla, Pushkar; Ingersoll, Andrew P.; Dones, Henry C. Luke; Verbiscer, Anne J.; Yung, Yuk

    2016-10-01

    Reflected light curves observed for exoplanets indicate that a few of them host bright clouds. We estimate how the light curve and total stellar heating of a planet depends on forward and backward scattering in the clouds based on Pioneer and Cassini spacecraft images of Jupiter and Saturn. We fit analytical functions to the local reflected brightnesses of Jupiter and Saturn depending on the planet's phase. These observations cover broad bands at 0.59–0.72 and 0.39–0.5 μm, and narrow bands at 0.938 (atmospheric window), 0.889 (CH4 absorption band), and 0.24–0.28 μm. We simulate the images of the planets with a ray-tracing model, and disk-integrate them to produce the full-orbit light curves. For Jupiter, we also fit the modeled light curves to the observed full-disk brightness. We derive spherical albedos for Jupiter and Saturn, and for planets with Lambertian and Rayleigh-scattering atmospheres. Jupiter-like atmospheres can produce light curves that are a factor of two fainter at half-phase than the Lambertian planet, given the same geometric albedo at transit. The spherical albedo is typically lower than for a Lambertian planet by up to a factor of ˜1.5. The Lambertian assumption will underestimate the absorption of the stellar light and the equilibrium temperature of the planetary atmosphere. We also compare our light curves with the light curves of solid bodies: the moons Enceladus and Callisto. Their strong backscattering peak within a few degrees of opposition (secondary eclipse) can lead to an even stronger underestimate of the stellar heating. This work is published: Dyudina, U.,et al., 2016: ApJ, 822, 76, http://arxiv.org/abs/1511.04415.

  11. CSI 2264: Characterizing Young Stars in NGC 2264 with Stochastically Varying Light Curves

    Science.gov (United States)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Hillenbrand, Lynne A.; Turner, Neal J.; Carpenter, John; Carey, Sean; Terebey, Susan; Morales-Calderón, María; Alencar, Silvia H. P.; McGinnis, Pauline; Sousa, Alana; Bouvier, Jerome; Venuti, Laura; Hartmann, Lee; Calvet, Nuria; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Barrado, David; Vrba, Frederick J.; Covey, Kevin; Herbst, William; Gillen, Edward; Medeiros Guimarães, Marcelo; Bouy, Herve; Favata, Fabio

    2016-03-01

    We provide CoRoT and Spitzer light curves and other supporting data for 17 classical T Tauri stars in NGC 2264 whose CoRoT light curves exemplify the “stochastic” light curve class as defined in 2014 by Cody et al. The most probable physical mechanism to explain the optical variability within this light curve class is time-dependent mass accretion onto the stellar photosphere, producing transient hot spots. Where we have appropriate spectral data, we show that the veiling variability in these stars is consistent in both amplitude and timescale with the optical light curve morphology. The veiling variability is also well-correlated with the strength of the He i 6678 Å emission line, predicted by models to arise in accretion shocks on or near the stellar photosphere. Stars with accretion burst light curve morphology also have variable mass accretion. The stochastic and accretion burst light curves can both be explained by a simple model of randomly occurring flux bursts, with the stochastic light curve class having a higher frequency of lower amplitude events. Members of the stochastic light curve class have only moderate mass accretion rates. Their Hα profiles usually have blueshifted absorption features, probably originating in a disk wind. The lack of periodic signatures in the light curves suggests that little of the variability is due to long-lived hot spots rotating into or out of our line of sight; instead, the primary driver of the observed photometric variability is likely to be instabilities in the inner disk that lead to variable mass accretion. Based on data from the Spitzer and CoRoT missions, as well as the Canada-France-Hawaii Telescope (CFHT) MegaCam CCD, and the European Southern Observatory Very Large Telescope, Paranal Chile, under program 088.C-0239. The CoRoT space mission was developed and is operated by the French space agency CNES, with particpiation of ESA’s RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain

  12. Characterizing the V-band light-curves of hydrogen-rich type II supernovae

    DEFF Research Database (Denmark)

    Anderson, Joseph P.; González-Gaitán, Santiago; Hamuy, Mario;

    2014-01-01

    measured at maximum light correlate more strongly with decline rates than those measured at other epochs: brighter supernovae at maximum generally have faster declining light-curves at all epochs. We find a relation between the decline rate during the "plateau" phase and peak magnitudes, which has...

  13. QUBIC: The QU Bolometric Interferometer for Cosmology

    CERN Document Server

    Battistelli, E; Bennett, D; Bergé, L; Bernard, J -Ph; de Bernardis, P; Bounab, A; Bréelle, É; Bunn, E F; Calvo, M; Charlassier, R; Collin, S; Cruciani, A; Curran, G; Dumoulin, L; Gault, A; Gervasi, M; Ghribi, A; Giard, M; Giordano, C; Giraud-Héraud, Y; Gradziel, M; Guglielmi, L; Hamilton, J -Ch; Haynes, V; Kaplan, J; Korotkov, A; Landé, J; Maffei, B; Maiello, M; Malu, S; Marnieros, S; Masi, S; Murphy, A; Nati, F; O'Sullivan, C; Pajot, F; Passerini, A; Peterzen, S; Piacentini, F; Piat, M; Piccirillo, L; Pisano, G; Polenta, G; Prêle, D; Romano, D; Rosset, C; Salatino, M; Schillacci, A; Sironi, G; Sordini, R; Spinelli, S; Tartari, A; Timbie, P; Tucker, G; Vibert, L; Voisin, F; Watson, R A; Zannoni, M

    2010-01-01

    One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the CMB. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic effects. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics effects advantages of interferometry. Methods: The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and interference fringes will be imaged ...

  14. Full Bayesian hierarchical light curve modeling of core-collapse supernova populations

    Science.gov (United States)

    Sanders, Nathan; Betancourt, Michael; Soderberg, Alicia Margarita

    2016-06-01

    While wide field surveys have yielded remarkable quantities of photometry of transient objects, including supernovae, light curves reconstructed from this data suffer from several characteristic problems. Because most transients are discovered near the detection limit, signal to noise is generally poor; because coverage is limited to the observing season, light curves are often incomplete; and because temporal sampling can be uneven across filters, these problems can be exacerbated at any one wavelength. While the prevailing approach of modeling individual light curves independently is successful at recovering inferences for the objects with the highest quality observations, it typically neglects a substantial portion of the data and can introduce systematic biases. Joint modeling of the light curves of transient populations enables direct inference on population-level characteristics as well as superior measurements for individual objects. We present a new hierarchical Bayesian model for supernova light curves, where information inferred from observations of every individual light curve in a sample is partially pooled across objects to constrain population-level hyperparameters. Using an efficient Hamiltonian Monte Carlo sampling technique, the model posterior can be explored to enable marginalization over weakly-identified hyperparameters through full Bayesian inference. We demonstrate our technique on the Pan-STARRS1 (PS1) Type IIP supernova light curve sample published by Sanders et al. (2015), consisting of nearly 20,000 individual photometric observations of more than 70 supernovae in five photometric filters. We discuss the Stan probabilistic programming language used to implement the model, computational challenges, and prospects for future work including generalization to multiple supernova types. We also discuss scientific results from the PS1 dataset including a new relation between the peak magnitude and decline rate of SNe IIP, a new perspective on the

  15. Photometric Observation and Light Curve Analysis of Binary System ER-Orionis

    Indian Academy of Sciences (India)

    M. M. Lame’e; B. Javanmardi; N. Riazi

    2010-06-01

    Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008 with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. We used these data to obtain the light curves and calculate the newtimes of minimum light in each filter and plot the O–C diagram of ER ORI. Using the Wilson’s computer code with the help of an auxiliary computer program to improve the optimizations, the light curve analyses were carried out to find out the photometric elements of the system.

  16. MEAN SPECTRAL ENERGY DISTRIBUTIONS AND BOLOMETRIC CORRECTIONS FOR LUMINOUS QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Krawczyk, Coleman M.; Richards, Gordon T.; Mehta, Sajjan S.; Vogeley, Michael S. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Gallagher, S. C. [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Leighly, Karen M. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2013-05-01

    We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119,652 luminous broad-lined quasars with 0.064 < z < 5.46 using mid-IR data from Spitzer and WISE, near-infrared data from the Two Micron All Sky Survey and UKIDSS, optical data from the Sloan Digital Sky Survey, and UV data from the Galaxy Evolution Explorer. The mean SED requires a bolometric correction (relative to 2500 A) of BC{sub 2500A} =2.75 {+-} 0.40 using the integrated light from 1 {mu}m-2 keV, and we further explore the range of bolometric corrections exhibited by individual objects. In addition, we investigate the dependence of the mean SED on various parameters, particularly the UV luminosity for quasars with 0.5 {approx}< z {approx}< 3 and the properties of the UV emission lines for quasars with z {approx}> 1.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED-dependent. Luminosity-dependent mean SEDs show that, relative to the high-luminosity SED, low-luminosity SEDs exhibit a harder (bluer) far-UV spectral slope ({alpha}{sub UV}), a redder optical continuum, and less hot dust. Mean SEDs constructed instead as a function of UV emission line properties reveal changes that are consistent with known Principal Component Analysis trends. A potentially important contribution to the bolometric correction is the unseen extreme UV (EUV) continuum. Our work suggests that lower-luminosity quasars and/or quasars with disk-dominated broad emission lines may require an extra continuum component in the EUV that is not present (or much weaker) in high-luminosity quasars with strong accretion disk winds. As such, we consider four possible models and explore the resulting bolometric corrections. Understanding these various SED-dependent effects will be important for accurate determination of quasar accretion rates.

  17. Exploring the Neutrinoless Double Beta Decay in the Inverted Neutrino Hierarchy with Bolometric Detectors

    CERN Document Server

    Artusa, D R; Azzolini, O; Balata, M; Banks, T I; Bari, G; Beeman, J; Bellini, F; Bersani, A; Biassoni, M; Brofferio, C; Bucci, C; Cai, X Z; Camacho, A; Canonica, L; Cao, X G; Capelli, S; Carbone, L; Cardani, L; Carrettoni, M; Casali, N; Chiesa, D; Chott, N; Clemenza, M; Cosmelli, C; Cremonesi, O; Creswick, R J; Dafinei, I; Dally, A; Datskov, V; De Biasi, A; Deninno, M M; Di Domizio, S; di Vacri, M L; Ejzak, L; Fang, D Q; Farach, H A; Faverzani, M; Fernandes, G; Ferri, E; Ferroni, F; Fiorini, E; Franceschi, M A; Freedman, S J; Fujikawa, B K; Giachero, A; Gironi, L; Giuliani, A; Goett, J; Gorla, P; Gotti, C; Gutierrez, T D; Haller, E E; Han, K; Heeger, K M; Hennings-Yeomans, R; Huang, H Z; Kadel, R; Kazkaz, K; Keppel, G; Kolomensky, Yu G; Li, Y L; Ligi, C; Liu, X; Ma, Y G; Maiano, C; Maino, M; Martinez, M; Maruyama, R H; Mei, Y; Moggi, N; Morganti, S; Napolitano, T; Nisi, S; Nones, C; Norman, E B; Nucciotti, A; O'Donnell, T; Orio, F; Orlandi, D; Ouellet, J L; Pallavicini, M; Palmieri, V; Pattavina, L; Pavan, M; Pedretti, M; Pessina, G; Pettinacci, V; Piperno, G; Pira, C; Pirro, S; Previtali, E; Rampazzo, V; Rosenfeld, C; Rusconi, C; Sala, E; Sangiorgio, S; Scielzo, N D; Sisti, M; Smith, A R; Taffarello, L; Tenconi, M; Terranova, F; Tian, W D; Tomei, C; Trentalange, S; Ventura, G; Vignati, M; Wang, B S; Wang, H W; Wielgus, L; Wilson, J; Winslow, L A; Wise, T; Woodcraft, A; Zanotti, L; Zarra, C; Zhu, B X; Zucchelli, S

    2014-01-01

    Neutrinoless double beta decay (0nubb) is one of the most sensitive probes for physics beyond the Standard Model, providing unique information on the nature of neutrinos. In this paper we review the status and outlook for bolometric 0nubb decay searches. We summarize recent advances in background suppression demonstrated using bolometers with simultaneous readout of heat and light signals. We simulate several configurations of a future CUORE-like bolometer array which would utilize these improvements and present the sensitivity reach of a hypothetical next-generation bolometric 0nubb experiment. We demonstrate that a bolometric experiment with the isotope mass of about 1 ton is capable of reaching the sensitivity to the effective Majorana neutrino mass (|mee|) of order 10-20 meV, thus completely exploring the so-called inverted neutrino mass hierarchy region. We highlight the main challenges and identify priorities for an R&D program addressing them.

  18. Timescale Stretch Parameterization of Type Ia Supernova B-band Light Curves

    CERN Document Server

    Goldhaber, Gerson; Kim, A; Aldering, G; Astier, Pierre; Conley, A; Deustua, S E; Ellis, R; Fabbro, S; Fruchter, A S; Goobar, A; Hook, I; Irwin, M; Kim, M; Knop, R A; Lidman, C E; McMahon, R; Nugent, P; Pain, R; Panagia, N; Pennypacker, C R; Perlmutter, S; Ruiz-Lapuente, P; Schaefer, B; Walton, N A; York, T; Project, The Supernova Cosmology

    2001-01-01

    R-band intensity measurements along the light curve of Type Ia supernovae discovered by the Supernova Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w = s(1+z). The data points are then individually aligned in the time-axis, normalized and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve which we call the ``composite curve''. The same procedure is applied to 18 low-redshift Calan/Tololo SNe with z < 0.11; these nearly 300 B-band photometry points are found to lie on the composite curve equally well. The SCP search technique produces several measurements before maximum light for each supernova. We demonstrate that the linear stretch factor, s, which parameterizes the light-curve timescale appears independent of z,and applies equally well to the declining and rising parts of the light curve. In fact, the B-band template that ...

  19. A novel method for designing dichroic color filter transmittance curves for lighting applications

    Science.gov (United States)

    Qi, Rui; Shum, Frank

    2014-09-01

    This paper focuses on designing dichroic filters for changing the color of light-emitting diode (LED) lamps. Dichroic filters are composed of multiple dielectric layers on a substrate. By applying a dichroic filter, some of the LED's spectral energy is reflected and some is transmitted, which changes the lamp's color. Conventional methods to obtain spectral transmittance curves have shortcomings. The design criteria for the transmittance curves are incompatible with the metrics used in lighting applications, such as correlated color temperature (CCT) and color rendering index (CRI). Thus, the color rendering performance and the optical transmission of a lighting system are not optimized. This observation leads to the development of a proposed method for designing dichroic filter transmittance curves to provide accurate color shift, high CRI, and sufficient optical transmission. The method initially uses the transmittance curve of an existing color filter that provides a roughly close color shift for the LED lamp to calculate the transmittance curve that causes an accurate color shift by polynomial approximation. Based on the approximated curve, a preliminary transmittance curve without the effect of the LED lamp's secondary optics is derived and verified in thin-film design and optical design software tools. Further, the derived preliminary transmittance curve is optimized by applying an algorithm to loop through a large amount of representative curves fluctuating near the preliminary curve. The resulting dichroic filter provides an accurate color shift (ΔCCT = -800±50K, Duv = ±0.003), high CRI (Ra and R9 <= 95), and sufficient luminous flux transmission (<= 70%).

  20. Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding

    Science.gov (United States)

    Matijevič, Gal; Prša, Andrej; Orosz, Jerome A.; Welsh, William F.; Bloemen, Steven; Barclay, Thomas

    2012-05-01

    We present an automated classification of 2165 Kepler eclipsing binary (EB) light curves that accompanied the second Kepler data release. The light curves are classified using locally linear embedding, a general nonlinear dimensionality reduction tool, into morphology types (detached, semi-detached, overcontact, ellipsoidal). The method, related to a more widely used principal component analysis, produces a lower-dimensional representation of the input data while preserving local geometry and, consequently, the similarity between neighboring data points. We use this property to reduce the dimensionality in a series of steps to a one-dimensional manifold and classify light curves with a single parameter that is a measure of "detachedness" of the system. This fully automated classification correlates well with the manual determination of morphology from the data release, and also efficiently highlights any misclassified objects. Once a lower-dimensional projection space is defined, the classification of additional light curves runs in a negligible time and the method can therefore be used as a fully automated classifier in pipeline structures. The classifier forms a tier of the Kepler EB pipeline that pre-processes light curves for the artificial intelligence based parameter estimator.

  1. Accretion Disc Time Lag Distributions: Applying CREAM to Simulated AGN Light Curves

    CERN Document Server

    Starkey, David; Villforth, Carolin

    2015-01-01

    Active Galactic Nuclei (AGN) vary in their brightness across all wavelengths. Moreover, longer wavelength ultraviolet - optical continuum light curves appear to be delayed with respect to shorter wavelength light curves. A simple way to model these delays is by assuming thermal reprocessing of a variable point source (a lamp post) by a blackbody accretion disc. We introduce a new method, CREAM (\\textbf{C}ontinuum \\textbf{RE}processed \\textbf{A}GN \\textbf{M}arkov Chain Monte Carlo), that models continuum variations using this lamp post model. The disc light curves lag the lamp post emission with a time delay distribution sensitive to the disc temperature-radius profile and inclination. We test CREAM's ability to recover both inclination and product of black hole mass and accretion rate $\\mmdot$, and show that the code is also able to infer the shape of the driving light curve. CREAM is applied to synthetic light curves expected from 1000 second exposures of a 17th magnitude AGN with a 2m telescope in Sloan g a...

  2. Supernova 2013by: A Type IIL Supernova with a IIP-like light curve drop

    CERN Document Server

    Valenti, S; Stritzinger, M; Howell, D A; Arcavi, I; McCully, C; Childress, M J; Hsiao, E Y; Contreras, C; Morrell, N; Phillips, M M; Gromadzki, M; Kirshner, R P; Marion, G H

    2015-01-01

    We present multi-band ultraviolet and optical light curves, as well as visual-wavelength and near-infrared spectroscopy of the Type II linear (IIL) supernova (SN) 2013by. We show that SN 2013by and other SNe IIL in the literature, after their linear decline phase that start after maximum, have a sharp light curve decline similar to that seen in Type II plateau (IIP) supernovae. This light curve feature has rarely been observed in other SNe IIL due to their relative rarity and the intrinsic faintness of this particular phase of the light curve. We suggest that the presence of this drop could be used as a physical parameter to distinguish between subclasses of SNe II, rather than their light curve decline rate shortly after peak. Close inspection of the spectra of SN 2013by indicate asymmetric line profiles and signatures of high-velocity hydrogen. Late (less than 90 days after explosion) near-infrared spectra of SN 2013by exhibit oxygen lines, indicating significant mixing within the ejecta. From the late-time...

  3. A FOURIER OPTICS METHOD FOR CALCULATING STELLAR OCCULTATION LIGHT CURVES BY OBJECTS WITH THIN ATMOSPHERES

    International Nuclear Information System (INIS)

    A stellar occultation occurs when a solar system object passes in front of a distant star. The light curves resulting from stellar occultations can reveal many aspects of the obscuring object. For airless bodies, the diffraction light curve specifies the object's size, distance and, if several chords are observed, shape. Occultation light curves are especially sensitive to the presence of atmospheres; the refraction light curve is a function of the atmosphere's density, pressure, and temperature profiles. The goal of this paper is to develop a practical algorithm to model the simultaneous effects of diffraction and refraction for objects in which both phenomena are observable. The algorithm we present is flexible: it can be used to calculate light curves by objects with arbitrary shapes and arbitrary atmospheres (including the presence of opacity sources such as hazes), provided that the atmosphere can be represented by a thin screen with a phase delay and an opacity defined at each location in the screen. Because the algorithm is limited at present to thin atmospheres (in which rays from a star are bent but undergo virtually no translation as they pass through an atmosphere), the gas giants, Earth, Mars, and Venus are not treated. Examples of stellar occultations are presented for round or irregularly shaped objects having thin atmospheres of various column densities.

  4. Long-Term Light Curve of Highly-Variable Protostellar Star GM Cep

    CERN Document Server

    Xiao, Limin; Henden, Arne A

    2010-01-01

    We present data from the archival plates at Harvard College Observatory and Sonneberg Observatory showing the field of the solar type pre-main sequence star GM Cep. A total of 186 magnitudes of GM Cep have been measured on these archival plates, with 176 in blue sensitivity, 6 in visible, and 4 in red. We combine our data with data from the literature and from the American Association of Variable Star Observers to depict the long-term light curves of GM Cep in both B and V wavelengths. The light curves span from 1895 until now, with two densely sampled regions (1935 to 1945 in B band, and 2006 until now in V band). The long-term light curves do not show any fast rise behavior as predicted by an accretion mechanism. Both the light curves and the magnitude histograms confirm the conclusion that the light curves are dominated by dips (possibly from extinction) superposed on some quiescence state, instead of outbursts caused by accretion flares.Our result excludes the possibility of GM Cep being a FUor, EXor, or ...

  5. Simultaneous Modelling of the Complete SN1993J Expansion and Radio Light Curves

    Science.gov (United States)

    Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.

    We report on our modelling of all the available VLBI data and radio light curves of supernova SN1993J. We have used the most complete expansion curve of a supernova ever, which spans more than a decade at several frequencies. For the data modelling, we have developed a new software capable of simulating the evolution of the radio emission of a supernova. We find that for explaining both the radio light curves and the expansion curve simultaneously, a radial structure of the magnetic field inside the radiating region and opacity effects from the ejected material have to be considered, together with a constant pre-supernova mass-loss rate (contrary to some results found by other authors).

  6. Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds

    Institute of Scientific and Technical Information of China (English)

    Xue-Feng Wu; Zi-Gao Dai; Yong-Feng Huang; Hai-Tao Ma

    2004-01-01

    Optical and radio afterglows arising from shocks by relativistic conical ejecta running into pre-burst massive stellar winds are revisited. Under the homogeneous thin-shell approximation and a realistic treatment for the lateral expansion of jets, our results show that a notable break exists in the optical light curve in most cases we calculated in which the physical parameters are varied within reasonable ranges. For a relatively tenuous wind which cannot decelerate the relativistic jet to cause a light curve break within days, the wind termination shock due to the ram pressure of the surrounding medium occurs at a small radius, namely, a few times 1017 cm. In such a structured wind environment, the jet will pass through the wind within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and then declines deeply, triggered by runaway lateral expansion.

  7. Nova light curves from the Solar Mass Ejection Imager (SMEI) - II. The extended catalog

    CERN Document Server

    Hounsell, R; Bode, M F; Harman, D J; Surina, F; Starrfield, S; Holdsworth, D L; Bewsher, D; Hick, P P; Jackson, B V; Buffington, A; Clover, J M; Shafter, A W

    2015-01-01

    We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time (t2). Interestingly, although of lower quality than those found in Hounsell et al. (2010a), two of the light curves may indicate the presence of a pre-maximum halt. In addition the high cadence of the SMEI instrument has allowed the detection of low amplitude variations in at least one of the nova light curves.

  8. An efficient method to compute microlensed light curves for point sources

    Science.gov (United States)

    Witt, Hans J.

    1993-01-01

    We present a method to compute microlensed light curves for point sources. This method has the general advantage that all microimages contributing to the light curve are found. While a source moves along a straight line, all micro images are located either on the primary image track or on the secondary image tracks (loops). The primary image track extends from - infinity to + infinity and is made of many sequents which are continuously connected. All the secondary image tracks (loops) begin and end on the lensing point masses. The method can be applied to any microlensing situation with point masses in the deflector plane, even for the overcritical case and surface densities close to the critical. Furthermore, we present general rules to evaluate the light curve for a straight track arbitrary placed in the caustic network of a sample of many point masses.

  9. AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves

    CERN Document Server

    Collins, Karen A; Stassun, Keivan G

    2016-01-01

    ImageJ is a graphical user interface (GUI) driven, public domain, Java-based, software package for general image processing traditionally used mainly in life sciences fields. The image processing capabilities of ImageJ are useful and extendable to other scientific fields. Here we present AstroImageJ (AIJ), which provides an astronomy specific image display environment and tools for astronomy specific image calibration and data reduction. Although AIJ maintains the general purpose image processing capabilities of ImageJ, AIJ is streamlined for time-series differential photometry, light curve detrending and fitting, and light curve plotting, especially for applications requiring ultra-precise light curves (e.g., exoplanet transits). AIJ reads and writes standard FITS files, as well as other common image formats, provides FITS header viewing and editing, and is World Coordinate System (WCS) aware, including an automated interface to the astrometry.net web portal for plate solving images. Although AIJ provides re...

  10. Phenomenological Modeling of the Light Curves of Algol-Type Eclipsing Binary Stars

    CERN Document Server

    Andronov, Ivan L

    2012-01-01

    We introduce a special class of functions for mathematical modeling of periodic signals of special shape with irregularly spaced arguments. This method was developed for determination of phenomenological characteristics of the light curves, which are necessary for registration in the "General Catalogue of Variable Stars" and other databases. For eclipsing binary stars with smooth light curves - of types EB and EW - it is recommended a trigonometric polynomial of optimal degree in a complete or symmetric form. For eclipsing binary systems with relatively narrow minima (EA-type), statistically optimal is an approximation of the light curves in a class of non-polynomial spline functions. It is used a combination of the second-order trigonometric polynomial (TP2, what describes effects of "reflection", "ellipsoidality" and "spotness") and localized contibutions of minima (parametrized in depth and profile separately for primary and secondary minima). Effectivity of the proposed method increases with decreasing ec...

  11. Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding

    CERN Document Server

    Matijevic, Gal; Orosz, Jerome A; Welsh, William F; Bloemen, Steven; Barclay, Thomas

    2012-01-01

    We present an automated classification of 2165 \\textit{Kepler} eclipsing binary (EB) light curves that accompanied the second \\textit{Kepler} data release. The light curves are classified using Locally Linear Embedding, a general nonlinear dimensionality reduction tool, into morphology types (detached, semi-detached, overcontact, ellipsoidal). The method, related to a more widely used Principal Component Analysis, produces a lower-dimensional representation of the input data while preserving local geometry and, consequently, the similarity between neighboring data points. We use this property to reduce the dimensionality in a series of steps to a one-dimensional manifold and classify light curves with a single parameter that is a measure of "detachedness" of the system. This fully automated classification correlates well with the manual determination of morphology from the data release, and also efficiently highlights any misclassified objects. Once a lower-dimensional projection space is defined, the classif...

  12. Exploring the Variable Sky with LINEAR. III. Classification of Periodic Light Curves

    Science.gov (United States)

    Palaversa, Lovro; Ivezić, Željko; Eyer, Laurent; Ruždjak, Domagoj; Sudar, Davor; Galin, Mario; Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana; Božić, Hrvoje; Loebman, Sarah; Sesar, Branimir; Rimoldini, Lorenzo; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Stuart, J. Scott; Becker, Andrew C.; Srdoč, Gregor; Wozniak, Przemyslaw; Oluseyi, Hakeem

    2013-10-01

    We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ~0.03 mag at r = 15 to ~0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ~200,000 most probable candidate variables with r learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median period increases from 5.9 hr to 8.8 hr. These large samples of robustly classified variable stars will enable detailed statistical studies of the Galactic structure and physics of binary and other stars and we make these samples publicly available.

  13. Light Curves and Spectra from a Thermonuclear Explosion of a White Dwarf Merger

    Science.gov (United States)

    van Rossum, Daniel R.; Kashyap, Rahul; Fisher, Robert; Wollaeger, Ryan T.; García-Berro, Enrique; Aznar-Siguán, Gabriela; Ji, Suoqing; Lorén-Aguilar, Pablo

    2016-08-01

    Double-degenerate (DD) mergers of carbon-oxygen white dwarfs have recently emerged as a leading candidate for normal Type Ia supernovae (SNe Ia). However, many outstanding questions surround DD mergers, including the characteristics of their light curves and spectra. We have recently identified a spiral instability in the post-merger phase of DD mergers and demonstrated that this instability self-consistently leads to detonation in some cases. We call this the spiral merger SN Ia model. Here, we utilize the SuperNu radiative transfer software to calculate three-dimensional synthetic light curves and spectra of the spiral merger simulation with a system mass of 2.1 {M}⊙ from Kashyap et al. Because of their large system masses, both violent and spiral merger light curves are slowly declining. The spiral merger resembles very slowly declining SNe Ia, including SN 2001ay, and provides a more natural explanation for its observed properties than other SN Ia explosion models. Previous synthetic light curves and spectra of violent DD mergers demonstrate a strong dependence on viewing angle, which is in conflict with observations. Here, we demonstrate that the light curves and spectra of the spiral merger are less sensitive to the viewing angle than violent mergers, in closer agreement with observation. We find that the spatial distribution of 56Ni and IMEs follows a characteristic hourglass shape. We discuss the implications of the asymmetric distribution of 56Ni for the early-time gamma-ray observations of 56Ni from SN 2014J. We suggest that DD mergers that agree with the light curves and spectra of normal SNe Ia will likely require a lower system mass.

  14. A precise distance indicator type Ia supernova multicolor light curve shapes

    CERN Document Server

    Riess, A; Kirshner, R P; Riess, Adam; Press, William; Kirshner, Robert

    1996-01-01

    We present an empirical method that uses multicolor light curve shapes (MLCS) to estimate the luminosity, distance, and total line-of-sight extinction of Type Ia supernovae (SN Ia). The empirical correlation between the MLCS and the luminosity is derived from a 'training set' of nine SN Ia light curves with independent distance and reddening estimates. We find that intrinsically dim SN Ia are redder and have faster light curves than the bright ones which are slow and blue. By thirty-five days after maximum the intrinsic color variations become negligible. A formal treatment of extinction employing Bayes' theorem is used to estimate the best value and its uncertainty. Applying MLCS to both light curves and to color curves provides enough information to determine which supernovae are dim because they are distant, which are intrinsically dim, and which are dim because of extinction by dust. The precision of the MLCS distances is examined by constructing a Hubble diagram with an independent set of twenty SN Ia's....

  15. Light Curve Stability and Period Behavior of the Contact Binary TZ Boo

    Indian Academy of Sciences (India)

    M. M. Elkhateeb; M. I. Nouh

    2013-12-01

    New CCD observations of the eclipsing binary TZ Boo in BVR bands were carried out in 2006 (presented three new minima) and used together with all published minima to study and update the orbital period of the system TZ Boo by means of an (O–C) diagram. The period variation from 1926 to 2011 is represented by polynomial of eighth degree and indicates period variation of about 9.752 × 10-10 days/yr. We studied light curve stability over 85 yr covering all published observations in the V band and confirm the cyclic light curve variations.

  16. The Varying Light Curve and Timings of the Ultra-short Period Contact Binary KIC 9532219

    CERN Document Server

    Lee, Jae Woo; Koo, Jae-Rim; Park, Jang-Ho

    2016-01-01

    KIC 9532219 is a W UMa-type eclipsing binary with an orbital period of 0.1981549 d that is below the short-period limit ($\\sim$0.22 d) of the period distribution for contact binaries. The {\\it Kepler} light curve of the system exhibits striking light changes in both eclipse depths and light maxima. Applying third-body and spot effects, the light-curve synthesis indicates that the eclipsing pair is currently in a marginal contact stage with a mass ratio of $q$=1.20, an orbital inclination of $i$=66.0 deg, a temperature difference of $\\Delta$ ($T_{1}$--$T_{2}$)=172 K, and a third light of $l_3$=75.9 \\%. To understand the light variations with time, we divided up the light curve into 312 segments and separately analyzed them. The results reveal that variation of eclipse depth is primarily caused by changing amounts of contamination due to the nearby star KIC9532228 between the {\\it Kepler} Quarters and that the variable O'Connell effect originates from the starspot activity on the less massive primary component....

  17. Gamma-Ray Pulsar Light Curves in Offset Polar Cap Geometry

    Science.gov (United States)

    Harding, Alice K.; DeCesar, Megan; Miller, M. Coleman

    2011-01-01

    Recent studies have shown that gamma-ray pulsar light curves are very sensitive to the geometry of the pulsar magnetic field. Pulsar magnetic field geometries, such as the retarded vacuum dipole and force-free magnetospheres, used to model high-energy light curves have distorted polar caps that are offset from the magnetic axis in the direction opposite to rotation. Since this effect is due to the sweepback of field lines near the light cylinder, offset polar caps are a generic property of pulsar magnetospheres and their effects should be included in gamma-ray pulsar light curve modeling. In slot gap models (having two-pole caustic geometry), the offset polar caps cause a strong azimuthal asymmetry of the particle acceleration around the magnetic axis. We have studied the effect of the offset polar caps in both retarded vacuum dipole and force-free geometry on the model high-energy pulse profile. We find that. corn pared to the profile:-; derived from :-;ymmetric caps, the flux in the pulse peaks, which are caustics formed along the trailing magnetic field lines. increases significantly relative to the off-peak emission. formed along leading field lines. The enhanced contrast produces greatly improved slot gap model fits to Fermi pulsar light curves like Vela, which show very little off-peak emIssIon.

  18. The model parameters of the mean light curves of the variable red giant stars in the near infrared colour-bands and compare them with the visual mean light curves

    CERN Document Server

    Kudashkina, L S

    2016-01-01

    The observational data of the near infrared bands (H and K) have been used for the modeling mean light curves. Also the visual observational data have been fitted the same. The infrared and visual mean light curves were compared. All parameters and Fourier-coefficients of the mean light curves were obtained. The periodogram analysis of the variation of the brightness have been carried out.

  19. THE VARYING LIGHT CURVE AND TIMINGS OF THE ULTRASHORT-PERIOD CONTACT BINARY KIC 9532219

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim; Park, Jang-Ho, E-mail: jwlee@kasi.re.kr, E-mail: kshong@kasi.re.kr, E-mail: koojr@kasi.re.kr, E-mail: pooh107162@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of)

    2016-03-20

    KIC 9532219 is a W UMa-type eclipsing binary with an orbital period of 0.1981549 days that is below the short-period limit (∼0.22 days) of the period distribution for contact binaries. The Kepler light curve of the system exhibits striking changes in both eclipse depths and light maxima. Applying third-body and spot effects, the light-curve synthesis indicates that the eclipsing pair is currently in a marginal contact stage with a mass ratio of q = 1.20, an orbital inclination of i = 66.°0, a temperature difference of T{sub 1}–T{sub 2} = 172 K, and a third light of l{sub 3} = 75.9%. To understand the light variations with time, we divided up the light curve into 312 segments and analyzed them separately. The results reveal that variation of eclipse depth is primarily caused by changing amounts of contamination due to the nearby star KIC 9532228 between the Kepler Quarters and that the variable O’Connell effect originates from the starspot activity on the less massive primary component. Based on our light-curve timings, a period study of KIC 9532219 indicates that the orbital period has varied as a combination of a downward parabola and a light-travel-time (LTT) effect due to a third body, which has a period of 1196 days and a minimum mass of 0.0892 M{sub ⊙} in an orbit of eccentricity 0.150. The parabolic variation could be a small part of a second LTT orbit due to a fourth component in a wider orbit, instead of either mass transfer or angular momentum loss.

  20. SHOCK BREAKOUT AND EARLY LIGHT CURVES OF TYPE II-P SUPERNOVAE OBSERVED WITH KEPLER

    Energy Technology Data Exchange (ETDEWEB)

    Garnavich, P. M. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN, 46556-5670 (United States); Tucker, B. E. [The Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, via Cotter Road, Weston Creek, ACT 2611 (Australia); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Shaya, E. J.; Olling, R. P. [Astronomy Department, University of Maryland, College Park, MD 20742-2421 (United States); Kasen, D [Department of Physics and Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Villar, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-03-20

    We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae (SNe II-P). Using the fast cadence of the Kepler observations we precisely estimate the rise time to maximum for KSN2011a and KSN2011d as 10.5 ± 0.4 and 13.3 ± 0.4 rest-frame days, respectively. Based on fits to idealized analytic models, we find the progenitor radius of KSN2011a (280 ± 20 R{sub ⊙}) to be significantly smaller than that for KSN2011d (490 ± 20 R{sub ⊙}), but both have similar explosion energies of 2.0 ± 0.3 × 10{sup 51} erg. The rising light curve of KSN2011d is an excellent match to that predicted by simple models of exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models predict, possibly due to the supernova shock wave moving into pre-existing wind or mass-loss from the RSG. A mass-loss rate of 10{sup −4}M{sub ⊙} yr{sup −1} from the RSG can explain the fast rise without impacting the optical flux at maximum light or the shape of the post-maximum light curve. No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar interaction suspected in the fast rising light curve. The early light curve of KSN2011d does show excess emission consistent with model predictions of a shock breakout. This is the first optical detection of a shock breakout from a SNe II-P.

  1. A SIGNATURE OF CHEMICAL SEPARATION IN THE COOLING LIGHT CURVES OF TRANSIENTLY ACCRETING NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Medin, Zach [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Cumming, Andrew, E-mail: zmedin@lanl.gov, E-mail: cumming@physics.mcgill.ca [Department of Physics, McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada)

    2014-03-01

    We show that convection driven by chemical separation can significantly affect the cooling light curves of accreting neutron stars after they go into quiescence. We calculate the thermal relaxation of the neutron star ocean and crust including the thermal and compositional fluxes due to convection. After the inward propagating cooling wave reaches the base of the neutron star ocean, the ocean begins to freeze, driving chemical separation. The resulting convection transports heat inward, giving much faster cooling of the surface layers than found assuming the ocean cools passively. The light curves including convection show a rapid drop in temperature weeks after outburst. Identifying this signature in observed cooling curves would constrain the temperature and composition of the ocean as well as offer a real time probe of the freezing of a classical multicomponent plasma.

  2. Light intensity distribution calculation of curved surface diffraction patterns applied in ICF

    International Nuclear Information System (INIS)

    Conventional numerical methods of diffractive calculation are usually for the plane, and they are infeasible when the diffraction field applied in ICF is curved surface. In this paper, a method based on the idea of layering calculation, combining the algorithm of fast Fourier transform (FFT) with the technology of numerical fitting, has been proposed to calculate the light intensity distribution on the curved observation surface. This method can be applied to the surface with arbitrary shape, and it has comparatively high accuracy at fast calculation speed. The computation results show that the accuracy is improved as the layer number increases, and thus the method can effectively realize the light intensity distribution calculation of curved surface diffraction patterns applied in ICF. (authors)

  3. The Kepler Light Curve of V344 Lyrae: Constraining the Thermal-viscous Limit Cycle Instability

    Science.gov (United States)

    Cannizzo, J. K.; Still, M. D.; Howell, S. B.; Wood, M. A.; Smale, A. P.

    2010-12-01

    We present time-dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short-period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long-term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate ~12 d mag-1, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the main features of the V344 Lyr light curve, including the peak outburst brightness. Nevertheless, there are obvious deficiencies in our model light curves. (1) The rise times we calculate, both for the normal and superoutbursts, are too fast. (2) The superoutbursts are too short. (3) The shoulders on the rise to superoutburst have more structure than the shoulders in the observed superoutbursts and are too slow, comprising about a third to half of the total viscous plateau, rather than the ~10% observed. However, one of the αcold αhot interpolation schemes we investigate (one that is physically motivated) does yield longer superoutbursts with suitably short, less structured shoulders.

  4. The Kepler Light Curve of V344 Lyrae: Constraining the Thermal-Viscous Limit Cycle Instability

    CERN Document Server

    Cannizzo, J K; Howell, S B; Wood, M A; Smale, A P

    2010-01-01

    We present time dependent modeling based on the accretion disk limit cycle model for a 270 d light curve of the short period SU UMa-type dwarf nova V344 Lyr taken by Kepler. The unprecedented precision and cadence (1 minute) far surpass that generally available for long term light curves. The data encompass two superoutbursts and 17 normal (i.e., short) outbursts. The main decay of the superoutbursts is nearly perfectly exponential, decaying at a rate ~12 d/mag, while the much more rapid decays of the normal outbursts exhibit a faster-than-exponential shape. Our modeling using the basic accretion disk limit cycle can produce the main features of the V344 Lyr light curve, including the peak outburst brightness. Nevertheless there are obvious deficiencies in our model light curves: (1) The rise times we calculate, both for the normal and superoutbursts, are too fast. (2) The superoutbursts are too short. (3) The shoulders on the rise to superoutburst have more structure than the shoulder in the observed superou...

  5. Light Curves and Spectra from a Thermonuclear Explosion of a White Dwarf Merger

    CERN Document Server

    van Rossum, Daniel R; Fisher, Robert; Wollaeger, Ryan T; Garcia-Berro, Enrique; Aznar-Siguan, Gabriela; Ji, Suoqing; Loren-Aguilar, Pablo

    2015-01-01

    Double-degenerate (DD) mergers of carbon-oxygen (CO) white dwarfs have recently emerged as a leading candidate for normal Type Ia supernovae (SNe Ia). However, many outstanding questions surround DD mergers, including the characteristics of their light curves and spectra. We have recently identified a spiral instability in the post-merger phase of DD mergers, and demonstrated that this instability self-consistently leads to detonation in some cases. We call this the spiral merger SN Ia model. Here, we utilize the \\supernu\\ radiative transfer software to calculate 3D synthetic light curves and spectra of the spiral merger simulation with a system mass of 2.1 $M_\\odot$ of Kashyap et al. 2015. Because of their large system masses, both violent and spiral merger light curves are slowly declining. The spiral merger resembles very slowly-declining SNe Ia, including SN 2001ay, and provides a more natural explanation for its observed properties than other SN Ia explosion models. Previous synthetic light curves and sp...

  6. Exploring the Potential Diversity of Early Type Ia Supernova Light Curves

    Science.gov (United States)

    Piro, Anthony L.; Morozova, Viktoriya S.

    2016-07-01

    During the first several days after explosion, Type Ia supernova light curves probe the outer layers of the exploding star, and therefore provide important clues for identifying their progenitors. We investigate how both the shallow 56Ni distribution and the presence of circumstellar material shape these early light curves. This is performed using a series of numerical experiments with parameterized properties for systematic exploration. Although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. We find that shallower 56Ni leads to steeper, bluer light curves. Differences in the shape of the rise can introduce errors in estimating the explosion time, and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. Circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. In some cases, the hot emission of circumstellar material may even lead to a signature similar to an interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves.

  7. Search for light curve modulations among Kepler candidates. Three very low-mass transiting companions

    CERN Document Server

    Lillo-Box, J; Barrado, D; Merín, B; Bouy, H

    2016-01-01

    Light curve modulations in the sample of Kepler planet candidates allows the disentangling of the nature of the transiting object by photometrically measuring its mass. This is possible by detecting the effects of the gravitational pull of the companion (ellipsoidal modulations) and in some cases, the photometric imprints of the Doppler effect when observing in a broad band (Doppler beaming). We aim to photometrically unveil the nature of some transiting objects showing clear modulations in the phase-folded Kepler light curve. We selected a subsample among the large crop of Kepler objects of interest (KOIs) based on their chances to show detectable light curve modulations, i.e., close ($a<12~R_{\\star}$) and large (in terms of radius) candidates. We modeled their phase-folded light curves with consistent equations for the three effects, namely, reflection, ellipsoidal and beaming (known as REB modulations). We provide detailed general equations for the fit of the REB modulations for the case of eccentric or...

  8. Disentangling planetary and stellar activity features in the CoRoT-2 light curve

    CERN Document Server

    Bruno, G; Almenara, J -M; Barros, S C C; Lanza, A F; Montalto, M; Boisse, I; Santerne, A; Lagrange, A -M; Meunier, N

    2016-01-01

    [Abridged] Context. Stellar activity is an important source of systematic errors and uncertainties in the characterization of exoplanets. Most of the techniques used to correct for this activity focus on an ad hoc data reduction. Aims. We have developed a software for the combined fit of transits and stellar activity features in high-precision long-duration photometry. Our aim is to take advantage of the modelling to derive correct stellar and planetary parameters, even in the case of strong stellar activity. Methods. We use an analytic approach to model the light curve. The code KSint, modified by adding the evolution of active regions, is implemented into our Bayesian modelling package PASTIS. The code is then applied to the light curve of CoRoT-2. The light curve is divided in segments to reduce the number of free parameters needed by the fit. We perform a Markov chain Monte Carlo analysis in two ways. In the first, we perform a global and independent modelling of each segment of the light curve, transits ...

  9. Fractal Property in the Light Curve of BL Lac Object S5 0716+714

    Indian Academy of Sciences (India)

    J. W. Ou; Y. G. Zheng

    2014-09-01

    In this paper, we compile the historical R-band data of S5 0716+714 from literature and obtain its fractal dimension by using a fractal method and then simulate the data with the Weierstrass–Mandelbrot (W–M) function. It is considered that the light curve has a fractal property.

  10. An 8 hour characteristic time-scale in submillimetre light curves of Sagittarius A*

    CERN Document Server

    Dexter, Jason; Bower, Geoffrey C; Marrone, Daniel P; Stone, Jordan; Plambeck, Richard; Doeleman, Sheperd S

    2013-01-01

    We compile and analyse long term (~10 year) submillimetre (1.3, 0.87, 0.43 mm, submm) wavelength light curves of the Galactic centre black hole, Sagittarius A*. The 0.87 and 0.43 mm data are taken from the literature, while the majority of the 1.3 mm light curve is from previously unpublished SMA and CARMA data. We use Monte Carlo simulations to show that on minute to few hour time-scales the variability is consistent with a red noise process with a 230 GHz power spectrum slope of 2.3+0.8-0.6 at 95% confidence. The light curve is de-correlated (white noise) on very long (month to year) times. In order to identify the transition time between red and white noise, we model the light curves as a stochastic damped random walk process. The models allow a quantitative estimate of this physical characteristic time-scale of 8-4+3 hours at 230 GHz at 95% confidence, with consistent results at 345 and 690 GHz. This corresponds to ~10 orbital times or ~1 inflow (viscous) time at R = 3 Rs, a typical radius producing the 2...

  11. Light curve modeling of eclipsing binaries towards the constellation of Carina

    CERN Document Server

    Dey, Aniruddha; Kumar, Subhash; Bhardwaj, Hrishabh; Bhattacharya, Barnmoy; Richa,; Sharma, Angad; Chauhan, Akshyata; Tiwari, Neha; Kaur, Sharanjit; Kumar, Suman; Abhishek,

    2015-01-01

    We present a detailed V-band photometric light curve modeling of 30 eclipsing binaries using the data from Pietrukowicz et al. (2009) collected with the European Southern Observatory Very Large Telescope (ESO VLT) of diameter 8-m. The light curve of these 30 eclipsing binaries were selected out of 148 of them available in the database on the basis of complete phase coverage, regular and smooth phased light curve shapes. Eclipsing binaries play pivotal role in the direct measurement of astronomical distances more accurately simply from their geometry of light curves. The accurate value of Hubble constant (H0) which measures the rate of expansion of the Universe heavily relies on extragalactic distance scale measurements. Classification of the selected binary stars in the sample were done, preliminarily on the basis of Fourier parameters in the a2-a4 plane and final classification was obtained from the Roche lobe geometry. Out of these 30 eclipsing binaries, only one was found to be detached binary system while...

  12. EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Palaversa, Lovro; Eyer, Laurent; Rimoldini, Lorenzo [Observatoire Astronomique de l' Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Ivezić, Željko; Loebman, Sarah; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Becker, Andrew C. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States); Ruždjak, Domagoj; Sudar, Davor; Božić, Hrvoje [Hvar Observatory, Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Galin, Mario [Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana [Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Srdoč, Gregor, E-mail: lovro.palaversa@unige.ch [Saršoni 90, 51216 Viškovo (Croatia); and others

    2013-10-01

    We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg{sup 2} of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the

  13. EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES

    International Nuclear Information System (INIS)

    We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median

  14. THE INFORMATION CONTENT IN ANALYTIC SPOT MODELS OF BROADBAND PRECISION LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08534 (United States); Basri, Gibor [Astronomy Department, University of California at Berkeley, Hearst Field Annex, Berkeley, CA 94720 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)

    2013-04-01

    We present the results of numerical experiments to assess degeneracies in light curve models of starspots. Using synthetic light curves generated with the Cheetah starspot modeling code, we explore the extent to which photometric light curves constrain spot model parameters, including spot latitudes and stellar inclination. We also investigate the effects of spot parameters and differential rotation on one's ability to correctly recover rotation periods and differential rotation in the Kepler light curves. We confirm that in the absence of additional constraints on the stellar inclination, such as spectroscopic measurements of vsin i or occultations of starspots by planetary transits, the spot latitude and stellar inclination are difficult to determine uniquely from the photometry alone. We find that for models with no differential rotation, spots that appear on opposite hemispheres of the star may cause one to interpret the rotation period to be half of the true period. When differential rotation is included, the changing longitude separation between spots breaks the symmetry of the hemispheres and the correct rotation period is more likely to be found. The dominant period found via periodogram analysis is typically that of the largest spot. Even when multiple spots with periods representative of the star's differential rotation exist, if one spot dominates the light curve the signal of differential rotation may not be detectable from the periodogram alone. Starspot modeling is applicable to stars with a wider range of rotation rates than other surface imaging techniques (such as Doppler imaging), allows subtle signatures of differential rotation to be measured, and may provide valuable information on the distribution of stellar spots. However, given the inherent degeneracies and uncertainty present in starspot models, caution should be exercised in their interpretation.

  15. CSI 2264: characterizing accretion-burst dominated light curves for young stars in NGC 2264

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Baglin, Annie [LESIA, Observatoire de Paris-Meudon, 5 place Jules Janssen, F-92195, Meudon (France); Alencar, Silvia [Departamento de Física-ICEx-UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Hillenbrand, Lynne A.; Carpenter, John; Findeisen, Krzysztof [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Venuti, Laura; Bouvier, Jerome [UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Plavchan, Peter [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, María [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, P.O. Box 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Micela, Giusi; Flaccomio, Ettore [INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States); Gutermuth, Rob [Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States); Hartmann, Lee, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States); and others

    2014-04-01

    Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief—several hours to one day—brightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u – g versus g – r color-color diagram with the largest UV excesses. These stars also have large Hα equivalent widths, and either centrally peaked, lumpy Hα emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest Hα equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.

  16. Search for light curve modulations among Kepler candidates. Three very low-mass transiting companions

    Science.gov (United States)

    Lillo-Box, J.; Ribas, A.; Barrado, D.; Merín, B.; Bouy, H.

    2016-07-01

    Context. Light curve modulations in the sample of Kepler planet candidates allows the disentangling of the nature of the transiting object by photometrically measuring its mass. This is possible by detecting the effects of the gravitational pull of the companion (ellipsoidal modulations) and in some cases, the photometric imprints of the Doppler effect when observing in a broad band (Doppler beaming). Aims: We aim to photometrically unveil the nature of some transiting objects showing clear light curve modulations in the phase-folded Kepler light curve. Methods: We selected a subsample among the large crop of Kepler objects of interest (KOIs) based on their chances to show detectable light curve modulations, i.e., close (a< 12 R⋆) and large (in terms of radius, according to their transit signal) candidates. We modeled their phase-folded light curves with consistent equations for the three effects, namely, reflection, ellipsoidal and beaming (known as REB modulations). Results: We provide detailed general equations for the fit of the REB modulations for the case of eccentric orbits. These equations are accurate to the photometric precisions achievable by current and forthcoming instruments and space missions. By using this mathematical apparatus, we find three close-in very low-mass companions (two of them in the brown dwarf mass domain) orbiting main-sequence stars (KOI-554, KOI-1074, and KOI-3728), and reject the planetary nature of the transiting objects (thus classifying them as false positives). In contrast, the detection of the REB modulations and transit/eclipse signal allows the measurement of their mass and radius that can provide important constraints for modeling their interiors since just a few cases of low-mass eclipsing binaries are known. Additionally, these new systems can help to constrain the similarities in the formation process of the more massive and close-in planets (hot Jupiters), brown dwarfs, and very low-mass companions.

  17. Four color light curves and period changes investigation of the contact binary BX Peg

    Science.gov (United States)

    Li, Kai; Hu, Shaoming; Guo, Difu; Jiang, Yunguo; Gao, Dongyang; Chen, Xu

    2015-11-01

    We presented BVRcIc light curves of BX Peg obtained by the Weihai Observatory 1.0-m telescope of Shandong University. The W-D code was used to analyze the four color light curves, it is shown that BX Peg is a W-subtype shallow contact binary with a fill-out factor of f = 14.6 % . The asymmetric light curves were explained by a dark spot on the less massive hot component. A total of 328 times of minimum light were used to study the orbital period variation of BX Peg. We found that the orbital period of BX Peg was continuous decrease with a rate of dp / dt = - 2.07 ×10-7 d yr-1 superimposed on a cyclic oscillation with a period of 57.8 yr. The secular period decrease should be caused by the angular momentum loss via magnetic stellar wind. The cyclic modulation is very likely to be produced by the light travel time effect due to a tertiary companion.

  18. Near-infrared light curves of Type Ia supernovae: Studying the properties of the second maximum

    CERN Document Server

    Dhawan, S; Spyromilio, J; Maguire, K

    2015-01-01

    Type Ia supernovae have been proposed to be much better distance indicators at near-infrared compared to optical wavelengths -- the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the $Y$, $J$ and $H$-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs $\\sim$ 15 to 30 days after $B$ ban...

  19. Near-infrared light curves of Type Ia supernovae: studying properties of the second maximum

    Science.gov (United States)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Maguire, K.

    2015-04-01

    Type Ia supernovae (SNe Ia) have been proposed to be much better distance indicators at near-infrared (NIR) compared to optical wavelengths - the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the Y, J and H-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light-curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs ˜ 15 to 30 d after B-band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesized in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.

  20. Relationship between width of pulses and Lorentz factor expected from the light curve of fireball sources

    Institute of Scientific and Technical Information of China (English)

    Zhang Fu-Wen; Qin Yi-Ping

    2005-01-01

    Time profiles of many gamma-ray bursts consist of distinct pulses, which provides a possibility of characterizing the temporal structure of these bursts. We employ a simple model of highly symmetric fireballs to analyse the effect of the expansion speed on the light curve arising from different forms of local pulses. The relationship between the ratio r of the FWHM width of the rising phase of the light curve to that of the decaying phase and the Lorentz factor is investigated. The analysis shows that, when the rest frame radiation form is ignored, temporal profiles of the light curve arising from pulses of fireballs will not be affected by the expansion speed (that is, r is almost a constant) as long as the fireball expands relativistically. When the rest frame radiation form is taken into account, there will be a break in the curves of r - log Γ. The location of the break depends mainly on the adopted value of the rest frame peak frequency v0,p. One would reach almost the same result when a jet is considered. In addition, we utilize a sample of 48individual GRB pulses to check the relationship between the ratio r and the expansion speed Γ. We find no significant correlation between them, and this is consistent with the theoretical analysis.

  1. Light curve solution and orbital period analysis of the contact binary V842 Herculis

    Science.gov (United States)

    Selam, S. O.; Albayrak, B.; Şenavci, H. V.; Aksu, O.

    2005-10-01

    New photoelectric BV light curves were obtained for the neglected eclipsing binary V842 Her at the TÜB{İTAK National Observatory (TUG) and studied for the first time in detail to determine the orbital parameters and geometry of the system. The solutions obtained simultaneously for the new light curves and the radial velocity curves in the literature by using the Wilson-Devinney code reveal a typical W-type contact system. The light curves exhibit the so-called O'Connell effect which the level of the primary maxima being higher than that of the secondary ones in both pass-bands. The O'Connell effect in the light curves is explained in terms of a dark-spot located on the more massive component which makes the more massive larger component slightly cooler than the less massive smaller one. The O-C diagram constructed for all available times of minima of V842 Her exhibits a cyclic character superimposed on a quadratic variation. The quadratic character yields a orbital period increase with a rate of dP/dt=7.76×10-7 days yr-1 which can be attributed to the mass exchange/loss mechanism in the system. By assuming the presence of a gravitationally bound third body in the system, the analysis of the cyclic nature in the O-C diagram revealed a third body with mass of 0.4M\\sun orbiting around the eclipsing pair. The possibility of magnetic activity cycle effect as a cause for the observed cyclic variation in the O-C diagram was also discussed.

  2. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  3. An ac bridge readout for bolometric detectors

    Science.gov (United States)

    Rieke, F. M.; Lange, A. E.; Beeman, J. W.; Haller, E. E.

    1989-01-01

    The authors have developed a bolometer readout circuit which greatly improves the low-frequency stability of bolometric detectors. The circuit uses an ac bias voltage and two matched bolometers and allows stable dc bolometer operation for integration times greater than 10 s. In astronomical applications the readout allows for qualitatively different observation modes (e.g. staring or slow-drift scanning) which are particularly well suited for space observations and for the use of arrays. In many applications the readout can increase sensitivity. The authors present noise spectra for 4He temperature bolometers with no excess noise at frequencies greater than 0.1 Hz. The measured optical responsivity of a bolometer operated with the present readout is the same as that of a bolometer operated with a conventional readout.

  4. Light curve solutions for bright detached eclipsing binaries in SMC: absolute dimensions and distance indicators

    CERN Document Server

    Graczyk, D

    2003-01-01

    This paper presents a careful and detailed light curve analysis of bright detached eclipsing binaries (DEB) in the Small Magellanic Cloud, discovered by OGLE collaboration, on the basis of recently available difference image analysis (DIA) photometry. The 19 binaries brighter than 16.4 mag in I band and with the depth of primary and secondary eclipse greater than 0.25 mag were investigated. The solutions were obtained by a modified version of the Wilson-Devinney program. The quality of DIA light curves - a good phase coverage and relatively small scatter - is enough to calculate realistic estimates for the third light l_3 and the argument of periastron. It was found that solutions of detached, eccentric systems with flat light curve between eclipses usually may suffer from indetermination of l_3 in contrast to those of similar systems having some proximity effects. The physical properties of the stars were estimated on the basis of their photometric elements and indices assuming the distance modulus to SMC ~1...

  5. Gamma-Ray Pulsar Light Curves in Vacuum and Force-Free Geometry

    Science.gov (United States)

    Harding, Alice K.; DeCesar, Megan E.; Miller, M. Coleman; Kalapotharakos, Constantinos; Contopoulos, Ioannis

    2011-01-01

    Recent studies have shown that gamma-ray pulsar light curves are very sensitive to the geometry of the pulsar magnetic field. Pulsar magnetic field geometries, such as the retarded vacuum dipole and force-free magnetospheres have distorted polar caps that are offset from the magnetic axis in the direction opposite to rotation. Since this effect is due to the sweepback of field lines near the light cylinder, offset polar caps are a generic property of pulsar magnetospheres and their effects should be included in gamma-ray pulsar light curve modeling. In slot gap models (having two-pole caustic geometry), the offset polar caps cause a strong azimuthal asymmetry of the particle acceleration around the magnetic axis. We have studied the effect of the offset polar caps in both retarded vacuum dipole and force-free geometry on the model high-energy pulse profiles. We find that, compared to the profiles derived from symmetric caps, the flux in the pulse peaks, which are caustics formed along the trailing magnetic field lines, increases significantly relative to the off-peak emission, formed along leading field lines. The enhanced contrast produces improved slot gap model fits to Fermi pulsar light curves like Vela, with vacuum dipole fits being more favorable.

  6. ELLC - a fast, flexible light curve model for detached eclipsing binary stars and transiting exoplanets

    CERN Document Server

    Maxted, P F L

    2016-01-01

    Very high quality light curves are now available for thousands of detached eclipsing binary stars and transiting exoplanet systems as a result of surveys for transiting exoplanets and other large-scale photometric surveys. I have developed a binary star model (ELLC) that can be used to analyse the light curves of detached eclipsing binary stars and transiting exoplanet systems that is fast and accurate, and that can include the effects of star spots, Doppler boosting and light-travel time within binaries with eccentric orbits. The model represents the stars as triaxial ellipsoids. The apparent flux from the binary is calculated using Gauss-Legendre integration over the ellipses that are the projection of these ellipsoids on the sky. The model can also be used to calculate the flux-weighted radial velocity of the stars during an eclipse (Rossiter-McLaughlin effect). The main features of the model have tested by comparison to observed data and other light curve models. The model is found to be accurate enough t...

  7. The millimeter-wave bolometric interferometer

    Science.gov (United States)

    Gault, Amanda Charlotte

    The Millimeter-wave Bolometric Interferometer (MBI) is a technology demonstrator for future searches for the B-mode polarization of the Cosmic Microwave Background (CMB). If observed, B-modes would be a direct probe of the energy scale of inflation, an energy scale that is impossible to reach with even the most sophisticated particle accelerators. In this thesis, I outline the technology differences between MBI and conventional interferometers, including the Faraday effect phase modulators (FPM) used both to control systematic effects and to allow for phase sensitive detection of signals. MBI is a four element adding interferometer with a Fizeau optical beam combiner. This allows simple scaling of the instrument to a large numbers of baselines without requiring complicated pair-wise correlations of signals. Interferometers have an advantage over imaging telescopes when measuring the CMB power spectrum as each baseline is sensitive to a single Fourier mode (angular scale) on the sky. Recovering individual baseline information with this combination scheme requires phase modulating the signal from each antenna. MBI performs this modulation with Faraday effect phase modulators. In these novel cryogenic devices a modulated magnetic field switches the phase of a millimeter-wave RF signal by +/- 90 degrees at frequencies up to a few Hertz. MBI's second season of observations occurred in the winter of 2009 at Pine Bluff Observatory a few miles west of Madsion, WI. We successfully observed interference fringes of a microwave test source located in the far field of the instrument that agree well with those expected from simulations. MBI has inspired a second generation bolometric interferometer, QUBIC, which will have hundreds of antennas and thousands of detectors. When it deploys in 2015, it will be sensitive enough to search for B-mode signals from the CMB.

  8. Multi-messenger light curves from gamma-ray bursts in the internal shock model

    CERN Document Server

    Bustamante, Mauricio; Winter, Walter

    2016-01-01

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure tend to be inefficient neutrino emitters and produce delayed high-energy gamma-ray s...

  9. Re-Analysis of QPO in 3C 273 Light Curve

    Indian Academy of Sciences (India)

    P. Mohan; A. Mangalam; Hum Chand; Alok C. Gupta

    2011-03-01

    We have developed analysis tools to search for quasi periodic oscillations in light curves from active galactic nuclei, using the following time series techniques: Wavelets, periodogram, Lomb–Scargle periodogram, structure function and multi-harmonic analysis of variance. The analysis tools incorporate different noise models with significant levels for all the techniques that is an improvement over the previous work. By looking for consistently high significance, we make the detection of periodicities more robust. We apply this tool to a previously reported QPO (Espaillat et al. 2008) in the X-ray light curve of 3C 273 with a periodicity of ∼ 3300 s and find that the significance is only 74% in the wavelet and fails to show up above 95% significance in the periodogram and multi-harmonic analysis of variance.

  10. A Periodicity Analysis of the Light Curve of 3C 454.3

    Institute of Scientific and Technical Information of China (English)

    Huai-Zhen Li; Guang-Zhong Xie; Shu-Bai Zhou; Hong-Tao Liu; Guang-Wei Cha; Li Ma; Li-Sheng Mao

    2006-01-01

    We analyzed the radio light curves of 3C 454.3 at frequencies 22 and 37 GHz taken from the database of Mets(a)hovi Radio Observatory, and found evidence of quasi-periodic activity. The light curves show great activity with very complicated non-sinusoidal variations. Two possible periods, a very weak one of 1.57 ± 0.12 yr and a very strong one of 6.15 ± 0.50 yr were consistently identified by two methods, the Jurkevich method and power spectrum estimation. The period of 6.15 ± 0.50 yr is consistent with results previously reported by Ciaramella et al. and Webb et al. Applying the binary black hole model to the central structure we found black hole masses of 1.53 × 109M⊙ and 1.86 × 108M⊙, and predicted that the next radio outburst is to take place in 2006 March and April.

  11. Kilonova Light Curves from the Disk Wind Outflows of Compact Object Mergers

    CERN Document Server

    Kasen, Daniel; Metzger, Brian

    2014-01-01

    We study the radioactively-powered transients produced by accretion disk winds following a compact object merger. Starting with the outflows generated in two-dimensional hydrodynamical disk models, we use wavelength-dependent radiative transfer calculations to generate synthetic light curves and spectra. We show that the brightness and color of the resulting kilonova transients carry information about the merger physics. In the regions of the wind where neutrino irradiation raises the electron fraction to Ye > 0.25, r-process nucleosynthesis halts before producing high-opacity, complex ions (the lanthanides). The kilonova light curves thus show two distinct components: a brief (~2 day) blue optical transient produced in the outer lanthanide-free ejecta, and a longer (~10 day) infrared transient produced in the inner, lanthanide line-blanketed region. Mergers producing a longer-lived neutron star, or a more rapidly spinning black hole, have stronger neutrino irradiation, generate more lanthanide-free ejecta, a...

  12. HEIDI: An Automated Process for the Identification and Extraction of Photometric Light Curves from Astronomical Images

    CERN Document Server

    Todd, M; Tanga, P; Coward, D M; Zadnik, M G

    2014-01-01

    The production of photometric light curves from astronomical images is a very time-consuming task. Larger data sets improve the resolution of the light curve, however, the time requirement scales with data volume. The data analysis is often made more difficult by factors such as a lack of suitable calibration sources and the need to correct for variations in observing conditions from one image to another. Often these variations are unpredictable and corrections are based on experience and intuition. The High Efficiency Image Detection & Identification (HEIDI) pipeline software rapidly processes sets of astronomical images. HEIDI automatically selects multiple sources for calibrating the images using an algorithm that provides a reliable means of correcting for variations between images in a time series. The algorithm takes into account that some sources may intrinsically vary on short time scales and excludes these from being used as calibration sources. HEIDI processes a set of images from an entire nigh...

  13. Corot 310266512: A Light Curve With Primary, Secondary And Tertiary Eclipses

    Directory of Open Access Journals (Sweden)

    Fernández Fernández Javier

    2015-01-01

    Full Text Available We present the photometric study of an interesting target in the CoRoT exoplanet database: CoRoT 310266512. Its light curve shows primary, secondary and tertiary eclipses that suggests the presence of at least three celestial bodies. The primary and secondary eclipses have the same orbital period, 7.42 days, and the tertiary eclipse has an orbital period of 3.27 days. Two of the tertiary eclipses fall within a primary eclipse and a secondary eclipse. The properties of the light curve indicate the presence of two physically separated systems. The primary and secondary eclipses corresponds to a binary system (System I. The tertiary eclipses correspond to a star-planet system or a star-dwarf system (System II. Some parameters of these two systems are obtained from JKTEBOP [1] program.

  14. Exposure-based Algorithm for Removing Systematics out of the CoRoT Light Curves

    CERN Document Server

    Guterman, P; Faigler, S

    2015-01-01

    The CoRoT space mission was operating for almost 6 years, producing thousands of continuous photometric light curves. The temporal series of exposures are processed by the production pipeline, correcting the data for known instrumental effects. But even after these model-based corrections, some collective trends are still visible in the light curves. We propose here a simple exposure-based algorithm to remove instrumental effects. The effect of each exposure is a function of only two instrumental stellar parameters, position on the CCD and photometric aperture. The effect is not a function of the stellar flux, and therefore much more robust. As an example, we show that the $\\sim2\\%$ long-term variation of the early run LRc01 is nicely detrended on average. This systematics removal process is part of the CoRoT legacy data pipeline.

  15. Modeling the Envelope of the Secular Light Curve of the Comete 1P/Halley

    CERN Document Server

    Rondón, Eduardo

    2011-01-01

    We have been modeling the envelope of the secular light curve (Ferr\\'in, 2010) of comet 1P/Halley. As the first step we have modeled the water production rate of the comet, for several active regions as a function of visual albedo and infrared albedo, and then we have used the correlation between the water production rate and the reduced magnitude (Jorda, 2008) for modeling the envelope of the secular light curve of the comet. We obtain probable orientations of the rotation axis (I,$\\Phi$). These orientations are compared with several solutions by several authors. We have calculated the surface temperature for the orientation of the rotation axis with minimal standar deviation. We have found that for near and far values of the perihelion the surface temperature as a function of the latitude is constant.

  16. 3D Modeling of Spectra and Light Curves of Hot Jupiters; A First Approach

    CERN Document Server

    Jiménez-Torres, Juan J

    2015-01-01

    In this paper, a detailed Global Circulation Model was employed to feed the PHOENIX code to calculate 3D spectra and light curves of hot Jupiters. Cloud free and dusty radiative luxes for the planet HD179949b were modeled to show differences between them. The PHOENIX simulations can explain the broad features of the observed 8 {\\mu}m light curves, including the fact that the planet-star flux ratio peaks before the secondary eclipse. The PHOENIX reflection spectrum matches the Spitzer secondary-eclipse depth at 3.6 {\\mu}m and underpredicts the eclipse depths at 4.5, 5.8 and 8.0 {\\mu}m. These discrepancies result from the chemical composition and provide motivation for incorporating different metallicities in future studies.

  17. The unusual X-ray light-curve of GRB 080307: the onset of the afterglow?

    CERN Document Server

    Page, K L; O'Brien, P T; Tanvir, N R; Osborne, J P; Zhang, B; Holland, S T; Levan, A J; Melandri, A; Starling, R L C; Bersier, D; Burrows, D N; Geach, J E; Maxted, P

    2009-01-01

    Swift-detected GRB 080307 showed an unusual smooth rise in its X-ray light-curve around 100 seconds after the burst, at the start of which the emission briefly softened. This `hump' has a longer duration than is normal for a flare at early times and does not demonstrate a typical flare profile. Using a two component power-law-to-exponential model, the rising emission can be modelled as the onset of the afterglow, something which is very rarely seen in Swift-X-ray light-curves. We cannot, however, rule out that the hump is a particularly slow early-time flare, or that it is caused by upscattered reverse shock electrons.

  18. BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Sonnett, S.; Mainzer, A.; Masiero, J.; Bauer, J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T., E-mail: Sarah.Sonnett@jpl.nasa.gov [Planetary Science Institute, Tucson, AZ (United States)

    2015-02-01

    Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival data set for close and contact binary Trojans and Hildas via their diagnostically large light curve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large light curve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14%-23% for Trojans larger than ∼12 km and 30%-51% for Hildas larger than ∼4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.

  19. Quasi-Periodic Oscillations in the X-ray Light Curves of Blazars

    Indian Academy of Sciences (India)

    Paul J. Wiita

    2011-03-01

    Any quasi-periodic variations discovered in blazar light curves would contain important information on the location and nature of the processes within the emission regions. In non-blazar active galactic nuclei, particularly Seyfert galaxies, any such fluctuations are very likely to be associated with the accretion disks, but in blazars they would almost certainly have to emanate from jets. This brief review summarizes recent claims for the presence of quasi-periodic variability in the X-ray emission of several AGN, focusing on blazars. Although no individual claim of the presence of a QPO in AGN X-ray light curves is absolutely convincing, there are some good cases for the presence of QPOs, including the Narrow Line Seyfert 1 galaxy, RE J1034+396, the quasar, 3C 273 and the BL Lac, PKS 2155−304.

  20. BEER analysis of Kepler and CoRoT light curves. III. Spectroscopic confirmation of seventy new beaming binaries discovered in CoRoT light curves

    Science.gov (United States)

    Tal-Or, L.; Faigler, S.; Mazeh, T.

    2015-08-01

    Context. The BEER algorithm searches stellar light curves for the BEaming, Ellipsoidal, and Reflection photometric modulations that are caused by a short-period companion. These three effects are typically of very low amplitude and can mainly be detected in light curves from space-based photometers. Unlike eclipsing binaries, these effects are not limited to edge-on inclinations. Aims: Applying the algorithm to wide-field photometric surveys such as CoRoT and Kepler offers an opportunity to better understand the statistical properties of short-period binaries. It also widens the window for detecting intrinsically rare systems, such as short-period brown-dwarf and massive-planetary companions to main-sequence stars. Methods: Applying the search to the first five long-run center CoRoT fields, we identified 481 non-eclipsing candidates with periodic flux amplitudes of 0.5-87 mmag. Optimizing the Anglo-Australian-Telescope pointing coordinates and the AAOmega fiber-allocations with dedicated softwares, we acquired six spectra for 231 candidates and seven spectra for another 50 candidates in a seven-night campaign. Analysis of the red-arm AAOmega spectra, which covered the range of 8342-8842 Å, yielded a radial-velocity precision of ~1 km s-1. Spectra containing lines of more than one star were analyzed with the two-dimensional correlation algorithm TODCOR. Results: The measured radial velocities confirmed the binarity of seventy of the BEER candidates - 45 single-line binaries, 18 double-line binaries, and 7 diluted binaries. We show that red giants introduce a major source of false candidates and demonstrate a way to improve BEER's performance in extracting higher fidelity samples from future searches of CoRoT light curves. The periods of the confirmed binaries span a range of 0.3-10 days and show a rise in the number of binaries per ΔlogP toward longer periods. The estimated mass ratios of the double-line binaries and the mass ratios assigned to the single

  1. The light curve of a transient X-ray source. [the aeriel satellites

    Science.gov (United States)

    Kaluzienski, L. J.; Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Eadie, G.; Pounds, K. A.; Ricketts, M. J.; Watson, M.

    1975-01-01

    The Ariel-V satellite monitored the X-ray light curve of A1524-62 almost continuously from 40 days prior to maximum light until its disappearance below the effective experimental sensitivity. The source exhibited maximum light on approximately 4 December 1974, at a level of 0.9 the apparent magnitude of the Crab Nebula in the energy band 3-6 keV. Although similar to previously reported transient sources with a decay time constant of approximately 2 months, the source exhibited an extended, variable pre-flare on-state of about 1 month at a level of greater than approximately 0.1 maximum light. The four bright (greater than 0.2 of the Crab Nebula) transient sources observed during the first half-year of Ariel-V operation are indicative of a galactic disk distribution, and a luminosity at maximum in excess of 10 to the 37th power ergs/sec.

  2. New Light Curves and Period Studies of V502 OPH W UMA System

    Science.gov (United States)

    Awadalla, Nabil S.

    NEW LIGHT CURVES AND PERIOD STUDIES OF V502 OPH W UMa SYSTEM N.S.Awadalla National Research Institute of Astronomy and Geophysics( NRIAG ) Helwan Cairo EGYPT New BVR photoelectric observations of the W UMa eclipsing binary system V502 Oph have been presented and analyzed. The geometric and physical elements of the system have been obtained and compared to the previous results. The classification of the system concerning the sub-type of the W UMa binary has been studied as well as its evolution stage. Its period variation in a view of the light time effect has been examin

  3. Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC

    Science.gov (United States)

    Budaj, Ján

    2012-04-01

    Program SHELLSPEC is designed to calculate light-curves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, shell or stars may be defined (embedded) in 3D and their composite synthetic spectrum calculated. The Roche model can be used as a boundary condition for the radiative transfer. Recently, a new model of the reflection effect, dust and Mie scattering were incorporated into the code. ɛ Aurigae is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed a dark, inclined, disk of dust with a central hole to explain the light-curve with a sharp mid-eclipse brightening. Our model consists of two geometrically thick flared disks: an internal optically thick disk and an external optically thin disk which absorbs and scatters radiation. Shallow mid-eclipse brightening may result from eclipses by nearly edge-on flared (dusty or gaseous) disks. Mid-eclipse brightening may also be due to strong forward scattering and optical properties of the dust which can have an important effect on the light-curves. There are many similarities between interacting binary stars and transiting extrasolar planets. The reflection effect which is briefly reviewed is one of them. The exact Roche shape and temperature distributions over the surface of all currently known transiting extrasolar planets have been determined. In some cases (HAT-P-32b, WASP-12b, WASP-19b), departures from the spherical shape can reach 7-15%.

  4. LFN, QPO and fractal dimension of X-ray light curves from black hole binaries

    Science.gov (United States)

    Prosvetov, Art; Grebenev, Sergey

    The origin of the low frequency noise (LFN) and quasi-periodic oscillations (QPO) observed in X-ray flux of Galactic black hole binaries is still not recognized in spite of multiple studies and attempts to model this phenomenon. There are known correlations between the QPO frequency, X-ray power density, X-ray flux and spectral state of the system, but there is no model that can do these dependences understandable. For the low frequency (~1 Hz) QPO we still have no even an idea capable to explain their production and don't know even what part of an accretion disc is responsible for them. Here we attempted to measure the fractal dimension of X-ray light curves of several black hole X-ray binaries and to study its correlation with the frequency of quasi periodic oscillations observed in their X-ray light-curves. The fractal dimension is a measure of the space-filling capacity of the light curves' profile. To measure the fractal dimension we used R/S method, which is fast enough and has good reputation in financial analytic and materials sciences. We found that if no QPO were observed in X-ray flux from the particular source, the fractal dimension is equal to the unique value which is independent on the source, its luminosity or its spectral state. On the other hand if QPO were detected in the flux, the fractal dimension deviated from its usual value. Also, we found a clear correlation between the QPO frequency and the fractal dimension of the emission. The relationship between these two parameters is solid but nonlinear. We believe that the analysis of X-ray light curves of black hole binaries using the fractal dimension has a good scientific potential and may provide an addition information on the geometry of accretion flow and fundamental physical parameters of the system.

  5. VizieR Online Data Catalog: V960 Mon light curves (Hackstein+, 2015)

    Science.gov (United States)

    Hackstein, M.; Haas, M.; Kospal, A.; Hambsch, F.-J.; Chini, R.; Abraham, P.; Moor, A.; Pozo Nunez, F.; Ramolla, M.; Westhues, C.; Kaderhandt, L.; Fein, C.; Barr Dominguez, A.; Hodapp, K.-W.

    2015-10-01

    Photometric light curves for V960Mon (2MASS J06593158-0405277) from different telescopes at multiple wavelengths between September 2009 to June 2015. This comprises optical observations from Universitaetssternwarte Bochum (USB) in Chile as part of the Bochum Galatic Disk Survey (GDS, 2015AN....336..590H), Konkoly Observatory in Hungary, and the Remote Observatory Atacama Desert (ROAD) in Chile, as well as near-infrared data from USB. (1 data file).

  6. Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method

    Indian Academy of Sciences (India)

    Ai-Jun Dong; Yan-Ke Tang; Ning Gai

    2014-09-01

    The Jurkevich method is a useful method to explore periodicity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states. That period may be correlated with black hole physics and accretion disk geometry.

  7. Afterglows from Jetted Gamma-Ray-Burst Remnant: Does the Light Curve Break?

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong-Feng; DAI Zi-Gao; LU Tan

    2000-01-01

    Afterglows from jetted gamma-ray bursts are generally believed to be characterized by an obvious break in the light curve at the relativistic stage. We show that it is not the case. However, an obvious break does exist at the transition from the relativistic phase to the non-relativistic phase. Although this break itself is parameter dependent, afterglows from jetted remnant are uniformly characterized by a quick decay during the non-relativistic phase.

  8. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    Energy Technology Data Exchange (ETDEWEB)

    Nousek, J.A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S.K.; Burrows, D.N.; Mangano, V.; Barthelmy, S.; Beardmore, A.P.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Falcone, A.D.; Gehrels, N.; Giommi, P.; Goad, M.; Godet, O.; Hurkett, C.; /Penn State U., Astron. Astrophys. /NASA, Marshall /Leicester

    2005-08-17

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay ({infinity} t{sup -a} with 3 {approx}< a{sub 1} {approx}< 5) , followed by (2) a very shallow decay (0.2 {approx}< a{sub 2} {approx}< 0.8), and finally (3) a somewhat steeper decay (1 {approx}< a{sub 3} {approx}< 1.5). These power law segments are separated by two corresponding break times, 300 s {approx}< t{sub break,1} {approx}< 500 s and 10{sup 3} s {approx}< t{sub break,2} {approx}< 10{sup 4} s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (t{sub break,1}) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a{sub 2}) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (t{sub break,2}). This energy injection increases the energy of the afterglow shock by at least a factor of f {approx}> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  9. X-Rays from the Explosion Site: Fifteen Years of Light Curves of SN 1993J

    Science.gov (United States)

    Chandra, Poonam; Dwarkadas, Vikram V.; Ray, Alak; Immler, Stefan; Pooley, David

    2009-01-01

    We present a comprehensive analysis of the X-ray light curves of SN 1993J in a nearby galaxy M81. This is the only supernova other than SN 1987A, which is so extensively followed in the X-ray bands. Here we report on SN 1993J observations with the Chandra in the year 2005 and 2008, and Swift observations in 2005, 2006 and 2008. We combined these observations with all available archival data of SN 1993J, which includes ROSAT, ASCA, Chandra, and XMM-Newton, observations from 1993 April to 2006 August. In this paper we report the X-ray light curves of SN 1993J, extending up to fifteen years, in the soft (0.3-2.4 keV), hard (2-8 keV) and combined (0.3-8 keV) bands. The hard and soft-band fluxes decline at different rates initially, but after about 5 years they both undergo a t(sup -1) decline. The soft X-rays, which are initially low, start dominating after a few hundred days. We interpret that most of the emission below 8 keV is coming from the reverse shock which is radiative initially for around first 1000-2000 days and then turn into adiabatic shock. Our hydrodynamic simulation also confirms the reverse shock origin of the observed light curves. We also compare the Ha line luminosity of SN 1993J with its X-ray light curve and note that the Ha line luminosity has a fairly high fraction of the X-ray emission, indicating presence of clumps in the emitting plasma.

  10. VizieR Online Data Catalog: Ji light curves of WTS-2 (Birkby+, 2014)

    Science.gov (United States)

    Birkby, J. L.; Cappetta, M.; Cruz, P.; Koppenhoefer, J.; Ivanyuk, O.; Mustill, A. J.; Hodgkin, S. T.; Pinfield, D. J.; Sipocz, B.; Kovacs, G.; Saglia, R.; Pavlenko, Y.; Barrado, D.; Bayo, A.; Campbell, D.; Catalan, S.; Fossati, L.; Galvez-Ortiz, M.-C.; Kenworthy, M.; Lillo-Box, J.; Martin, E. L.; Mislis, D.; de Mooij, E. J. W.; Nefs, S. V.; Snellen, I. A. G.; Stoev, H.; Zendejas, J.; Del Burgo, C.; Barnes, J.; Goulding, N.; Haswell, C. A.; Kuznetsov, M.; Lodieu, N.; Murgas, F.; Palle, E.; Solano, E.; Steele, P.; Tata, R.

    2015-07-01

    The infrared light curves of the WTS were generated from time series photometry taken with the WFCAM imager mounted at the prime focus of UKIRT. In order to confirm the transit of WTS-2 b and to help constrain the transit model, on 2010 July 18 we obtained further time series photometry in the Sloan i band using the Wide Field Camera (WFC) on the 2.5m Isaac Newton Telescope (INT) at Roque de Los Muchachos, La Palma. (2 data files).

  11. Ensemble Learning Method for Outlier Detection and its Application to Astronomical Light Curves

    Science.gov (United States)

    Nun, Isadora; Protopapas, Pavlos; Sim, Brandon; Chen, Wesley

    2016-09-01

    Outlier detection is necessary for automated data analysis, with specific applications spanning almost every domain from financial markets to epidemiology to fraud detection. We introduce a novel mixture of the experts outlier detection model, which uses a dynamically trained, weighted network of five distinct outlier detection methods. After dimensionality reduction, individual outlier detection methods score each data point for “outlierness” in this new feature space. Our model then uses dynamically trained parameters to weigh the scores of each method, allowing for a finalized outlier score. We find that the mixture of experts model performs, on average, better than any single expert model in identifying both artificially and manually picked outliers. This mixture model is applied to a data set of astronomical light curves, after dimensionality reduction via time series feature extraction. Our model was tested using three fields from the MACHO catalog and generated a list of anomalous candidates. We confirm that the outliers detected using this method belong to rare classes, like Novae, He-burning, and red giant stars; other outlier light curves identified have no available information associated with them. To elucidate their nature, we created a website containing the light-curve data and information about these objects. Users can attempt to classify the light curves, give conjectures about their identities, and sign up for follow up messages about the progress made on identifying these objects. This user submitted data can be used further train of our mixture of experts model. Our code is publicly available to all who are interested.

  12. Light curves and spectra from off-axis gamma-ray bursts

    Science.gov (United States)

    Salafia, O. S.; Ghisellini, G.; Pescalli, A.; Ghirlanda, G.; Nappo, F.

    2016-10-01

    If gamma-ray burst prompt emission originates at a typical radius, and if material producing the emission moves at relativistic speed, then the variability of the resulting light curve depends on the viewing angle. This is due to the fact that the pulse evolution time-scale is Doppler contracted, while the pulse separation is not. For off-axis viewing angles θview ≳ θjet + Γ-1, the pulse broadening significantly smears out the light-curve variability. This is largely independent of geometry and emission processes. To explore a specific case, we set up a simple model of a single pulse under the assumption that the pulse rise and decay are dominated by the shell curvature effect. We show that such a pulse observed off-axis is (i) broader, (ii) softer and (iii) displays a different hardness-intensity correlation with respect to the same pulse seen on-axis. For each of these effects, we provide an intuitive physical explanation. We then show how a synthetic light curve made by a superposition of pulses changes with increasing viewing angle. We find that a highly variable light curve (as seen on-axis) becomes smooth and apparently single-pulsed (when seen off-axis) because of pulse overlap. To test the relevance of this fact, we estimate the fraction of off-axis gamma-ray bursts detectable by Swift as a function of redshift, finding that a sizeable fraction (between 10 per cent and 80 per cent) of nearby (z < 0.1) bursts are observed with θview ≳ θjet + Γ-1. Based on these results, we argue that low-luminosity gamma-ray bursts are consistent with being ordinary bursts seen off-axis.

  13. Testing the recovery of stellar rotation signals from Kepler light curves using a blind hare-and-hounds exercise

    CERN Document Server

    Aigrain, S; Ceillier, T; Chagas, M L das; Davenport, J R A; Garcia, R A; Hay, K L; Lanza, A F; McQuillan, A; Mazeh, T; de Medeiros, J R; Nielsen, M B; Reinhold, T

    2015-01-01

    We present the results of a blind exercise to test the recoverability of stellar rotation and differential rotation in Kepler light curves. The simulated light curves lasted 1000 days and included activity cycles, Sun-like butterfly patterns, differential rotation and spot evolution. The range of rotation periods, activity levels and spot lifetime were chosen to be representative of the Kepler data of solar like stars. Of the 1000 simulated light curves, 770 were injected into actual quiescent Kepler light curves to simulate Kepler noise. The test also included five 1000-day segments of the Sun's total irradiance variations at different points in the Sun's activity cycle. Five teams took part in the blind exercise, plus two teams who participated after the content of the light curves had been released. The methods used included Lomb-Scargle periodograms and variants thereof, auto-correlation function, and wavelet-based analyses, plus spot modelling to search for differential rotation. The results show that th...

  14. Distribution of Micronuclei in Human Fibroblasts across the Bragg Curve of Light and Heavy Ions

    Science.gov (United States)

    Hada, M.; Lacy, S.; Gridley, D. S.; Rusek, A.; Cucinotta, F. A.; Wu, H.

    2007-01-01

    The space environment consists of energetic particles of varying mass and energy, and understanding the :biological Bragg curve" is essential in optimizing shielding effectiveness against space radiation induced biological impacts. The "biological Bragg curve" is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Previously, we studied the induction of micronuclei (MN) across the Bragg curve of energetic Fe and Si ions, and observed no increased yield of MN at the location of the Bragg peak. However, the ratio of mono- to bi-nucleated cells, which indicates inhibition of cell progression, was found higher at the Bragg peak location in comparison to the plateau region of the Bragg curve. Here, we report the induction of MN in normal human fibroblast cells across the Bragg curve of incident protons generated at Loma Linda University. Similar to Si and Fe ions, the ratio of mono- to bi-nucleated cells showed a clear spike as the protons reached the Bragg peak. Unlike the two heavy ions, however, the MN yield also increased at the Bragg peak location. These results confirm the hypothesis that severely damaged cells at the Bragg peak of heavy, but not light ions are more likely to go through reproductive death and not be evaluated for micronuclei.

  15. Characterizing Exoplanet Atmospheres: From Light-curve Observations to Radiative-transfer Modeling

    CERN Document Server

    Cubillos, Patricio E

    2016-01-01

    Multi-wavelength transit and secondary-eclipse light-curve observations are some of the most powerful techniques to probe the thermo-chemical properties of exoplanets. Although the large planet-to-star brightness contrast and few available spectral bands produce data with low signal-to-noise ratios, a Bayesian approach can robustly reveal what constraints we can set, without over-interpreting the data. Here I performed an end-to-end analysis of transiting exoplanet data. I analyzed space-telescope data for three planets to characterize their atmospheres and refine their orbits, investigated correlated noise estimators, and contributed to the development of the respective data-analysis pipelines. Chapters 2 and 3 describe the Photometry for Orbits, Eclipses and Transits (POET) pipeline to model Spitzer Space Telescope light curves, applied to secondary-eclipse observations of the Jupiter-sized planets WASP-8b and TrES-1. Chapter 4 studies commonly used correlated-noise estimators for exoplanet light-curve mode...

  16. Periods in a 87 Years Light Curve of the Symbiotic Star MWC 560

    CERN Document Server

    Leibowitz, Elia M

    2015-01-01

    We have constructed a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of 3 basic clocks of the periods P1=19000 d, P2=1943 d and P3=722 d. These periods can plausibly, and consistently with the observations, be attributed to 3 physical mechanisms in the system. They are, respectively, the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle and the sidereal rotation cycle of the giant star. MWC 560 is the 7th symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  17. SDSSJ14584479+3720215: A Benchmark JHK Blazar Light Curve from the 2MASS Calibration Scans

    CERN Document Server

    Davenport, James R A; Becker, Andrew C; Macleod, Chelsea L; Cutri, Roc M

    2015-01-01

    Active galactic nuclei (AGNs) are well-known to exhibit flux variability across a wide range of wavelength regimes, but the precise origin of the variability at different wavelengths remains unclear. To investigate the relatively unexplored near-IR variability of the most luminous AGNs, we conduct a search for variability using well sampled JHKs-band light curves from the 2MASS survey calibration fields. Our sample includes 27 known quasars with an average of 924 epochs of observation over three years, as well as one spectroscopically confirmed blazar (SDSSJ14584479+3720215) with 1972 epochs of data. This is the best-sampled NIR photometric blazar light curve to date, and it exhibits correlated, stochastic variability that we characterize with continuous auto-regressive moving average (CARMA) models. None of the other 26 known quasars had detectable variability in the 2MASS bands above the photometric uncertainty. A blind search of the 2MASS calibration field light curves for AGN candidates based on fitting C...

  18. The First Systematic Study of Type Ibc Supernova Multi-color Light-curves

    CERN Document Server

    Drout, Maria R; Gal-Yam, A; Cenko, S B; Fox, D B; Leonard, D C; Sand, D J; Moon, D -S; Arcavi, I; Green, Y

    2010-01-01

    We present detailed optical photometry for 25 Type Ibc supernovae within d~150 Mpc obtained with the robotic Palomar 60-inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-color SNe Ibc light-curves available to date. We correct the light-curves for host galaxy extinction using a new technique based on the photometric color evolution, namely, we show that the (V-R) color of extinction-corrected SNe Ibc at t~10 days after V-band maximum is tightly distributed, (V-R)=0.26+-0.06 mag. Using this technique, we find that SNe Ibc typically suffer from significant host galaxy extinction, E(B-V)~0.4 mag. A comparison of the extinction-corrected light-curves for SNe Ib and Ic reveals that they are statistically indistinguishable, both in luminosity and decline rate. We report peak absolute magnitudes of M_R=-17.9+-0.9 mag and M_R=-18.3+-0.6 mag for SNe Ib and Ic, respectively. Focusing on the broad-lined SNe Ic, we find that they are more luminous than the n...

  19. Dusty tails of evaporating exoplanets. II. Physical modelling of the KIC 12557548b light curve

    CERN Document Server

    van Lieshout, R; Dominik, C; Brogi, M; de Graaff, T; Hekker, S; Kama, M; Keller, C U; Ridden-Harper, A; van Werkhoven, T I M

    2016-01-01

    Evaporating rocky exoplanets, such as KIC 12557548b, eject large amounts of dust grains, which can trail the planet in a comet-like tail. When such objects occult their host star, the resulting transit signal contains information about the dust in the tail. We aim to use the detailed shape of the Kepler light curve of KIC 12557548b to constrain the size and composition of the dust grains that make up the tail, as well as the mass loss rate of the planet. Using a self-consistent numerical model of the dust dynamics and sublimation, we calculate the shape of the tail by following dust grains from their ejection from the planet to their destruction due to sublimation. From this dust cloud shape, we generate synthetic light curves (incorporating the effects of extinction and angle-dependent scattering), which are then compared with the phase-folded Kepler light curve. We explore the free-parameter space thoroughly using a Markov chain Monte Carlo method. Our physics-based model is capable of reproducing the obser...

  20. Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC

    CERN Document Server

    Budaj, Jan

    2011-01-01

    Program SHELLSPEC is designed to calculate light-curves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, ufo, shell or stars may be defined (embedded) in 3D and their composite synthetic spectrum calculated. Roche model can be used as a boundary condition for the radiative transfer. Recently a new model of the reflection effect, dust and Mie scattering were incorporated into the code. $\\epsilon$ Aurigae is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed dark, inclined, disk of dust with the central hole to explain the light-curve with a sharp mid-eclipse brightening. Our model consists of two geometrically thick flared disks. Internal optically thi...

  1. THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

    Energy Technology Data Exchange (ETDEWEB)

    Leibowitz, Elia M.; Formiggini, Liliana, E-mail: elia@astro.tau.ac.il [The Wise Observatory and the School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2015-08-15

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  2. Uninterrupted optical light curves of main-belt asteroids from the K2 Mission

    CERN Document Server

    Szabó, R; Sárneczky, K; Szabó, Gy M; Molnár, L; Kiss, L L; Hanyecz, O; Plachy, E; Kiss, Cs

    2016-01-01

    Due to the failure of the second reaction wheel, a new mission was conceived for the otherwise healthy Kepler space telescope. In the course of the K2 Mission, the telescope is staring at the plane of the Ecliptic, hence thousands of Solar System bodies cross the K2 fields, usually causing extra noise in the highly accurate photometric data. In this paper we follow the someone's noise is another one's signal principle and investigate the possibility of deriving continuous asteroid light curves, that has been unprecedented to date. In general, we are interested in the photometric precision that the K2 Mission can deliver on moving Solar System bodies. In particular, we investigate space photometric optical light curves of main-belt asteroids. We study the K2 superstamps covering the M35 and Neptune/Nereid fields observed in the long cadence (29.4-min sampling) mode. Asteroid light curves are generated by applying elongated apertures. We use the Lomb-Scargle method to find periodicities due to rotation. We deri...

  3. Light curve modeling of the short-period W UMa star GSC 02049-01164

    Science.gov (United States)

    Fox-Machado, Lester; Echevarria, Juan; Gonzalez-Buitrago, Diego; Michel, Raul

    2015-08-01

    The preliminary results of an analysis of the time-series photometric data of the binary star GSC 02049-01164 (ROTSE1 J164341.65+251748.1) are presented.GSC 02049-01164 was observed for eight consecutive nights from 2013, May 31 to June 07 UT with the 0.84m telescope of the San Pedro Martir Observatory in Mexico. The data were acquired through a Johnson V filter. The propierties of the GSC 02040-01164 light curve are consistent with a short period contact binary of W UMa type. The light curve is characterized by a small difference between the two out-of-eclipse maxima by about 0.035 mag and a flat bottom at the secondary minimum due to a total eclipse. Moreover, the primary and secondary eclipses accur almost at 0.5 phase interval suggesting a circular orbit. The period of the binary is 0.3256 d. In an effort to gain a better understanding of the binary system and determine its physical properties we have analyzed the light curve with the software PHOEBE V.0 0.31a. We have found that GSC 02049-01164 binary system has a mass ratio of ~ 0.42, an inclination of ~ 85 degrees, a semi-major axis of ~ 2.23 Rsun. The degree of overcontact of the stellar components is about 13 %.

  4. The Rotational Light Curve of (79360) Sila-Nunam, an Eclipsing Binary in the Kuiper Belt

    CERN Document Server

    Rabinowitz, David; Grundy, William; Verbiscer, Anne

    2014-01-01

    We combine long-term photometric observations in multiple band passes to determine the rotational light curve for the binary Kuiper-Belt object (79360) Sila-Nunam. We measure an unambiguous fundamental period of 6.2562 +/- 0.002 d, within 0.02% of half the orbital period (Porb = 12.50995 +/- 0.00036 d) determined earlier from HST observations resolving the binary. The light curve is double-peaked, and well fit by the sum of two sinusoids: a primary with period Porb/2 and peak-to-peak amplitude 0.120 +/- 0.012 mag and a secondary with period Porb and peak-to-peak amplitude 0.044 +/- 0.010 mag. Excluding observations within ~0.1 deg of opposition, we measure a linear solar phase dependence with slope 0.147 +/- 0.018 mag deg-1 and a mean absolute magnitude in the Gunn g band of 6.100 +/- 0.006 mag. There is no rotational color variation exceeding 4%. We also observe that eclipses occur centered on light curve minima to within 0.3%, requiring the long axis of at least one of the two bodies to point precisely towa...

  5. The 2010 Eruption of the Recurrent Nova U Scorpii: The Multi-Wavelength Light Curve

    CERN Document Server

    Pagnotta, Ashley; Clem, James L; Landolt, Arlo U; Handler, Gerald; Page, Kim L; Osborne, Julian P; Schlegel, Eric M; Hoffman, Douglas I; Kiyota, Seiichiro; Maehara, Hiroyuki

    2015-01-01

    The recurrent nova U Scorpii most recently erupted in 2010. Our collaboration observed the eruption in bands ranging from the Swift XRT and UVOT w2 (193 nm) to K-band (2200 nm), with a few serendipitous observations stretching down to WISE W2 (4600 nm). Considering the time and wavelength coverage, this is the most comprehensively observed nova eruption to date. We present here the resulting multi-wavelength light curve covering the two months of the eruption as well as a few months into quiescence. For the first time, a U Sco eruption has been followed all the way back to quiescence, leading to the discovery of new features in the light curve, including a second, as-yet-unexplained, plateau in the optical and near-infrared. Using this light curve we show that U Sco nearly fits the broken power law decline predicted by Hachisu & Kato, with decline indices of -1.71 +/- 0.02 and -3.36 +/- 0.14. With our unprecedented multi-wavelength coverage, we construct daily spectral energy distributions and then calcul...

  6. TESTING MICROVARIABILITY IN QUASAR DIFFERENTIAL LIGHT CURVES USING SEVERAL FIELD STARS

    Energy Technology Data Exchange (ETDEWEB)

    De Diego, José A.; De Leo, Mario A.; Verdugo, Tomás [Instituto de Astronomía, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Ciudad Universitaria, C.P. 04510, Distrito Federal (Mexico); Polednikova, Jana; Bongiovanni, Angel; Pérez García, Ana M.; Cepa, Jordi, E-mail: jdo@astro.unam.mx [Instituto de Astrofísica de Canarias-Universidad de La Laguna (Spain)

    2015-08-15

    Microvariability consists of small timescale variations of low amplitude in the photometric light curves of quasars and represents an important tool to investigate their inner core. Detection of quasar microvariations is challenging because of their non-periodicity, as well as the need for high monitoring frequency and a high signal-to-noise ratio. Statistical tests developed for the analysis of quasar differential light curves usually show either low power or low reliability, or both. In this paper we compare two statistical procedures to perform tests on several stars with enhanced power and high reliability. We perform light curve simulations of variable quasars and non-variable stars and analyze them with statistical procedures developed from the F-test and the analysis of variance. The results show a large improvement in the power of both statistical probes and a larger reliability when several stars are included in the analysis. The results from the simulations agree with those obtained from observations of real quasars. The high power and high reliability of the tests discussed in this paper improve the results that can be obtained from short and long timescale variability studies. These techniques are not limited to quasar variability; on the contrary, they can be easily implemented for other sources, such as variable stars. Their applications to future research and to the analysis of large-field photometric monitoring archives could reveal new variable sources.

  7. Reflected Light Curves, Spherical and Bond Albedos of Jupiter- and Saturn-like Exoplanets

    CERN Document Server

    Dyudina, Ulyana; Li, Liming; Kopparla, Pushkar; Yung, Yuk L; Ingersoll, Andrew P; Dones, Luke

    2015-01-01

    We estimate how the light curve and total stellar heating of a planet depend on forward and backward scattering clouds. To do that, we construct light curves for Jupiter- and Saturn-like planet based on observations. We fit analytical functions to the reflected brightness of Jupiter's and Saturn's surface versus planet's phase. We use Pioneer and Cassini spacecraft images to estimate these functions. These observations cover broad bands at 0.59-0.72 microns and 0.39-0.5 microns, and narrow bands at 0.938 microns (atmospheric window), 0.889 microns (CH4 absorption band), and 0.24-0.28 microns. We simulate the images of the planets at different phases with ray-tracing model of a planet by Dyudina et al. (2005). The full-disk luminosity of these simulated images changes with planet's phase producing the full-orbit light curves. We also derive total planet's reflection integrated in all directions (spherical albedos) for Jupiter, Saturn, and for planets with Lambertian and Rayleigh-scattering atmosphere. For Jupi...

  8. Fast evolving pair-instability supernova models: Evolution, explosion, light curves

    Science.gov (United States)

    Kozyreva, Alexandra; Gilmer, Matthew; Hirschi, Raphael; Fröhlich, Carla; Blinnikov, Sergey; Wollaeger, Ryan T.; Noebauer, Ulrich M.; van Rossum, Daniel R.; Heger, Alexander; Even, Wesley P.; Waldman, Roni; Tolstov, Alexey; Chatzopoulos, Emmanouil; Sorokina, Elena

    2016-10-01

    With an increasing number of superluminous supernovae (SLSNe) discovered the question of their origin remains open and causes heated debates in the supernova community. Currently, there are three proposed mechanisms for SLSNe: (1) pair-instability supernovae (PISN), (2) magnetar-driven supernovae, and (3) models in which the supernova ejecta interacts with a circumstellar material ejected before the explosion. Based on current observations of SLSNe, the PISN origin has been disfavoured for a number of reasons. Many PISN models provide overly broad light curves and too reddened spectra, because of massive ejecta and a high amount of nickel. In the current study we re-examine PISN properties using progenitor models computed with the GENEC code. We calculate supernova explosions with FLASH and light curve evolution with the radiation hydrodynamics code STELLA. We find that high-mass models (200 M⊙ and 250 M⊙) at relatively high metallicity (Z = 0.001) do not retain hydrogen in the outer layers and produce relatively fast evolving PISNe Type I and might be suitable to explain some SLSNe. We also investigate uncertainties in light curve modelling due to codes, opacities, the nickel-bubble effect and progenitor structure and composition.

  9. Light Curves for Type II Cepheids in M3 and M5

    Science.gov (United States)

    Rabidoux, K.; Smith, H. A.; Wells, K.; Randall, J.; Hartley, D.; LaCluyze, A.; De Lee, N.; Ingber, M.; Ireland, M.; KInemuchi, K.; Pellegrini, E.; Purdum, L. E.; Pritzl, B. J.; Lustig, R.; Osborn, W.; Lacy, J.; Curtis, M.; Smolinski, J.

    2005-12-01

    Many of the longer period Cepheids within globular clusters do not have modern light curves in the standard B, V, and Cousins-I photometric bandpasses. As part of a larger program to secure B, V, and I band photometry for these type II Cepheids, we have obtained CCD images of the globular clusters M3 and M5. Data were obtained with the 60-cm telescope at Michigan State University and the 40-cm telescopes at Macalester College and Central Michigan University. Light curves are presented for several Cepheids in these clusters. V84 in M5 shows evidence of alternating high and low maxima, indicative of RV Tauri behavior, and may mark the dividing line between pulsations of the type II Cepheid and RV Tauri variety. Observations have also been obtained for type II Cepheids in the globular clusters M2, M10, M12, and M13. Light curves for these variables will be used to investigate the period-luminosity relation for globular cluster Cepheids and to study their pulsational properties. This work has been supported in part by the National Science Foundation.

  10. Cumulative light curves of gamma-ray bursts and relaxation systems

    CERN Document Server

    McBreen, S; Hanlon, L O; Quilligan, F

    2002-01-01

    The cumulative light curves of a large sample of gamma-ray bursts (GRBs) were obtained by summing the BATSE counts. The smoothed profiles are much simpler than the complex and erratic running light curves that are normally used. For most GRBs the slope of the cumulative light curve (S) is approximately constant over a large fraction of the burst. The bursts are modelled as relaxation systems that continuously accumulate energy in the reservoir and discontinuously release it. The slope is a measure of the cumulative power output of the central engine. A plot of S versus peak flux in 64ms (P64ms) shows a very good correlation over a wide range for both short and long GRBs. No relationship was found between S and GRBs with known redshift. The standard slope (S'), which is representative of the power output per unit time, is correlated separately with P64ms for both sub-classes indicating more powerful outbursts for the short GRBs. S' is also anticorrelated with GRB duration. These results imply that GRBs are pow...

  11. Long-term, Multiwavelength Light Curves of Ultra-Cool Dwarfs: II. The evolving Light Curves of the T2.5 SIMP 0136 & the Uncorrelated Light Curves of the M9 TVLM 513

    CERN Document Server

    Croll, Bryce; Lichtman, Jack; Han, Eunkyu; Dalba, Paul A; Radigan, Jacqueline

    2016-01-01

    We present 17 nights of ground-based, near-infrared photometry of the variable L/T transition brown dwarf SIMP J013656.5+093347 and an additional 3 nights of ground-based photometry of the radio-active late M-dwarf TVLM 513-46546. Our TVLM 513-46546 photometry includes 2 nights of simultaneous, multiwavelength, ground-based photometry, in which we detect obvious J-band variability, but do not detect I-band variability of similar amplitude, confirming that the variability of TVLM 513-46546 most likely arises from clouds or aurorae, rather than starspots. Our photometry of SIMP J013656.5+093347 includes 15 nights of J-band photometry that allow us to observe how the variable light curve of this L/T transition brown dwarf evolves from rotation period to rotation period, night-to-night and week-to-week. We estimate the rotation period of SIMP J013656.5+093347 as 2.406 +/- 0.008 hours, and do not find evidence for obvious differential rotation. The peak-to-peak amplitude displayed by SIMP J013656.5+093347 in our l...

  12. OO Aquilae: a solar-type contact binary with intrinsic light curve changes

    Science.gov (United States)

    Li, Hua-Li; Wei, Jian-Yan; Yang, Yuan-Gui; Dai, Hai-Feng

    2016-01-01

    New multi-color photometry of the solar-type contact binary OO Aql was obtained in 2012 and 2013, using the 60 cm telescope at Xinglong Station of the National Astronomical Observatories, Chinese Academy of Sciences. From two sets of light curves LC1 and LC2, photometric models were performed by using the 2003 version of the Wilson-Devinney code. The overcontact factor of the binary system was determined to be f = 37.0(±0.5)%. The intrinsic variability of this binary occurs in light maxima and minima, which could result from a possible third component and magnetic activity of the late type components. Based on all available light minimum times, the orbital period may change in a complicated mode, i.e., sudden period jumps or continuous period variations. The period of OO Aql may possibly undergo a secular period decrease with a rate of dP/dt = -3.63(±0.30) × 10-8 d yr-1, superimposed by two possible cyclic variations in the O - C curve. The long-term period decrease may be interpreted as conserved mass transfer from the more massive component to the less massive one. The 21.5-yr oscillation may be attributed to cyclic magnetic activity, and the 69.3-yr one may result from the light-time effect of an unseen tertiary body.

  13. Period and light-curve fluctuations of the Kepler Cepheid V1154 Cygni

    Science.gov (United States)

    Derekas, A.; Szabó, Gy. M.; Berdnikov, L.; Szabó, R.; Smolec, R.; Kiss, L. L.; Szabados, L.; Chadid, M.; Evans, N. R.; Kinemuchi, K.; Nemec, J. M.; Seader, S. E.; Smith, J. C.; Tenenbaum, P.

    2012-09-01

    We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V1154 Cyg; V = 9.1 mag, P ≈ 4.9 d) based on almost 600 d of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle fluctuations in the pulsation period, indicating that classical Cepheids may not be as accurate astrophysical clocks as commonly believed: regardless of the specific points used to determine the O - C values, the cycle lengths show a scatter of 0.015-0.02 d over 120 cycles covered by the observations. A very slight correlation between the individual Fourier parameters and the O - C values was found, suggesting that the O - C variations might be due to the instability of the light-curve shape. Random-fluctuation tests revealed a linear trend up to a cycle difference 15, but for long term, the period remains around the mean value. We compare the measurements with simulated light curves that were constructed to mimic V1154 Cyg as a perfect pulsator modulated only by the light travel time effect caused by low-mass companions. We show that the observed period jitter in V1154 Cyg represents a serious limitation in the search for binary companions. While the Kepler data are accurate enough to allow the detection of planetary bodies in close orbits around a Cepheid, the astrophysical noise can easily hide the signal of the light-time effect.

  14. CCD Photometric Observations and Light Curve Synthesis of the Near-Contact Binary XZ Canis Minoris

    Science.gov (United States)

    Kim, Chun-Hwey; Park, Jang-Ho; Lee, Jae Woo; Jeong, Jang-Hae

    2009-06-01

    Through the photometric observations of the near-contact binary, XZ CMi, new BV light curves were secured and seven times of minimum light were determined. An intensive period study with all published timings, including ours, confirms that the period of XZ CMi has varied in a cyclic period variation superposed on a secular period decrease over last 70 years. Assuming the cyclic change of period to occur by a light-time effect due to a third-body, the light-time orbit with a semi-amplitude of 0.0056d, a period of 29y and an eccentricity of 0.71 was calculated. The observed secular period decrease of -5.26× 10^{-11} d/P was interpreted as a result of simultaneous occurrence of both a period decrease of -8.20 × 10^{-11} d/P by angular momentum loss (AML) due to a magnetic braking stellar wind and a period increase of 2.94 × 10^{-11} d/P by a mass transfer from the less massive secondary to the primary components in the system. In this line the decreasi! ng rate of period due to AML is about 3 times larger than the increasing one by a mass transfer in their absolute values. The latter implies a mass transfer of dot M_{s}= 3.21 × 10^{-8} M_⊙ y^{-1} from the less massive secondary to the primary. The BV light curves with the latest Wilson-Devinney binary code were analyzed for two separate models of 8200K and 7000K as the photospheric temperature of the primary component. Both models confirm that XZ CMi is truly a near-contact binary with a less massive secondary completely filling Roche lobe and a primary inside the inner Roche lobe and there is a third-light corresponding to about 15-17% of the total system light. However, the third-light source can not be the same as the third-body suggested from the period study. At the present, however, we can not determine which one between two models is better fitted to the observations because of a negligible difference of sum (O-C)^2 between them. The diversity of mass ratios, with which previous investigators were in

  15. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Science.gov (United States)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-02-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330-390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  16. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Qi, E-mail: qidai@tongji.edu.cn [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China); Hao, Luoxi; Lin, Yi; Cui, Zhe [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China)

    2016-02-07

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  17. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    International Nuclear Information System (INIS)

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions

  18. Modeling Type IIn Supernovae: Understanding How Shock Development Effects Light Curves Properties

    Science.gov (United States)

    De La Rosa, Janie

    2016-06-01

    Type IIn supernovae are produced when massive stars experience dramatic mass loss phases caused by opacity edges or violent explosions. Violent mass ejections occur quite often just prior to the collapse of the star. If the final episode happens just before collapse, the outward ejecta is sufficiently dense to alter the supernova light-curve, both by absorbing the initial supernova light and producing emission when the supernova shock hits the ejecta. Initially, the ejecta is driven by shock progating through the interior of the star, and eventually expands through the circumstellar medium, forming a cold dense shell. As the shock wave approaches the shell, there is an increase in UV and optical radiation at the location of the shock breakout. We have developed a suite of simple semi-analytical models in order to understand the relationship between our observations and the properties of the expanding SN ejecta. When we compare Type IIn observations to a set of modeled SNe, we begin to see the influence of initial explosion conditions on early UV light curve properties such as peak luminosities and decay rate.The fast rise and decay corresponds to the models representing a photosphere moving through the envelope, while the modeled light curves with a slower rise and decay rate are powered by 56Ni decay. However, in both of these cases, models that matched the luminosity were unable to match the low radii from the blackbody models. The effect of shock heating as the supernova material blasts through the circumstellar material can drastically alter the temperature and position of the photosphere. The new set of models redefine the initial modeling conditions to incorporate an outer shell-like structure, and include late-time shock heating from shocks produced as the supernova ejecta travels through the inhomogeneous circumstellar medium.

  19. ellc: A fast, flexible light curve model for detached eclipsing binary stars and transiting exoplanets

    Science.gov (United States)

    Maxted, P. F. L.

    2016-06-01

    Context. Very high quality light curves are now available for thousands of detached eclipsing binary stars and transiting exoplanet systems as a result of surveys for transiting exoplanets and other large-scale photometric surveys. Aims: I have developed a binary star model (ellc) that can be used to analyse the light curves of detached eclipsing binary stars and transiting exoplanet systems that is fast and accurate, and that can include the effects of star spots, Doppler boosting and light-travel time within binaries with eccentric orbits. Methods: The model represents the stars as triaxial ellipsoids. The apparent flux from the binary is calculated using Gauss-Legendre integration over the ellipses that are the projection of these ellipsoids on the sky. The model can also be used to calculate the flux-weighted radial velocity of the stars during an eclipse (Rossiter-McLaghlin effect). The main features of the model have been tested by comparison to observed data and other light curve models. Results: The model is found to be accurate enough to analyse the very high quality photometry that is now available from space-spaced instruments, flexible enough to model a wide range of eclipsing binary stars and extrasolar planetary systems, and fast enough to enable the use of modern Monte Carlo methods for data analysis and model testing. The software package is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A111

  20. Fast bolometric measurements on the TCV tokamak

    Science.gov (United States)

    Furno, I.; Weisen, H.; Mlynar, J.; Pitts, R. A.; Llobet, X.; Marmillod, Ph.; Pochon, G. P.

    1999-12-01

    The design and first results are presented from a bolometric diagnostic with high temporal resolution recently installed on the TCV tokamak. The system consists of two pinhole cameras viewing the plasma from above and below at the same toroidal location. Each camera is equipped with an AXUV-16ELO linear array of 16 p-n junction photodiodes, characterized by a flat spectral sensitivity from ultraviolet to x-ray energies, a high temporal response (<0.5 μs), and insensitivity to low-energy neutral particles emitted by the plasma. This high temporal resolution allows the study of transient phenomena such as fast magnetohydrodynamic (MHD) activity hitherto inaccessible with standard bolometry. In the case of purely electromagnetic radiation, good agreement has been found when comparing results from the new diagnostic with those from a standard metal foil bolometer system. This comparison has also revealed that the contribution of neutrals to the foil bolometer measurements can be extremely important under certain operating conditions, precluding the application of tomographic techniques for reconstruction of the radiation distribution.

  1. The Millimeter-wave Bolometric Interferometer (MBI)

    Science.gov (United States)

    Gault, Amanda C.; Ade, P. A. R.; Bierman, E.; Bunn, E. F.; Hyland, P. O.; Keating, B. G.; Korotkov, A. L.; Malu, S. S.; O'Sullivan, C.; Piccirillo, L.; Timbie, P. T.; Tucker, G. S.

    2009-01-01

    We report on the design and tests of a prototype of the Millimeter-wave Bolometric Interferometer (MBI). MBI is designed to make sensitive measurements of the polarization of the cosmic microwave background (CMB). It combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. The prototype, which we call MBI-4, views the sky directly through four corrugated horn antennas. MBI ultimately will have 1000 antennas. These antennas have low sidelobes and nearly symmetric beam patterns, so spurious instrumental polarization from reflective optics is avoided. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines, determined by placement of the four antennas, results in sensitivity to CMB polarization fluctuations over the multipole range l = 150 - 270. The signals are combined with a Fizeau beam combiner and interference fringes are detected by an array of spiderweb bolometers. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Initial tests and observations have been made at Pine Bluff Observatory (PBO) outside Madison, WI. This work was supported by NASA grants NAG5-12758, NNX07AG82G, the Rhode Island Space Grant and the Wisconsin Space Grant.

  2. $Extrasolar~Storms$: Pressure-dependent Changes In Light Curve Phase In Brown Dwarfs From Simultaneous $Hubble$ and $Spitzer$ Observations

    CERN Document Server

    Yang, Hao; Marley, Mark S; Karalidi, Theodora; Flateau, Davin; Showman, Adam P; Metchev, Stanimir; Buenzli, Esther; Radigan, Jacqueline; Artigau, Étienne; Lowrance, Patrick J; Burgasser, Adam J

    2016-01-01

    We present $Spitzer$/IRAC Ch1 and Ch2 monitoring of six brown dwarfs during 8 different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous $HST$/WFC3 G141 Grism spectra during two epochs and derived light curves in five narrow-band filters. Probing different pressure levels in the atmospheres, the multi-wavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 h to 13 h. We compare the shapes of the light curves and estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. ...

  3. Multiperiodicity, modulations and flip-flops in variable star light curves I. Carrier fit method

    CERN Document Server

    Pelt, J; Mantere, M J; Tuominen, I

    2011-01-01

    The light curves of variable stars are commonly described using simple trigonometric models, that make use of the assumption that the model parameters are constant in time. This assumption, however, is often violated, and consequently, time series models with components that vary slowly in time are of great interest. In this paper we introduce a class of data analysis and visualization methods which can be applied in many different contexts of variable star research, for example spotted stars, variables showing the Blazhko effect, and the spin-down of rapid rotators. The methods proposed are of explorative type, and can be of significant aid when performing a more thorough data analysis and interpretation with a more conventional method.Our methods are based on a straightforward decomposition of the input time series into a fast "clocking" periodicity and smooth modulating curves. The fast frequency, referred to as the carrier frequency, can be obtained from earlier observations (for instance in the case of p...

  4. Investigation of Structure in the Light Curves of a Sample of Newly Discovered Long Period Variable Stars

    Science.gov (United States)

    Craine, E. R.; Culver, R. B.; Eykholt, R.; Flurchick, K. M.; Kraus, A. L.; Tucker, R. A.; Walker, D. K.

    2015-09-01

    Long period variable stars exhibit hump structures, and possibly flares, in their light curves. While the existence of humps is not controversial, the presence of flaring activity is less clear. Mining of a sky survey database of new variable star discoveries (the first MOTESS-GNAT Variable Star Catalog (MG1-VSC)) has led to identification of 47 such stars for which there are sufficient data to explore the presence of anomalous light curve features. We find a number of hump structures, and see one possible flare, suggesting that they are rare events. We present light curves and measured parameters for these stars, and a population statistical analysis.

  5. The diverse broad-band light-curves of Swift GRBs reproduced with the cannonball model

    CERN Document Server

    Dado, Shlomo; De Rújula, A

    2009-01-01

    Two radiation mechanisms, inverse Compton scattering (ICS) and synchrotron radiation (SR), suffice within the cannonball (CB) model of long gamma ray bursts (LGRBs) and X-ray flashes (XRFs) to provide a very simple and accurate description of their observed prompt emission and afterglows. Simple as they are, the two mechanisms and the burst environment generate the rich structure of the light curves at all frequencies and times. This is demonstrated for 33 selected Swift LGRBs and XRFs, which are well sampled from early time until late time and well represent the entire diversity of the broad band light curves of Swift LGRBs and XRFs. Their prompt gamma-ray and X-ray emission is dominated by ICS of glory light. During their fast decline phase, ICS is taken over by SR which dominates their broad band afterglow. The pulse shape and spectral evolution of the gamma-ray peaks and the early-time X-ray flares, and even the delayed optical `humps' in XRFs, are correctly predicted. The canonical and non-canonical X-ra...

  6. Shock Breakout and Early Light Curves of Type II-P Supernovae Observed with Kepler

    CERN Document Server

    Garnavich, P M; Rest, A; Shaya, E J; Olling, R P; Kasen, D; Villar, A

    2016-01-01

    We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae. Using the fast cadence of the Kepler observations we precisely estimate the rise time to maximum for KSN2011a and KSN2011d as 10.5$\\pm 0.4$ and 13.3$\\pm 0.4$ rest-frame days respectively. Based on fits to idealized analytic models, we find the progenitor radius of KSN2011a (280$\\pm 20$ R$_\\odot$) to be significantly smaller than that for KSN2011d (490$\\pm 20$ R$_\\odot$) but both have similar explosion energies of 2.0$\\pm 0.3\\times 10^{51}$ erg. The rising light curve of KSN2011d is an excellent match to that predicted by simple models of exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models predict possibly due to the supernova shockwave moving into pre-existing wind or mass-loss from the RSG. A mass loss rate of $10^{-4}$ M$_\\odot$ yr$^{-1}$ from the RSG can explain the fast rise without impacting the optical flux at maximum light or the shape ...

  7. Sensitivity of a Bolometric Interferometer to the CMB power spectrum

    CERN Document Server

    Hamilton, J -Ch; Cressiot, C; Kaplan, J; Piat, M; Rosset, C

    2008-01-01

    Context. The search for the B-mode polarization fluctuations in the Cosmic Microwave Background is one of the main challenges of modern cosmology. The expected level of the B-mode signal is very low and therefore implies the development of highly sensitive and low systematics instruments. An appealing possibility is bolometric interferometry. Aims. We compare in this article the sensitivity on the CMB angular power spectrum achieved with direct imaging, heterodyne and bolometric interferometry. Methods. Using a simple power spectrum estimator, we calculate its variance leading to the counterpart for Bolometric Interferometry of the well known Knox formula for direct imaging. Results. We find that bolometric interferometry is almost as sensitive as direct imaging for very large scales but suffers from the lack of equivalent/redondant baselines at smaller scales. However, as expected, it ends up being more sensitive than heterodyne interferometry thanks to the low noise of the bolometers. It therefore appears a...

  8. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    Science.gov (United States)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  9. ELECTROMAGNETIC EMISSION FROM LONG-LIVED BINARY NEUTRON STAR MERGER REMNANTS. II. LIGHT CURVES AND SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Daniel M. [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany); Ciolfi, Riccardo, E-mail: daniel.siegel@aei.mpg.de, E-mail: riccardo.ciolfi@unitn.it [Physics Department, University of Trento, Via Sommarive 14, I-38123 Trento (Italy)

    2016-03-01

    Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have profound implications for multimessenger astronomy with joint EM and gravitational-wave (GW) observations of BNS mergers, which will soon become reality thanks to the ground-based advanced LIGO/Virgo GW detector network. Here we explore such EM signatures based on the model presented in a companion paper, which provides a self-consistent evolution of the post-merger system and its EM emission up to ∼10{sup 7} s. Light curves and spectra are computed for a wide range of post-merger physical properties. We present X-ray afterglow light curves corresponding to the “standard” and the “time-reversal” scenario for SGRBs (prompt emission associated with the merger or with the collapse of the long-lived NS). The light curve morphologies include single and two-plateau features with timescales and luminosities that are in good agreement with Swift observations. Furthermore, we compute the X-ray signal that should precede the SGRB in the time-reversal scenario, the detection of which would represent smoking-gun evidence for this scenario. Finally, we find a bright, highly isotropic EM transient peaking in the X-ray band at ∼10{sup 2}–10{sup 4} s after the BNS merger with luminosities of L{sub X} ∼ 10{sup 46}–10{sup 48} erg s{sup −1}. This signal represents a very promising EM counterpart to the GW emission from BNS mergers.

  10. Magnetar-driven Shock Breakout and Double-peaked Supernova Light Curves

    Science.gov (United States)

    Kasen, Daniel; Metzger, Brian D.; Bildsten, Lars

    2016-04-01

    The light curves of some luminous supernovae are suspected to be powered by the spindown energy of a rapidly rotating magnetar. Here we describe a possible signature of the central engine: a burst of shock breakout emission occurring several days after the supernova explosion. The energy input from the magnetar inflates a high-pressure bubble that drives a shock through the pre-exploded supernova ejecta. If the magnetar is powerful enough, that shock will near the ejecta surface and become radiative. At the time of shock breakout, the ejecta will have expanded to a large radius (∼ {10}14 cm) so that the radiation released is at optical/ultraviolet wavelengths ({T}{{eff}} ≈ 20,000 K) and lasts for several days. The luminosity and timescale of this magnetar-driven shock breakout are similar to the first peak observed recently in the double-peaked light curve of SN-LSQ14BDQ. However, for a large region of model parameter space, the breakout emission is predicted to be dimmer than the diffusive luminosity from direct magnetar heating. A distinct double-peaked light curve may therefore only be conspicuous if thermal heating from the magnetar is suppressed at early times. We describe how such a delay in heating may naturally result from inefficient dissipation and thermalization of the pulsar wind magnetic energy. Without such suppression, the breakout may only be noticeable as a small bump or kink in the early luminosity or color evolution, or as a small but abrupt rise in the photospheric velocity. A similar breakout signature may accompany other central engines in supernovae, such as a black hole accreting fallback material.

  11. Episodic modulations in supernova radio light curves from luminous blue variable supernova progenitor models

    OpenAIRE

    Moriya, Takashi J.; Groh, Jose H.; Meynet, Georges

    2013-01-01

    Ideally, one would like to know which type of core-collapse SNe is produced by different progenitors and the channels of stellar evolution leading to these progenitors. These links have to be very well known to use the observed frequency of different types of SN events for probing the star formation rate and massive star evolution in different types of galaxies. We investigate the link between LBV as SN progenitors and the appearance of episodic radio light curve modulations of the SN event...

  12. Multi-band optical light-curve behavior of core-collapse supernovae

    CERN Document Server

    Kumar, Brijesh

    2013-01-01

    We present survey results obtained from the UBVRI optical photometric follow-up of 19 bright core-collapse SNe during 2002-2012 using 1-m class optical telescopes operated by the Aryabhatta Research Institute of Observational Science (acronym ARIES), Nainital India. This homogeneous set of data have been used to study behavior of optical light/color curve, and to gain insight into object-to-object peculiarity. We derive integrated luminosities for types IIP, Ibc and luminous SNe. Two peculiar type IIP events having photometric properties similar to normal IIP and spectroscopic properties similar to sub-luminous IIP have been identified.

  13. THE FIRST SYSTEMATIC STUDY OF TYPE Ibc SUPERNOVA MULTI-BAND LIGHT CURVES

    International Nuclear Information System (INIS)

    We present detailed optical photometry for 25 Type Ibc supernovae (SNe Ibc) within d ≈ 150 Mpc obtained with the robotic Palomar 60 inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ibc light curves available to date. We correct the light curves for host galaxy extinction using a new technique based on the photometric color evolution, namely, we show that the (V – R) color of extinction-corrected SNe Ibc at Δt ≈ 10 days after V-band maximum is tightly distributed, ((V – R)V10) = 0.26 ± 0.06 mag. Using this technique, we find that SNe Ibc typically suffer from significant host galaxy extinction, (E(B – V)) ≈ 0.4 mag. A comparison of the extinction-corrected light curves for helium-rich (Type Ib) and helium-poor (Type Ic) SNe reveals that they are statistically indistinguishable, both in luminosity and decline rate. We report peak absolute magnitudes of (MR ) = –17.9 ± 0.9 mag and (MR ) = –18.3 ± 0.6 mag for SNe Ib and Ic, respectively. Focusing on the broad-lined (BL) SNe Ic, we find that they are more luminous than the normal SNe Ibc sample, (MR ) = –19.0 ± 1.1 mag, with a probability of only 1.6% that they are drawn from the same population of explosions. By comparing the peak absolute magnitudes of SNe Ic-BL with those inferred for local engine-driven explosions (GRB-SN 1998bw, XRF-SN 2006aj, and SN 2009bb) we find a 25% probability that relativistic SNe are drawn from the overall SNe Ic-BL population. Finally, we fit analytic models to the light curves to derive typical 56Ni masses of MNi ≈ 0.2 and 0.5 M☉ for SNe Ibc and SNe Ic-BL, respectively. With reasonable assumptions for the photospheric velocities, we further extract kinetic energy and ejecta mass values of Mej ≈ 2 M☉ and EK ≈ 1051 erg for SNe Ibc, while for SNe Ic-BL we find higher values, Mej ≈ 5 M☉ and EK ≈ 1052 erg. We discuss the implications for the progenitors of SNe Ibc and their

  14. Effect of repeated insertions of curved sequences in DNA plasmids: a light-scattering study

    Science.gov (United States)

    Beretta, Stefano; Chirico, Giuseppe; Baldini, Giancarlo; Kapp, U.; Badaracco, G.

    1993-06-01

    The effect of the insertion of different amounts (from 0 to 6) of the curved sequence AluI in pUC18m plasmid (2686 base pairs, bp) is studied by dynamic light scattering. This sequence is a highly repeated 113 base pairs long sequence from Artemia Franciscana shrimp. A 30% compaction of the plasmids containing 2 and 6 adjacent AluI sequences compared to pUC8 plasmid (2717 bp) is observed. Furthermore the behavior of the translational diffusion coefficient Dt versus the number of adjacent AluI insertion is not monotonic.

  15. Dynamics and Afterglow Light Curves of GRB Blast Waves Encountering a Density Bump or Void

    OpenAIRE

    Uhm, Z. Lucas; Zhang, Bing

    2014-01-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst (GRB) blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structures in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics, for blast waves with either a long-lived or short-lived RS. We show that, when the ambient medium density drops, the b...

  16. 10 Years of XRT light curves: a general view of the X-ray afterglow

    CERN Document Server

    Bardho, O; Gendre, B

    2015-01-01

    During the pre-Swift era, a clustering of light curves was observed in the X-ray, optical and infrared afterglow of gamma-ray bursts. We used a sample of 254 GRB X-ray afterglows to check this fact in the Swift era. We corrected fluxes for distance, time dilation and losses of energy due to cosmological effects. With all our data in hand, we faced with a problem: our data were scattered. We investigated 3 possibilities to explain this, namely: the clustering does not exist, there are problems during calibration of data, and there are instrumental problems. We finally confirm that our sample is consistent with Dainotti correlation.

  17. The Kepler Light Curves of KSwAGS AGN: A Unique Window into Accretion Physics

    OpenAIRE

    Smith, Krista Lynne; Mushotzky, Richard; Boyd, Padi; Edelson, Rick; Howell, Steve; Gelino, Dawn; Brown, Alex.

    2016-01-01

    The Kepler-Swift Active Galaxies Survey (KSwAGS) discovered ~160 AGN in the Kepler and K2 fields. The optical Kepler and K2 light curves of these AGN are by far the most precise and evenly-sampled ever obtained. There are unique challenges involved in adapting Kepler/K2 data for use with AGN since the Kepler pipeline removes stochasticity; however, once mitigated, these data provide an unprecedented glimpse of the accretion disk's variability. We have also conducted follow-up spectral obs...

  18. Timing Analysis of Light Curves in the Tartarus Active Galactic Nuclei Database

    CERN Document Server

    O'Neill, P M; Papadakis, I E; Turner, T J; Neill, Paul M. O'; Nandra, Kirpal; Papadakis, Iossif E.

    2004-01-01

    The Tartarus database contains products for 529 ASCA observations of active galactic nuclei. We have been updating Tartarus to include observing sequences conducted after 1999 January. The revised database will contain products for 375 objects, with a total of 614 observing sequences. We have begun a systematic timing analysis of the Tartarus light curves. We present here some preliminary results of an investigation into the relation between excess variance and black-hole mass. Having optimised our analysis to minimize the scatter in the variance measurements, we find that the narrow-line active galactic nuclei follow roughly the same relation as the broad-line objects.

  19. VizieR Online Data Catalog: Light curves of WASP-67 transit events (Mancini+, 2014)

    Science.gov (United States)

    Mancini, L.; Southworth, J.; Ciceri, S.; Calchi Novati, S.; Dominik, M.; Henning, T.; Jorgensen, U. G.; Korhonen, H.; Nikolov, N.; Alsubai, K. A.; Bozza, V.; Bramich, D. M.; D'Ago, G.; Figuera Jaimes, R.; Galianni, P.; Gu, S.-H.; Harpose, K.; Hinse, T.; Hundertmark, M.; Juncher, D.; Kains, N.; Popovas, A.; Rabus, M.; Rahvar, S.; Skottfelt, J.; Snodgrass, C.; Street, R.; Surdej, J.; Tsapras, Y.; Vilela, C.; Wang, X.-B.; Wertz, O.

    2014-07-01

    5 light curves of two transits of the extrasolar planetary system WASP-67, observed on 2012 June 4 and 2013 June 22, are presented. Four of the datasets were obtained using the MPG 2.2-m telescope, GROND camera and filters similar to Sloan g', r', i', z', at the ESO Observatory in La Silla (Chile). Another data set was obtained using the 1.54-m Danish telescope, DFOSC camera and Bessel-R filter at the ESO Observatory in La Silla (Chile). (5 data files).

  20. VizieR Online Data Catalog: Light curves of WASP-80 transit events (Mancini+, 2014)

    Science.gov (United States)

    Mancini, L.; Southworth, J.; Ciceri, S.; Dominik, M.; Henning, T.; Jorgensen, U. G.; Lanza, A. F.; Rabus, M.; Snodgrass, C.; Vilela, C.; Alsubai, K. A.; Bozza, V.; Bramich, D. M.; Calchi Novati, S.; D'Ago, G.; Figuera Jaimes, R.; Galianni, P.; Gu, S.-H.; Harpose, K.; Hinse, T.; Hundertmark, M.; Juncher, D.; Kains, N.; Korhonen, H.; Popovas, A.; Rahvar, S.; Skottfelt, J.; Street, R.; Surdej, J.; Tsapras, Y.; Wang, X.-B.; Wertz, O.

    2014-01-01

    8 light curves of one transit of the extrasolar planetary system WASP-80, observed on 2013 June 16, are presented. Seven of the datasets were obtained using the MPG/ESO 2.2-m telescope, GROND camera and filters similar to Sloan g', r', i', z', and J, H, K at the ESO Observatory in La Silla (Chile). Another data set was obtained using the 1.54-m Danish telescope, DFOSC camera and Bessel-i filter at La Silla (Chile). (8 data files).

  1. Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Hicken, Malcolm; /Harvard-Smithsonian Ctr. Astrophys. /Harvard U.; Wood-Vasey, W.Michael; /Pittsburgh U.; Blondin, Stephane; /European Southern Observ.; Challis, Peter; /Harvard-Smithsonian Ctr. Astrophys.; Jha, Saurabh; /Rutgers U., Piscataway; Kelly, Patrick L.; /KIPAC, Menlo Park; Rest, Armin; /Harvard U. /Cerro-Tololo InterAmerican Obs.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2012-04-06

    We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. to form the Constitution set and, combined with a BAO prior, produces 1 + w = 0.013{sub -0.068}{sup +0.066} (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light-curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R{sub V} = 3.1), and MLCS2k2 (R{sub V} = 1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < {Delta} < 1.2. MLCS2k2 with R{sub V} = 3.1 overestimates host-galaxy extinction while R{sub V} {approx} 1.7 does not. Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2{sigma}, suggesting that they may come from different populations. We also find that SN Ia in Scd/Sd/Irr hosts have low scatter (0.1 mag) and reddening. Current systematic errors can be reduced by improving SN Ia photometric accuracy, by including the CfA3 sample to retrain light-curve fitters, by combining optical SN Ia photometry with near-infrared photometry to understand host-galaxy extinction, and by determining if different environments give rise to different intrinsic SN Ia luminosity after correction for light-curve shape and color.

  2. VizieR Online Data Catalog: Light curves for the eclipsing binary V1094 Tau (Maxted+, 2015)

    Science.gov (United States)

    Maxted, P. F. L.; Hutcheon, R. J.; Torres, G.; Lacy, C. H. S.; Southworth, J.; Smalley, B.; Pavlovski, K.; Marschall, L. A.; Clausen, J. V.

    2015-04-01

    Photometric light curves of the detached eclipsing binary V1094 Tau in the Stroemgren u-,v-,b- and y-bands, and in the Johnson V-band. The curves in the Stroemgren bands were obtained with the Stroemgren Automatic Telescope (SAT) at ESO, La Silla. The curves in the V-band were obtained with the NFO telescope in New Mexico and with the URSA telescope at the University of Arkansas. (6 data files).

  3. Inverse Compton light curves of blazars under non-linear, time-dependent synchrotron-self Compton cooling

    CERN Document Server

    Zacharias, Michael

    2014-01-01

    Blazars exhibit flares with a doubling time scale on the order of minutes. Such rapid flares are theoretically challenging and several {models} have been put forward to explain the fast variability. In this paper we continue the discussion concerning the effects of non-linear, time-dependent synchrotron self-Compton (SSC) cooling. In previous papers we were able to show that the non-linearity{, introduced by a time-dependent electron injection,} has severe consequences for both the spectral energy distribution (SED) and the monochromatic synchrotron light curve. The non-linear cooling introduces novel breaks in the SED, which are usually explained by complicated underlying electron distributions, while the much faster cooling of the SSC process {causes significant differences in the synchrotron light curves}. In this paper we calculate the inverse Compton light curves, taking into account both the SSC and the external Compton process. The light curves are calculated from the monochromatic intensities by intro...

  4. A unique UV flare in the optical light curve of the quasar J004457.9+412344

    Directory of Open Access Journals (Sweden)

    Hatzidimitriou D.

    2012-12-01

    Full Text Available We found that the nova candidate J004457.9+412344 is a radio-quiet quasar at z ∼ 2. Its optical long-term light curve, covering more than half a century, shows quasar typical flux variations superimposed by a spectacular single flare lasting more than one year (observer frame. We could not find comparable light curves among the several thousand catalogued radio-quiet quasars in the stripe 82 of the Sloan Digital Sky Survey. The decreasing part of the flare light curve roughly follows a power law t−5/3. The quasar spectrum, the total energy of the flare, and the decline of the light curve are consistent with the tidal disruption of a ∼10 Mʘ giant star by a supermassive black hole of a few 108 Mʘ. We argue that the alternative explanation by gravitational microlensing is less likely, though it cannot be definitely excluded.

  5. Understanding the light curves of the HST-1 knot in M87 with internal relativistic shock waves along its jet

    Science.gov (United States)

    Coronado, Y.; López-Corona, O.; Mendoza, S.

    2016-10-01

    Knots or blobs observed in astrophysical jets are commonly interpreted as shock waves moving along them. Long-time observations of the HST-1 knot inside the jet of the galaxy M87 have produced detailed multiwavelength light curves. In this paper, we model these light curves using the semi-analytical approach developed by Mendoza et al. This model was developed to account for the light curves produced by working surfaces (blobs) moving along relativistic jets. These working surfaces are generated by periodic oscillations of the injected flow velocity and mass ejection rates at the base of the jet. Using genetic algorithms to fit the parameters of the model, we are able to explain the outbursts observed in the light curves of the HST-1 knot with an accuracy greater than a 2σ statistical confidence level.

  6. KIC 4552982: outbursts and pulsations in the longest-ever pseudo-continuous light curve of a ZZ Ceti

    Directory of Open Access Journals (Sweden)

    Bell K. J.

    2015-01-01

    Full Text Available KIC 4552982 was the first ZZ Ceti (hydrogen-atmosphere pulsating white dwarf identified to lie in the Kepler field, resulting in the longest pseudo-continuous light curve ever obtained for this type of variable star. In addition to the pulsations, this light curve exhibits stochastic episodes of brightness enhancement unlike any previously studied white dwarf phenomenon. We briefly highlight the basic outburst and pulsation properties in these proceedings.

  7. CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae

    CERN Document Server

    Friedman, Andrew S; Marion, G H; Challis, Peter; Mandel, Kaisey S; Bloom, Joshua S; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan; Klein, Christopher R; Starr, Dan L; Morgan, Adam; Rest, Armin; Blake, Cullen H; Miller, Adam A; Falco, Emilio E; Wyatt, William F; Mink, Jessica; Skrutskie, Michael F; Kirshner, Robert P

    2014-01-01

    CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light curves for Type Ia supernovae (SN Ia) obtained with the 1.3m PAIRITEL (Peters Automated InfraRed Imaging TELescope). This data set includes 4607 measurements of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from maximum in the B-band. More than half of the light curves begin before the time of maximum and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for supernova cosmology studies in the NIR. ...

  8. Afterglow Light Curves from Jetted Gamma-ray Burst Ejecta in Stellar Winds

    CERN Document Server

    Wu, X F; Huang, Y F; Ma, H T

    2003-01-01

    We revisit optical and radio afterglows arising from the shocks by relativistic conical ejecta running into pre-burst massive stellar winds. Under the homogeneous thin-shell approximation and the realistic treatment for lateral expansion of jets, our results show that a notable break of optical light curve within one decade in time indeed exists in most cases of our calculations by varying physical parameters within reasonable ranges. We rectify the conclusions of previous works on the jet+wind model, which claimed that there was no sharp break as the transition time lasts for two decades. Even for a relatively tenuous wind which cannot decelerate the relativistic jet to cause a sharp break within days, the wind termination shock due to the ram pressure balance by surrounding medium occurs at a small radius, i.e. several times $10^{17}$ cm. The jet will pass through the wind environment within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallowe...

  9. Modelling the $\\gamma$-ray and radio light curves of the double pulsar system

    CERN Document Server

    Seyffert, A S; Harding, A K; Johnson, T J

    2014-01-01

    Guillemot et al. recently reported the discovery of $\\gamma$-ray pulsations from the 22.7ms pulsar (pulsar A) in the famous double pulsar system J0737-3039A/B. The $\\gamma$-ray light curve (LC) of pulsar A has two peaks separated by approximately half a rotation, and these are non-coincident with the observed radio and X-ray peaks. This suggests that the $\\gamma$-ray emission originates in a part of the magnetosphere distinct from where the radio and X-ray radiation is generated. Thus far, three different methods have been applied to constrain the viewing geometry of pulsar A (its inclination and observer angles $\\alpha$ and $\\zeta$): geometric modelling of the radio and $\\gamma$-ray light curves, modelling of the position angle sweep in phase seen in the radio polarisation data, and independent studies of the time evolution of the radio pulse profile of pulsar A. These three independent, complementary methods have yielded consistent results: pulsar A's rotation axis is likely perpendicular to the orbital pla...

  10. Off-Axis Afterglow Light Curves from High-Resolution Hydrodynamical Jet Simulations

    CERN Document Server

    van Eerten, H J; Zhang, W

    2011-01-01

    Numerical jet simulations serve a valuable role in calculating gamma-ray burst afterglow emission beyond analytical approximations. Here we present the results of high resolution 2D simulations of decelerating relativistic jets performed using the RAM adaptive mesh refinement relativistic hydrodynamics code. We have applied a separate synchrotron radiation code to the simulation results in order to calculate light curves at frequencies varying from radio to X-ray for observers at various angles from the jet axis. We provide a confirmation from radio light curves from simulations rather than from a simplified jet model for earlier results in the literature finding that only a very small number of local Ibc supernovae can possibly harbor an orphan afterglow. Also, recent studies have noted an unexpected lack of observed jet breaks in the Swift sample. Using a jet simulation with physical parameters representative for an average Swift sample burst, such as a jet half opening angle of 0.1 rad and a source redshif...

  11. The quiescent light curve and orbital period of GRO$\\sim$J0422+32

    CERN Document Server

    Chevalier, C; Chevalier, Claude; Ilovaisky, Sergio A

    1996-01-01

    CCD photometry of the black hole candidate GRO~J0422+32 in quiescence, obtained at Haute-Provence from 1994 November to 1995 February, reveals a double-wave modulation at a period close to the value we found during outbursts and also close to one of the possible periods derived by Filippenko, Matheson and Ho (1995) from spectroscopic observations with the W. M. Keck 10-m telescope. A period of 0.212140 \\pm 0.000003 d (5.09136 \\pm 0.00007 h) fits all our photometric data from 1993 January to 1995 February and yields a minimum in our light curves at the inferior conjunction of the M star, as determined from the radial velocity data of Filippenko et al. (1995). The quiescent R_{c} band light curve exhibits a changing asymmetry of shape and a variable amplitude. On two consecutive nights the source was found constant to within \\pm 0.05 mag, suggesting an upper limit on the ellipsoidal effect in this band.

  12. Phase Lags in the Optical-Infrared Light Curves of AGB Stars

    CERN Document Server

    Smith, B J; Moffett, A J; Smith, Beverly J.; Price, Stephan D.; Moffett, Amanda J.

    2005-01-01

    To search for phase lags in the optical-infrared light curves of asymptotic giant branch stars, we have compared infrared data from the COBE DIRBE satellite with optical light curves from the AAVSO and other sources. We found 17 examples of phase lags in the time of maximum in the infrared vs. that in the optical, and 4 stars with no observed lags. There is a clear difference between the Mira variables and the semi-regulars in the sample, with the maximum in the optical preceding that in the near-infrared in the Miras, while in most of the semi-regulars no lags are observed. Comparison to published theoretical models indicates that the phase lags in the Miras are due to strong titanium oxide absorption in the visual at stellar maximum, and suggests that Miras pulsate in the fundamental mode, while at least some semi-regulars are first overtone pulsators. There is a clear optical-near-infrared phase lag in the carbon-rich Mira V CrB; this is likely due to C2 and CN absorption variations in the optical.

  13. Cosmological Parameter Uncertainties from SALT-II Type Ia Supernova Light Curve Models

    CERN Document Server

    Mosher, J; Kessler, R; Astier, P; Marriner, J; Betoule, M; Sako, M; El-Hage, P; Biswas, R; Pain, R; Kuhlmann, S; Regnault, N; Frieman, J A; Schneider, D P

    2014-01-01

    We use simulated SN Ia samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and the bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: 120 low-redshift (z < 0.1) SNe Ia, 255 SDSS SNe Ia (z < 0.4), and 290 SNLS SNe Ia (z <= 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (winput - wrecovered) ranging from -0.005 +/- 0.012 to -0.024 +/- 0.010. These biases a...

  14. Hydrodynamics associated to the X-ray light curve of A0620-00

    CERN Document Server

    Coronado, Y

    2014-01-01

    From 1975 to 1976, an outburst was detected in the light curve of the X-ray transient A0620-00 using the Ariel V and SAS-3 experiments. In this letter we model the outburst with the hydrodynamical model proposed by Mendoza et al. (2009). The physical model is constructed assumming basic mass and momentum conservation laws associated to the motion of the shock waves developed inside the expanding relativistic jet of the source. These internal shock waves are produced as a result of periodic variations of the inyected mass and velocity of the flow at the base of the jet. The observations of this X-ray light curve present two clear bumps. The first one is modelled assuming periodic variations of the inyected velocity at the base of the jet, while the second one can either be modelled by a further velocity oscillations, or by a periodic variation of the mass injection rate at the base of the jet at a latter time. The fitting of the data fixes different parameters of the model, such as the mean mass injection rate...

  15. Hydrodynamics associated to the X-ray light curve of A0620-00

    Science.gov (United States)

    Coronado, Y.; Mendoza, S.

    2015-12-01

    From 1975 to 1976, an outburst was detected in the light curve of the X-ray transient A0620-00 using the Ariel V and SAS-3 experiments. In this article we model the outburst with the hydrodynamical model proposed by Mendoza et al. (Mon. Not. R. Astron. Soc. 395:1403, 2009). The physical model is constructed assuming basic mass and momentum conservation laws associated to the motion of the shock waves developed inside the expanding relativistic jet of the source. These internal shock waves are produced as a result of periodic variations of the injected mass and velocity of the flow at the base of the jet. The observations of this X-ray light curve present two clear bumps. The first one is modelled assuming periodic variations of the injected velocity at the base of the jet, while the second one can either be modelled by further velocity oscillations, or by a periodic variation of the mass injection rate at the base of the jet at a latter time. This latter model is statistically more significant for the observed data, than the former. The fitting of the data fixes different parameters of the model, such as the mean mass injection rate at the base of the jet and the oscillation frequency of the flow as measured on the rest frame of the central source.

  16. Type II supernova energetics and comparison of light curves to shock-cooling models

    CERN Document Server

    Rubin, Adam; De Cia, Annalisa; Horesh, Assaf; Khazov, Danny; Ofek, Eran O; Kulkarni, S R; Arcavi, Iair; Manulis, Ilan; Yaron, Ofer; Vreeswijk, Paul; Kasliwal, Mansi M; Ben-Ami, Sagi; Perley, Daniel A; Cao, Yi; Cenko, S Bradley; Rebbapragada, Umaa D; Woźniak, P R; Filippenko, Alexei V; Clubb, K I; Nugent, Peter E; Pan, Y -C; Badenes, C; Howell, D Andrew; Valenti, Stefano; Sand, David; Sollerman, J; Johansson, Joel; Leonard, Douglas C; Horst, J Chuck; Armen, Stephen F; Fedrow, Joseph M; Quimby, Robert M; Mazzali, Paulo; Pian, Elena; Sternberg, Assaf; Matheson, Thomas; Sullivan, M; Maguire, K; Lazarevic, Sanja

    2015-01-01

    During the first few days after explosion, Type II supernovae (SNe) are dominated by relatively simple physics. Theoretical predictions regarding early-time SN light curves in the ultraviolet (UV) and optical bands are thus quite robust. We present, for the first time, a sample of $57$ $R$-band Type II SN light curves that are well monitored during their rise, having $>5$ detections during the first 10 days after discovery, and a well-constrained time of explosion to within $1-3$ days. We show that the energy per unit mass ($E/M$) can be deduced to roughly a factor of five by comparing early-time optical data to the model of Rabinak & Waxman (2011), while the progenitor radius cannot be determined based on $R$-band data alone. We find that Type II SN explosion energies span a range of $E/M=(0.2-20)\\times 10^{51} \\; \\rm{erg/(10 M}_\\odot$), and have a mean energy per unit mass of $\\left\\langle E/M \\right\\rangle = 0.85\\times 10^{51} \\; \\rm{erg/(10 M}_\\odot$), corrected for Malmquist bias. Assuming a small sp...

  17. POST-FLARE ULTRAVIOLET LIGHT CURVES EXPLAINED WITH THERMAL INSTABILITY OF LOOP PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Reale, F. [Dipartimento di Fisica, Universita degli Studi di Palermo, Piazza del Parlamento 1, 90134 Palermo (Italy); Landi, E. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Orlando, S. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo (Italy)

    2012-02-10

    In the present work, we study the C8 flare that occurred on 2000 September 26 at 19:49 UT and observed by the Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation spectrometer from the beginning of the impulsive phase to well beyond the disappearance in the X-rays. The emission first decayed progressively through equilibrium states until the plasma reached 2-3 MK. Then, a series of cooler lines, i.e., Ca X, Ca VII, Ne VI, O IV, and Si III (formed in the temperature range log T = 4.3-6.3 under equilibrium conditions), are emitted at the same time and all evolve in a similar way. Here, we show that the simultaneous emission of lines with such a different formation temperature is due to thermal instability occurring in the flaring plasma as soon as it has cooled below {approx}2 MK. We can qualitatively reproduce the relative start time of the light curves of each line in the correct order with a simple (and standard) model of a single flaring loop. The agreement with the observed light curves is greatly improved, and a slower evolution of the line emission is predicted, if we assume that the model loop consists of an ensemble of subloops or strands heated at slightly different times. Our analysis can be useful for flare observations with the Solar Dynamics Observatory/Extreme ultraviolet Variability Experiment.

  18. CSI 2264: Characterizing Young Stars in NGC 2264 with Stochastically Varying Light Curves

    CERN Document Server

    Stauffer, John; Rebull, Luisa; Hillenbrand, Lynne A; Turner, Neal J; Carpenter, John; Carey, Sean; Terebey, Susan; Morales-Calderon, Maria; Alencar, Silvia H P; McGinnis, Pauline; Sousa, Alana; Bouvier, Jerome; Venuti, Laura; Hartmann, Lee; Calvet, Nuria; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Barrado, David; Vrba, Frederick J; Covey, Kevin; Herbst, William; Gillen, Edward; Guimaraes, Marcelo Medeiros; Bouy, Herve; Favata, Fabio

    2016-01-01

    We provide CoRoT and Spitzer light curves, as well as broad-band multi-wavelength photometry and high resolution, multi- and single-epoch spectroscopy for 17 classical T Tauris in NGC 2264 whose CoRoT light curves (LCs) exemplify the "stochastic" LC class as defined in Cody et al. (2014). The most probable physical mechanism to explain the optical variability in this LC class is time-dependent mass accretion onto the stellar photosphere, producing transient hot spots. As evidence in favor of this hypothesis, multi-epoch high resolution spectra for a subset of these stars shows that their veiling levels also vary in time and that this veiling variability is consistent in both amplitude and timescale with the optical LC morphology. Furthermore, the veiling variability is well-correlated with the strength of the HeI 6678A emission line, a feature predicted by models to arise in accretion shocks on or near the stellar photosphere. Stars with accretion burst LC morphology (Stauffer et al. 2014) are also attributed...

  19. The 1991-2012 light curve of the old nova HR Lyrae

    Energy Technology Data Exchange (ETDEWEB)

    Honeycutt, R. K. [Astronomy Department, Indiana University, Swain Hall West, Bloomington, IN 47405 (United States); Shears, J. [Bunbury Observatory, Pemberton, School Lane, Bunbury, Tarporley, Cheshire CW6 9NR (United Kingdom); Kafka, S. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Robertson, J. W. [Department of Physical Sciences, Arkansas Tech University, 1701 N. Boulder, Russellville, AR 72801-2222 (United States); Henden, A. A., E-mail: honey@astro.indiana.edu, E-mail: bunburyobservatory@hotmail.com, E-mail: skafka@aip.org, E-mail: Jeff.Robertson@atu.edu, E-mail: arne@aavso.org [American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138-1203 (United States)

    2014-05-01

    The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ∼0.6 mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012 ± 0.005 mag yr{sup –1} is apparent, consistent with the fading of irradiation-induced M-dot following the nova. The equivalent width of Hα is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which Hα was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.

  20. Investigation of the energy dependence of the orbital light curve in LS 5039

    CERN Document Server

    Chang, Z; Ji, L; Chen, Y P; Kretschmar, P; Kuulkers, E; Collmar, W; Liu, C Z

    2016-01-01

    LS 5039 is so far the best studied $\\gamma$-ray binary system at multi-wavelength energies. A time resolved study of its spectral energy distribution (SED) shows that above 1 keV its power output is changing along its binary orbit as well as being a function of energy. To disentangle the energy dependence of the power output as a function of orbital phase, we investigated in detail the orbital light curves as derived with different telescopes at different energy bands. We analysed the data from all existing \\textit{INTEGRAL}/IBIS/ISGRI observations of the source and generated the most up-to-date orbital light curves at hard X-ray energies. In the $\\gamma$-ray band, we carried out orbital phase-resolved analysis of \\textit{Fermi}-LAT data between 30 MeV and 10 GeV in 5 different energy bands. We found that, at $\\lesssim$100 MeV and $\\gtrsim$1 TeV the peak of the $\\gamma$-ray emission is near orbital phase 0.7, while between $\\sim$100 MeV and $\\sim$1 GeV it moves close to orbital phase 1.0 in an orbital anti-cl...

  1. Post-flare UV light curves explained with thermal instability of loop plasma

    CERN Document Server

    Reale, F; Orlando, S

    2011-01-01

    In the present work we study the C8 flare occurred on September 26, 2000 at 19:49 UT and observed by the SOHO/SUMER spectrometer from the beginning of the impulsive phase to well beyond the disappearance in the X-rays. The emission first decayed progressively through equilibrium states until the plasma reached 2-3 MK. Then, a series of cooler lines, i.e. Ca x, Ca vii, Ne vi, O iv and Si iii (formed in the temperature range log T = 4.3 - 6.3 under equilibrium conditions), are emitted at the same time and all evolve in a similar way. Here we show that the simultaneous emission of lines with such a different formation temperature is due to thermal instability occurring in the flaring plasma as soon as it has cooled below ~ 2 MK. We can qualitatively reproduce the relative start time of the light curves of each line in the correct order with a simple (and standard) model of a single flaring loop. The agreement with the observed light curves is greatly improved, and a slower evolution of the line emission is predi...

  2. Cosmological Parameter Uncertainties from SALT-II Type Ia Supernova Light Curve Models

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, J. [Pennsylvania U.; Guy, J. [LBL, Berkeley; Kessler, R. [Chicago U., KICP; Astier, P. [Paris U., VI-VII; Marriner, J. [Fermilab; Betoule, M. [Paris U., VI-VII; Sako, M. [Pennsylvania U.; El-Hage, P. [Paris U., VI-VII; Biswas, R. [Argonne; Pain, R. [Paris U., VI-VII; Kuhlmann, S. [Argonne; Regnault, N. [Paris U., VI-VII; Frieman, J. A. [Fermilab; Schneider, D. P. [Penn State U.

    2014-08-29

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ~120 low-redshift (z < 0.1) SNe Ia, ~255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ~290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w (input) – w (recovered)) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty, the average bias on w is –0.014 ± 0.007.

  3. Discovery of a tight correlation for gamma ray burst afterglows with `canonical' light curves

    CERN Document Server

    Dainotti, M G; Capozziello, S; Cardone, V F; Ostrowski, M

    2010-01-01

    Gamma Ray Bursts (GRB) observed up to redshifts $z>8$ are fascinating objects to study due to their still unexplained relativistic outburst mechanisms and a possible use to test cosmological models. Our analysis of 77 GRB afterglows with known redshifts revealed a physical subsample of long GRBs with canonical {\\it plateau breaking to power-law} light curves with a significant {\\it luminosity $L^*_X$ - break time $T^*_a$} correlation in the GRB rest frame. This subsample forms approximately the {\\it upper envelope} of the studied distribution. We have also found a similar relation for a small sample of GRB afterglows that belong to the intermediate class (IC) between the short and the long ones. It proves that within the full sample of afterglows there exist physical subclasses revealed here by tight correlations of their afterglow properties. The afterglows with regular (`canonical') light curves obey not only a mentioned tight physical scaling, but -- for a given $T^*_a$ -- the more regular progenitor explo...

  4. Fast evolving pair-instability supernova models: evolution, explosion, light curves

    CERN Document Server

    Kozyreva, Alexandra; Hirschi, Raphael; Frohlich, Carla; Blinnikov, Sergey; Wollaeger, Ryan T; Noebauer, Ulrich M; van Rossum, Daniel R; Heger, Alexander; Even, Wesley P; Waldman, Roni; Tolstov, Alexey; Chatzopoulos, Emmanouil; Sorokina, Elena

    2016-01-01

    With an increasing number of superluminous supernovae (SLSNe) discovered the question of their origin remains open and causes heated debates in the supernova community. Currently, there are three proposed mechanisms for SLSNe: (1) pair-instability supernovae (PISN), (2) magnetar-driven supernovae, and (3) models in which the supernova ejecta interacts with a circumstellar material ejected before the explosion. Based on current observations of SLSNe, the PISN origin has been disfavoured for a number of reasons. Many PISN models provide overly broad light curves and too reddened spectra, because of massive ejecta and a high amount of nickel. In the current study we re-examine PISN properties using progenitor models computed with the GENEC code. We calculate supernova explosions with FLASH and light curve evolution with the radiation hydrodynamics code STELLA. We find that high-mass models (200 and 250 solar masses) at relatively high metallicity (Z=0.001) do not retain hydrogen in the outer layers and produce r...

  5. CSI 2264: Characterizing Accretion-Burst Dominated Light Curves for Young Stars in NGC 2264

    CERN Document Server

    Stauffer, John; Baglin, Annie; Alencar, Silvia H P; Rebull, Luisa; Hillenbrand, Lynne A; Venuti, Laura; Turner, Neal J; Carpenter, John; Plavchan, Peter; Findeisen, Krzysztof; Carey, Sean; Terebey, Susan; Morales-Calderón, María; Bouvier, Jerome; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Hartmann, Lee; Calvet, Nuria; Whitney, Barbara; Barrado, David; Vrba, Frederick J; Covey, Kevin; Herbst, William; Furesz, Gabor; Aigrain, Suzanne

    2014-01-01

    Based on more than four weeks of continuous high cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high quality, multi-wavelength light curves for young stellar objects (YSOs) whose optical variability is dominated by short duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief -- several hour to one day -- brightenings at optical and near-infrared (IR) wavelengths with amplitudes generally in the range 5-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a thirty day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u-g vs. g-r color-color diagram with the largest UV excesses. These stars also have large Halpha equivalent widths, and either centrally peaked, lumpy Halpha emission...

  6. Broad band turbulent spectra in gamma-ray burst light curves

    CERN Document Server

    van Putten, Maurice H P M; Frontera, Filippo

    2014-01-01

    Broad band power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long GRBs. We describe a chirp search method which steps aside Fourier analysis for signal detection in the Poisson noise-dominated 2 kHz sampled BeppoSAX light curves. An efficient numerical implementation is described in $O(Nn\\log n)$ operations, where $N$ is the number of chirp templates and $n$ is the length of the light curve time series, suited for embarrassingly parallel processing. For detection of individual chirps of duration $\\tau=1$ s, the method is one order of magnitude more sensitive in SNR than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope up to 1 kHz of turbulence identified in low frequency Fourier analysis. The same continuation is observed in an ensemble averaged spectrum of 40 bright long GRBs. An outlook on a similar analysis of upcoming gra...

  7. Numerical Modeling of the Early Light Curves of Type IIP Supernovae

    CERN Document Server

    Morozova, Viktoriya; Renzo, Mathieu; Ott, Christian D

    2016-01-01

    The early rise of Type IIP supernovae (SN IIP) provides important information for constraining the properties of their progenitors. This can in turn be compared to pre-explosion imaging constraints and stellar models to develop a more complete picture of how massive stars evolve and end their lives. Using the SuperNova Explosion Code (SNEC), we model the first 40 days of SNe IIP to better understand what constraints can be derived from their early light curves. We use two sets of red supergiant progenitor models with zero-age main sequence masses in the range between 9 Msol and 20 Msol. We find that the early properties of the light curve depend most sensitively on the radius of the progenitor, and thus provide a relation between the g-band rise time and the radius at the time of explosion. This relation will be useful for deriving constraints on progenitors from future observations, especially in cases where detailed modeling of the entire rise is not practical. When comparing to observed rise times, the rad...

  8. Period estimation for sparsely-sampled quasi-periodic light curves applied to Miras

    CERN Document Server

    He, Shiyuan; Huang, Jianhua Z; Long, James; Macri, Lucas M

    2016-01-01

    We develop a non-linear semi-parametric Gaussian process model to estimate periods of Miras with sparsely-sampled light curves. The model uses a sinusoidal basis for the periodic variation and a Gaussian process for the stochastic changes. We use maximum likelihood to estimate the period and the parameters of the Gaussian process, while integrating out the effects of other nuisance parameters in the model with respect to a suitable prior distribution obtained from earlier studies. Since the likelihood is highly multimodal for period, we implement a hybrid method that applies the quasi-Newton algorithm for Gaussian process parameters and search the period/frequency parameter over a dense grid. A large-scale, high-fidelity simulation is conducted to mimic the sampling quality of Mira light curves obtained by the M33 Synoptic Stellar Survey. The simulated data set is publicly available and can serve as a testbed for future evaluation of different period estimation methods. The semi-parametric model outperforms a...

  9. Effect of stellar activity on the high precision transit light curve

    Directory of Open Access Journals (Sweden)

    Oshagh, M.

    2015-01-01

    Full Text Available Stellar activity features such as spots and plages can create difficulties in determining planetary parameters through spectroscopic and photometric observations. The overlap of a transiting planet and a stellar spot, for instance, can produce anomalies in the transit light curve that may lead to inaccurate estimation of the transit duration, depth, and timing. Such inaccuracies can affect the precise derivation of the planet’s radius. In this talk we will present the results of a quantitative study on the effects of stellar spots on high precision transit light curves. We show that spot anomalies can lead to the estimate of a planet radius that is 4% smaller than the real value. The effects on the transit duration can also be of the order of 4%, longer or shorter. Depending on the size and distribution of spots, anomalies can also produce transit timing variations with significant amplitudes. For instance, TTVs with signal amplitudes of 200 seconds can be produced by spots as large as the largest sunspot. Finally, we examine the impact of active regions on the transit depth measurements in different wavelengths, in order to probe the impact of this effect on transmission spectroscopy measurements. We show that significant (up to 10% underestimation/overestimation of the planet-to-star radius ratio can be measured, especially in the short wavelength regime.

  10. Period and light curve fluctuations of the Kepler Cepheid V1154 Cyg

    CERN Document Server

    Derekas, A; Berdnikov, L; Szabo, R; Smolec, R; Kiss, L L; Szabados, L; Chadid, M; Evans, N R; Kinemuchi, K; Nemec, J M; Seader, S E; Smith, J C; Tenenbaum, P

    2012-01-01

    We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V =9.1 mag, P~4.9 d) based on almost 600 days of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle fluctuations in the pulsation period, indicating that classical Cepheids may not be as accurate astrophysical clocks as commonly believed: regardless of the specific points used to determine the O-C values, the cycle lengths show a scatter of 0.015-0.02 days over the 120 cycles covered by the observations. A very slight correlation between the individual Fourier parameters and the O-C values was found, suggesting that the O - C variations might be due to the instability of the light curve shape. Random fluctuation tests revealed a linear trend up to a cycle difference 15, but for long term, the period remains around the mean value. We compare the measurements with simulated light curves that were constructed to mimic V1154 Cyg as a perfect pulsator modulated only by the ligh...

  11. The complex light curve of the afterglow of GRB 071010A

    International Nuclear Information System (INIS)

    We present and discuss the results of an extensive observational campaign devoted to GRB 071010A, a long-duration gamma-ray burst detected by the Swift satellite. This event was followed for almost a month in the optical/near-infrared (NIR) with various telescopes starting from about 2 min after the high-energy event. Swift XRT observations started only later at about 0.4 d. The light-curve evolution allows us to single out an initial rising phase with a maximum at about 7 min, possibly the afterglow onset in the context of the standard fireball model, which is then followed by a smooth decay interrupted by a sharp re-brightening at about 0.6 d. The re-brightening was visible in both the optical/NIR and X-rays and can be interpreted as an episode of discrete energy injection, although various alternatives are possible. A steepening of the afterglow light curve is recorded at about 1 d. The entire evolution of the optical/NIR afterglow is consistent with being achromatic. This could be one of the few identified GRB afterglows with an achromatic break in the X-ray through the optical/NIR bands. Polarimetry was also obtained at about 1 d, just after the re-brightening and almost coincident with the steepening. This provided a fairly tight upper limit of 0.9 per cent for the polarized-flux fraction. (authors)

  12. The complex light curve of the afterglow of GRB 071010A

    Energy Technology Data Exchange (ETDEWEB)

    Covino, S.; D' Avanzo, P.; Campana, S.; Chincarini, G.; Guidorzi, C.; Tagliaferri, G.; Fugazza, D.; Molinari, E.; Moretti, A.; Romano, P.; Zerbi, F. [INAF Osservatorio Astron Brera, I-23807 Merate, LC, (Italy); D' Avanzo, P. [Univ Insubria, Dipartimento Matemat and Fis, I-22100 Como, (Italy); Klotz, A.; Boeer, M. [Observ Haute Provence, F-04870 St Michel L' observatoire, (France); Klotz, A. [Univ Toulouse, CESR, F-31400 Toulouse, (France); Perley, D.A.; Bloom, J.S.; Filippenko, A.V.; Foley, R.J.; Kocevksi, D.; Modjaz, M.; Poznanski, D.; Silverman, J.M. [Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 (United States); Amati, L.; Maiorano, E.; Masetti, N.; Palazzi, E. [Ist Astrofis Spaziale and Fis Cosm Bologna, INAF, I-40129 Bologna, (Italy); Chincarini, G.; Guidorzi, C. [Univ Milan, I-20126 Milan, (Italy); Cucchiara, A. [Penn State Univ, Dept Astron and Astrophys, University Pk, PA 16802 (United States); D' Elia, V.; Guetta, D.; Antonelli, L. A.; D' Alessio, F.; Piranomonte, S.; Stella, L.; Testa, V.; Vitali, F. [INAF Osservatorio Astron Roma, I-00040 Monte Porzio Catone, Roma, (Italy); Kann, D.A. [Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, (Germany); Yoldas, A. Kuepcue; Greiner, J.; Primak, N. [Max Planck Inst Extraterr Phys, D-85748 Garching, (Germany); Misra, K.; Pandey, S.B.; Roy, R. [Aryabhatta Res Inst Observat Sci ARIES, Naini Tal 263129, (India); Misra, K. [Inter Univ Ctr Astron and Astrophys, Pune 411007, Maharashtra, (India); Olofsson, G. [Stockholm Observ, S-10691 Stockholm, (Sweden); Berger, E. [Observ Carnegie Inst Washington, Pasadena, CA 91101 (United States); Della Valle, M. [INAF Osservatorio Astron Capodimonte, I-80131 Naples, (Italy); Della Valle, M. [Int Ctr Relativist Astrophys Network, Icranet, Pescara, (Italy); Della Valle, M. [European So Observ, D-8046 Garching, (Germany); Alighieri, S. di Serego [INAF Osservatorio Astrofis Arcetri, I-50125 Florence, (Italy)] [and others

    2008-07-01

    We present and discuss the results of an extensive observational campaign devoted to GRB 071010A, a long-duration gamma-ray burst detected by the Swift satellite. This event was followed for almost a month in the optical/near-infrared (NIR) with various telescopes starting from about 2 min after the high-energy event. Swift XRT observations started only later at about 0.4 d. The light-curve evolution allows us to single out an initial rising phase with a maximum at about 7 min, possibly the afterglow onset in the context of the standard fireball model, which is then followed by a smooth decay interrupted by a sharp re-brightening at about 0.6 d. The re-brightening was visible in both the optical/NIR and X-rays and can be interpreted as an episode of discrete energy injection, although various alternatives are possible. A steepening of the afterglow light curve is recorded at about 1 d. The entire evolution of the optical/NIR afterglow is consistent with being achromatic. This could be one of the few identified GRB afterglows with an achromatic break in the X-ray through the optical/NIR bands. Polarimetry was also obtained at about 1 d, just after the re-brightening and almost coincident with the steepening. This provided a fairly tight upper limit of 0.9 per cent for the polarized-flux fraction. (authors)

  13. Optical and X-ray Rest-frame Light Curves of the BAT6 sample

    CERN Document Server

    Melandri, A; Rogantini, D; Salvaterra, R; Sbarufatti, B; Bernardini, M G; Campana, S; D'Avanzo, P; D'Elia, V; Fugazza, D; Ghirlanda, G; Ghisellini, G; Nava, L; Vergani, S D; Tagliaferri, G

    2014-01-01

    We present the rest-frame light curves in the optical and X-ray bands of an unbiased and complete sample of Swift long Gamma-Ray Bursts (GRBs), namely the BAT6 sample. The unbiased BAT6 sample (consisting of 58 events) has the highest level of completeness in redshift ($\\sim$ 95%), allowing us to compute the rest-frame X-ray and optical light curves for 55 and 47 objects, respectively. We compute the X-ray and optical luminosities accounting for any possible source of absorption (Galactic and intrinsic) that could affect the observed fluxes in these two bands. We compare the behaviour observed in the X-ray and in the optical bands to assess the relative contribution of the emission during the prompt and afterglow phases. We unarguably demonstrate that the GRBs rest-frame optical luminosity distribution is not bimodal, being rather clustered around the mean value Log(L$_{R}$) = 29.9 $\\pm$ 0.8 when estimated at a rest frame time of 12 hr. This is in contrast with what found in previous works and confirms that t...

  14. Cosmological parameter uncertainties from SALT-II type Ia supernova light curve models

    International Nuclear Information System (INIS)

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ∼120 low-redshift (z < 0.1) SNe Ia, ∼255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ∼290 SNLS SNe Ia (z ≤ 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w input – w recovered) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty; the average bias on w is –0.014 ± 0.007.

  15. A Light Curve And Period Analysis Of AE Ursae Majoris, CY Aquarii, And DY Pegasi

    Science.gov (United States)

    Joner, Michael D.; Iverson, E. P.; Jolley, J. W.; Joner, L. A.; Swenson, C. A.

    2007-12-01

    We present a light curve analysis of three high amplitude delta Scuti stars (HADs). Data for this presentation were all secured during spring and fall of 2007. Most of the observations were obtained using the facilities of the Brigham Young University West Mountain Observatory. The variable stars we observed in this investigation include AE Ursae Majoris, CY Aquarii, and DY Pegasi. We present evidence for small period changes as well as an analysis of the light curve components for each of the variables. We compare the results obtained in the present investigation with prior studies of these same targets. This investigation is part of an initiative to provide a mentored learning environment at the West Mountain Observatory and to promote a variety of undergraduate research experiences. Tools developed in this investigation include the data reduction procedures that enable us to process the several thousand CCD frames that are secured each night as raw observations. We thank the Department of Physics and Astronomy and the College of Physical and Mathematical Sciences at Brigham Young University for the continued support of mentored undergraduate research.

  16. Phase response curve to 1 h light pulses for the European rabbit (Oryctolagus cuniculus).

    Science.gov (United States)

    Kennedy, Gerard A; Hudson, Robyn

    2016-01-01

    While much is known about the circadian systems of rodents, chronobiological studies of other mammalian groups have been limited. One of the most extensively studied nonrodent species, both in the laboratory and in the wild, is the European rabbit. The aim of this study was to extend knowledge of the rabbit circadian system by examining its phasic response to light. Twelve Dutch-Himalayan cross rabbits of both sexes were allowed to free-run in constant darkness and then administered 1 h light pulses (1000 lux) at multiple predetermined circadian times. Changes in the phase of the rabbits' circadian wheel-running rhythms were measured after each light pulse and used to construct a phase-response curve (PRC). The rabbits' PRC and free-running period (τ) conformed to the empirical regularities reported for other predominantly nocturnal animals, including rodents and predatory marsupials. The results of the study are thus consistent with reports that the rabbit is essentially a nocturnal animal and show that it can entrain to light/dark (LD) cycles via discrete phase shifts. Knowledge about the rabbit's circadian range of entrainment to LD cycles gained in this study will be useful for examining the putative circadian processes believed to underlie the unusual rhythm of very brief, once-daily nest visits by nursing rabbit mothers and other nursing lagomorphs. PMID:27305519

  17. Implementation of a goodness-of-fit test for finding optimal concurrent radio and {\\gamma}-ray pulsar light curves

    CERN Document Server

    Seyffert, A S; Harding, A K; Allison, J; Schutte, W D

    2016-01-01

    Since the launch of the Fermi Large Area Telescope in 2008 the number of known ${\\gamma}$-ray pulsars has increased immensely to over 200, many of which are also visible in the radio and X-ray bands. Seyffert et al. (2011) demonstrated how constraints on the viewing geometries of some of these pulsars could be obtained by comparing their observed radio and ${\\gamma}$-ray light curves by eye to light curves from geometric models. While these constraints compare reasonably well with those yielded by more rigorous single-wavelength approaches, they are still a somewhat subjective representation of how well the models reproduce the observed radio and ${\\gamma}$-ray light curves. Constructing a more rigorous approach is, however, made difficult by the large uncertainties associated with the ${\\gamma}$-ray light curves as compared to those associated with the radio light curves. Naively applying a ${\\chi}^{2}$-like goodness-of-fit test to both bands invariably results in constraints dictated by the radio light curv...

  18. Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. II. 3-5 micron direct imaging with MagAO+Clio, and the empirical bolometric luminosity of a self-luminous giant planet

    CERN Document Server

    Morzinski, Katie M; Skemer, Andy J; Close, Laird M; Hinz, Phil M; Rodigas, T J; Puglisi, Alfio; Esposito, Simone; Riccardi, Armando; Pinna, Enrico; Xompero, Marco; Briguglio, Runa; Bailey, Vanessa P; Follette, Katherine B; Kopon, Derek; Weinberger, Alycia J; Wu, Ya-Lin

    2015-01-01

    Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet $\\beta$ Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star $\\beta$ Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the first CCD detection of this planet with MagAO+VisAO. Here we present four MagAO+Clio images of $\\beta$ Pic b at 3.1 $\\mu$m, 3.3 $\\mu$m, $L^\\prime$, and $M^\\prime$, including the first observation in the fundamental CH$_4$ band. To remove systematic errors from the spectral energy distribution (SED), we re-calibrate the literature photometry and combine it with our own data, for a total of 22 independent measurements at 16 passbands from 0.99--4.8 $\\mu$m. Atmosphere models demonstrate the planet is cloudy but are degenerate in effective temperature and radius. The measured SED now covers $>$80\\% of the planet's energy, so we approach ...

  19. UBVRI Light Curves of the Seyfert Galaxy NGC 7469 During 1990-1998: Microvariability

    Science.gov (United States)

    Merkulova, N. I.

    2000-02-01

    Observations of the nuclear region of the Seyfert galaxy NGC 7469 obtained at Crimean Astrophysical Observatory with the 1.25 m telescope are presented. During 64 nights on nine observational runs between 1990 September 24 and 1998 October 22 in each spectral band of the Johnson UBVRI system, about 1500 measurements have been performed simultaneously through the round aperture 20" in diameter using differential photometry techniques. The estimated accuracy of each measurement is about 0.01 mag. During the observing period 1990-1996 the mean luminosity of the nucleus was almost constant; only overlapping brightness fluctuations were observed. The mean luminosity level has been raised in 1996 October. The peak amplitude (maximum flux/minimum flux) Fmax/Fmin=2.09 on the light curves was observed in the U band, while the minimum amplitude Fmax/Fmin=1.32 was in the I band for the entire observation period. Using structure function (SF) analysis, the following conclusions have been made: (1) Long-term variability is caused by the same processes in the optical, because the slope b of the SF is approximately equal for all wave bands, except for the I band the slope is appreciably distinguished from the others. This would be an indication of the presence of an independent IR energy source in NGC 7469. (2) Considering the same time interval (from 6 minutes to 2 hr) for intranight variability on SFs at different wave bands, one can conclude that flicker noise causes variations observed on the light curve at the UV region (U and B bands), while at the near-IR region the light curve is formed by mixed shot noise and flicker noise-the greater the wavelength, the more the contribution of shot noise processes. (3) On intranight light curves of the NGC 7469 there exist rapid flares with durations ~25 minutes at U band, ~55 minutes at B, V bands, and ~2 hr at R, I bands-a typical timescale of intranight variability increasing with the increasing wavelength. In order to examine the

  20. Exploring the neutrinoless double beta decay in the inverted neutrino hierarchy with bolometric detectors

    Energy Technology Data Exchange (ETDEWEB)

    Artusa, D.R. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); INFN-Laboratori Nazionali del Gran Sasso, Assergi, L' Aquila (Italy); Avignone, F.T.; Chott, N.; Creswick, R.J.; Farach, H.A.; Rosenfeld, C.; Wilson, J. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Azzolini, O.; Camacho, A.; De Biasi, A.; Keppel, G.; Palmieri, V.; Pira, C.; Rampazzo, V. [INFN-Laboratori Nazionali di Legnaro, Legnaro, Padua (Italy); Balata, M.; Bucci, C.; Canonica, L.; Casali, N.; Di Vacri, M.L.; Goett, J.; Gorla, P.; Nisi, S.; Orlandi, D.; Pattavina, L.; Pirro, S.; Zarra, C. [INFN-Laboratori Nazionali del Gran Sasso, Assergi, L' Aquila (Italy); Banks, T.I. [INFN-Laboratori Nazionali del Gran Sasso, Assergi, L' Aquila (Italy); University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Bari, G.; Deninno, M.M.; Moggi, N. [INFN-Sezione di Bologna, Bologna (Italy); Beeman, J. [Lawrence Berkeley National Laboratory, Materials Science Division, Berkeley, CA (United States); Bellini, F.; Cardani, L.; Cosmelli, C.; Ferroni, F.; Piperno, G. [Sapienza Universita di Roma, Dipartimento di Fisica, Rome (Italy); INFN-Sezione di Roma, Rome (Italy); Bersani, A. [INFN-Sezione di Genova, Genoa (Italy); Biassoni, M.; Brofferio, C.; Capelli, S.; Carrettoni, M.; Chiesa, D.; Clemenza, M.; Faverzani, M.; Ferri, E.; Fiorini, E.; Giachero, A.; Gironi, L.; Gotti, C.; Maiano, C.; Maino, M.; Nucciotti, A.; Pavan, M.; Sala, E.; Sisti, M.; Terranova, F.; Zanotti, L. [Universita di Milano-Bicocca, Dipartimento di Fisica, Milan (Italy); INFN-Sezione di Milano Bicocca, Milan (Italy); Cai, X.Z.; Cao, X.G.; Fang, D.Q.; Li, Y.L.; Ma, Y.G.; Tian, W.D.; Wang, H.W. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); Carbone, L.; Cremonesi, O.; Datskov, V.; Pessina, G.; Previtali, E.; Rusconi, C. [INFN-Sezione di Milano Bicocca, Milan (Italy); Dafinei, I.; Morganti, S.; Orio, F.; Pettinacci, V.; Tomei, C.; Vignati, M. [INFN-Sezione di Roma, Rome (Italy); Dally, A.; Ejzak, L.; Wielgus, L. [University of Wisconsin, Department of Physics, Madison, WI (United States); Di Domizio, S.; Fernandes, G.; Pallavicini, M. [INFN-Sezione di Genova, Genoa (Italy); Universita di Genova, Dipartimento di Fisica, Genoa (Italy); Franceschi, M.A.; Ligi, C.; Napolitano, T. [INFN-Laboratori Nazionali di Frascati, Frascati, Rome (Italy); Freedman, S.J. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Fujikawa, B.K.; Han, K.; Mei, Y.; Smith, A.R. [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Giuliani, A.; Tenconi, M. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay (France); Gutierrez, T.D. [California Polytechnic State University, Physics Department, San Luis Obispo, CA (United States); Haller, E.E. [Lawrence Berkeley National Laboratory, Materials Science Division, Berkeley, CA (United States); University of California, Department of Materials Science and Engineering, Berkeley, CA (United States); Heeger, K.M.; Maruyama, R.H. [Yale University, Department of Physics, New Haven, CT (United States); Hennings-Yeomans, R.; O' Donnell, T. [University of California, Department of Physics, Berkeley, CA (United States); Huang, H.Z.; Liu, X.; Trentalange, S.; Winslow, L.A.; Zhu, B.X. [University of California, Department of Physics and Astronomy, Los Angeles, CA (United States); Kadel, R. [Lawrence Berkeley National Laboratory, Physics Division, Berkeley, CA (United States); Kazkaz, K.; Pedretti, M.; Sangiorgio, S.; Scielzo, N.D. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Kolomensky, Yu.G. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Physics Division, Berkeley, CA (United States); Martinez, M. [Universidad de Zaragoza, Laboratorio de Fisica Nuclear y Astroparticulas, Saragossa (Spain); Nones, C. [CEA/Saclay, Service de Physique des Particules, Gif-sur-Yvette (France); Norman, E.B.; Wang, B.S. [Lawrence Livermore National Laboratory, Livermore, CA (United States); University of California, Department of Nuclear Engineering, Berkeley, CA (United States); Ouellet, J.L. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Taffarello, L. [INFN-Sezione di Padova, Padua (Italy); Ventura, G. [Universita di Firenze, Dipartimento di Fisica, Florence (Italy); INFN-Sezione di Firenze, Florence (Italy); Wise, T. [University of Wisconsin, Department of Physics, Madison, WI (United States); Yale University, Department of Physics, New Haven, CT (United States); Woodcraft, A. [University of Edinburgh, SUPA, Institute for Astronomy, Edinburgh (United Kingdom); Zucchelli, S. [INFN-Sezione di Bologna, Bologna (Italy); Universita di Bologna, Dipartimento di Fisica, Bologna (Italy)

    2014-10-15

    Neutrinoless double beta decay (0νββ) is one of the most sensitive probes for physics beyond the Standard Model, providing unique information on the nature of neutrinos. In this paper we review the status and outlook for bolometric 0νββ decay searches. We summarize recent advances in background suppression demonstrated using bolometers with simultaneous readout of heat and light signals. We simulate several configurations of a future CUORE-like bolometer array which would utilize these improvements and present the sensitivity reach of a hypothetical next-generation bolometric 0νββ experiment. We demonstrate that a bolometric experiment with the isotope mass of about 1 ton is capable of reaching the sensitivity to the effective Majorana neutrino mass (vertical stroke m{sub ee} vertical stroke) of order 10-20 meV, thus completely exploring the so-called inverted neutrino mass hierarchy region. We highlight the main challenges and identify priorities for an R and D program addressing them. (orig.)

  1. The Multi-color Light Curves of the W UMa type Contact Binary EP Andromedae

    Science.gov (United States)

    Liao, W.-P.; Qian, S.-B.; Li, K.; He, J.-J.; Zhao, E.-G.; Zhou, X.

    2013-10-01

    New multi-color CCD photometric light curves of the eclipsing binary EP And were obtained over six nights in 2006, 2011, and 2012. Using the Wilson-Devinney code, we computed the photometric elements of this system. It was discovered that EP And is a W-type W UMa contact binary system with a mass ratio of q = 2.685 and a degree of contact factor f = 24.9%, rather than an A-type system. Combining 28 newly determined times of minimum light derived from 1999 to 2012 with others collected from the literature, a long-term increase (dP/dt = +5.22 × 10-8 days yr-1) with a sinusoidal variation (A = 0.0109 days T = 40.89 yr) in the orbital period was found. The orbital period secular increases may be interpreted as conservative mass transfer from the less massive component to the more massive one, and cyclic variations of the orbital period may be caused by the light-travel time effect through the presence of a third body. The evolutionary status and the age of the system are also discussed.

  2. Bayesian Estimates of Astronomical Time Delays between Gravitationally Lensed Stochastic Light Curves

    CERN Document Server

    Tak, Hyungsuk; van Dyk, David A; Kashyap, Vinay L; Meng, Xiao-Li; Siemiginowska, Aneta

    2016-01-01

    The gravitational field of a galaxy can act as a lens and deflect the light emitted by a more distant object such as a quasar. If the galaxy is a strong gravitational lens, it can produce multiple images of the same quasar in the sky. Since the light in each gravitationally lensed image traverses a different path length from the quasar to the Earth, fluctuations in the source brightness are observed in the several images at different times. The time delay between these fluctuations can be used to constrain cosmological parameters and can be inferred from the time series of brightness data or light curves of each image. To estimate the time delay, we construct a model based on a state-space representation for irregularly observed time series generated by a latent continuous-time Ornstein-Uhlenbeck process. We account for microlensing, an additional source of independent long-term extrinsic variability, via a polynomial regression. Our Bayesian strategy adopts a Metropolis-Hastings within Gibbs sampler. We impr...

  3. Few layer graphene to graphitic films: infrared photoconductive versus bolometric response

    Science.gov (United States)

    Kurra, Narendra; Bhadram, Venkata Srinu; Narayana, Chandrabhas; Kulkarni, Giridhar U.

    2012-12-01

    incandescent bulb is shown in Fig. S4. Fig. S5 shows the fall and rise of resistance of the FLG with respect to the IR beam turning on and off respectively. The temporal IR photoresponse of the FLG films on the quartz and sapphire substrates is shown in Fig. S6. Rise and fall curves for the resistance of the bulk graphitic samples are shown in Fig. S7. The band level diagram in Fig. S8 explains the photoconductive and bolometric responses of the graphitic samples. See DOI: 10.1039/c2nr32861e

  4. Bolometric Lightcurves of Peculiar Type II-P Supernovae

    CERN Document Server

    Lusk, Jeremy A

    2016-01-01

    We examine the bolometric lightcurves of five Type II-P supernovae (SNe 1998A, 2000cb, 2006V, 2006au and 2009E) which are thought to originate from blue supergiant progenitors using a new python package named SuperBoL. With this code, we calculate SNe lightcurves using three different techniques common in the literature: the quasi-bolometric method, which integrates the observed photometry, the direct integration method, which additionally corrects for unobserved flux in the UV and IR, and the bolometric correction method, which uses correlations between observed colors and V-band bolometric corrections. We present here the lightcurves calculated by SuperBoL along with previously published lightcurves, as well as peak luminosities and Ni-56 yields. We find that the direct integration and bolometric correction lightcurves largely agree with previously published lightcurves, but with what we believe to be more robust error calculations, with $0.2 \\leq \\delta L_{bol}/L_{bol} \\leq 0.5$. Peak luminosities and Ni-5...

  5. Light Curve Analysis for W UMa-Type Eclipsing Binary Star Systems

    Science.gov (United States)

    Henderson, Scott; Peach, N.; Olsen, T.

    2006-12-01

    We report results from summer 2006 in an ongoing study of eclipsing binary stars. Our investigations have focused on the measurement and interpretation of light curves for W UMa-type systems 44i Boötis and VW Cephei. These contact binaries have component stars of spectral type G, and revolve with periods of 6.43 and 6.67 hours. Dome automation and scripting capabilities introduced this summer have significantly reduced experimental uncertainties in our data. In support of previous findings we continue to observe an increase in the orbital period of 44i Boo at a rate of 10.4 µs/epoch or 14.2 ms/yr. Residuals computed after incorporating the increasing period suggest an underlying sinusoidal oscillation with a 61.5 year period and amplitude of 648 seconds. AAPT Member Thomas Olsen is sponsoring the lead presenter, SPS Member Scott Henderson, and the co-presenter, SPS Member Nick Peach.

  6. Simulation of microlensing light curves by combining contouring and ray-shooting

    CERN Document Server

    Haugan, S V H

    1995-01-01

    The contouring methods described by Lewis et al. (1993) and Witt (1993) are very efficient and elegant for obtaining the magnification of a point source moving along a straight track in the source plane. The method is, however, not very efficient for extended sources, because the amplification needs to be computed for numerous parallel tracks and then convolved with the source profile. Rayshooting is an efficient algorithm for relatively large sources, but the computing time increases with the inverse of the source area for a given noise level. This poster presents a hybrid method, using the contouring method in order to find only those parts of the lens area that contribute to the light curve through the rayshooting. Calculations show that this method has the potential to be 10--10^5 times more efficient than crude rayshooting techniques.

  7. Using Light Charged Particles to Probe the Asymmetry Dependence of the Nuclear Caloric Curve

    CERN Document Server

    McIntosh, Alan B; Kohley, Zachary; Cammarata, Paul J; Hagel, Kris; Heilborn, Lauren; Mabiala, Justin; May, Larry W; Marini, Paola; Raphelt, Andrew; Souliotis, George A; Wuenschel, Sara; Zarrella, Andrew; Yennello, Sherry J

    2013-01-01

    Recently, we observed a clear dependence of the nuclear caloric curve on neutron-proton asymmetry $\\frac{N-Z}{A}$ through examination of fully reconstructed equilibrated quasi-projectile sources produced in heavy ion collisions at E/A = 35 MeV. In the present work, we extend our analysis using multiple light charged particle probes of the temperature. Temperatures are extracted with five distinct probes using a kinetic thermometer approach. Additionally, temperatures are extracted using two probes within a chemical thermometer approach (Albergo method). All seven measurements show a significant linear dependence of the source temperature on the source asymmetry. For the kinetic thermometer, the strength of the asymmetry dependence varies with the probe particle species in a way which is consistent with an average emission-time ordering.

  8. Assessment of evolutionary status of eclipsing binaries using light-curve parameters and spectral classification

    CERN Document Server

    Ekaterina, Avvakumova

    2014-01-01

    We have developed a procedure for the classification of eclipsing binaries from their light-curve parameters and spectral type. The procedure was tested on more than 1000 systems with known classification, and its efficiency was estimated for every evolutionary status we use. The procedure was applied to about 4700 binaries with no classification, and the vast majority of them was classified successfully. Systems of relatively rare evolutionary classes were detected in that process, as well as systems with unusual and/or contradictory parameters. Also, for 50 previously unclassified cluster binaries evolutionary classes were identified. These stars can serve as tracers for age and distance estimation of their parent stellar systems. The procedure proved itself as fast, flexible and effective enough to be applied to large ground based and space born surveys, containing tens of thousands of eclipsing binaries.

  9. Light-curve modelling constraints on the obliquities and aspect angles of the young Fermi pulsars

    Science.gov (United States)

    Pierbattista, M.; Harding, A. K.; Grenier, I. A.; Johnson, T. J.; Caraveo, P. A.; Kerr, M.; Gonthier, P. L.

    2015-03-01

    In more than four years of observation the Large Area Telescope on board the Fermi satellite has identified pulsed γ-ray emission from more than 80 young or middle-aged pulsars, in most cases providing light curves with high statistics. Fitting the observed profiles with geometrical models can provide estimates of the magnetic obliquity α and of the line of sight angle ζ, yielding estimates of the radiation beaming factor and radiated luminosity. Using different γ-ray emission geometries (Polar Cap, Slot Gap, Outer Gap, One Pole Caustic) and core plus cone geometries for the radio emission, we fit γ-ray light curves for 76 young or middle-aged pulsars and we jointly fit their γ-ray plus radio light curves when possible. We find that a joint radio plus γ-ray fit strategy is important to obtain (α,ζ) estimates that can explain simultaneously detectable radio and γ-ray emission: when the radio emission is available, the inclusion of the radio light curve in the fit leads to important changes in the (α,ζ) solutions. The most pronounced changes are observed for Outer Gap and One Pole Caustic models for which the γ-ray only fit leads to underestimated α or ζ when the solution is found to the left or to the right of the main α-ζ plane diagonal respectively. The intermediate-to-high altitude magnetosphere models, Slot Gap, Outer Gap, and One pole Caustic, are favoured in explaining the observations. We find no apparent evolution of α on a time scale of 106 years. For all emission geometries our derived γ-ray beaming factors are generally less than one and do not significantly evolve with the spin-down power. A more pronounced beaming factor vs. spin-down power correlation is observed for Slot Gap model and radio-quiet pulsars and for the Outer Gap model and radio-loud pulsars. The beaming factor distributions exhibit a large dispersion that is less pronounced for the Slot Gap case and that decreases from radio-quiet to radio-loud solutions. For all

  10. The BVRI Light Curves And Period Analysis Of The Beta Lyrae System XX Leonis

    CERN Document Server

    Zasche, P; Svoboda, P

    2007-01-01

    The contact eclipsing binary system XX Leonis (P = 0.97 days, sp A8) has been analysed using the PHOEBE programme, based on the Wilson Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T=(7889+/-61)K, the inclination of the orbit is i=(89.98+/-2.45)deg and the photometric mass ratio q=(0.41+/-0.01). Also the third body hypothesis was suggested, based on the period analysis using 57 minimum times and resulting the period of the third body p3= (52.96+/-0.01)yr, amplitude A=(0.057+/-0.029)d and eccentricity e=(0.79+/-0.08) which gives the minimum mass m3,min=(3.6+/-0.8)M_sun.

  11. Light-Curve Modelling Constraints on the Obliquities and Aspect Angles of the Young Fermi Pulsars

    Science.gov (United States)

    Pierbattista, M.; Harding, A. K.; Grenier, I. A.; Johnson, T. J.; Caraveo, P. A.; Kerr, M.; Gonthier, P. L.

    2015-01-01

    In more than four years of observation the Large Area Telescope on board the Fermi satellite has identified pulsed gamma-ray emission from more than 80 young or middle-aged pulsars, in most cases providing light curves with high statistics. Fitting the observed profiles with geometrical models can provide estimates of the magnetic obliquity alpha and of the line of sight angle zeta, yielding estimates of the radiation beaming factor and radiated luminosity. Using different gamma-ray emission geometries (Polar Cap, Slot Gap, Outer Gap, One Pole Caustic) and core plus cone geometries for the radio emission, we fit gamma-ray light curves for 76 young or middle-aged pulsars and we jointly fit their gamma-ray plus radio light curves when possible. We find that a joint radio plus gamma-ray fit strategy is important to obtain (alpha, zeta) estimates that can explain simultaneously detectable radio and gamma-ray emission: when the radio emission is available, the inclusion of the radio light curve in the fit leads to important changes in the (alpha, gamma) solutions. The most pronounced changes are observed for Outer Gap and One Pole Caustic models for which the gamma-ray only fit leads to underestimated alpha or zeta when the solution is found to the left or to the right of the main alpha-zeta plane diagonal respectively. The intermediate-to-high altitude magnetosphere models, Slot Gap, Outer Gap, and One pole Caustic, are favored in explaining the observations. We find no apparent evolution of a on a time scale of 106 years. For all emission geometries our derived gamma-ray beaming factors are generally less than one and do not significantly evolve with the spin-down power. A more pronounced beaming factor vs. spin-down power correlation is observed for Slot Gap model and radio-quiet pulsars and for the Outer Gap model and radio-loud pulsars. The beaming factor distributions exhibit a large dispersion that is less pronounced for the Slot Gap case and that decreases from

  12. Observations and light curve solutions of four ultrashort-period binaries

    Directory of Open Access Journals (Sweden)

    Kjurkchieva D.

    2016-01-01

    Full Text Available The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+ 445850, CSS J214633.8+120016 and CSS J224326.0+154532 are over contact binaries with fill out factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

  13. Finite source sizes and the information content of macho-type lens search light curves

    Science.gov (United States)

    Nemiroff, Robert J.; Wickramasinghe, W. A. D. T.

    1994-01-01

    If the dark halo matter is primarily composed of Massive Compact Halo Objects (MACHOs) toward the lower end of the possible detection range (less than 10(exp -3) solar mass) a fraction of the lens detection events should involve the lens crossing directly in front of the disk of the background star. Previously, Nemiroff has shown that each crossing would create an inflection point in the light curve of the MACHO event. Such inflection points would allow a measure of the time it took for the lens to cross the stellar disk. Given an independent estimate of the stellar radius by other methods, one could then obtain a more accurate estimate of the velocity of the lens. This velocity could then, in turn, be used to obtain a more accurate estimate of the mass range for the MACHO or disk star doing the lensing.

  14. Chandra Observations of SN 1987A: The Soft X-Ray Light Curve Revisited

    Science.gov (United States)

    Helder, E. A.; Broos, P. S.; Dewey, D.; Dwek, E.; McCray, R.; Park, S.; Racusin, J. L.; Zhekov, S. A.; Burrows, D. N.

    2013-01-01

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by approximately 6 x 10(exp-13) erg s(exp-1)cm(exp-2) per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  15. Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping

    Science.gov (United States)

    Sluse, D.; Tewes, M.

    2014-11-01

    The advent of large area photometric surveys has raised a great deal of interest in the possibility of using broadband photometric data, instead of spectra, to measure the size of the broad line region of active galactic nuclei. We describe here a new method that uses time-delay lensed quasars where one or several images are affected by microlensing due to stars in the lensing galaxy. Because microlensing decreases (or increases) the flux of the continuum compared to the broad line region, it changes the contrast between these two emission components. We show that this effect can be used to effectively disentangle the intrinsic variability of those two regions, offering the opportunity to perform reverberation mapping based on single-band photometric data. Based on simulated light curves generated using a damped random walk model of quasar variability, we show that measurement of the size of the broad line region can be achieved using this method, provided one spectrum has been obtained independently during the monitoring. This method is complementary to photometric reverberation mapping and could also be extended to multi-band data. Because the effect described above produces a variability pattern in difference light curves between pairs of lensed images that is correlated with the time-lagged continuum variability, it can potentially produce systematic errors in measurement of time delays between pairs of lensed images. Simple simulations indicate that time-delay measurement techniques that use a sufficiently flexible model for the extrinsic variability are not affected by this effect and produce accurate time delays.

  16. Testing for periodicities in near-IR light curves of Sgr A*

    Energy Technology Data Exchange (ETDEWEB)

    Do, Tuan; Ghez, Andrea M; Morris, Mark R; Yelda, Sylvana; Lu, Jessica R [Physics and Astronomy Department, Los Angeles, CA 90095-1547 (United States); Hornstein, Seth D [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Matthews, Keith [California Institute of Technology, Pasadena, CA (United States)], E-mail: tdo@astro.ucla.edu

    2008-10-15

    We present the results of near-infrared (2 {mu}m) monitoring of Sgr A*-IR with 1 minute time sampling using laser guide star adaptive optics (LGS AO) system at the Keck II telescope. Sgr A*-IR was observed continuously for up to three hours on each of seven nights, between 2006 May and 2007 August. Sgr A*-IR is detected at all times and is continuously variable. These observations allow us to investigate Nyquist sampled periods ranging from about 2 minutes to an hour. Of particular interest are periods of {approx}20 min, which corresponds to a quasi-periodic (QPO) signal claimed based upon previous near-infrared observations and interpreted as the orbit of a 'hot spot' at or near the last stable orbit of a spinning black hole. We investigate these claims by comparing periodograms of the light curves with models for red noise and find no significant deviations that would indicate QPO activity at any time scale probed in the study. We find that the variability of Sgr A* is consistent with a model based on correlated noise with a power spectrum having a frequency dependence of {approx} f{sup -2.5}, consistent with that observed in AGNs. Furthermore, the periodograms show power down to the minimum sampling time of 2 min, well below the period of the last stable orbit of a maximally spinning black hole, indicating that the Sgr A*-IR light curves observed in this study is unlikely to be from the Keplerian motion of a single 'hot spot' of orbiting plasma.

  17. Ground-based Light Curves Two Pluto Days Before the New Horizons Passage

    Science.gov (United States)

    Bosh, A. S.; Pasachoff, J. M.; Babcock, B. A.; Durst, R. F.; Seeger, C. H.; Levine, S. E.; Abe, F.; Suzuki, D.; Nagakane, M.; Sickafoose, A. A.; Person, M. J.; Zuluaga, C.; Kosiarek, M. R.

    2015-12-01

    We observed the occultation of a 12th magnitude star, one of the two brightest occultation stars ever in our dozen years of continual monitoring of Pluto's atmosphere through such studies, on 29 June 2015 UTC. At Canterbury University's Mt. John University Observatory on the south island of New Zealand, in clear sky, we used our POETS frame-transfer CCD at 10 Hz with GPS timing on the 1-m McLellan telescope as well as an infrared camera on an 0.6-m telescope and three-color photometry at a slower cadence on a second 0.6-m telescope. The light curves show a central flash, indicating that we were close to the center of the occultation path, and allowing us to explore Pluto's atmosphere lower than usual. The light curves show that Pluto's atmosphere remained robust. Observations from 0.5- and 0.4-m telescopes at the Auckland Observatory gave the first half of the occultation before clouds came in. We coordinated our observations with aircraft observations with NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) and its High Speed Imaging Photometer for Occultations (HIPO). Our ground-based and airborne stellar-occultation effort came only just over two weeks of Earth days and two Pluto days (based on Pluto's rotational period) before the flyby of NASA's New Horizons spacecraft, meaning that the mission's exquisite snapshot of Pluto's atmosphere can be placed in the context of our series of ground-based occultation observations carried out on a regular basis since 2002 following a first Pluto occultation observed in 1988 from aloft. Our observations were supported by NASA Planetary Astronomy grants NNX12AJ29G to Williams College, NNX15AJ82G to Lowell Observatory, and NNX10AB27G to MIT, and by the National Research Foundation of South Africa. We thank Alan Gilmore, Pam Kilmartin, Robert Lucas, Paul Tristam, and Carolle Varughese for assistance at Mt. John.

  18. Modeling Indications of Technology in Planetary Transit Light Curves-Dark-side Illumination

    Science.gov (United States)

    Korpela, Eric J.; Sallmen, Shauna M.; Leystra Greene, Diana

    2015-08-01

    We analyze potential effects of an extraterrestrial civilization’s use of orbiting mirrors to illuminate the dark side of a synchronously rotating planet on planetary transit light curves. Previous efforts to detect civilizations based on side effects of planetary-scale engineering have focused on structures affecting the host star output (e.g., Dyson spheres). However, younger civilizations are likely to be less advanced in their engineering efforts, yet still capable of sending small spacecraft into orbit. Since M dwarfs are the most common type of star in the solar neighborhood, it seems plausible that many of the nearest habitable planets orbit dim, low-mass M stars, and will be in synchronous rotation. Logically, a civilization evolving on such a planet may be inspired to illuminate their planet’s dark side by placing a single large mirror at the L2 Lagrangian point, or launching a fleet of small thin mirrors into planetary orbit. We briefly examine the requirements and engineering challenges of such a collection of orbiting mirrors, then explore their impact on transit light curves. We incorporate stellar limb darkening and model a simplistic mirror fleet’s effects for transits of Earth-like (R = 0.5 to 2 {R}{Earth}) planets which would be synchronously rotating for orbits within the habitable zone of their host star. Although such an installation is undetectable in Kepler data, the James Webb Space Telescope will provide the sensitivity necessary to detect a fleet of mirrors orbiting Earth-like habitable planets around nearby stars.

  19. The long-term light curve of the cataclysmic variable V794 Aquilae

    Energy Technology Data Exchange (ETDEWEB)

    Honeycutt, R. K. [Astronomy Department, Indiana University, Swain Hall West, Bloomington, IN 47405 (United States); Kafka, S. [Department of Terrestrial Magnetism, Carnegie Inst. of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Robertson, J. W., E-mail: honey@astro.indiana.edu, E-mail: skafka@aip.org, E-mail: Jeff.Robertson@atu.edu [Arkansas Tech University, Department of Physical Sciences, 1701 N. Boulder, Russellville, AR 72801-2222 (United States)

    2014-01-01

    The 1990-2012 light curve of the nova-like (NL) cataclysmic variable V794 Aql is studied in order to characterize and better understand the transitions to and from the faint state, and the variations within the bright state. Investigations of earlier portions of this data had concluded that the transitions to the low state were much slower than the rapid recovery, giving a sawtoothed appearance to the light curve. This behavior differs from that of most other VY Scl stars, which led to an interpretation of the large amplitude sawtooths as being due to an accretion disk (AD) instability. However, more recent photometry strongly suggests that the bright state itself has transitions of 1-1.5 mag, and that earlier studies had intermixed these bright state variations with the transitions to the low state. These newly recognized variations within the bright state sometimes appear as small outbursts (OBs) with typical amplitudes of 0.5-1.5 mag and spacings of ∼15-50 days. The rise times of the OBs are 2-3 times faster than the decline times. We argue that the V794 Aql bright state variations are due to AD behavior similar to that seen in dwarf novae, but with varying degrees of stability. Similar regular small OBs have also been reported in other NL CVs, which we compare with V794 Aql. The true deep low states in V794 Aql appear to be normal, having transition speeds and shapes very similar to the transitions in other VY Scl stars.

  20. Light curve analysis of GSC 2750-0054 and GSC 03208-02644

    Science.gov (United States)

    Elkhateeb, M. M.; Nouh, M. I.

    2016-11-01

    We present the first photometric analysis for the newly discovered eclipsing binary systems of Algole-type GSC 2750-0054 and GSC 03208-02644. Our analysis was carried out by means of the most recent version of Wilson Devinney (WD) code, which applies the model atmosphere by (Kurucz, R., 1993. In: Milon, E. (Ed.), Light Curve Modeling of Eclipsing Binary Stars. Springer-Verlag, New York, p. 93) with a prescription in passband for the radiative treatment. The accepted light curve solutions reveal absolute physical parameters and the spectral classifications for the components are adopted. We derived the spectral types of the system GSC 2750-0054 as K3 and K7. The physical parameters of the system are M1 = 0.72 ± 0.03 M⊙, M2 = 0.47 ± 0.02 M⊙, R1 = 0.81 ± 0.03 R⊙, R2 = 0.62 ± 0.03 R⊙, L1 = 0.27 ± 0.01 L⊙ and L2 = 0.1 ± 0.004 L⊙. For the system, GSC 03208 02644 the spectral types of the components are A5 and A8. The physical parameters are M1 = 1.86 ± 0.076 M⊙, M2 = 1.21 ± 0.049 M⊙, R1 = 1.84 ± 0.075 R⊙, R2 = 1.75 ± 0.072 R⊙, L1 = 13.58 ± 0.55 L⊙ and L2 = 9.94 ± 0.41 L⊙. Comparison with the evolutionary models as well as the empirical databases is presented.

  1. GAMMA-RAY BURSTS FROM MAGNETIC RECONNECTION: VARIABILITY AND ROBUSTNESS OF LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra’anana 4353701 (Israel)

    2016-01-10

    The dissipation mechanism that powers gamma-ray bursts (GRBs) remains uncertain almost half a century after their discovery. The two main competing mechanisms are the extensively studied internal shocks and the less studied magnetic reconnection. Here we consider GRB emission from magnetic reconnection accounting for the relativistic bulk motions that it produces in the jet's bulk rest frame. Far from the source the magnetic field is almost exactly normal to the radial direction, suggesting locally quasi-spherical thin reconnection layers between regions of oppositely directed magnetic field. We show that if the relativistic motions in the jet's frame are confined to such a quasi-spherical uniform layer, then the resulting GRB light curves are independent of their direction distribution within this layer. This renders previous results for a delta-function velocity-direction distribution applicable to a much more general class of reconnection models, which are suggested by numerical simulations. Such models that vary in their velocity-direction distribution differ mainly in the size of the bright region that contributes most of the observed flux at a given emission radius or observed time. The more sharply peaked this distribution, the smaller this bright region, and the stronger the light curve variability that may be induced by deviations from a uniform emission over the thin reconnection layer, which may be expected in a realistic GRB outflow. This is reflected both in the observed image at a given observed time and in the observer-frame emissivity map at a given emission radius, which are calculated here for three simple velocity-direction distributions.

  2. An efficient phase-shifting scheme for bolometric additive interferometry

    CERN Document Server

    Charlassier, R; Bréelle, É; Ghribi, A; Giraud-Héraud, Y; Kaplan, J; Piat, M; Prêle, D

    2008-01-01

    Context: Most upcoming CMB polarization experiments will use direct imaging to search for the primordial gravitational waves through the B-modes. Bolometric interferometry is an appealing alternative to direct imaging that combines the advantages of interferometry in terms of systematic effects handling and those of bolometric detectors in terms of sensitivity. Aims: We calculate the signal from a bolometric interferometer in order to investigate its sensitivity to the Stokes parameters paying particular attention to the choice of the phase-shifting scheme applied to the input channels in order to modulate the signal. Methods: The signal is expressed as a linear combination of the Stokes parameter visibilities whose coefficients are functions of the phase-shifts. Results: We show that the signal to noise ratio on the reconstructed visibilities can be maximized provided the fact that the phase-shifting scheme is chosen in a particular way called coherent summation of equivalent baselines. As a result, a bolome...

  3. The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey

    Energy Technology Data Exchange (ETDEWEB)

    Hayden, Brian T.; /Notre Dame U.; Garnavich, Peter M.; /Notre Dame U.; Kessler, Richard; /KICP, Chicago /Chicago U., EFI; Frieman, Joshua A.; /KICP, Chicago /Chicago U. /Fermilab; Jha, Saurabh W.; /Stanford U., Phys. Dept. /Rutgers U., Piscataway; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Cinabro, David; /Wayne State U.; Dilday, Benjamin; /Rutgers U., Piscataway; Kasen, Daniel; /UC, Santa Cruz; Marriner, John; /Fermilab; Nichol, Robert C.; /Portsmouth U., ICG /Baltimore, Space Telescope Sci. /Johns Hopkins U.

    2010-01-01

    We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 {+-} 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, t{sub r} - t{sub f} {approx}< 2 days and t{sub r} - t{sub f} > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble

  4. The EB Factory Project I. A Fast, Neural Net Based, General Purpose Light Curve Classifier Optimized for Eclipsing Binaries

    CERN Document Server

    Paegert, M; Burger, D M

    2014-01-01

    We describe a new neural-net based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as LSST. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98\\% and a false-positive rate of 2\\% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes,...

  5. Optical Transients Powered by Magnetars: Dynamics, Light Curves, and Transition to the Nebular Phase

    CERN Document Server

    Wang, L J; Dai, Z G; Xu, Dong; Han, Yan-Hui; Wu, X F; Wei, Jian-Yan

    2016-01-01

    Millisecond magnetars can be formed via several channels: core-collapse of massive stars, accretion-induced collapse of white dwarfs (WDs), double WD mergers, double neutron star (NS) mergers, and WD-NS mergers. Because the mass of ejecta from these channels could be quite different, their light curves are also expected to be diverse. We evaluate the dynamic evolution of optical transients powered by millisecond magnetars. We find that the magnetar with short spin-down timescale converts its rotational energy mostly into the kinetic energy of the transient, while the energy of a magnetar with long spin-down timescale goes into radiation of the transient. This leads us to speculate that hypernovae could be powered by magnetars with short spin-down timescales. At late times the optical transients will gradually evolve into a nebular phase because of the photospheric recession. We treat the photosphere and nebula separately because their radiation mechanisms are different. In some cases the ejecta could be light...

  6. A method to discriminate solar and antisolar differential rotation in high-precision light curves

    CERN Document Server

    Reinhold, T

    2015-01-01

    Surface differential rotation (DR) is one major ingredient of the magnetic field generation process in the Sun and likely in other stars. The term solar-like differential rotation describes the observation that solar equatorial regions rotate faster than polar ones. The opposite effect of polar regions rotating faster than equatorial ones (termed as antisolar DR) has only been observed in a few stars, although there is evidence from theoretical dynamo models. We present a new method to detect the sign of DR (i.e. solar-like or antisolar DR) by analyzing long-term high-precision light curves with the Lomb-Scargle periodogram.We compute the Lomb-Scargle periodogram and identify a set of significant periods $P_k$, which we associate with active regions located at different latitudes on the the stellar surface. If detectable, the first harmonics ($P_k'$) of these periods were identified to compute their peak-height-ratios $r_k:=h(P_k')/h(P_k)$. Spots rotating at lower latitudes generate less sine-shaped light cur...

  7. Detection Level Enhancement of Gravitational Microlensing Events from the Light Curves

    CERN Document Server

    Ibrahim, Ichsan; Djamal, Mitra; Kunjaya, Chatief; Jaelani, Anton Timur; Putri, Gerhana Puannandra

    2015-01-01

    In Astronomy, intensity of the source light is expressed in magnitude. Conventionally, magnitude is defined by logarithmic function of the received flux. This relationship is known as Pogson formulae. For received flux with small signal to noise ratio (S/N), the formulae gives large magnitude error. We want to inspect whether using Inverse Hyperbolic Sine function (hereinafter referred to as Asinh magnitude) can give an alternative calculation of magnitudes for small S/N flux and gives better results to represent the magnitude for that region. We study the possibility of increasing detection level of gravitational microlensing from 40 selected microlensing events light curves for 2013 and 2014 season by using Asinh magnitude. We obtained that the use of the Asinh make the events brighter than using logarithmic with average of about 3.42 x 10^-2 magnitude. We find also average of magnitude error difference between logarithmic magnitude and Asinh magnitude to is about 2.21 x 10^-2 magnitude, so we propose a lim...

  8. Looking for Stars and Finding the Moon: Effects of Lunar Gamma-ray Emission on Fermi LAT Light Curves

    CERN Document Server

    Corbet, Robin; Kerr, Matthew; Ray, Paul S

    2013-01-01

    We are conducting a search for new gamma-ray binaries by making high signal-to-noise light curves of all cataloged Fermi LAT sources and searching for periodic variability using appropriately weighted power spectra. The light curves are created using a variant of aperture photometry where photons are weighted by the probability that they came from the source of interest. From this analysis we find that the light curves of a number of sources near the ecliptic plane are contaminated by gamma-ray emission from the Moon. This shows itself as modulation on the Moon's sidereal period in the power spectra. We demonstrate that this contamination can be removed by excluding times when the Moon was too close to a source. We advocate that this data screening should generally be used when analyzing LAT data from a source located close to the path of the Moon.

  9. The Effects on Supernova Shock Breakout and Swift Light Curves Due to the Mass of the Hydrogen-Rich Envelope

    CERN Document Server

    Bayless, Amanda J; Frey, Lucille H; Fryer, Chris L; Roming, Peter W A; Young, Patrick A

    2014-01-01

    Mass loss remains one of the primary uncertainties in stellar evolution. In the most massive stars, mass loss dictates the circumstellar medium and can significantly alter the fate of the star. Mass loss is caused by a variety of wind mechanisms and also through binary interactions. Supernovae are excellent probes of this mass loss, both the circumstellar material and the reduced mass of the hydrogen-rich envelope. In this paper, we focus on the effects of reducing the hydrogen-envelope mass on the supernova light curve, studying both the shock breakout and peak light curve emission for a wide variety of mass loss scenarios. Even though the trends of this mass loss will be masked somewhat by variations caused by different progenitors, explosion energies, and circumstellar media, these trends have significant effects on the supernova light-curves that should be seen in supernova surveys. We conclude with a comparison of our results to a few key observations.

  10. Vertical Convection in Turbulent Accretion Disks and Light Curves of the A0620-00 1975 Outburst

    CERN Document Server

    Malanchev, Konstantin

    2015-01-01

    We present a model of the non-stationary $\\alpha$-disk with account for the irradiation and the vertical convection in the outer accretion disk where hydrogen is partially ionized. We include the viscous energy generation in the mix-length convection equations in accretion disks. The optical and X-ray light curves of X-ray nova A0620-00 are investigated in terms of this model. The turbulent viscosity parameter of the accretion disk is estimated, $\\alpha = 0.5 \\div 0.6$, which is necessary to explain the luminosity decay rate on the descending branch of the X-ray light curve for the A0620-00 1975 outburst. The secondary luminosity maximum on the light curves is explained by assuming an additional injection of matter into the accretion disk from the optical companion.

  11. VizieR Online Data Catalog: BAT6 sample optical and X-ray light curves (Melandri+, 2014)

    Science.gov (United States)

    Melandri, A.; Covino, S.; Rogantini, D.; Salvaterra, R.; Sbarufatti, B.; Bernardini, M. G.; Campana, S.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2014-03-01

    We followed the classification scheme described in Margutti et al. (2013, Cat. J/MNRAS/428/729/) that divided the light curves in four main classes: class 0 for events decaying with simple power-law; class Ia (Ib) for a smooth broken power-law that goes from a shallower (steeper) to a steeper (shallower) decay; class IIa or IIb for events that display steep-shallow-steep (canonical) or shallow-steep-shallow decays respectively; and finally, class III for those events that show a late-time break in their light curves. (6 data files).

  12. Investigation of the energy dependence of the orbital light curve in LS 5039

    Science.gov (United States)

    Chang, Z.; Zhang, S.; Ji, L.; Chen, Y. P.; Kretschmar, P.; Kuulkers, E.; Collmar, W.; Liu, C. Z.

    2016-11-01

    LS 5039 is so far the best-studied γ-ray binary system at multiwavelength energies. A time-resolved study of its spectral energy distribution (SED) shows that above 1 keV its power output is changing along its binary orbit as well as being a function of energy. To disentangle the energy dependence of the power output as a function of orbital phase, we investigated in detail the orbital light curves as derived with different telescopes at different energy bands. We analysed the data from all existing International Gamma-Ray Astrophysics Laboratory (INTEGRAL)/INTEGRAL on-board Imager/INTEGRAL Soft Gamma-Ray Imager observations of the source and generated the most up-to-date orbital light curves at hard X-ray energies. In the γ-ray band, we carried out orbital phase-resolved analysis of Fermi-Large Area Telescope (LAT) data between 30 MeV and 10 GeV in five different energy bands. We found that, at ≲100 MeV and ≳1 TeV the peak of the γ-ray emission is near orbital phase 0.7, while between ˜100 MeV and ˜1 GeV it moves close to orbital phase 1.0 in an orbital anticlockwise manner. This result suggests that the transition region in the SED at soft γ-rays (below a hundred MeV) is related to the orbital phase interval of 0.5-1.0 but not to the one of 0.0-0.5, when the compact object is `behind' its companion. Another interesting result is that between 3 and 20 GeV no orbital modulation is found, although Fermi-LAT significantly (˜18σ) detects LS 5039. This is consistent with the fact that at these energies, the contributions to the overall emission from the inferior conjunction phase region (INFC, orbital phase 0.45-0.9) and from the superior conjunction phase region (orbital phase 0.9-0.45) are equal in strength. At TeV energies the power output is again dominant in the INFC region and the flux peak occurs at phase ˜0.7.

  13. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park; Konigl, Arieh; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  14. Bolometric Luminosity Correction of H2O Maser AGNs

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2014-09-01

    For the H2O maser host AGN sample, we derived their bolometric luminosity corrections, based on their X-ray data and [O III] emission line luminosities. Our results for maser AGNs is comparable to that of non-maser AGNs.

  15. Optical Transients Powered by Magnetars: Dynamics, Light Curves, and Transition to the Nebular Phase

    Science.gov (United States)

    Wang, Ling-Jun; Wang, S. Q.; Dai, Z. G.; Xu, Dong; Han, Yan-Hui; Wu, X. F.; Wei, Jian-Yan

    2016-04-01

    Millisecond magnetars can be formed via several channels: core collapse of massive stars, accretion-induced collapse of white dwarfs (WDs), double WD mergers, double neutron star (NS) mergers, and WD-NS mergers. Because the mass of ejecta from these channels could be quite different, their light curves are also expected to be diverse. We evaluate the dynamic evolution of optical transients powered by millisecond magnetars. We find that the magnetar with a short spin-down timescale converts its rotational energy mostly into the kinetic energy of the transient, while the energy of a magnetar with a long spin-down timescale goes into radiation of the transient. This leads us to speculate that hypernovae could be powered by magnetars with short spin-down timescales. At late times the optical transients will gradually evolve into a nebular phase because of the photospheric recession. We treat the photosphere and nebula separately because their radiation mechanisms are different. In some cases the ejecta could be light enough that the magnetar can accelerate it to a relativistic speed. It is well known that the peak luminosity of a supernova (SN) occurs when the luminosity is equal to the instantaneous energy input rate, as shown by Arnett. We show that photospheric recession and relativistic motion can modify this law. The photospheric recession always leads to a delay of the peak time {t}{pk} relative to the time {t}× at which the SN luminosity equals the instantaneous energy input rate. Relativistic motion, however, may change this result significantly.

  16. Probing millisecond pulsar emission geometry using light curves from the Fermi Large Area Telescope

    CERN Document Server

    Venter, C; Guillemot, L

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of B-field lines, in the geometric context of polar cap (PC), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by TPC and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We...

  17. The time ending the shallow decay of the X-ray light curves of long GRBs

    CERN Document Server

    Nava, L; Ghirlanda, G; Cabrera, J I; Firmani, C; Avila-Reese, V

    2007-01-01

    The early X-ray light curve of Gamma Ray Bursts (GRBs) is complex, and shows a typical steep-flat-steep behaviour. The time T_a at which the flat (plateau) part ends may bear some important physical information, especially if it plays the same role of the so called jet break time t_jet. To this aim, stimulated by the recent analysis of Willingale et al., we have assembled a sample of GRBs of known redshifts, spectral parameters of the prompt emission, and T_a. By using T_a as a jet angle indicator, and then estimating the collimation corrected prompt energetics, we find a correlation between the latter quantity and the peak energy of the prompt emission. However, this correlation has a large dispersion, similar to the dispersion of the Amati correlation and it is not parallel to the Ghirlanda correlation. Furthermore, we show that the correlation itself results mainly from the dependence of the jet opening angle on the isotropic prompt energy, with the time T_a playing no role, contrary to what we find for th...

  18. The Effect of a Time-Varying Accretion Disk Size on Quasar Microlensing Light Curves

    CERN Document Server

    Blackburne, Jeffrey A

    2010-01-01

    Microlensing perturbations to the magnification of gravitationally lensed quasar images are dependent on the angular size of the quasar. If quasar variability at visible wavelengths is caused by a change in the area of the accretion disk, it will affect the microlensing magnification. We derive the expected signal, assuming that the luminosity scales with some power of the disk area, and estimate its amplitude using simulations. We discuss the prospects for detecting the effect in real-world data and for using it to estimate the logarithmic slope of the luminosity's dependence on disk area. Such an estimate would provide a direct test of the standard thin accretion disk model. We tried fitting 6 seasons of the light curves of the lensed quasar HE 0435-1223 including this effect as a modification to the Kochanek et al. (2006) approach to estimating time delays. We find a dramatic improvement in the goodness of fit and relatively plausible parameters, but a robust estimate will require a full numerical calculat...

  19. The nature of very faint X-ray binaries; hints from light curves

    CERN Document Server

    Heinke, C O; Degenaar, N; Wijnands, R

    2014-01-01

    Very faint X-ray binaries (VFXBs), defined as having peak luminosities Lx of 10^34-10^36 erg/s, have been uncovered in significant numbers, but remain poorly understood. We analyse three published outburst light curves of two transient VFXBs using the exponential and linear decay formalism of King and Ritter (1998). The decay timescales and brink luminosities suggest orbital periods of order 1 hour. We review various estimates of VFXB properties, and compare these with suggested explanations of the nature of VFXBs. We suggest that: 1) VFXB outbursts showing linear decays might be explained as partial drainings of the disc of "normal" X-ray transients, and many VFXB outbursts may belong to this category; 2) VFXB outbursts showing exponential decays are best explained by old, short-period systems involving mass transfer from a low-mass white dwarf or brown dwarf; 3) persistent (or quasi-persistent) VFXBs, which maintain an Lx of 10^34-10^35 erg/s for years, may be explained by magnetospheric choking of the accr...

  20. Discovery of four periodic methanol masers and updated light curve for a further one

    CERN Document Server

    Szymczak, M; Bartkiewicz, A

    2015-01-01

    We report the discovery of 6.7 GHz methanol maser periodic flares in four massive star forming regions and the updated light curve for the known periodic source G22.357+0.066. The observations were carried out with the Torun 32 m radio telescope between June 2009 and April 2014. Flux density variations with period of 120 to 245 d were detected for some or all spectral features. A variability pattern with a fast rise and relatively slow fall on time-scale of 30-60 d dominated. A reverse pattern was observed for some features of G22.357+0.066, while sinusoidal-like variations were detected in G25.411+0.105. A weak burst lasting ~520 d with the velocity drift of 0.24 km/s/yr occurred in G22.357+0.066. For three sources for which high resolution maps are available, we found that the features with periodic behaviour are separated by more than 500 au from those without any periodicity. This suggests that the maser flares are not triggered by large-scale homogeneous variations in either the background seed photon fl...

  1. Study of GRB light curve decay indices in the afterglow phase

    CERN Document Server

    Del Vecchio, Roberta; Ostrowski, Michał

    2016-01-01

    In this work we study the distribution of temporal power-law decay indices, $\\alpha$, in the Gamma Ray Burst (GRB) afterglow phase, fitted for $176$ GRBs (139 long GRBs, 12 short GRBs {\\it with extended emission} and 25 X-Ray Flashes (XRFs)) with known redshifts. These indices are compared to the values of characteristic afterglow luminosity, $L_a$, the time, $T_a^*$, and the decay index, $\\alpha_W$, derived with global light curve fitting using the \\cite{willingale07} model. This model fitting yields similar distributions of $\\alpha_W$ to the fitted $\\alpha$, but for individual bursts a difference can be significant. Analysis of the ($\\alpha$, $L_a$) distribution reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB $\\alpha$ values along the $L_a$ versus $T_a^*$ (LT) distribution, with systematic variation of $\\alpha$ parameter distribution with luminosity for any selected $T_a^*$. We analyze this systematics with respect to the fitted LT co...

  2. Kepler light curve analysis of the blazar W2R 1926+42

    CERN Document Server

    Mohan, P; Bachev, R; Strigachev, A

    2015-01-01

    We study the long term Kepler light curve of the blazar W2R 1926+42 ($\\sim$ 1.6 years) which indicates a variety of variability properties during different intervals of observation. The normalized excess variance, $F_{\\rm var}$ ranges from 1.8 % in the quiescent phase and 43.3 % in the outburst phase. We find no significant deviation from linearity in the $F_{\\rm var}$-flux relation. Time series analysis is conducted using the Fourier power spectrum and the wavelet analysis methods to study the power spectral density (PSD) shape, infer characteristic timescales and statistically significant quasi-periodic oscillations (QPOs). A bending power law with an associated timescale of $T_B = 6.2^{+6.4}_{-3.1}$ hours is inferred in the PSD analysis. We obtain a black hole mass of $M_\\bullet = (1.5 - 5.9) \\times 10^7 M_\\odot$ for the first time using $F_{\\rm var}$ and the bend timescale for this source. From a mean outburst lifetime of days, we infer a distance from the jet base $r \\leq 1.75$ pc indicating that the out...

  3. The Kepler Cepheid V1154 Cyg revisited: light curve modulation and detection of granulation

    CERN Document Server

    Derekas, A; Molnar, L; Sodor, A; Benko, J M; Szabados, L; Bognar, Zs; Csak, B; Szabo, Gy M; Szabo, R; Pal, A

    2016-01-01

    We present a detailed analysis of the bright Cepheid-type variable star V1154 Cygni using 4 years of continuous observations by the Kepler space telescope. We detected 28 frequencies using standard Fourier transform method.We identified modulation of the main pulsation frequency and its harmonics with a period of ~159 d. This modulation is also present in the Fourier parameters of the light curve and the O-C diagram. We detected another modulation with a period of about 1160 d. The star also shows significant power in the low-frequency region that we identified as granulation noise. The effective timescale of the granulation agrees with the extrapolated scalings of red giant stars. Non-detection of solar-like oscillations indicates that the pulsation inhibits other oscillations. We obtained new radial velocity observations which are in a perfect agreement with previous years data, suggesting that there is no high mass star companion of V1154 Cygni. Finally, we discuss the possible origin of the detected frequ...

  4. Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves

    CERN Document Server

    Hicken, Malcolm; Blondin, Stephane; Challis, Peter; Jha, Saurabh; Kelly, Patrick L; Rest, Armin; Kirshner, Robert P

    2009-01-01

    We combine the CfA3 supernova Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. (2008) to form the Constitution set and, combined with a BAO prior, produces 1+w=0.013 +0.066/-0.068 (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically-useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R_V=3.1), and MLCS2k2 (R_V=1.7). SALT and SALT2 produce high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < Delta < 1.2. MLCS2k2 with R_V=3.1 overestimates host-galaxy extinction while R_V=1.7 does not. Our investi...

  5. The Effect of Different Magnetospheric Structures on Predictions of Gamma-ray Pulsar Light Curves

    CERN Document Server

    Breed, M; Harding, A K; Johnson, T J

    2015-01-01

    The second pulsar catalogue of the Fermi Large Area Telescope (LAT) will contain in excess of 100 gamma-ray pulsars. The light curves (LCs) of these pulsars exhibit a variety of shapes, and also different relative phase lags with respect to their radio pulses, hinting at distinct underlying emission properties (e.g., inclination and observer angles) for the individual pulsars. Detailed geometric modelling of the radio and gamma-ray LCs may provide constraints on the B-field structure and emission geometry. We used different B-field solutions, including the static vacuum dipole and the retarded vacuum dipole, in conjunction with an existing geometric modelling code, and constructed radiation sky maps and LCs for several different pulsar parameters. Standard emission geometries were assumed, namely the two-pole caustic (TPC) and outer gap (OG) models. The sky maps and LCs of the various B-field and radiation model combinations were compared to study their effect on the resulting LCs. As an application, we compa...

  6. Light curves of the latest FUor: Indication of a close binary

    CERN Document Server

    Hackstein, M; Kóspál, Á; Hambsch, F -J; Chini, R; Ábrahám, P; Moór, A; Nuñez, F Pozo; Ramolla, M; Westhues, Ch; Kaderhandt, L; Fein, Ch; Domínguez, A Barr; Hodapp, K -W

    2015-01-01

    We monitored the recent FUor 2MASS J06593158-0405277 (V960 Mon) since November 2009 at various observatories and multiple wavelengths. After the outburst by nearly 2.9 mag in $r$ around September 2014 the brightness gently fades until April 2015 by nearly 1 mag in $U$ and 0.5 mag in $z$. Thereafter the brightness at $\\lambda>5000 \\AA$ was constant until June 2015 while the shortest wavelengths ($U, B$) indicate a new rise, similar to that seen for the FUor V2493 Cyg (HBC722). Our near-infrared (NIR) monitoring between December 2014 and April 2015 shows a smaller outburst amplitude ($\\sim$2 mag) and a smaller (0.2 $-$ 0.3 mag) post-outburst brightness decline. Optical and NIR color-magnitude diagrams indicate that the brightness decline is caused by growing extinction. The post-outburst light curves are modulated by an oscillating color-neutral pattern with a period of about 17 days and an amplitude declining from $\\sim$0.08 mag in October 2014 to $\\sim$0.04 mag in May 2015. The properties of the oscillating p...

  7. Millisecond dips in the RXTE/PCA light curve of Sco X-1 and TNO occultation

    CERN Document Server

    Chang, H K; Liu, C Y; King, S K; Chang, Hsiang-Kuang; Liang, Jau-Shian; Liu, Chih-Yuan; King, Sun-Kun

    2007-01-01

    Millisecond dips in the RXTE/PCA light curve of Sco X-1 were reported recently (Chang et al. 2006), which were interpreted as the occultation of X-rays from Sco X-1 caused by Trans-Neptunian Objects (TNO) of hundred-meter size. Inconclusive signatures of possible instrumental effects in many of these dip events related to high-energy cosmic rays were later found (Jones et al. 2006) and the TNO interpretation became shaky. Here we report more detailed analysis aiming at distinguishing true occultation events from those related to cosmic rays. Based on some indicative criteria derived from housekeeping data and two-channel spectral information, we suggest that about 10% of the dips are probable events of occultation. The total number of TNOs of size from 60 m to 100 m is estiamted to be about 10^{15} accordingly. Limited by the coarser time resolution of standard data modes of RXTE/PCA, however, definite results cannot be obtained. Adequately configured observations with RXTE or other new instruments in the fut...

  8. TEMPORAL DECONVOLUTION STUDY OF LONG AND SHORT GAMMA-RAY BURST LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, P. N.; Briggs, Michael S.; Connaughton, Valerie; Paciesas, William; Burgess, Michael; Chaplin, Vandiver; Goldstein, Adam; Guiriec, Sylvain [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Kouveliotou, Chryssa; Fishman, Gerald [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander J.; Meegan, Charles A. [Center for Space Plasma and Aeronomic Research (CSPAR), Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Bissaldi, Elisabetta [Institute of Astro and Particle Physics, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Gruber, David [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Fitzpatrick, Gerard [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); Gibby, Melissa; Giles, Misty M. [Jacobs Technology, Inc., Huntsville, AL 35806 (United States); and others

    2012-01-10

    The light curves of gamma-ray bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within the framework of the internal shock model for GRB prompt emission.

  9. CfAIR2: Near-infrared Light Curves of 94 Type Ia Supernovae

    Science.gov (United States)

    Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Michael F.; Kirshner, Robert P.

    2015-09-01

    CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes {{JHK}}s photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z ˜ 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains ˜13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

  10. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves

    CERN Document Server

    Barth, A J; Canalizo, G; Filippenko, A V; Gates, E L; Greene, J E; Li, W; Malkan, M A; Pancoast, A; Sand, D J; Stern, D; Treu, T; Woo, J -H; Assef, R J; Bae, H -J; Brewer, B J; Cenko, S B; Clubb, K I; Cooper, M C; Diamond-Stanic, A M; Hiner, K D; Hoenig, S F; Hsiao, E; Kandrashoff, M T; Lazarova, M S; Nierenberg, A M; Rex, J; Silverman, J M; Tollerud, E J; Walsh, J L

    2015-01-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the AGN continuum, and measurements of the broad H-beta line widths in mean and root-mean square (rms) spectra. For the most highly variable AGNs we also measured broad H-beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H-beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H-beta ve...

  11. A New Relationship Between Soft X-Rays and EUV Flare Light Curves

    Science.gov (United States)

    Thiemann, Edward

    2016-05-01

    Solar flares are the result of magnetic reconnection in the solar corona which converts magnetic energy into kinetic energy resulting in the rapid heating of solar plasma. As this plasma cools, it emits radiation at different EUV wavelengths when the dropping temperature passes a line’s temperature of formation. This results in a delay in the emissions from cooler EUV lines relative to hotter EUV lines. Therefore, characterizing how this hot plasma cools is important for understanding how the corresponding geo-effective extreme ultraviolet (EUV) irradiance evolves in time. I present a simple new framework in which to study flare cooling by using a Lumped Element Thermal Model (LETM). LETM is frequently used in science and engineering to simplify a complex multi-dimensional thermal system by reducing it to a 0-D thermal circuit. For example, a structure that conducts heat out of a system is simplified with a resistive element and a structure that allows a system to store heat is simplified with a capacitive element. A major advantage of LETM is that the specific geometry of a system can be ignored, allowing for an intuitive analysis of the major thermal processes. I show that LETM is able to accurately reproduce the temporal evolution of cooler flare emission lines based on hotter emission line evolution. In particular, it can be used to predict the evolution of EUV flare light curves using the NOAA X-Ray Sensor (XRS).

  12. The Lick AGN Monitoring Project: Photometric Light Curves and Optical Variability Characteristics

    CERN Document Server

    Walsh, Jonelle L; Bentz, Misty C; Barth, Aaron J; Baliber, Nairn; Li, Weidong; Stern, Daniel; Bennert, Vardha Nicola; Brown, Timothy M; Canalizo, Gabriela; Filippenko, Alexei V; Gates, Elinor L; Greene, Jenny E; Malkan, Matthew A; Sakata, Yu; Street, Rachel A; Treu, Tommaso; Woo, Jong-Hak; Yoshii, Yuzuru

    2009-01-01

    The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10^6-10^7 solar masses, as well as the well-studied AGN NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broad-band B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76-m Katzman Automatic Imaging Telescope (KAIT), the 2-m Multicolor Active Galactic Nuclei Monitoring (MAGNUM) telescope, the Palomar 60-in (1.5-m) telescope, and the 0.80-m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the ph...

  13. Characterizing high-energy light curves of Fermi/Lat GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Gillette, Jarred [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-21

    A systematic analysis of the light curves of Gamma-Ray Burst (GRBs) with redshift and detected at high-energy (> 100 MeV) by Fermi/LAT has never been done before our work, because there were only a handful of detections. Now we have 20 of those, which we can use to characterize the GRBs in their rest frame. We compared a characteristic decay times Tc of GRBs with redshifts using the new “Pass 8” data, and used a Crystal Ball function to parametrize GRB characteristics. An unexpected anti-correlation between Tc and the peak flux was observed. This means that brighter peaked GRBs have shorter durations. There is also no correlation between the Tc and the decay index, which makes the anti-correlation with brightness more clear. This results appears to be consistent with the External Shock model, which is one of the competing hypothesis on the origin of the high-energy emission. We did not observe any bimodality, which is seen in GRBs at lower energies.

  14. Characterizing high-energy light curves of Fermi/LatGRBs - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Gillette, Jarred [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-23

    A systematic analysis of the light curves of Gamma-Ray Burst (GRBs) with redshift and detected at high-energy (> 100 MeV) by Fermi/LAT has never been done before our work, because there were only a handful of detections. Now we have 20 of those, which we can use to characterize the GRBs in their rest frame. We compared a characteristic decay times Tc of GRBs with redshifts using the new "Pass8" data, and used a Crystal Ball function to parametrize GRB characteristics. An unexpected anti-correlation between Tc and the peak flux was observed. This means that brighter peaked GRBs have shorter durations. There is also no correlation between Tc and the decay index, which is one of the competing hypothesis on the origin of the high-energy emission. We did not observe any bimodality, which is seen in GRBs at lower energies.

  15. Discovery of one new class in the light curve of GRS 1915+105

    CERN Document Server

    Pahari, Mayukh

    2009-01-01

    From the study of X-ray light curve and color-color diagram of the low mass X-ray binary GRS 1915+105, observed by on board proportional counter array (PCA) of Rossi X-ray Timing Explorer (RXTE), we discover a new class of variability, which we name $\\epsilon$ class. We have studied observations between MJD 51200 and 51450. The class shows unusual periodic-like variation in count rate during rise time of two x-ray bursts. The class take place when the source is in radio quiet state. The huge expansion in color-intensity diagram indicates the class to be an adjusting stage of increasing accretion rate. Spectral analysis shows that during lower count rate, the spectrum is hard power-law dominating, indicating similarity towards hard intermediate state, and during higher count rate, the spectrum is thermal disk blackbody component dominating, indicating similarity towards high soft state. Hence, this class is important in understanding the way of state transition leads to change in accretion rate. No signature o...

  16. Analysis of Kepler Light Curve of the Novalike Cataclysmic Variable KIC 8751494

    CERN Document Server

    Kato, Taichi

    2013-01-01

    We analyzed the Kepler light curve of KIC 8751494, the recently recognized novalike cataclysmic variable in the Kepler field. We detected a stable periodicity of 0.114379(1) d, which we identified as being the orbital period. The stronger photometric period around 0.12245 d, which had been detected from the ground-based observation, was found to be variable, and we identified this period as being the positive superhump period. Most unexpectedly, this superhump period showed short-term (10--20 d) and strong variations in period when the object entered a slightly faint state. The fractional superhump excess varied as large as ~30%. The variation of the period very well traced the variation of the brightness of the system. The time-scales of this variation of the superhump period was too slow for the thermal disk instability. We interpret that the period variation was caused by the varying pressure effect on the period of positive superhumps. This finding suggests that the pressure effect, at least in novalike s...

  17. VizieR Online Data Catalog: UBVRIz light curves of 51 Type II supernovae (Galbany+, 2016)

    Science.gov (United States)

    Galbany, L.; Hamuy, M.; Phillips, M. M.; Suntzeff, N. B.; Maza, J.; de Jaeger, T.; Moraga, T.; Gonzalez-Gaitan, S.; Krisciunas, K.; Morrell, N. I.; Thomas-Osip, J.; Krzeminski, W.; Gonzalez, L.; Antezana, R.; Wishnjewski, M.; McCarthy, P.; Anderson, J. P.; Gutierrez, C. P.; Stritzinger, M.; Folatelli, G.; Anguita, C.; Galaz, G.; Green, E. M.; Impey, C.; Kim, Y.-C.; Kirhakos, S.; Malkan, M. A.; Mulchaey, J. S.; Phillips, A. C.; Pizzella, A.; Prosser, C. F.; Schmidt, B. P.; Schommer, R. A.; Sherry, W.; Strolger, L.-G.; Wells, L. A.; Williger, G. M.

    2016-08-01

    This paper presents a sample of multi-band, visual-wavelength light curves of 51 type II supernovae (SNe II) observed from 1986 to 2003 in the course of four different surveys: the Cerro Tololo Supernova Survey, the Calan Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernovae Survey (CATS). Near-infrared photometry and optical spectroscopy of this set of SNe II will be published in two companion papers. A list of the SNe II used in this study is presented in Table1. The first object in our list is SN 1986L and it is the only SN observed with photoelectric techniques (by M.M.P and S.K., using the Cerro Tololo Inter-American Observatory (CTIO) 0.9m equipped with a photometer and B and V filters). The remaining SNe were observed using a variety of telescopes equipped with CCD detectors and UBV(RI)KCz filters (see Table5). The magnitudes for the photometric sequences of the 51 SNe II are listed in Table4. In every case, these sequences were derived from observations of Landolt standards (see Appendix D in Hamuy et al. 2001ApJ...558..615H for the definition of the z band and Stritzinger et al. 2002AJ....124.2100S for the description of the z-band standards). Table5 lists the resulting UBVRIz magnitudes for the 51 SNe. (3 data files).

  18. Can Large Time Delays Observed in Light Curves of Coronal Loops be Explained by Impulsive Heating?

    CERN Document Server

    Lionello, Roberto; Winebarger, Amy R; Linker, Jon A; Mikić, Zoran

    2015-01-01

    The light curves of solar coronal loops often peak first in channels associated with higher temperatures and then in those associated with lower. The time delays between the different narrowband EUV channels have been measured for many individual loops and recently for every pixel of an active region observation. Time delays between channels for an active region exhibit a wide range of values, with maxima $>$ 5,000\\,s. These large time delays make up 3-26\\% (depending on the channel pair) of the pixels where a significant, positive time delay is measured. It has been suggested that time delays can be explained by impulsive heating. In this paper, we investigate whether the largest observed time delays can be explained by this hypothesis by simulating a series of coronal loops with different heating rates, loop lengths, abundances, and geometries to determine the range of expected time delays between a set of four EUV channels. We find that impulsive heating cannot address the largest time delays observed in t...

  19. Dynamics and Afterglow Light Curves of GRB Blast Waves Encountering a Density Bump or Void

    CERN Document Server

    Uhm, Z Lucas

    2014-01-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst (GRB) blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structures in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics, for blast waves with either a long-lived or short-lived RS wave. We show that, when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage), due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that correct modeling of blast waves needs to satisfy. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that, as a response to density s...

  20. Temporal Deconvolution study of Long and Short Gamma-Ray Burst Light curves

    CERN Document Server

    Bhat, P N; Connaughton, Valerie; Kouveliotou, Chryssa; van der Horst, Alexander J; Paciesas, William; Meegan, Charles A; Bissaldi, Elisabetta; Burgess, Michael; Chaplin, Vandiver; Diehl, Roland; Fishman, Gerald; Fitzpatrick, Gerard; Foley, Suzanne; Gibby, Melissa; Giles, Misty M; Goldstein, Adam; Greiner, Jochen; Gruber, David; Guiriec, Sylvain; von Kienlin, Andreas; Kippen, Marc; McBreen, Sheila; Preece, Robert; Rau, Arne; Tierney, Dave; Wilson-Hodge, Colleen

    2011-01-01

    The light curves of Gamma-Ray Bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within t...

  1. "Secular Light Curve of Comet 103P/Hartley 2, Target of the EPOXI Mission"

    CERN Document Server

    Ferrin, Ignacio

    2010-01-01

    In support of the EPOXI mission, we have compiled the secular light curve (SLC) of comet 103P/Hartley 2, the next target of EPOXI. a) Of the order of 30 photometric parameters are measured, over 20 of them new. The turn on point of activity is -4.2 +/- 0.1 AU from the Sun, which corresponds to -400 +/- 40 d before perihelion. The total active time is TACTIVE= 1484 +/- 43 d. b) 103P is a young dwarf comet, young because it has a photometric age P-AGE(1,1) = 15 +/- 2 cy (comet years), and dwarf because its diameter is DEFFE = 1.14 +/- 0.16 km. c) The nucleus is very active, and the amplitude of the SLC is ASEC= 10.8 +/- 0.1 mag in 1997. This comet is as active as 1P/Halley, but much smaller. d) After remaining active up to aphelion, the comet spills-over its activity into the next orbit. e) Two linear laws change slope at a break point located at RBP = -1.20 +/- 0.1 AU before perihelion, and magnitude mBP = 9.4 +/- 0.1. Sublimation is not controlled by water ice. The controlling substance may be CO or CO2 ice. ...

  2. IRTF/SPEX OBSERVATIONS OF THE UNUSUAL KEPLER LIGHT CURVE SYSTEM KIC 8462852

    Energy Technology Data Exchange (ETDEWEB)

    Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Sitko, M. L. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 (United States); Marengo, M., E-mail: carey.lisse@jhuapl.edu [Department of Physics and Astronomy, Iowa State University, 12 Physics Hall, Ames, IA 50010 (United States)

    2015-12-20

    We have utilized the NASA/IRTF 3 m SpeX instrument’s high-resolution spectral mode to observe and characterize the near-infrared flux emanating from the unusual Kepler light curve system KIC 8462852. By comparing the resulting 0.8–4.2 μm spectrum to a mesh of model photospheric spectra, the 6 emission line analyses of the Rayner et al. catalog, and the 25 system collections of debris disks we have observed to date using SpeX under the Near InfraRed Debris disk Survey, we have been able to additionally characterize the system. Within the errors of our measurements, this star looks like a normal solar abundance main-sequence F1V to F3V dwarf star without any obvious traces of significant circumstellar dust or gas. Using Connelley and Greene’s emission measures, we also see no evidence of significant ongoing accretion onto the star nor any stellar outflow away from it. Our results are inconsistent with large amounts of static close-in obscuring material or the unusual behavior of a YSO system, but are consistent with the favored episodic giant comet models of a Gyr old stellar system favored by Boyajian et al. We speculate that KIC 8462852, like the ∼1.4 Gyr old F2V system η Corvi, is undergoing a late heavy bombardment, but is only in its very early stages.

  3. Modeling Indications of Technology in Planetary Transit Light Curves -- Dark-side illumination

    CERN Document Server

    Korpela, Eric J; Green, Diana Leystra

    2015-01-01

    We analyze potential effects of an extraterrestrial civilization's use of orbiting mirrors to illuminate the dark side of a synchronously rotating planet on planetary transit light curves. Previous efforts to detect civilizations based on side effects of planetary-scale engineering have focused on structures affecting the host star output (e.g. Dyson spheres). However, younger civilizations are likely to be less advanced in their engineering efforts, yet still capable of sending small spacecraft into orbit. Since M dwarfs are the most common type of star in the solar neighborhood, it seems plausible that many of the nearest habitable planets orbit dim, low-mass M stars, and will be in synchronous rotation. Logically, a civilization evolving on such a planet may be inspired to illuminate their planet's dark side by placing a single large mirror at the L2 Lagrangian point, or launching a fleet of small thin mirrors into planetary orbit. We briefly examine the requirements and engineering challenges of such a co...

  4. Gamma-ray burst optical light-curve zoo: comparison with X-ray observations

    CERN Document Server

    Zaninoni, Elena; Margutti, Raffaella; Oates, Samantha; Chincarini, Guido

    2013-01-01

    We present a comprehensive analysis of the optical and X-ray light curves (LCs) and spectral energy distributions (SEDs) of a large sample of gamma-ray burst (GRB) afterglows to investigate the relationship between the optical and X-ray emission after the prompt phase. We collected the optical data from the literature and determined the shapes of the optical LCs. Then, using previously presented X-ray data we modeled the optical/X-ray SEDs. We studied the SED parameter distributions and compared the optical and X-ray LC slopes and shapes. The optical and X-ray spectra become softer as a function of time while the gas-to-dust ratios of GRBs are higher than the values calculated for the Milky Way and the Large and Magellanic Clouds. For 20% of the GRBs the difference between the optical and X-ray slopes is consistent with 0 or 1=4 within the uncertainties (we did it not consider the steep decay phase), while in the remaining 80% the optical and X-ray afterglows show significantly different temporal behaviors. I...

  5. Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping

    CERN Document Server

    Sluse, D

    2014-01-01

    Owing to the advent of large area photometric surveys, the possibility to use broad band photometric data, instead of spectra, to measure the size of the broad line region of active galactic nuclei, has raised a large interest. We describe here a new method using time-delay lensed quasars where one or several images are affected by microlensing due to stars in the lensing galaxy. Because microlensing decreases (or increases) the flux of the continuum compared to the broad line region, it changes the contrast between these two emission components. We show that this effect can be used to effectively disentangle the intrinsic variability of those two regions, offering the opportunity to perform reverberation mapping based on single band photometric data. Based on simulated light curves generated using a damped random walk model of quasar variability, we show that measurement of the size of the broad line region can be achieved using this method, provided one spectrum has been obtained independently during the mo...

  6. Eclipsing binaries observed with the WIRE satellite. II. beta Aurigae and non-linear limb darkening in light curves

    CERN Document Server

    Southworth, J; Buzasi, D L; Southworth, John; Bruntt, Hans; Buzasi, Derek L.

    2007-01-01

    We present the most precise light curve ever obtained of a detached eclipsing binary star and use it investigate the inclusion of non-linear limb darkening laws in eclipsing binary light curve models. This light curve, of the bright system beta Aurigae, was obtained using the star tracker aboard the WIRE satellite and contains 30000 datapoints with a scatter of 0.3 mmag. We analyse it using a version of the EBOP code modified to include non-linear limb darkening and to directly incorporate observed times of minimum light and spectroscopic light ratios into the solution as individual observations. We also analyse the dataset with the WD code to ensure that the two models give consistent results. EBOP provides an excellent fit to the WIRE data. Whilst the fractional radii are only defined to a precision of 5%, including an accurate published spectroscopic light ratio improves this dramatically to 0.5%. Using non-linear limb darkening improves the quality of the fit significantly and causes the measured radii to...

  7. The effect of an offset-dipole magnetic field on the Vela pulsar's gamma-ray light curves

    CERN Document Server

    Breed, M; Harding, A K; Johnson, T J

    2015-01-01

    Over the past six years, the Fermi Large Area Telescope has detected more than 150 gamma-ray pulsars, discovering a variety of light curve trends and classes. Such diversity hints at distinct underlying magnetospheric and/or emission geometries. We implemented an offset-dipole magnetic field, with an offset characterised by parameters epsilon and magnetic azimuthal angle, in an existing geometric pulsar modelling code which already includes static and retarded vacuum dipole fields. We use these different magnetic field solutions in conjunction with standard emission geometries, namely the two-pole caustic and outer gap models (the latter only for non-offset dipoles), and construct intensity maps and light curves for several pulsar parameters. We compare our model light curves to the Vela data from the second pulsar catalogue of Fermi. We use a refined chi-square grid search method for finding best-fit light curves for each of the different models. Our best fit is for the retarded vacuum dipole field and the o...

  8. Multicolor Light Curve Simulations of Population III Core-Collapse Supernovae: From Shock Breakout to 56Co Decay

    Science.gov (United States)

    Tolstov, Alexey; Nomoto, Ken’ichi; Tominaga, Nozomu; Ishigaki, Miho N.; Blinnikov, Sergey; Suzuki, Tomoharu

    2016-04-01

    The properties of the first generation of stars and their supernova (SN) explosions remain unknown due to the lack of actual observations. Recently, many transient surveys have been conducted and the feasibility of detecting supernovae (SNe) of Pop III stars is growing. In this paper, we study the multicolor light curves for a number of metal-free core-collapse SN models (25–100 {M}ȯ ) to determine the indicators for the detection and identification of first generation SNe. We use mixing-fallback supernova explosion models that explain the observed abundance patterns of metal-poor stars. Numerical calculations of the multicolor light curves are performed using the multigroup radiation hydrodynamic code stella. The calculated light curves of metal-free SNe are compared with non-zero-metallicity models and several observed SNe. We have found that the shock breakout characteristics, the evolution of the photosphere’s velocity, the luminosity, and the duration and color evolution of the plateau, that is, all of the SN phases from shock breakout to 56Co decay, are helpful for estimating the parameters of the SN progenitor: the mass, the radius, the explosion energy, and the metallicity. We conclude that the multicolor light curves could potentially be used to identify first-generation SNe in current (Subaru/HSC) and future transient surveys (LSST, James Webb Space Telescope). They are also suitable for identifying low-metallicity SNe in the nearby universe (PTF, Pan-STARRS, Gaia).

  9. Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves Encountering a Density Bump or Void

    Science.gov (United States)

    Uhm, Z. Lucas; Zhang, Bing

    2014-07-01

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  10. Clustering of LAT light curves: a clue to the origin of high-energy emission in Gamma-Ray Bursts

    CERN Document Server

    Nava, L; Omodei, N; Ghisellini, G; Ghirlanda, G; Celotti, A; Longo, F; Desiante, R; Duran, R Barniol

    2014-01-01

    The physical origin of the >0.1 GeV emission detected from Gamma-Ray Bursts (GRBs) by the Fermi satellite has not yet been completely understood. In this work we consider the GeV light curves of ten GRBs with measured redshift detected by the Fermi-LAT. These light curves are characterised by a long-lived ($\\gtrsim10^2$ seconds) emission, whose luminosity decays in time as a power-law. While the decay rate is similar for all GRBs (i.e. $L_{LAT}\\propto t^{-1.2}$), the normalisation spans about two orders of magnitude in luminosity. However, after re-normalising the luminosities to the prompt energetics $E_{iso}$ the light curves overlap. We consider the scenario in which the temporally extended LAT emission is dominated by synchrotron radiation from electrons accelerated at the forward external shock. According to this model, at high-energies (i.e. above the typical synchrotron frequencies) a small dispersion of the $E_{iso}$-normalised light curves is expected. The fact that the LAT temporally extended emissi...

  11. Precessing jets interacting with interstellar material as the origin for the light curves of gamma-ray bursts

    CERN Document Server

    Zwart, S F P; Totani, Tomo

    2000-01-01

    We present an internal shock model with external characteristics for explaining the complicated light curves of gamma-ray bursts. Shocks produce gamma-rays in the interaction between a precessing beam of relativistic particles and the interstellar medium. Each time the particle beam passes the same line of sight with the observer the inter stellar medium is pushed outward. Subsequent interactions between the medium and the beam are delayed by the extra distance to be traveled for the particles before the shock can form. This results in a natural retardation and leads to an intrinsic asymmetry in the produced light curves for gamma-ray bursts. In addition we account for the cooling of the electron proton plasma in the shocked region, which gives rise to a exponential decay in the gamma-ray flux. The combination of these effects and the precessing jet of ultra relativistic particles produces light curves which can be directly compared with observed gamma-ray burst light curves. We illustrate the model by fittin...

  12. Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

    International Nuclear Information System (INIS)

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  13. Non-regularized inversion method from light scattering applied to ferrofluid magnetization curves for magnetic size distribution analysis

    NARCIS (Netherlands)

    Rijssel, J.; Kuipers, B.W.M.; Erné, B.H.

    2014-01-01

    A numerical inversion method known from the analysis of light scattering by colloidal dispersions is now applied to magnetization curves of ferrofluids. The distribution of magnetic particle sizes or dipole moments is determined without assuming that the distribution is unimodal or of a particular s

  14. Wavelet-based filter methods for the detection of small transiting planets: Application to Kepler and K2 light curves

    Science.gov (United States)

    Grziwa, Sascha; Korth, Judith; Paetzold, Martin; KEST

    2016-10-01

    The Rheinisches Institut für Umweltforschung (RIU-PF) has developed the software package EXOTRANS for the detection of transits of exoplanets in stellar light curves. This software package was in use during the CoRoT space mission (2006-2013). EXOTRANS was improved by different wavelet-based filter methods during the following years to separate stellar variation, orbital disturbances and instrumental effects from stellar light curves taken by space telescopes (Kepler, K2, TESS and PLATO). The VARLET filter separates faint transit signals from stellar variations without using a-priori information about the target star. VARLET considers variations by frequency, amplitude and shape simultaneously. VARLET is also able to extract most instrumental jumps and glitches. The PHALET filter separates periodic features independent of their shape and is used with the intention to separate diluting stellar binaries. It is also applied for the multi transit search. Stellar light curves of the K2 mission are constructed from the processing of target pixel files which corrects disturbances caused by the reduced pointing precision of the Kepler telescope after the failure of two gyroscopes. The combination of target pixel file processing with both filter techniques and the proven detection pipeline EXOTRANS lowers the detection limit, reduces false alarms and simplifies the detection of faint transits in light curves of the K2 mission. Using EXOTRANS many new candidates were detected in K2 light curves by using EXOTRANS which were successfully confirmed by ground-based follow-up observation of the KEST collaboration. New candidates and confirmed planets are presented.

  15. Early-Time Flux Measurements of SN 2014J Obtained with Small Robotic Telescopes: Extending the AAVSO Light Curve

    CERN Document Server

    Poppe, B; Zheng, W; Shivvers, I; Itagaki, K; Filippenko, A V; Kunz, J

    2015-01-01

    In this work, early-time photometry of supernova (SN) 2014J is presented, extending the AAVSO CCD database to prediscovery dates. The applicability of NASA's small robotic MicroObservatory Network telescopes for photometric measurements is evaluated. Prediscovery and postdiscovery photometry of SN 2014J is measured from images taken by two different telescopes of the network, and is compared to measurements from the Katzman Automatic Imaging Telescope and the Itagaki Observatory. In the early light-curve phase (which exhibits stable spectral behavior with constant color indices), these data agree with reasonably high accuracy (better than 0.05 mag around maximum brightness, and 0.15 mag at earlier times). Owing to the changing spectral energy distribution of the SN and the different spectral characteristics of the systems used, differences increase after maximum light. We augment light curves of SN 2014J downloaded from the American Association of Variable Star Observers (AAVSO) online database with these dat...

  16. Multichroic Bolometric Detector Architecture for Cosmic Microwave Background Polarimetry Experiments

    Science.gov (United States)

    Suzuki, Aritoki

    Characterization of the Cosmic Microwave Background (CMB) B-mode polarization signal will test models of inflationary cosmology, as well as constrain the sum of the neutrino masses and other cosmological parameters. The low intensity of the B-mode signal combined with the need to remove polarized galactic foregrounds requires a sensitive millimeter receiver and effective methods of foreground removal. Current bolometric detector technology is reaching the sensitivity limit set by the CMB photon noise. Thus, we need to increase the optical throughput to increase an experiment's sensitivity. To increase the throughput without increasing the focal plane size, we can increase the frequency coverage of each pixel. Increased frequency coverage per pixel has additional advantage that we can split the signal into frequency bands to obtain spectral information. The detection of multiple frequency bands allows for removal of the polarized foreground emission from synchrotron radiation and thermal dust emission, by utilizing its spectral dependence. Traditionally, spectral information has been captured with a multi-chroic focal plane consisting of a heterogeneous mix of single-color pixels. To maximize the efficiency of the focal plane area, we developed a multi-chroic pixel. This increases the number of pixels per frequency with same focal plane area. We developed multi-chroic antenna-coupled transition edge sensor (TES) detector array for the CMB polarimetry. In each pixel, a silicon lens-coupled dual polarized sinuous antenna collects light over a two-octave frequency band. The antenna couples the broadband millimeter wave signal into microstrip transmission lines, and on-chip filter banks split the broadband signal into several frequency bands. Separate TES bolometers detect the power in each frequency band and linear polarization. We will describe the design and performance of these devices and present optical data taken with prototype pixels and detector arrays. Our

  17. Study of GRB Light-curve Decay Indices in the Afterglow Phase

    Science.gov (United States)

    Del Vecchio, Roberta; Giovanna Dainotti, Maria; Ostrowski, Michał

    2016-09-01

    In this work, we study the distribution of temporal power-law decay indices, α, in the gamma-ray burst (GRB) afterglow phase, fitted for 176 GRBs (139 long GRBs, 12 short GRBs with extended emission, and 25 X-ray flashes) with known redshifts. These indices are compared with the temporal decay index, α W , derived with the light-curve fitting using the Willingale et al. model. This model fitting yields similar distributions of α W to the fitted α, but for individual bursts a difference can be significant. Analysis of (α, L a ) distribution, where L a is the characteristic luminosity at the end of the plateau, reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB α values along the Dainotti et al. correlation between L a and the end time of the plateau emission in the rest frame, {T}a* , hereafter LT correlation. We note a systematic variation of the α parameter distribution with luminosity for any selected {T}a* . We analyze this systematics with respect to the fitted LT correlation line, expecting that the presented trend may allow us to constrain the GRB physical models. We also attempted to use the derived correlation of α ({T}a) versus {L}a({T}a) to diminish the luminosity scatter related to the variations of α along the LT distribution, a step forward in the effort of standardizing GRBs. A proposed toy model accounting for this systematics applied to the analyzed GRB distribution results in a slight increase of the LT correlation coefficient.

  18. ANALYTICAL LIGHT CURVE MODELS OF SUPERLUMINOUS SUPERNOVAE: {chi}{sup 2}-MINIMIZATION OF PARAMETER FITS

    Energy Technology Data Exchange (ETDEWEB)

    Chatzopoulos, E.; Wheeler, J. Craig; Vinko, J. [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); Horvath, Z. L.; Nagy, A., E-mail: manolis@astro.as.utexas.edu [Department of Optics and Quantum Electronics, University of Szeged (Hungary)

    2013-08-10

    We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including {sup 56}Ni and {sup 56}Co radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich superluminous supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx, and SN 2010kd, as well as to the interacting SN 2008iy and PTF 09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to the LCs of most of the events we examine. We discuss the possibility that collision of supernova ejecta with hydrogen-deficient CSM accounts for some of the hydrogen-deficient SLSNe (SLSN-I) and may be a plausible explanation for the explosion mechanism of SN 2007bi, the pair-instability supernova candidate. We characterize and discuss issues of parameter degeneracy.

  19. CAN LARGE TIME DELAYS OBSERVED IN LIGHT CURVES OF CORONAL LOOPS BE EXPLAINED IN IMPULSIVE HEATING?

    Energy Technology Data Exchange (ETDEWEB)

    Lionello, Roberto; Linker, Jon A.; Mikić, Zoran [Predictive Science, Inc., 9990 Mesa Rim Rd., Ste. 170, San Diego, CA 92121-3933 (United States); Alexander, Caroline E.; Winebarger, Amy R., E-mail: lionel@predsci.com, E-mail: linkerj@predsci.com, E-mail: mikicz@predsci.com, E-mail: caroline.e.alexander@nasa.gov, E-mail: amy.r.winebarger@nasa.gov [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35805 (United States)

    2016-02-20

    The light curves of solar coronal loops often peak first in channels associated with higher temperatures and then in those associated with lower temperatures. The delay times between the different narrowband EUV channels have been measured for many individual loops and recently for every pixel of an active region observation. The time delays between channels for an active region exhibit a wide range of values. The maximum time delay in each channel pair can be quite large, i.e., >5000 s. These large time delays make-up 3%–26% (depending on the channel pair) of the pixels where a trustworthy, positive time delay is measured. It has been suggested that these time delays can be explained by simple impulsive heating, i.e., a short burst of energy that heats the plasma to a high temperature, after which the plasma is allowed to cool through radiation and conduction back to its original state. In this paper, we investigate whether the largest observed time delays can be explained by this hypothesis by simulating a series of coronal loops with different heating rates, loop lengths, abundances, and geometries to determine the range of expected time delays between a set of four EUV channels. We find that impulsive heating cannot address the largest time delays observed in two of the channel pairs and that the majority of the large time delays can only be explained by long, expanding loops with photospheric abundances. Additional observations may rule out these simulations as an explanation for the long time delays. We suggest that either the time delays found in this manner may not be representative of real loop evolution, or that the impulsive heating and cooling scenario may be too simple to explain the observations, and other potential heating scenarios must be explored.

  20. THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A.; Treu, Tommaso [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Pancoast, Anna [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sand, David J. [Texas Tech University, Physics Department, Box 41051, Lubbock, TX 79409-1051 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Assef, Roberto J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Brewer, Brendon J. [Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, MC 661, Greenbelt, MD 20771 (United States); and others

    2015-04-15

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  1. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-line Light Curves

    Science.gov (United States)

    Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E..; Li, Weidong; Malkan, Matthew A.; Pancoast, Anna; Sand, David J.; Stern, Daniel; Cenko, S. Bradley

    2016-01-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hß line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad H beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H beta velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad H beta velocity shifted by approximately 250 km s(exp -1) over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  2. Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions and Absolute Magnitudes

    CERN Document Server

    Sheppard, Scott S

    2007-01-01

    (Abridged) I report new light curves and determine the rotations and phase functions of several large Kuiper Belt objects, including the dwarf planet Eris (2003 UB313). (120348) 2004 TY364 shows a light curve which if double-peaked has a period of 11.70+-0.01 hours and peak-to-peak amplitude of 0.22+-0.02 magnitudes. (84922) 2003 VS2 has a well defined double-peaked light curve of 7.41+-0.02 hours with a 0.21+-0.02 magnitude range. (126154) 2001 YH140 shows variability of 0.21+-0.04 magnitudes with a possible 13.25+-0.2 hour single-peaked period. The seven new KBOs in the sample which show no discernible variations within the uncertainties on short rotational time scales are 2001 UQ18, (55565) 2002 AW197, (119979) 2002 WC19, (120132) 2003 FY128, (136108) Eris 2003 UB313, (90482) Orcus 2004 DW, and (90568) 2004 GV9. The three medium to large sized Kuiper Belt objects 2004 TY364, Orcus and 2004 GV9 show fairly steep linear phase curves (~0.18 to 0.26 mags per degree) between phase angles of 0.1 and 1.5 degrees....

  3. AGN Broad Line Regions Scale with Bolometric Luminosity

    CERN Document Server

    Trippe, Sascha

    2015-01-01

    The masses of supermassive black holes in active galactic nuclei (AGN) can be derived spectroscopically via virial mass estimators based on selected broad optical/ultraviolet emission lines. These estimates commonly use the line width as a proxy for the gas speed and the monochromatic continuum luminosity as a proxy for the radius of the broad line region. However, if the size of the broad line region scales with bolometric rather than monochromatic AGN luminosity, mass estimates based on different emission lines will show a systematic discrepancy which is a function of the color of the AGN continuum. This has actually been observed in mass estimates based on H-alpha / H-beta and C IV lines, indicating that AGN broad line regions indeed scale with bolometric luminosity. Given that this effect seems to have been overlooked as yet, currently used single-epoch mass estimates are likely to be biased.

  4. Optimal I-V Curve Scan Time of Solar Cells and Modules in Light of Irradiance Level

    Directory of Open Access Journals (Sweden)

    Matic Herman

    2012-01-01

    Full Text Available High-efficiency solar cells and modules exhibit strong capacitive character resulting in limited speed of transient responses. A too fast I-V curve measurement can thus introduce a significant error due to its internal capacitances. This paper analyses the I-V curve error of a measured solar cell or module in light of scan time and irradiance level. It rests on a two-diode solar cell model extended by two bias-dependent capacitances, modelling the junction, and the diffusion capacitance. A method for determination of all extended model parameters from a quasistatic I-V curve and open-circuit voltage decay measurement is presented and validated. Applicability of the extended model and the developed parameter extraction method to PV modules is demonstrated and confirmed. SPICE simulations of the extended model are used to obtain the I-V curve error versus scan time dependence and the I-V curve hysteresis. Determination of the optimal scan time is addressed, and finally the influence of the irradiance level on the I-V curve scan time and error is revealed. The method is applied but is not limited to three different wafer-based silicon solar cell types.

  5. ASTEROID LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY SURVEY: ROTATION PERIODS AND PHASE FUNCTIONS FROM SPARSE PHOTOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Waszczak, Adam [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Chang, Chan-Kao; Cheng, Yu-Chi; Ip, Wing-Huen; Kinoshita, Daisuke [Institute of Astronomy, National Central University, Jhongli, Taiwan (China); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot (Israel); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Masci, Frank; Helou, George [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Levitan, David; Prince, Thomas A.; Kulkarni, Shrinivas, E-mail: waszczak@caltech.edu [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-09-15

    We fit 54,296 sparsely sampled asteroid light curves in the Palomar Transient Factory survey to a combined rotation plus phase-function model. Each light curve consists of 20 or more observations acquired in a single opposition. Using 805 asteroids in our sample that have reference periods in the literature, we find that the reliability of our fitted periods is a complicated function of the period, amplitude, apparent magnitude, and other light-curve attributes. Using the 805-asteroid ground-truth sample, we train an automated classifier to estimate (along with manual inspection) the validity of the remaining ∼53,000 fitted periods. By this method we find that 9033 of our light curves (of ∼8300 unique asteroids) have “reliable” periods. Subsequent consideration of asteroids with multiple light-curve fits indicates a 4% contamination in these “reliable” periods. For 3902 light curves with sufficient phase-angle coverage and either a reliable fit period or low amplitude, we examine the distribution of several phase-function parameters, none of which are bimodal though all correlate with the bond albedo and with visible-band colors. Comparing the theoretical maximal spin rate of a fluid body with our amplitude versus spin-rate distribution suggests that, if held together only by self-gravity, most asteroids are in general less dense than ∼2 g cm{sup −3}, while C types have a lower limit of between 1 and 2 g cm{sup −3}. These results are in agreement with previous density estimates. For 5–20 km diameters, S types rotate faster and have lower amplitudes than C types. If both populations share the same angular momentum, this may indicate the two types’ differing ability to deform under rotational stress. Lastly, we compare our absolute magnitudes (and apparent-magnitude residuals) to those of the Minor Planet Center’s nominal (G = 0.15, rotation-neglecting) model; our phase-function plus Fourier-series fitting reduces asteroid photometric rms

  6. Photosynthesis-Light Response Curve Derived from Light Absorbed in a Leaf : II. Soybean and Corn Plants

    OpenAIRE

    Hirota, Osamu

    1987-01-01

    Using the model proposed in this paper, the linear relationship of incident light with photosynthetic rates of soybean and corn leaves was obtained in low light intensity. In this range, efficiencies of light energy conversion for PhAR were 3.5-9.1 %in soybean and 7.4-16.4 %in corn leaves. The linear relationship between light and Photosynthesis started to deviate at light intensity 0.036-0.078 cal (PhAR)/cm^2 min for soybean and at 0.073-0.116 cal (PhAR)/cm^2 min for corn. Using both these v...

  7. BEER ANALYSIS OF KEPLER AND CoRoT LIGHT CURVES. II. EVIDENCE FOR SUPERROTATION IN THE PHASE CURVES OF THREE KEPLER HOT JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Faigler, S.; Mazeh, T. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2015-02-10

    We analyzed the Kepler light curves of four transiting hot Jupiter systems—KOI-13, HAT-P-7, TrES-2, and Kepler-76, which show BEaming, Ellipsoidal, and Reflection (BEER) phase modulations. The mass of the four planets can be estimated from either the beaming or the ellipsoidal amplitude, given the mass and radius of their parent stars. For KOI-13, HAT-P-7, and Kepler-76 we find that the beaming-based planetary mass estimate is larger than the mass estimated from the ellipsoidal amplitude, consistent with previous studies. This apparent discrepancy may be explained by equatorial superrotation of the planet atmosphere, which induces an angle shift of the planet reflection/emission phase modulation, as was suggested for Kepler-76 in the first paper of this series. We propose a modified BEER model that supports superrotation, assuming either a Lambertian or geometric reflection/emission phase function, and provides a photometry-consistent estimate of the planetary mass. Our analysis shows that for Kepler-76 and HAT-P-7, the Lambertian superrotation BEER model is highly preferable over an unshifted null model, while for KOI-13 it is preferable only at a 1.4σ level. For TrES-2 we do not find such preference. For all four systems the Lambertian superrotation model mass estimates are in excellent agreement with the planetary masses derived from, or constrained by, radial velocity measurements. This makes the Lambertian superrotation BEER model a viable tool for estimating the masses of hot Jupiters from photometry alone. We conclude that hot Jupiter superrotation may be a common phenomenon that can be detected in the visual light curves of Kepler.

  8. Spatial and Temporal Variations of Light Curves in Gravitationally Lensed Sources

    CERN Document Server

    Minakov, A A

    2004-01-01

    Effects of macro-and microlensing on the spatial and temporal characteristics of images of remote sources, observed through the inner regions of lensing galaxies are discussed. A particular attention was given to the case, when microlenses, - stars, star-like or planetary bodies, - are situated near the critical curves of macrolenses, - galaxies, stellar clusters, etc. The investigation is of interest for the gravitational lens (GL) systems, where the lensed images are observed close to the critical curve of a macrolens. Annular, arched or confluent images should be regarded as an indication to such a proximity. Numerical simulation allowed to determine the structure of critical curves and caustics, formed by macro and microlenses, and to evaluate possible distortions, caused by microlenses for various locations with respect to the critical curve of a regular lens. The difference of our results from those obtained earlier with the standard (linearized) approach to describe the regular gravitational lens was s...

  9. Alternate slicing and deposition strategies for fused deposition modelling of light curved parts

    Directory of Open Access Journals (Sweden)

    B. Huang

    2012-12-01

    Full Text Available Fused deposition modeling (FDM, as one of the additive manufacturing (AM techniques, has been widely used in the manufacturing industry from the 1990s. It is relatively cheaper than other AM methods and there are other advantages such as being able to process a variety of other polymers. Currently, FDM is more likely to be suitable for direct production of the terminal-use parts, in some cases challenging traditional process such as injection molding. Research evidences indicate that change of road and layer structure would have significant influence on the meso-structure and thus impact the mechanical properties of the resulting polymer parts. Adaptive flat layer deposition and curved layer deposition have been introduced to improve the mechanical properties of terminal-use product. It is necessary that an appropriate deposition scheme is essential to ensure the best interroad and inter-layer connectivity. Uninterrupted connections are likely to result in a continuous network of polymer chains, as in the case of the conventional processes. The current research proposes conventional flat layer deposition, adaptive flat layer deposition and curved layer deposition for FDM. In particular for curved parts, curved layer deposition in expected to ensure fiber continuity and better meso-structure. Mathematical models are developed for curved slicing, practically implemented to print physical parts and test results suggest marked improvement in the mechanical characteristics of curved parts.

  10. The mean light curves of the Mira-type stars in the H- and K-bands

    CERN Document Server

    Kudashkina, L S

    2016-01-01

    For nine Mira-type stars (o Cet, R Leo, S Car, U Her, X Oph, R Aql, RR Aql, S Ori, S Scl,) and one semi-regular star (L2 Pup), the mean light curves have been obtained. The initial values of the brightness (observations) were fitted by a trigonometric polynomial of the statistically optimal order. The Fourier coefficients and the additional parameters (degree of the trigonometric polynomial, amplitude of the brightness, the maximal slope of ascending and descending branch, semi-amplitudes and initial epochs for the brightness maximum (minimum magnitude) of each harmonic contribution, etc., were given in the tables reported earlier (Kudashkina, 2015). In this study, we have received several interesting correlations between these parameters in the bands H and K. It was particularly noted the anomalous position on the figures of the star X Oph. The mean light curves of the investigated stars are commonly symmetric in the near infrared region (H and K).

  11. A Revised Gyro-Age for M 67 from Kepler/K2-Campaign-5 Light Curves

    CERN Document Server

    Gonzalez, Guillermo

    2016-01-01

    We revisit the photometric variability of stars in the M 67 field using Kepler/K2-Campaign-5 light curves. In our previous work, we limited the search area around M\\,67 to that of a recent ground-based study. In the present work, we expand the search area and apply a more rigorous period-finding algorithm to determine the rotation periods of 98 main sequence cluster members from the same data. In addition, we derive periods of 40 stars from the K2SC detrended light curves. We determine the mean period of single sun-like main sequence cluster members to be $29.6 \\pm 0.6$ d. Assuming the periods correspond to stellar rotation, the corresponding mean gyro-age is $5.4 \\pm 0.2$ Gyr.

  12. An adaptive-binning method for generating constant-uncertainty/constant-significance light curves with Fermi-LAT data

    CERN Document Server

    Lott, B; Larsson, S; Ballet, J

    2012-01-01

    We present a method enabling the creation of constant-uncertainty/constant-significance light curves with the data of the Fermi-Large Area Telescope (LAT). The adaptive-binning method enables more information to be encapsulated within the light curve than with the fixed-binning method. Although primarily developed for blazar studies, it can be applied to any sources. This method allows the starting and ending times of each interval to be calculated in a simple and quick way during a first step. The reported mean flux and spectral index (assuming the spectrum is a power-law distribution) in the interval are calculated via the standard LAT analysis during a second step. The absence of major caveats associated with this method has been established by means of Monte-Carlo simulations. We present the performance of this method in determining duty cycles as well as power-density spectra relative to the traditional fixed-binning method.

  13. The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data

    Energy Technology Data Exchange (ETDEWEB)

    Holtzman, Jon A.; /New Mexico State U.; Marriner, John; /Fermilab; Kessler, Richard; /KICP, Chicago /Chicago U., EFI; Sako, Masao; /KIPAC, Menlo Park /Pennsylvania U.; Dilday, Ben; /KICP, Chicago /Chicago U.; Frieman, Joshua A.; /Fermilab /KICP, Chicago /Chicago U., Astron. Astrophys. Ctr.; Schneider, Donald P.; /Penn State U., Astron. Astrophys.; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Cinabro, David; /Wayne State U.; DeJongh, Fritz; /KICP, Chicago; Depoy, Darren L.; /Ohio State U., Dept. Astron.; Doi, Mamoru; /Tokyo U., Inst. Astron.; Garnavich, Peter M.; /Notre Dame U.; Hogan, Craig J.; /Washington U., Seattle, Astron. Dept.; Jha, Saurabh; /KIPAC, Menlo Park /Rutgers U., Piscataway; Konishi, Kohki; /Tokyo U., ICRR; Lampeitl, Hubert; /Baltimore, Space Telescope Sci. /Portsmouth U., ICG; Marshall, Jennifer L.; /Ohio State U., Dept. Astron.; McGinnis, David; Miknaitis, Gajus; /KICP, Chicago /Portsmouth U., ICG /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Rochester Inst. Tech. /KIPAC, Menlo Park /Portsmouth U., ICG /Tokyo U., Inst. Astron. /South African Astron. Observ. /Cape Town U. /Tokyo U., ICRR /KIPAC, Menlo Park

    2010-08-26

    We present ugriz light curves for 146 spectroscopically confirmed or spectroscopically probable Type Ia supernovae from the 2005 season of the SDSS-II Supernova survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that supernova brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.

  14. Radio emission of SN1993J: the complete picture. II. Simultaneous fit of expansion and radio light curves

    Science.gov (United States)

    Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.; Guirado, J. C.; Pérez-Torres, M. A.; Ros, E.

    2011-02-01

    We report on a simultaneous modelling of the expansion and radio light curves of the supernova SN1993J. We developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with a standard emission model for supernovae, which is extended with some physical considerations, such as an evolution in the opacity of the ejecta material, a radial decline in the magnetic fields within the radiating region, and a changing radial density profile for the circumstellar medium starting from day 3100 after the explosion.

  15. Radio emission of SN1993J. The complete picture: II. Simultaneous fit of expansion and radio light curves

    CERN Document Server

    Marti-Vidal, I; Alberdi, A; Guirado, J C; Perez-Torres, M A; Ros, E

    2010-01-01

    We report on a simultaneous modelling of the expansion and radio light curves of SN1993J. We have developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with an standard emission model for supernovae extended with some physical considerations, as an evolution in the opacity of the ejecta material, a radial drop of the magnetic fields inside the radiating region, and a changing radial density profile of the circumstellar medium beyond day 3100 after explosion.

  16. A correlation between intrinsic brightness and average decay rate of Swift UVOT GRB optical/UV light curves

    CERN Document Server

    Oates, S R; De Pasquale, M; Schady, P; Breeveld, A A; Holland, S T; Kuin, N P M; Marshall, F E

    2012-01-01

    We examine a sample of 48 Swift/UVOT long Gamma-ray Burst light curves and find a correlation between the logarithmic luminosity at 200s and average decay rate determined from 200s onwards, with a Spearman rank coefficient of -0.58 at a significance of 99.998% (4.2 sigma). We discuss the causes of the log L_200s - alpha_>200s correlation, finding it to be an intrinsic property of long GRBs, and not resulting from the selection criteria. We find two ways to produce the correlation. One possibility is that there is some property of the central engine, outflow or external medium that affects the rate of energy release so that the bright afterglows release their energy more quickly and decay faster than the fainter afterglows. Alternatively, the correlation may be produced by variation of the observers viewing angle, with observers at large viewing angles observing fainter and slower decaying light curves.

  17. The Infrared Light Curve of SN 2011fe in M101 and the Distance to M101

    CERN Document Server

    Matheson, T; Allen, L E; Saha, A; Silva, D R; Wood-Vasey, W M; Adams, J J; Anderson, R E; Beck, T L; Bentz, M C; Bershady, M A; Binkert, W S; Butler, K; Camarata, M A; Eigenbrot, A; Everett, M; Gallagher, J S; Glikman, P M Garnavich E; Harbeck, D; Hargis, J R; Herbst, H; Horch, E P; Howell, S B; Jha, S; Kaczmarek, J F; Knezek, P; Manne-Nicholas, E; Mathieu, R D; Meixner, M; Milliman, K; Power, J; Rajagopal, J; Reetz, K; Rhode, K L; Schechtman-Rook, A; Schwamb, M E; Schweiker, H; Simmons, B; Simon, J D; Summers, D; Young, M D; Weyant, A; Wilcots, E M; Will, G; Williams, D

    2012-01-01

    We present near infra-red light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting fourteen days before maximum brightness in the B-band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera (WHIRC). When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 \\pm 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depending on which absolute calibration for Type Ia SNe is used.

  18. Analysis of MOST light curves of five young stars in Taurus-Auriga and Lupus~3 Star Forming Regions

    CERN Document Server

    Siwak, Michal; Matthews, Jaymie M; Kuschnig, Rainer; Guenther, David B; Moffat, Anthony F J; Sasselov, Dimitar; Weiss, Werner W

    2011-01-01

    Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light curve modelling under the assumption of internal invariability of spots, we obtained small values of the solar-type differential-rotation parameter (k=0.0005-0.009) for three spotted weak-line T Tau stars, V410 Tau, V987 Tau and Lupus 3-14; for another spotted WTTS, Lupus 3-48, the data are consistent with a rigidly rotating surface (k=0). Three flares of similar rise (4 min 30 sec) and decay (1 h 45 min) times were detected in the light curve of Lupus 3-14. The brightness of the classical T Tau star RY Tau continuously decreased over 3 weeks of its observations with a variable modulation not showing any obvious periodic signal.

  19. A Revised Gyro-Age for M 67 from Kepler/K2-Campaign-5 Light Curves

    Science.gov (United States)

    Gonzalez, Guillermo

    2016-09-01

    We revisit the photometric variability of stars in the M 67 field using Kepler/K2-Campaign-5 light curves. In our previous work, we limited the search area around M 67 to that of a recent ground-based study. In the present work, we expand the search area and apply a more rigorous period-finding algorithm to determine the rotation periods of 98 main sequence cluster members from the same data. In addition, we derive periods of 40 stars from the K2SC detrended light curves. We determine the mean period of single sun-like main sequence cluster members to be 29.6 ± 0.6 d. Assuming the periods correspond to stellar rotation, the corresponding mean gyro-age is 5.4 ± 0.2 Gyr.

  20. Non-regularized inversion method from light scattering applied to ferrofluid magnetization curves for magnetic size distribution analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H., E-mail: B.H.Erne@uu.nl

    2014-03-15

    A numerical inversion method known from the analysis of light scattering by colloidal dispersions is now applied to magnetization curves of ferrofluids. The distribution of magnetic particle sizes or dipole moments is determined without assuming that the distribution is unimodal or of a particular shape. The inversion method enforces positive number densities via a non-negative least squares procedure. It is tested successfully on experimental and simulated data for ferrofluid samples with known multimodal size distributions. The created computer program MINORIM is made available on the web. - Highlights: • A method from light scattering is applied to analyze ferrofluid magnetization curves. • A magnetic size distribution is obtained without prior assumption of its shape. • The method is tested successfully on ferrofluids with a known size distribution. • The practical limits of the method are explored with simulated data including noise. • This method is implemented in the program MINORIM, freely available online.

  1. Radioactivity and Thermalization in the Ejecta of Compact Object Mergers and Their Impact on Kilonova Light Curves

    Science.gov (United States)

    Barnes, Jennifer; Kasen, Daniel; Wu, Meng-Ru; Martínez-Pinedo, Gabriel

    2016-10-01

    One promising electromagnetic signature of compact object mergers are kilonovae: approximately isotropic radioactively powered transients that peak days to weeks post-merger. Key uncertainties in kilonova modeling include the emission profiles of the radioactive decay products—non-thermal β -particles, α -particles, fission fragments, and γ -rays—and the efficiency with which their kinetic energy is absorbed by the ejecta. The radioactive energy emitted, along with its thermalization efficiency, sets the luminosity budget and is therefore crucial for predicting kilonova light curves. We outline uncertainties in the radioactivity, describe the processes by which the decay products transfer energy to the ejecta, and calculate time-dependent thermalization efficiencies for each particle type. We determine the net thermalization efficiency and explore its dependence on r-process yields—in particular, the production of α -decaying translead nuclei—and on ejecta mass, velocity, and magnetic fields. We incorporate our results into detailed radiation transport simulations, and calculate updated kilonova light curve predictions. Thermalization effects reduce kilonova luminosities by a factor of roughly 2 at peak, and by an order of magnitude at later times (15 days or more after explosion). We present analytic fits to time-dependent thermalization efficiencies, which can be used to improve light curve models. We revisit the putative kilonova that accompanied gamma-ray burst 130603B, and estimate the mass ejected in that event. We find later time kilonova light curves can be significantly impacted by α -decay from translead isotopes; data at these times may therefore be diagnostic of ejecta abundances.

  2. K2SC: flexible systematics correction and detrending of K2 light curves using Gaussian process regression

    Science.gov (United States)

    Aigrain, S.; Parviainen, H.; Pope, B. J. S.

    2016-07-01

    We present K2SC (K2 Systematics Correction), a PYTHON pipeline to model instrumental systematics and astrophysical variability in light curves from the K2 mission. K2SC uses Gaussian Process regression to model position-dependent systematics and time-dependent variability simultaneously, enabling the user to remove both (e.g. for transit searches) or to remove systematics while preserving variability (for variability studies). For periodic variables, K2SC automatically computes estimates of the period, amplitude and evolution time-scale of the variability. We apply K2SC to publicly available K2 data from Campaigns 3-5 showing that we obtain photometric precision approaching that of the original Kepler mission. We compare our results to other publicly available K2 pipelines, showing that we obtain similar or better results, on average. We use transit injection and recovery tests to evaluate the impact of K2SC on planetary transit searches in K2 Pre-search Data Conditioning data, for planet-to-star radius ratios down to Rp/R* = 0.01 and periods up to P = 40 d, and show that K2SC significantly improves the ability to distinguish between true and false detections, particularly for small planets. K2SC can be run automatically on many light curves, or manually tailored for specific objects such as pulsating stars or large amplitude eclipsing binaries. It can be run on ASCII and FITS light-curve files, regardless of their origin. Both the code and the processed light curves are publicly available, and we provide instructions for downloading and using them. The methodology used by K2SC will be applicable to future transit search missions such as TESS and PLATO.

  3. Gamma-ray pulsar physics: gap-model populations and light-curve analyses in the Fermi era

    International Nuclear Information System (INIS)

    This thesis research focusses on the study of the young and energetic isolated ordinary pulsar population detected by the Fermi gamma-ray space telescope. We compared the model expectations of four emission models and the LAT data. We found that all the models fail to reproduce the LAT detections, in particular the large number of high E objects observed. This inconsistency is not model dependent. A discrepancy between the radio-loud/radio-quiet objects ratio was also found between the observed and predicted samples. The Lγ α E0.5 relation is robustly confirmed by all the assumed models with particular agreement in the slot gap (SG) case. On luminosity bases, the intermediate altitude emission of the two pole caustic SG model is favoured. The beaming factor fΩ shows an E dependency that is slightly visible in the SG case. Estimates of the pulsar orientations have been obtained to explain the simultaneous gamma and radio light-curves. By analysing the solutions we found a relation between the observed energy cutoff and the width of the emission slot gap. This relation has been theoretically predicted. A possible magnetic obliquity α alignment with time is rejected -for all the models- on timescale of the order of 106 years. The light-curve morphology study shows that the outer magnetosphere gap emission (OGs) are favoured to explain the observed radio-gamma lag. The light curve moment studies (symmetry and sharpness) on the contrary favour a two pole caustic SG emission. All the model predictions suggest a different magnetic field layout with an hybrid two pole caustic and intermediate altitude emission to explain both the pulsar luminosity and light curve morphology. The low magnetosphere emission mechanism of the polar cap model, is systematically rejected by all the tests done. (author)

  4. DYNAMICS AND AFTERGLOW LIGHT CURVES OF GAMMA-RAY BURST BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    International Nuclear Information System (INIS)

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  5. PLUTO AND CHARON WITH THE HUBBLE SPACE TELESCOPE. I. MONITORING GLOBAL CHANGE AND IMPROVED SURFACE PROPERTIES FROM LIGHT CURVES

    International Nuclear Information System (INIS)

    We present new light-curve measurements of Pluto and Charon taken with the Advanced Camera for Surveys High-resolution Camera on the Hubble Space Telescope. The observations were collected from 2002 June to 2003 June at 12 distinct sub-Earth longitudes over a range of solar phase angle 0.036-1.074-a larger range than previously measured. The new measurements of Pluto show that the light-curve amplitude has decreased since the mutual event season in the late 1980s. We also show that the average brightness has increased in the F555W (Johnson V equivalent) passband while the brightness has decreased in the F435W (Johnson B equivalent) passband. These data thus indicate a substantial reddening of the reflected light from Pluto. We find a weighted mean (B - V) = 0.9540 ± 0.0010 that is considerably higher than the long-standing value of (B - V) = 0.868 ± 0.003 most recently measured in 1992-1993. This change in color cannot be explained by the evolving viewing geometry and provides the strongest evidence to date for temporal changes on the surface of Pluto that are expected to be linked to volatile transport processes. We also report on the discovery of a new rotational modulation of Pluto's hemispherical color that ranges from 0.92 to 0.98 with the least red color at the longitude of maximum light and most red at minimum light. The phase coefficient of Pluto is nearly the same as measured in 1992-1993 with a value of β B = 0.0392 ± 0.0064 and β V = 0.0355 ± 0.0045 mag deg-1 for the F435W and F555W data, respectively. The Pluto phase curve is still very close to linear but a small but significant nonlinearity is seen in the data. In contrast, the light curve of Charon is essentially the same as in 1992/1993, albeit with much less noise. We confirm that Charon's Pluto-facing hemisphere is 8% brighter than the hemisphere facing away from Pluto. The color of Charon is independent of longitude and has a mean weighted value of (B - V) = 0.7315 ± 0.0013. The phase

  6. A transit timing analysis of nine RISE light curves of the exoplanet system TrES-3

    CERN Document Server

    Gibson, N P; Skillen, I; Simpson, E K; Barros, S; Joshi, Y C; Todd, I; Benn, C; Christian, D; Hrudková, M; Keenan, F P; Steele, I A

    2009-01-01

    We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte-Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be Rp/Rstar=0.1664^{+0.0011}_{-0.0018} and i = 81.73^{+0.13}_{-0.04} respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving chi^2 = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a con...

  7. Multicolor light curves simulations of Population III core-collapse supernovae: from shock breakout to $^{56}$Co decay

    CERN Document Server

    Tolstov, Alexey; Tominaga, Nozomu; Ishigaki, Miho; Blinnikov, Sergey; Suzuki, Tomoharu

    2015-01-01

    The properties of the first generation of stars and their supernova (SN) explosions remains unknown due to the lack of their actual observations. Recently many transient surveys are conducted and the feasibility of the detection of supernovae (SNe) of Pop III stars is growing. In this paper we study the multicolor light curves for a number of metal-free core-collapse SN models (25-100 M$_{\\odot}$) to provide the indicators for finding and identification of first generation SNe. We use mixing-fallback supernova explosion models which explain the observed abundance patterns of metal poor stars. Numerical calculations of the multicolor light curves are performed using multigroup radiation hydrodynamic code STELLA. The calculated light curves of metal-free SNe are compared with non-zero metallicity models and several observed SNe. We have found that the shock breakout characteristics, the evolution of the photosphere's velocity, the luminosity, the duration and color evolution of the plateau - all the SN phases a...

  8. Multi-frequency properties of synthetic blazar radio light curves within the shock-in-jet scenario

    CERN Document Server

    Fromm, C M; Perucho, M

    2014-01-01

    Blazars are among the most powerful extragalactic objects, as a sub-class of active galactic nuclei. They launch relativistic jets and their emitted radiation shows strong variability across the entire electro-magnetic spectrum. The mechanisms producing the variability are still controversial and different models have been proposed to explain the observed variations in multi-frequency blazar light curves.We investigate the capabilities of the classical shock-in-jet model to explain and reconstruct the observed evolution of flares in the turnover frequency turnover flux density plane and their frequency-dependent light curve parameters. With a detailed parameter space study we provide the framework for future, detailed comparisons of observed flare signatures with the shock-in-jet scenario. Based on the shock model we compute synthetic single-dish light curves at different radio frequencies (2.6 to 345 GHz) and for different physical conditions in a conical jet (e.g. magnetic field geometry and Doppler factor)...

  9. Nonlinear time series analysis of the light curves from the black hole system GRS1915+105

    Institute of Scientific and Technical Information of China (English)

    K.P Harikrishnan; Ranjeev Misra; G.Ambika

    2011-01-01

    GRS 1915+105 is a prominent black hole system exhibiting variability over a wide range of time scales and its observed light curves have been classified into 12 temporal states. Here we undertake a complete analysis of these light curves from all the states using various quantifiers from nonlinear time series analysis, such as the correlation dimension (D2), the correlation entropy (K2), singular value decomposition (SVD) and the multifractal spectrum (f(α) spectrum). An important aspect of our analysis is that, for estimating these quantifiers, we use algorithmic schemes which we have recently proposed and successfully tested on synthetic as well as practical time series from various fields. Though the schemes are based on the conventional delay embedding technique, they are automated so that the above quantitative measures can be computed using conditions prescribed by the algorithm and without any intermediate subjective analysis. We show that nearly half of the 12 temporal states exhibit deviation from randomness and their complex temporal behavior could be approximated by a few (three or four) coupled ordinary nonlinear differential equations. These results could be important for a better understanding of the processes that generate the light curves and hence for modeling the temporal behavior of such complex systems.To our knowledge, this is the first complete analysis of an astrophysical object (let alone a black hole system) using various techniques from nonlinear dynamics.

  10. Towards Characterization of the Type IIP Supernova Progenitor Population: a Statistical Sample of Light Curves from Pan-STARRS1

    CERN Document Server

    Sanders, N E; Gezari, S; Betancourt, M; Chornock, R; Berger, E; Foley, R J; Challis, P; Drout, M; Kirshner, R P; Lunnan, R; Marion, G H; Margutti, R; McKinnon, R; Milisavljevic, D; Narayan, G; Rest, A; Kankare, E; Mattila, S; Smartt, S J; Huber, M E; Burgett, W S; Draper, P W; Hodapp, K W; Kaiser, N; Kudritzki, R P; Magnier, E A; Metcalfe, N; Morgan, J S; Price, P A; Tonry, J L; Wainscoat, R J; Waters, C

    2014-01-01

    In recent years, the advent of wide-field sky surveys which obtain deep multi-band imaging has presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SN): systematic light curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1 (PS1), obtained over a constant survey program of 4 years and classified using both spectroscopy and machine learning-based photometric techniques. We develop and apply a new Bayesian model for the full multi-band evolution of each light curve in the sample. We find no evidence for the existence of a discontinuous sub-population of fast-declining explosions (historically referred to as "Type IIL" SNe). However, we identify a highly significant continuous relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single predominant explosion parameter, likely determined by initial stellar mass, controlling the most significant observational ...

  11. Effect of a High Opacity on the Light Curves of Radioactively Powered Transients from Compact Object Mergers

    CERN Document Server

    Barnes, Jennifer

    2013-01-01

    The coalescence of compact objects are a promising astrophysical sources of gravitational wave (GW) signals. The ejection of r-process material from such mergers may lead to a radioactively-powered electromagnetic counterpart which, if discovered, would enhance the science return of a GW detection. As very little is known about the optical properties of heavy r-process elements, previous light curve models have adopted opacities similar to those of iron group elements. Here we report that the presence of heavier elements, particularly the lanthanides, increase the ejecta opacity by several orders of magnitude. We include these higher opacities in time dependent, multi-wavelength radiative transport calculations to predict the broadband light curves of one-dimensional models over a range of parameters (ejecta masses from 0.001 to 0.1 solar masses and velocities from 0.1 to 0.3c). We find that the higher opacities lead to much longer duration light curves which can last a week or more. The emission is shifted t...

  12. Against the Wind: Radio Light Curves of Type Ia Supernovae Interacting with Low-Density Circumstellar Shells

    CERN Document Server

    Harris, Chelsea E; Kasen, Daniel N

    2016-01-01

    For decades, a wide variety of observations spanning the radio through optical and on to the x-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, as shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves, and identify a fiducial set of models that all obey a common evolution and can be used to generate radio light curves for interaction with an arbitrary shell. The relations obeyed by the fiducial mod...

  13. Magnetar powered GRBs: Explaining the extended emission and X-ray plateau of short GRB light curves

    CERN Document Server

    Gompertz, B P; Wynn, G A

    2013-01-01

    Extended emission (EE) is a high-energy, early time rebrightening sometimes seen in the light curves of short gamma-ray bursts (GRBs). We present the first contiguous fits to the EE tail and the later X-ray plateau, unified within a single model. Our central engine is a magnetar surrounded by a fall-back accretion disc, formed by either the merger of two compact objects or the accretion-induced collapse of a white dwarf. During the EE phase, material is accelerated to super-Keplarian velocities and ejected from the system by the rapidly rotating ($P \\approx 1 - 10$ ms) and very strong ($10^{15}$ G) magnetic field in a process known as magnetic propellering. The X-ray plateau is modelled as magnetic dipole spin-down emission. We first explore the range of GRB phenomena that the propeller could potentially reproduce, using a series of template light curves to devise a classification scheme based on phenomology. We then obtain fits to the light curves of 9 GRBs with EE, simultaneously fitting both the propeller ...

  14. On the Light Curve and Spectra of X-Rays and Gamma-Rays from the Crab Pulsar

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; K. S. Cheng; MEI Dong-Cheng

    2000-01-01

    We use a three-dimensional pulsar magnetosphere model to study the light curve and spectra of x-rays and gamma-rays from the Crab pulsar. In this model, the vertical size of the outer gap is first determined by a self-consistent model in which the outer gap is limited by pair production from collisions of thermal photons produced by polar cap heating of backflow outer gap current and curvature photons emitted by gap accelerated charged particles. The transverse size of the outer gap is determined by local pair production conditions. In principle, there are two topologically disconnected outer gaps present in the magnetosphere of a pulsar, and both incoming and outgoing particle flows are allowed. However, double-peak light curves with strong bridges are most common, Making use of the three-dimensional structure of the outer gap and its local properties, we compare the results of our model with the light curve and phase-resolved spectra of the Crab pulsar.

  15. The effect of scattered light sensor orientation on roughness measurement of curved polished surfaces

    DEFF Research Database (Denmark)

    Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

    with crossed surface lay to document the robustness of the method. The instrument area-integrating measuring principle (figure 1) is based on a non-coherent light beam of ∅ 0.9 mm and 670 nm wavelength illuminating the measured surface, reflection of the incident light from the surface slopes in spatial......The effect of angular orientation of a scattered light sensor with respect to main curvature and surface lay on roughness measurements is evaluated. A commercial scattered light sensor OS 500-32 from Optosurf GmbH was used. The investigation was performed on polished cylindrical surfaces...... directions, and its acquisition within ± 16º angular range with a linear detector array. From the distribution of the acquired scattered light intensity, a number of statistical parameters describing the surface texture are calculated, where the Aq parameter (variance of the scattered light distribution...

  16. Variability in Proto-Planetary Nebulae: IV. Light Curve Analyses of Four Oxygen-Rich, F Spectral-Type Objects

    CERN Document Server

    Hrivnak, Bruce J; Nault, Kristie A

    2015-01-01

    We present new light curves covering 14 to 19 years of observations of four bright proto-planetary nebulae (PPNs), all O-rich and of F spectral type. They each display cyclical light curves with significant variations in amplitude. All four were previously known to vary in light. Our data were combined with published data and searched for periodicity. The results are as follows: IRAS 19475+3119 (HD 331319; 41.0 days), 17436+5003 (HD 161796; 45.2 days), 19386+0155 (101.8 days), and 18095+2704 (113.3 days). The two longer periods are in agreement with previous studies while the two shorter periods each reveal for the first time reveal a dominant period over these long observing intervals. Multiple periods were also found for each object. The secondary periods were all close to the dominant periods, with P2/P1 ranging from 0.86 to 1.06. The variations in color reveal maximum variations in T(eff) of 400 to 770 K. These variations are due to pulsations in these post-AGB objects. Maximum seasonal light variations a...

  17. Fourier Decomposition of RR Lyrae light curves and the SX Phe population in the central region of NGC 3201

    CERN Document Server

    Ferro, A Arellano; Calderón, J H; Kains, N

    2014-01-01

    CCD time-series observations of the central region of the globular cluster NGC~3201 were obtained with the aim of performing the Fourier decomposition of the light curves of the RR~Lyrae stars present in that field. This procedure gave the mean values, for the metallicity, of [Fe/H]$_{ZW}=-1.483 \\pm 0.006$ (statistical) $\\pm 0.090$ (systematical), and for the distance, $5.000 \\pm 0.001$~kpc (statistical) $\\pm 0.220$ (systematical). The values found from two RRc stars are consistent with those derived previously. The differential reddening of the cluster was investigated and individual reddenings for the RR Lyrae stars were estimated from their $V-I$ curves. We found an average value of $E(B-V)= 0.23 \\pm 0.02$. An investigation of the light curves of stars in the {\\it blue stragglers} region led to the discovery of three new SX~Phe stars. The period-luminosity relation of the SX~Phe stars was used for an independent determination of the distance to the cluster and of the individual reddenings. We found a dista...

  18. Fast bolometric response by high T sub c detectors measured with subnanosecond synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Carr, G.L.; Quijada, M.; Tanner, D.B. (Department of Physics, University of Florida, Gainesville, Florida 32611 (USA)); Hirschmugl, C.J.; Williams, G.P. (National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973 (USA)); Etemad, S.; Dutta, B.; DeRosa, F.; Inam, A.; Venkatesan, T. (Bell Communications Research, Red Bank, New Jersey 07701 (USA)); Xi, X. (Department of Physics, Rutgers University, Piscataway, New Jersey 08855 (USA))

    1990-12-17

    We have measured a fast response by thin-film YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} detectors to pulsed, broadband, infrared radiation. Synchrotron light from an electron storage ring was used as the infrared source, providing subnanosecond pulses from far infrared through visible. Pulse responsivities as high as 10{sup 6} V/J and as fast as 4 ns have been observed. For film thicknesses in the range 400--3200 A, the detector response follows the film absorptivity while the speed varies inversely with thickness, suggesting a bolometric mechanism. Calculations based on such a model are in accord with the data. We find no evidence for any nonbolometric components in the response.

  19. CUORE and Beyond: Bolometric Techniques to Explore Inverted Neutrino Mass Hierarchy

    Science.gov (United States)

    Artusa, D. R.; Avignone, F. T.; Azzolini, O.; Balata, M.; Banks, T. I.; Bari, G.; Beeman, J.; Bellini, F.; Bersani, A.; Biassoni, M.; Brofferio, C.; Bucci, C.; Cai, X. Z.; Camacho, A.; Canonica, L.; Cao, X. G.; Capelli, S.; Carbone, L.; Cardani, L.; Carrettoni, M.; Casali, N.; Chiesa, D.; Chott, N.; Clemenza, M.; Copello, S.; Cosmelli, C.; Cremonesi, O.; Creswick, R. J.; Dafinei, I.; Dally, A.; Datskov, V.; De Biasi, A.; Deninno, M. M.; Di Domizio, S.; di Vacri, M. L.; Ejzak, L.; Fang, D. Q.; Farach, H. A.; Faverzani, M.; Fernandes, G.; Ferri, E.; Ferroni, F.; Fiorini, E.; Franceschi, M. A.; Freedman, S. J.; Fujikawa, B. K.; Giachero, A.; Gironi, L.; Giuliani, A.; Goett, J.; Gorla, P.; Gotti, C.; Gutierrez, T. D.; Haller, E. E.; Han, K.; Heeger, K. M.; Hennings-Yeomans, R.; Huang, H. Z.; Kadel, R.; Kazkaz, K.; Keppel, G.; Kolomensky, Yu. G.; Li, Y. L.; Ligi, C.; Liu, X.; Ma, Y. G.; Maiano, C.; Maino, M.; Martinez, M.; Maruyama, R. H.; Mei, Y.; Moggi, N.; Morganti, S.; Napolitano, T.; Nisi, S.; Nones, C.; Norman, E. B.; Nucciotti, A.; O'Donnell, T.; Orio, F.; Orlandi, D.; Ouellet, J. L.; Pallavicini, M.; Palmieri, V.; Pattavina, L.; Pavan, M.; Pedretti, M.; Pessina, G.; Pettinacci, V.; Piperno, G.; Pira, C.; Pirro, S.; Previtali, E.; Rampazzo, V.; Rosenfeld, C.; Rusconi, C.; Sala, E.; Sangiorgio, S.; Scielzo, N. D.; Sisti, M.; Smith, A. R.; Taffarello, L.; Tenconi, M.; Terranova, F.; Tian, W. D.; Tomei, C.; Trentalange, S.; Ventura, G.; Vignati, M.; Wang, B. S.; Wang, H. W.; Wielgus, L.; Wilson, J.; Winslow, L. A.; Wise, T.; Woodcraft, A.; Zanotti, L.; Zarra, C.; Zhu, B. X.; Zucchelli, S.

    The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of 130Te. With 741 kg of TeO2 crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is 1.6 × 1026 y at 1σ (9.5 × 1025 y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40-100 meV (50-130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with 130Te and possibly other double beta decay candidate nuclei.

  20. Effect of Longitudinally Varying Cloud Coverage on Visible Wavelength Reflected-Light Exoplanet Phase Curves

    CERN Document Server

    Webber, Matthew W; Marley, Mark; Morley, Caroline; Fortney, Jonathan; Cahoy, Kerri

    2015-01-01

    We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. The presence of clouds on these exoplanets significantly alters their planetary albedo spectra. We confirm that non-uniform cloud coverage on the dayside of tidally locked exoplanets will manifest as changes to the magnitude and shift of the phase curve. In this work, we first investigate a test case of our model using a Jupiter-like planet, at temperatures consistent to 2.0 AU insolation from a solar type star, to consider the effect of H2O clouds. We then extend our application of the model to the exoplanet Kepler-7b and consider the effect of varying cloud species, sedimentation efficiency, particle size, and cloud altitude. We show that, depending on the observational filter, the largest possible shift of the phase curve maximum will be 2-10 deg for a Jupiter-like planet, and up to 30 deg (0.08 in fractional orbital phase) for hot-Jupiter exoplanets at visible wavelengths as a function of dayside cl...

  1. One-phase and two-phase homologous curves for coolant pumps of the pressurized light water nuclear reactors

    International Nuclear Information System (INIS)

    The two-phase coolant pump model of pressurized light water nuclear reactors is an important point for the loss of primary coolant accident analysis. The single-phase pump characteristics are an essential feature for operational transients studies, for example, the shut-down and start-up of pump. These parameters, in terms of the homologous curves, set up the complete performance of the pump and are input for transients and accidents analysis thermal-hydraulic codes. This work propose a mathematical model able to predict the single-phase and two-phase homologous curves where it was incorporated geometric and operational pump condition. The results were compared with the experimental tests data from literature and it has showed a good agreement. (author)

  2. CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH SHORT-DURATION PERIODIC FLUX DIPS IN THEIR LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Plavchan, Peter; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); McGinnis, Pauline; Alencar, Silvia H. P. [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Hillenbrand, Lynne A.; Carpenter, John [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, María [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Bouvier, Jerome; Venuti, Laura [Université de Grenoble, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble (France); CNRS, IPAG, F-38000 Grenoble (France); Hartmann, Lee; Calvet, Nuria [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States); Micela, Giusi; Flaccomio, Ettore [INAF—Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602–2451 (United States); Gutermuth, Rob, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); and others

    2015-04-15

    We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical CoRoT light curves exhibiting short-duration, shallow periodic flux dips. All of these stars have infrared excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHMs generally less than 1 day, depths almost always less than 15%, and periods (3 < P < 11 days) consistent with dust near the Keplerian co-rotation period. The flux dips vary considerably in their depth from epoch to epoch, but usually persist for several weeks and, in two cases, were present in data collected in successive years. For several of these stars, we also measure the photospheric rotation period and find that the rotation and dip periods are the same, as predicted by standard “disk-locking” models. We attribute these flux dips to clumps of material in or near the inner disk wall, passing through our line of sight to the stellar photosphere. In some cases, these dips are also present in simultaneous Spitzer IRAC light curves at 3.6 and 4.5 microns. We characterize the properties of these dips, and compare the stars with light curves exhibiting this behavior to other classes of YSOs in NGC 2264. A number of physical mechanisms could locally increase the dust scale height near the inner disk wall, and we discuss several of those mechanisms; the most plausible mechanisms are either a disk warp due to interaction with the stellar magnetic field or dust entrained in funnel-flow accretion columns arising near the inner disk wall.

  3. Forecasting life: a study of activity cycles in low-mass stars: lessons from long-term stellar light curves.

    Science.gov (United States)

    Kafka, Stella

    2012-06-01

    Magnetic activity cycles are indirect traces of magnetic fields and can provide an insight on the nature and action of stellar dynamos and stellar magnetic activity. This, in turn, can determine local space weather and activity effects on stellar habitable zones. Using photometric monitoring of low-mass stars, we study the presence and properties of their magnetic activity cycles. We introduce long-term light curves of our sample stars, and discuss the properties of the observed trends, especially at spectral types where stars are fully convective (later than M3).

  4. A New Radiation Hydrodynamics Code and Application to the Calculation of Type Ia Supernovae Light Curves and Continuum Spectra

    CERN Document Server

    Zhang, X; Zhang, Xiao-he; Sutherland, Peter

    1993-01-01

    A new, fully dynamic and self-consistent radiation hydrodynamics code, suitable for the calculation of supernovae light curves and continuum spectra, is described. It is a multigroup (frequency-dependent) code and includes all important $O(v/c)$ effects. It is applied to the model W7 of Nomoto, Thielemann, \\& Yokoi (1984) for supernovae of type Ia. Radioactive energy deposition is incorporated through use of tables based upon Monte Carlo results. Effects of line opacity (both static or line blanketing and expansion or line blocking) are neglected, although these may prove to be important. At maximum light, models based upon different treatments of the opacity lead to values for $M_{B,max}$ in the range of -19.0 to -19.4. This range falls between the values for observed supernova claimed by Leibundgut \\& Tammann (1990) and by Pierce, Ressler, \\& Shure (1992).

  5. Seven new binaries discovered in the Kepler light curves through the BEER method confirmed by radial-velocity observations

    CERN Document Server

    Faigler, S; Quinn, S N; Latham, D W; Tal-Or, L

    2011-01-01

    We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic radial-velocity follow-up observations, indicating minimum secondary masses in the range of 0.07-0.4 Msun. The discovered binaries establish for the first time the feasibility of the BEER algorithm as a new detection method for short-perio...

  6. Light-curve solutions of 20 eclipsing Kepler binaries, most of them with pronounced spot and flare activity

    Science.gov (United States)

    Kjurkchieva, D.; Atanasova, T.; Dimitrov, D.

    2016-07-01

    We carried out light curve solutions of the Kepler light curves of twenty detached eclipsing binaries with circular orbits and determined the orbital inclinations, temperatures. relative radii and luminosities of their components. We studied the quality of the solutions with respect to the adopted limb-darkening law and its coefficients. The detailed tracing of the numerous and uninterrupted data of our targets gave us an unique possibility to detect and learn their spot and flare activity. We established that the out-of-eclipse variability of the most targets gradually changes from small-amplitude two-waved type to big-amplitude one-waved type and vice versa, i.e. their spot activity cycles pass through phase of two almost diametrically opposite spots and phase of big polar cool spot. We found that the low-temperature targets show flare activity of UV Cet-type with amplitudes of 0.002-0.22 mag and duration of up to several hours. Data from Kepler

  7. Early ($<$0.3 day) R-band light curve of the optical afterglow of GRB030329

    CERN Document Server

    Urata, Y; Nishiura, S; Tamagawa, T; Burenin, R A; Sekiguchi, T; Miyasaka, S; Yoshizumi, C; Suzuki, J; Mito, H; Nakada, Y; Aoki, T; Soyano, T; Tarusawa, K; Shiki, S; Makishima, K

    2004-01-01

    We observed the optical afterglow of the bright gamma-ray burst GRB030329 on the nights of 2003 March 29, using the Kiso observatory (the University of Tokyo) 1.05 m Schmidt telescope. Data were taken from March 29 13:21:26 UT to 17:43:16 (0.072 to 0.253 days after the burst), using an $Rc$-band filter. The obtained $Rc$-band light curve has been fitted successfully by a single power law function with decay index of $0.891\\pm0.004$. These results remain unchanged when incorporating two early photometric data points at 0.065 and 0.073 days, reported by Price et al.(2003) using the SSO 40 inch telescope, and further including RTT150 data (Burenin et al. 2003) covering at about 0.3 days. Over the period of 0.065-0.285 days after the burst, any deviation from the power-law decay is smaller than $\\pm$0.007 mag. The temporal structure reported by Uemura et al. (2003) does not show up in our $R$-band light curve.

  8. Quark-novae Occurring in Massive Binaries : A Universal Energy Source in Superluminous Supernovae with Double-peaked Light Curves

    Science.gov (United States)

    Ouyed, Rachid; Leahy, Denis; Koning, Nico

    2016-02-01

    A quark-nova (QN; the sudden transition from a neutron star into a quark star), which occurs in the second common envelope (CE) phase of a massive binary, gives excellent fits to superluminous, hydrogen-poor, supernovae (SLSNe) with double-peaked light curves, including DES13S2cmm, SN 2006oz, and LSQ14bdq (http://www.quarknova.ca/LCGallery.html). In our model, the H envelope of the less massive companion is ejected during the first CE phase, while the QN occurs deep inside the second, He-rich, CE phase after the CE has expanded in size to a radius of a few tens to a few thousands of solar radii; this yields the first peak in our model. The ensuing merging of the quark star with the CO core leads to black hole formation and accretion, explaining the second long-lasting peak. We study a sample of eight SLSNe Ic with double-humped light curves. Our model provides good fits to all of these, with a universal explosive energy of 2 × 1052 erg (which is the kinetic energy of the QN ejecta) for the first hump. The late-time emissions seen in iPTF13ehe and LSQ14bdq are fit with a shock interaction between the outgoing He-rich (i.e., second) CE and the previously ejected H-rich (i.e., first) CE.

  9. Discovery of Irradiation Induced Variations in the Light Curve of the Classical Nova Cygni 2001 No.2 (V2275 Cyg)

    CERN Document Server

    Balman, S; Retter, A; Saygac, T; Esenoglu, H

    2004-01-01

    We present the CCD photometry, light curve and time series analysis of the classical nova V2275 Cyg (N Cyg 2001 No.2). The source was observed for 14 nights in total using an R filter in 2002 and 2003 with the 1.5 m Russian-Turkish joint telescope (RTT150) at the TUBITAK (The Scientific and Technical Research Council of Turkey) National Observatory in Antalya Turkey, as part of a large program on the CCD photometry of Cataclysmic Variables (CVs). We report the detection of two distinct periodicities in the light curve of the nova : a) P_1=0.31449(15) d -- 7.6 h, b) P_2=0.017079(17) d -- 24.6 min. The first period is evident in both 2002 and 2003 whereas the second period is only detected in the 2003 data set. We interpret the first period as the orbital period of the system and attribute the orbital variations to aspect changes of the secondary irradiated by the hot WD. We suggest that the nova was a Super Soft X-ray source in 2002 and, perhaps, in 2003. The second period could be a QPO originating from the o...

  10. SOPIE: An R Package for the Nonparametric Estimation of the Off-Pulse Interval of a Pulsar Light Curve

    Science.gov (United States)

    Schutte, Willem D.; Swanepoel, Jan W. H.

    2016-06-01

    An automated tool to derive the off-pulse interval of a light curve originating from a pulsar is needed. Firstly, we derive a powerful and accurate nonparametric sequential estimation technique to estimate the off-pulse interval of a pulsar light curve in an objective manner. This is in contrast to the subjective `eye-ball' (visual) technique, and complementary to the Bayesian Block method which is currently used in the literature. The second aim involves the development of a statistical package, necessary for the implementation of our new estimation technique. We develop a statistical procedure to estimate the off-pulse interval in the presence of noise. It is based on a sequential application of p-values obtained from goodness-of-fit tests for uniformity. The Kolmogorov-Smirnov, Cramér-von Mises, Anderson-Darling and Rayleigh test statistics are applied.The details of the newly developed statistical package SOPIE (Sequential Off-Pulse Interval Estimation) are discussed. The developed estimation procedure is applied to simulated and real pulsar data. Finally, the SOPIE estimated off-pulse intervals of two pulsars are compared to the estimates obtained with the Bayesian Block method and yield very satisfactory results. We provide the code to implement the SOPIE package, which is publicly available at http://CRAN.R-project.org/package=SOPIE.

  11. Reconstruction of the Structure of Accretion Disks in Dwarf Novae from the Multi-Band Light Curves of Early Superhumps

    CERN Document Server

    Uemura, M; Ohshima, T; Maehara, H

    2012-01-01

    We propose a new method to reconstruct the structure of accretion disks in dwarf novae using multi-band light curves of early superhumps. Our model assumes that early superhumps are caused by the rotation effect of non-axisymmetrically flaring disks. We have developed a Bayesian model for this reconstruction, in which a smoother disk-structure tends to have a higher prior probability. We analyzed simultaneous optical and near-infrared photometric data of early superhumps of the dwarf nova, V455 And using this technique. The reconstructed disk has two flaring parts in the outermost region of the disk. These parts are responsible for the primary and secondary maxima of the light curves. The height-to-radius ratio is h/r=0.20---0.25 in the outermost region. In addition to the outermost flaring structures, flaring arm-like patterns can be seen in an inner region of the reconstructed disk. The overall profile of the reconstructed disk is reminiscent of the disk structure which is deformed by the tidal effect. Howe...

  12. Can X-ray emission powered by a spinning-down magnetar explain some GRB light curve features?

    CERN Document Server

    Lyons, N; Zhang, B; Willingale, R; Troja, E; Starling, R L C

    2009-01-01

    Long duration gamma-ray bursts (GRBs) are thought to be produced by the core-collapse of a rapidly-rotating massive star. This event generates a highly relativistic jet and prompt gamma-ray and X-ray emission arises from internal shocks in the jet or magnetised outflows. If the stellar core does not immediately collapse to a black hole, it may form an unstable, highly magnetised millisecond pulsar, or magnetar. As it spins down, the magnetar would inject energy into the jet causing a distinctive bump in the GRB light curve where the emission becomes fairly constant followed by a steep decay when the magnetar collapses. We assume that the collapse of a massive star to a magnetar can launch the initial jet. By automatically fitting the X-ray lightcurves of all GRBs observed by the Swift satellite we identified a subset of bursts which have a feature in their light curves which we call an internal plateau -- unusually constant emission followed by a steep decay -- which may be powered by a magnetar. We use the d...

  13. An unbinned test for Quantum Gravity effects in high-energy light-curves

    CERN Document Server

    de Almeida, U Barres

    2009-01-01

    Some models of quantum gravity can predict observable effects on the propagation of light: most notably an energy dependent dispersion, where the speed of light is seen to vary with the energy of the photon. As quantum gravity effects should appear at the Planck scale they will be very small and so require very high energy photons to travel large distances before even becoming noticeable. Precisely because this effect is greater for the most energetic photons (dt ~ 10 s/TeV/Gpc), ground-based gamma-ray measurements of large AGN flares are the ideal resource for performing such tests. The modest photon flux combined with the fact that these experiments are capable of recording the photon times with great resolution suggests the use of unbinned algorithms as an optimal solution for testing models of quantum gravity. In this paper we discuss the application of a non-parametric test to such datasets, analysing its limitations and exploring the potential benefits.

  14. Discovery of periodic dips in the light curve of GX 13+1: the X-ray orbital ephemeris of the source

    CERN Document Server

    Iaria, R; Burderi, L; Riggio, A; D'Ai, A; Robba, N R

    2013-01-01

    The bright low-mass X-ray binary (LMXB) GX 13+1 is one of the most peculiar Galactic binary systems. A periodicity of 24.27 d with a formal statistical error of 0.03 d was observed in its power spectrum density obtained with RXTE All Sky Monitor (ASM) data spanning 14 years. Starting from a recent study, indicating GX 13+1 as a possible dipping source candidate, we systematically searched for periodic dips in the X-ray light curves of GX 13+1 from 1996 up to 2013 using RXTE/ASM, and MAXI data to determine for the first time the X-ray orbital ephemeris of GX 13+1. We searched for a periodic signal in the ASM and MAXI light curves, finding a common periodicity of 24.53 d. We folded the 1.3-5 keV and 5-12.1 keV ASM light curves and the 2-4 and 4-10 keV MAXI light curves at the period of 24.53 d finding a periodic dip. To refine the value of the period we used the timing technique dividing the ASM light curve in eight intervals and the MAXI light curve in two intervals, obtaining four and two dip arrival times fr...

  15. The host galaxy and optical light curve of the gamma-ray burst GRB 980703

    DEFF Research Database (Denmark)

    Holland, S.; Fynbo, J.P.U.; Hjorth, J.;

    2001-01-01

    that is approximate to0.2 mag bluer than the outer regions of the galaxy. The galaxy has a star-formation rate of 8-13 M-circle dot yr(-1), assuming no extinction in the host. We find that the galaxy is best fit by a Sersic R-1/n profile with n approximate to 1.0 and a half-light radius of 0." 13 (= 0:72h(100...

  16. Fast bolometric sensor built-in into polycrystalline CVD diamond

    International Nuclear Information System (INIS)

    Diamond, with its unique combination of physical properties, is a promising material for electronic devices operating under extreme conditions. Due to its exceptionally high thermal conductivity, diamond-based bolometers should possess very short response time. A fast bolometric sensor was formed within a polycrystalline diamond plate by ion implantation and subsequent annealing. The response kinetics of the structure was studied under a nitrogen laser pulsed illumination. The response time at room temperature was less than 20 ns. The spatial-temporal distribution of responses allowed us to distinguish between thermal responses and those of different nature (e.g. photoconductivity). This study was supported by the Russian Foundation for Basic Research, project nos. 05-02-17545 and 07-02-00575

  17. Fast bolometric sensor built-in into polycrystalline CVD diamond

    Energy Technology Data Exchange (ETDEWEB)

    Klokov, A Yu [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation); Sharkov, A I [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation); Galkina, T I [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation); Khmelnitsky, R A [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation); Dravin, V A [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation); Ralchenko, V G [General Physics Institute, Vavilova ul., 38, 119991 Moscow (Russian Federation); Gippius, A A [P.N. Lebedev Physical Institute, Leninskii pr., 53, 119991 Moscow (Russian Federation)

    2007-12-15

    Diamond, with its unique combination of physical properties, is a promising material for electronic devices operating under extreme conditions. Due to its exceptionally high thermal conductivity, diamond-based bolometers should possess very short response time. A fast bolometric sensor was formed within a polycrystalline diamond plate by ion implantation and subsequent annealing. The response kinetics of the structure was studied under a nitrogen laser pulsed illumination. The response time at room temperature was less than 20 ns. The spatial-temporal distribution of responses allowed us to distinguish between thermal responses and those of different nature (e.g. photoconductivity). This study was supported by the Russian Foundation for Basic Research, project nos. 05-02-17545 and 07-02-00575.

  18. Soft x-ray and bolometric tomography in RFX

    International Nuclear Information System (INIS)

    The article presents the design and the first results of a new eight camera, soft x-ray (SXR) and bolometric tomography which has been installed in RFX, a large (R=2 m, a=0.46 m), high current reverse field pinch experiment operating in Padova. The main features of the diagnostic, which has been designed with standards compatible with the requirements of large fusion experiments, are: (a) it allows simultaneous reconstruction of both SXR and total radiation emissivity structures with high spatial and time resolution (bandwidth up to 200 kHz for SXR and 10 kHz for bolometry). Moreover, computer controlled remote actions which interchange up to five material filters in front of the detectors allow the exploration of different energy ranges; (b) it can be easily decoupled from the machine without breaking the main vacuum and can be operated during first wall baking up to 300 degree C thanks to a cooling circuit; (c) the detection chain is designed to measure very low signals [in the order of 1 nA for SXR diodes and of 100 μV for bolometers]; (d) it is equipped with a VME based 1 MHz data acquisition system which allows on-line processing of a large amount of data. To accomplish these features the diagnostic consists of eight fully remotely controlled manipulators which can insert eight photocameras, carrying 78 top-rated Si SXR and 48 miniaturized metal film bolometric detectors in their operating positions. Initial results are presented. copyright 1997 American Institute of Physics

  19. What Powers the 3000-Day Light Curve of SN 2006gy?

    CERN Document Server

    Fox, Ori D; Ammons, S Mark; Andrews, Jennifer; Bostroem, K Azalee; Cenko, S Bradley; Clayton, Geoffrey C; Dwek, Eli; Filippenko, Alexei V; Gallagher, Joseph S; Kelly, Patrick L; Mauerhan, Jon C; Miller, Adam M; Van Dyk, Schuyler D

    2015-01-01

    SN 2006gy was the most luminous SN ever observed at the time of its discovery and the first of the newly defined class of superluminous supernovae (SLSNe). The extraordinary energetics of SN 2006gy and all SLSNe (>10^51 erg) require either atypically large explosion energies (e.g., pair-instability explosion) or the efficient conversion of kinetic into radiative energy (e.g., shock interaction). The mass-loss characteristics can therefore offer important clues regarding the progenitor system. For the case of SN 2006gy, both a scattered and thermal light echo from circumstellar material (CSM) have been reported at later epochs (day ~800), ruling out the likelihood of a pair-instability event and leading to constraints on the characteristics of the CSM. Owing to the proximity of the SN to the bright host-galaxy nucleus, continued monitoring of the light echo has not been trivial, requiring the high resolution offered by the Hubble Space Telescope (HST) or ground-based adaptive optics (AO). Here we report detect...

  20. Late-time Light Curves of Type II Supernovae: Physical Properties of SNe and Their Environment

    CERN Document Server

    Otsuka, Masaaki; Panagia, Nino; Fabbri, Joanna; Barlow, Michael J; Clayton, Geoffrey C; Gallagher, Joseph S; Sugerman, Ben E K; Wesson, Roger; Andrews, Jennifer E; Ercolano, Barbara; Welch, Douglas

    2011-01-01

    We present BVRIJHK band photometry of 6 core-collapse supernovae, SNe 1999bw, 2002hh, 2003gd, 2004et, 2005cs, and 2006bc measured at late epochs (>2 yrs) based on Hubble Space Telescope (HST), Gemini north, and WIYN telescopes. We also show the JHK lightcurves of a supernova impostor SN 2008S up to day 575. Of our 43 HST observations in total, 36 observations are successful in detecting the light from the SNe alone and measuring magnitudes of all the targets. HST observations show a resolved scattered light echo around SN 2003gd at day 1520 and around SN 2002hh at day 1717. Our Gemini and WIYN observations detected SNe 2002hh and 2004et, as well. Combining our data with previously published data, we show VRIJHK-band lightcurves and estimate decline magnitude rates at each band in 4 different phases. Our prior work on these lightcurves and other data indicate that dust is forming in our targets from day ~300-400, supporting SN dust formation theory. In this paper we focus on other physical properties derived f...

  1. Colossal Magnetoresistive Manganite Based Fast Bolometric X-ray Sensors for Total Energy Measurements of Free Electron Lasers

    International Nuclear Information System (INIS)

    Bolometric detectors based on epitaxial thin films of rare earth perovskite manganites have been proposed as total energy monitors for X-ray pulses at the Linac Coherent Light Source free electron laser. We demonstrate such a detector scheme based on epitaxial thin films of the perovskite manganese oxide material Nd0.67Srx0.33MnO3, grown by pulsed laser deposition on buffered silicon substrates. The substrate and sensor materials are chosen to meet the conflicting requirements of radiation hardness, sensitivity, speed and linearity over a dynamic range of three orders of magnitude. The key challenge in the material development is the integration of the sensor material with Si. Si is required to withstand the free electron laser pulse impact and to achieve a readout speed three orders of magnitude faster than conventional cryoradiometers for compatibility with the Linac Coherent Light Source pulse rate. We discuss sensor material development and the photoresponse of prototype devices. This Linac Coherent Light Source total energy monitor represents the first practical application of manganite materials as bolometric sensors

  2. Light Curve Solutions of an Eclipsing Binary OGLE-GD-ECL-04451 with a Dramatic Change in Amplitude

    CERN Document Server

    Gang, Li; jianning, Fu

    2016-01-01

    We present light curve solutions of the W UMa-type eclipsing binary OGLE-GD-ECL-04451, observed by both the \\emph{Optical Gravitational Lensing Ex-periment} (\\emph{OGLE}) program in 2006 and the \\emph{Antarctica Survey Telescope} (\\emph{AST3-1}) in 2012 at Dome A. We analyzed this binary system with the Wilson-Devinney(W-D) method 2013 version and derived the mass ratio $q=2.91 \\pm 0.07$, the inclination $i=76.86^\\circ \\pm 0.23^\\circ$, and the light variattion amplitud was $0^m.51$ based on the \\emph{OGLE} data. From the \\emph{AST3-1}'s data, we find that the amplitude dropped to $0^m.44$(2012) and the difference of magnitudes of the two light maxima is $0^m.03$. A hot spot was then added on the surface of the secondary to demonstrate the amplitude change and O'Conell effect of the binary system.

  3. Supernova Neutrino Light Curves and Spectra for Various Progenitor Stars: From Core Collapse to Proto-neutron Star Cooling

    CERN Document Server

    Nakazato, Ken'ichiro; Suzuki, Hideyuki; Totani, Tomonori; Umeda, Hideyuki; Yamada, Shoichi

    2012-01-01

    We present a new series of supernova neutrino light curves and spectra calculated by numerical simulations for a variety of progenitor stellar masses (13-50Msolar) and metallicities (Z = 0.02 and 0.004), which would be useful for a broad range of supernova neutrino studies, e.g., simulations of future neutrino burst detection by underground detectors, or theoretical predictions for the relic supernova neutrino background. To follow the evolution from the onset of collapse to 20 s after the core bounce, we combine the results of neutrino-radiation hydrodynamic simulations for the early phase and quasi-static evolutionary calculations of neutrino diffusion for the late phase, with different values of shock revival time as a parameter that should depend on the still unknown explosion mechanism. We here describe the calculation methods and basic results including the dependence on progenitor models and the shock revival time. The neutrino data are publicly available electronically.

  4. Theoretical fit of Cepheid light an radial velocity curves in the Large Magellanic Cloud cluster NGC 1866

    CERN Document Server

    Marconi, Marcella; Ripepi, Vincenzo; Musella, Ilaria; Brocato, Enzo

    2012-01-01

    We present a theoretical investigation of multifilter (U,B,V, I and K) light and radial velocity curves of five Classical Cepheids in NGC 1866, a young massive cluster of the Large Magellanic Cloud. The best fit models accounting for the luminosity and radial velocity variations of the five selected variables, four pulsating in the fundamental mode and one in the first overtone, provide direct estimates of their intrinsic stellar parameters and individual distances. The resulting stellar properties indicate a slightly brighter Mass Luminosity relation than the canonical one, possibly due to mild overshooting and/or mass loss. As for the inferred distances, the individual values are consistent within the uncertainties. Moreover, their weighted mean value corresponds to a distance modulus of 18.56 + - 0.03 (stat) + - 0.1 (syst) mag, in agreement with several independent results in the literature.

  5. Radioactivity and thermalization in the ejecta of compact object mergers and their impact on kilonova light curves

    CERN Document Server

    Barnes, Jennifer; Wu, Meng-Ru; Mart'inez-Pinedo, Gabriel

    2016-01-01

    One of the most promising electromagnetic signatures of compact object mergers are kilonovae: approximately isotropic radioactively-powered transients that peak days to weeks post-merger. Key uncertainties in modeling kilonovae include the emission profiles of the radioactive decay products---non-thermal beta- and alpha-particles, fission fragments, and gamma-rays---and the efficiency with which they deposit their energy in the ejecta. The total radioactive energy and the efficiency of its thermalization sets the luminosity budget and is therefore necessary for predicting kilonova light curves. We outline the uncertainties in r-process decay, describe the physical processes by which the energy of the decay products is absorbed in the ejecta, and present time-dependent thermalization efficiencies for each particle type. We determine the net heating efficiency and explore its dependence on r-process yields---in particular, the production of translead nuclei that undergo alpha-decay---and on the ejecta's mass, v...

  6. SUPERNOVA NEUTRINO LIGHT CURVES AND SPECTRA FOR VARIOUS PROGENITOR STARS: FROM CORE COLLAPSE TO PROTO-NEUTRON STAR COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Nakazato, Ken' ichiro; Suzuki, Hideyuki [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Sumiyoshi, Kohsuke [Numazu Collage of Technology, 3600 Ooka, Numazu, Shizuoka 410-8501 (Japan); Totani, Tomonori [Department of Astronomy, Kyoto University, Kita-shirakawa Oiwake-cho, Sakyo, Kyoto 606-8502 (Japan); Umeda, Hideyuki [Department of Astronomy, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Yamada, Shoichi, E-mail: nakazato@rs.tus.ac.jp [Department of Physics, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

    2013-03-01

    We present a new series of supernova neutrino light curves and spectra calculated by numerical simulations for a variety of progenitor stellar masses (13-50 M {sub Sun }) and metallicities (Z = 0.02 and 0.004), which would be useful for a broad range of supernova neutrino studies, e.g., simulations of future neutrino burst detection by underground detectors or theoretical predictions for the relic supernova neutrino background. To follow the evolution from the onset of collapse to 20 s after the core bounce, we combine the results of neutrino-radiation hydrodynamic simulations for the early phase and quasi-static evolutionary calculations of neutrino diffusion for the late phase, with different values of shock revival time as a parameter that should depend on the still unknown explosion mechanism. We describe the calculation methods and basic results, including the dependence on progenitor models and the shock revival time. The neutrino data are publicly available electronically.

  7. A hydrodynamical model for the Fermi-LAT γ-ray light curve of blazar PKS 1510-089

    Directory of Open Access Journals (Sweden)

    Cabrera J.I.

    2013-12-01

    Full Text Available A physical description of the formation and propagation of working surfaces inside the relativistic jet of the blazar PKS 1510-089 are used to model its γ -ray variability light curve using Fermi-LAT data from 2008 to 2012. The physical model is based on conservation laws of mass and momentum at the working surface as explained by Mendoza et al. (2009. The hydrodynamical description of a working surface is parametrized by the initial velocity and mass injection rate at the base of the jet. We show that periodic variations on the injected velocity profiles are able to account for the observed luminosity, fixing model parameters such as mass ejection rates of the central engine injected at the base of the jet, oscillation frequencies of the flow and maximum Lorentz factors of the bulk flow during a particular burst.

  8. VizieR Online Data Catalog: ASAS 101538-5933.1 BV light curves (Berdnikov, 2013)

    Science.gov (United States)

    Berdnikov, L. N.

    2013-04-01

    In the plate collection of the Harvard College Observatory, we have obtained 528 photographic magnitude estimates for the recently discovered long-period classical Cepheid ASAS 101538-5933.1 (P=51.4-days). Together with the published photoelectric and CCD observations, our data have allowed us to construct an O-C diagram spanning a time interval of 120 years. The O-C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary increase in the period, dP/dt=51.8(+/-4.8)s/yr or (dP/dt)/P=7.3(+/-0.7)s, in agreement with the results of theoretical calculations for the third crossing of the instability strip. The available data reduced by the method of Eddington and Plakidis reveal small random period fluctuations that do not distort the evolutionary trend in the O-C residuals. (1 data file).

  9. Thermal light curves of Earth-like planets: 1. Varying surface and rotation on planets in a terrestrial orbit

    Science.gov (United States)

    Gómez-Leal, I.; Codron, F.; Selsis, F.

    2016-05-01

    The integrated thermal emission of an exoplanet and its variations along the orbital motion can carry information about the climatic conditions and the rotation of the planet. In this study, we use the LMDZ 3D Global Climate Model (GCM) to simulate the climate of a synthetic Earth and three quasi-Earth configurations: a slowly rotating Earth, an ocean-covered Earth and its snowball counterpart. We also generate the time-dependent broadband thermal emission of the planet from these simulations. In a first step, we validate the model by comparing the synthetic Earth emission with the actual emission of our planet as constrained by observations. Then, we determine the main properties of the climate and emission of the three Earth-like planets and compare them to those of the Earth. We show that planets with an uneven distribution of continents exhibit a maximum of emission during the summer of the hemisphere with larger continental masses, and they may exhibit a maximum of emission at apastron. Large convective clouds might form over the continents of slow rotating planets, having an important effect over their climate and their emission. We also show that, in all the modeled cases, the equilibrium temperature, the Bond albedo and the rotation period can in theory be retrieved from the light curve by a distant observer. The values obtained at transiting geometries have a low deviation from the global values for cases with an axis tilt similar to that of the Earth, and we are able to distinguish between the four planets presented here by the data obtained from their light curves. However, this might not be the case under different conditions.

  10. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR 21a

    Science.gov (United States)

    Gosset, Eric; Nazé, Yaël

    2016-05-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1 × 10-5 M⊙ yr-1 for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evidence, notably the width of the dip in the X-ray light curve and the absence of variations in the UV light curve. Afterwards, the emission slowly recovers, with a strong hysteresis effect. The observed behaviour is compatible with predictions from general wind-wind collision models although the absorption increase is too shallow. Based on observations collected at ESO as well as with Swift, Chandra, and the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  11. LSQ14bdq: A Type Ic super-luminous supernova with a double-peaked light curve

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Sim, S A; Inserra, C; Anderson, J P; Baltay, C; Benetti, S; Chambers, K; Chen, T -W; Elias-Rosa, N; Feindt, U; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Huber, M E; Kangas, T; Kankare, E; Kotak, R; Krühler, T; Maguire, K; McKinnon, R; Rabinowitz, D; Rostami, S; Schulze, S; Smith, K W; Sullivan, M; Tonry, J L; Valenti, S; Young, D R

    2015-01-01

    We present data for LSQ14bdq, a hydrogen-poor super-luminous supernova (SLSN) discovered by the La Silla QUEST survey and classified by the Public ESO Spectroscopic Survey of Transient Objects. The spectrum and light curve are very similar to slow-declining SLSNe such as PTF12dam. However, detections within $\\sim1$ day after explosion show a bright and relatively fast initial peak, lasting for $\\sim15$ days, prior to the usual slow rise to maximum light. The broader, main peak can be fit with either central engine or circumstellar interaction models. We discuss the implications of the precursor peak in the context of these models. It is too bright and narrow to be explained as a normal \\Ni-powered SN, and we suggest that interaction models may struggle to fit the precursor and main peak simultaneously. We propose that the initial peak is from the post-shock cooling of an extended stellar envelope, and reheating by a central engine drives the second peak. In this picture, we show that an explosion energy of $\\...

  12. SEVEN NEW BINARIES DISCOVERED IN THE KEPLER LIGHT CURVES THROUGH THE BEER METHOD CONFIRMED BY RADIAL-VELOCITY OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Faigler, S.; Mazeh, T.; Tal-Or, L. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Quinn, S. N.; Latham, D. W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2012-02-20

    We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity (RV) modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well-known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M{sub Sun }. The binaries discovered establish for the first time the feasibility of the BEER algorithm as a new detection method for short-period non-eclipsing binaries, with the potential to detect in the near future non-transiting brown-dwarf secondaries, or even massive planets.

  13. HD 240121 - an ACV variable showing anti-phase variations of the B and V light curves

    CERN Document Server

    Gröbel, Rainer; Paunzen, Ernst; Bernhard, Klaus

    2016-01-01

    The variability of HD 240121 = BD+59 2602 was first suspected by S\\"arg & Wramdemark (1970) and later confirmed by Gr\\"obel (1992a,b). Because of the observed anti-phase variations of the B and V light curves, the latter author tentatively suggested an ACV type. Apart from its inclusion in the catalog of New Suspected Variables (NSV 25977), no further investigations of the star have been published. HD 240121 was included into our target list of ACV candidates and investigated in order to determine the reason for the observed brightness variations. All available information on HD 240121 were collected via an exhaustive data mining procedure. Data from Gr\\"obel (1992a,b) were re-analysed and photometric observations from the NSVS and Hipparcos archives were procured and investigated. Line-of-sight reddening and stellar parameters were calculated from archival photometric data. HD 240121 is a young, late B-type CP2 star of the silicon subgroup. The observed period, amplitude of light variations and variabili...

  14. Hard X-ray photon index as an indicator of bolometric correction in active galactic nuclei

    OpenAIRE

    Zhou, Xin-Lin; Zhao, Yong-Heng

    2010-01-01

    We propose the rest-frame 2-10 keV photon index, \\ga, acting as an indicator of the bolometric correction, \\lb/$L_{\\rm 2-10keV}$ (where \\lb~ is the bolometric luminosity and $L_{\\rm 2-10keV}$ is the rest-frame 2-10 keV luminosity), in radio-quiet active galactic nuclei (AGNs). Correlations between \\ga~ and both bolometric correction and Eddington ratio are presented, based on simultaneous X-ray, UV, and optical observations of reverberation -mapped AGNs. These correlations can be compared wit...

  15. Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars

    CERN Document Server

    Krawczyk, Coleman M; Mehta, Sajjan S; Vogeley, Michael S; Gallagher, S C; Leighly, Karen M; Ross, Nicholas P; Schneider, Donald P; 10.1088/0067-0049/206/1/4

    2013-01-01

    We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119,652 luminous broad-lined quasars with 0.0641.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED dependent. Luminosity-dependent mean SEDs show that, relative to the high-luminosity SED, low-luminosity SEDs exhibit a harder (bluer) far-UV spectral slope, a redder optical continuum, and less hot dust. Mean SEDs constructed instead as a function of UV emission line properties reveal changes that are consistent with known Principal Component Analysis (PCA) trends. A potentially important contribution to the bolometric correction is the unseen extream-UV (EUV) continuum. Our work suggests that lower-luminosity quasars and/or quasars with disk-dominated broad emission lines may require an extra continuum component in the EUV that is not present (or much weaker) in high-luminosity quasars with strong accretion disk winds. As such, we consider four possib...

  16. SOAP-T: a tool to study the light curve and radial velocity of a system with a transiting planet and a rotating spotted star

    Science.gov (United States)

    Oshagh, M.; Boisse, I.; Boué, G.; Montalto, M.; Santos, N. C.; Bonfils, X.; Haghighipour, N.

    2013-01-01

    We present an improved version of SOAP named "SOAP-T", which can generate the radial velocity variations and light curves for systems consisting of a rotating spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and the active zones of their host stars. Tests of the code are presented to illustrate its performance and to validate its capability when compared with analytical models and real data. Finally, we apply SOAP-T to the active star, HAT-P-11, observed by the NASA Kepler space telescope and use this system to discuss the capability of this tool in analyzing light curves for the cases where the transiting planet overlaps with the star's spots. The tool's public interface is available at http://www.astro.up.pt/resources/soap-t/

  17. SOAP-T: A tool to study the light-curve and radial velocity of a system with a transiting planet and a rotating spotted star

    CERN Document Server

    Oshagh, M; Boué, G; Montalto, M; Santos, N C; Bonfils, X; Haghighipour, N

    2012-01-01

    We present an improved version of SOAP (Boisse et al. 2012) named "SOAP-T", which can generate the radial velocity variations and light-curves for systems consisting of a rotating spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light-curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and active zones of their host stars. Tests of the code are presented to illustrate its performance and to validate its capability when compared with analytical models and real data. Finally, we apply SOAP-T to the active star, HAT-P-11, observed by the NASA Kepler space telescope and use this system to discuss the capability of this tool in analyzing light-curves for the cases where the transiting planet overlaps with the star's spots.

  18. A LIGHT-CURVE MODEL OF THE SYMBIOTIC NOVA PU Vul (1979): A VERY QUIET EXPLOSION WITH LONG-LASTING FLAT PEAK

    International Nuclear Information System (INIS)

    We present a light-curve model of the symbiotic nova PU Vul (Nova Vulpeculae 1979) that shows a long-lasting flat peak with no spectral indication of wind mass loss before decline. Our quasi-evolution models consisting of a series of static solutions explain both the optical flat peak and ultraviolet (UV) light curve simultaneously. The white dwarf mass is estimated to be ∼0.6 Msun. We also provide a new determination of the reddening, E(B - V) = 0.43 ± 0.05, from UV spectral analysis. Theoretical light-curve fitting of UV 1455 A provides the distance of d = 3.8 ± 0.7 kpc.

  19. TOWARD CHARACTERIZATION OF THE TYPE IIP SUPERNOVA PROGENITOR POPULATION: A STATISTICAL SAMPLE OF LIGHT CURVES FROM Pan-STARRS1

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, N. E.; Soderberg, A. M.; Chornock, R.; Berger, E.; Challis, P.; Drout, M.; Kirshner, R. P.; Lunnan, R.; Marion, G. H.; Margutti, R.; McKinnon, R.; Milisavljevic, D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gezari, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Betancourt, M. [Department of Statistics, University of Warwick, Coventry (United Kingdom); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Narayan, G. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Rest, A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Kankare, E.; Mattila, S. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö (Finland); Smartt, S. J., E-mail: nsanders@cfa.harvard.edu [Astrophysics Research Centre, School of Mathematics and Physics, Queens University, BT7 1NN, Belfast (United Kingdom); and others

    2015-02-01

    In recent years, wide-field sky surveys providing deep multiband imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SNe): systematic light-curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1, obtained over a constant survey program of 4 yr and classified using both spectroscopy and machine-learning-based photometric techniques. We develop and apply a new Bayesian model for the full multiband evolution of each light curve in the sample. We find no evidence of a subpopulation of fast-declining explosions (historically referred to as ''Type IIL'' SNe). However, we identify a highly significant relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single parameter, likely determined by initial stellar mass, predominantly controlling the explosions of red supergiants. This relation could also be applied for SN cosmology, offering a standardizable candle good to an intrinsic scatter of ≲ 0.2 mag. We compare each light curve to physical models from hydrodynamic simulations to estimate progenitor initial masses and other properties of the Pan-STARRS1 Type IIP SN sample. We show that correction of systematic discrepancies between modeled and observed SN IIP light-curve properties and an expanded grid of progenitor properties are needed to enable robust progenitor inferences from multiband light-curve samples of this kind. This work will serve as a pathfinder for photometric studies of core-collapse SNe to be conducted through future wide-field transient searches.

  20. A catalog of optical/near-infrared data on GRB afterglows in the pre-Swift era. I. Light curve information

    OpenAIRE

    Kann, D. A.; Zeh, A.; Klose, S.

    2005-01-01

    The present catalog is the result of our attempts to collect all published photometric data on GRB afterglows observed in the pre-Swift era by the end of 2004 in order to gain statistical insight on the phenomenology of GRB afterglows. Part I contains all published data on GRB afterglows in filters we used in Zeh, Klose, & Kann (2005) to create reference light curves and derive light curve parameters (mostly R band, but a few bursts have better data in other colors) including the correspondin...

  1. MOST light-curve analysis of the γ Doradus pulsator HR 8799, showing resonances and amplitude variations

    Science.gov (United States)

    Sódor, Á.; Chené, A.-N.; De Cat, P.; Bognár, Zs.; Wright, D. J.; Marois, C.; Walker, G. A. H.; Matthews, J. M.; Kallinger, T.; Rowe, J. F.; Kuschnig, R.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2014-08-01

    Context. The central star of the HR 8799 system is a γ Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not accurately known because the estimation depends greatly on the age of the system, which is also not known with sufficient accuracy. Asteroseismic studies of the star might help to better constrain the age of HR 8799. We organized an extensive photometric and multi-site spectroscopic observing campaign to study the pulsations of the central star. Aims: The aim of the present study is to investigate the pulsation properties of HR 8799 in detail via the ultra-precise 47 d nearly continuous photometry obtained with the Microvariability and Oscillations in STars (MOST) space telescope, and to find as many independent pulsation modes as possible, which is the prerequisite for an asteroseismic age determination. Methods: We carried out Fourier analysis of the wide-band photometric time series. Results: We find that resonance and sudden amplitude changes characterize the pulsation of HR 8799. The dominant frequency is always at f1 = 1.978 d-1.Many multiples of one-ninth of the dominant frequency appear in the Fourier spectrum of the MOST data: n/9 f1, where n = {1,2,3,4,5,6,7,8,9,10,13,14,17,18}. Our analysis also reveals that many of these peaks show strong amplitude decrease and phase variations even on the 47 d time scale. The dependencies between the pulsation frequencies of HR 8799 make the planned subsequent asteroseismic analysis rather difficult. We point out some resemblance between the light curve of HR 8799 and the modulated pulsation light curves of Blazhko RR Lyrae stars. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.

  2. CSI 2264: Characterizing Young Stars in NGC 2264 with Short-Duration, Periodic Flux Dips in their Light Curves

    CERN Document Server

    Stauffer, John; McGinnis, Pauline; Rebull, Luisa; Hillenbrand, Lynne A; Turner, Neal J; Carpenter, John; Plavchan, Peter; Carey, Sean; Terebey, Susan; Morales-Calderón, María; Alencar, Silvia H P; Bouvier, Jerome; Venuti, Laura; Hartmann, Lee; Calvet, Nuria; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Barrado, David; Vrba, Frederick J; Covey, Kevin; Padgett, Debbie; Herbst, William; Gillen, Edward; Lyra, Wladimir; Guimaraes, Marcelo Medeiros; Bouy, Herve; Favata, Fabio

    2015-01-01

    We identify nine young stellar objects (YSOs) in the NGC 2264 star-forming region with optical {\\em CoRoT} light curves exhibiting short-duration, shallow, periodic flux dips. All of these stars have infrared (IR) excesses that are consistent with their having inner disk walls near the Keplerian co-rotation radius. The repeating photometric dips have FWHM generally less than one day, depths almost always less than 15%, and periods (3

  3. The secondary maxima in black hole X-ray nova light curves - Clues toward a complete picture

    Science.gov (United States)

    Chen, Wan; Livio, Mario; Gehrels, Neil

    1993-01-01

    We study the secondary maxima observed commonly in the X-ray/optical light curves of black hole X-ray novae and show that they can play an important role in our understanding of the X-ray nova phenomenon. We discuss the observational characteristics of the secondary maxima and possible mechanisms to produce them. We propose a complete scenario for black hole X-ray nova events. The main outburst is caused by a disk instability. The second maximum is caused by X-ray evaporation of the matter near the inner Lagrangian (L1) region when the disk becomes optically thin. The third maximum (or the final minioutburst) is due to a mass transfer instability caused by hard X-ray heating of the subphotospheric layers of the secondary during the outburst. We predict that the newly discovered X-ray nova GRO J0422 + 32 may develop a final minioutburst in early 1993 and that its binary orbital period is less than 7 hr.

  4. Using Gaussian processes to model light curves in the presence of flickering: the eclipsing cataclysmic variable ASASSN-14ag

    CERN Document Server

    McAllister, M J; Dhillon, V S; Marsh, T R; Ashley, R P; Bours, M C P; Breedt, E; Hardy, L K; Hermes, J J; Kengkriangkrai, S; Kerry, P; Rattanasoon, S; Sahman, D I

    2016-01-01

    The majority of cataclysmic variable (CV) stars contain a stochastic noise component in their light curves, commonly referred to as flickering. This can significantly affect the morphology of CV eclipses and increases the difficulty in obtaining accurate system parameters with reliable errors through eclipse modelling. Here we introduce a new approach to eclipse modelling, which models CV flickering with the help of Gaussian processes (GPs). A parameterised eclipse model - with an additional GP component - is simultaneously fit to 8 eclipses of the dwarf nova ASASSN-14ag and system parameters determined. We obtain a mass ratio $q$ = 0.149 $\\pm$ 0.016 and inclination $i$ = 83.4 $^{+0.9}_{-0.6}$ $^{\\circ}$. The white dwarf and donor masses were found to be $M_{w}$ = 0.63 $\\pm$ 0.04 $M_{\\odot}$ and $M_{d}$ = 0.093 $^{+0.015}_{-0.012}$ $M_{\\odot}$, respectively. A white dwarf temperature $T_{w}$ = 14000 $^{+2200}_{-2000}$ K and distance $d$ = 146 $^{+24}_{-20}$ pc were determined through multicolour photometry. W...

  5. Confirming the 115.5-day periodicity in the X-ray light curve of ULX NGC 5408 X-1

    Institute of Scientific and Technical Information of China (English)

    Xu Han; Tao An; Jun-Yi Wang; Ji-Ming Lin; Ming-Jie Xie; Hai-Guang Xu; Xiao-Yu Hong; Sandor Frey

    2012-01-01

    The Swift/XRT light curve of the ultraluminous X-ray source NGC 5408 X-1 was re-analyzed with two new numerical approaches,the Weighted Wavelet Ztransform and CLEANest,and the results are different from previous studies.Both techniques detected a prominent periodicity with a time scale of 115.5 ± 1.5 days,in excellent agreement with the detection of the same periodicity first reported by Strohmayer.Monte Carlo simulations were employed to test the statisitical confidence of the 115.5-day periodicity,yielding a statistical significance of > 99.98% (or >3.8σ).The robust detection of the 115.5-day quasi-periodic oscillations,if they are due to the orbital motion of the binary,would infer a mass of a few thousand M⊙ for the central black hole,implying there is an intermediate-mass black hole in NGC 5408 X-1.

  6. Noise reduction methods in analysis of near infrared lunar occultation light curves for high angular resolution measurements

    CERN Document Server

    Baug, Tapas

    2013-01-01

    Lunar occultation (LO) technique in the near-infrared provides angular resolution down to milliarcseconds on the occulted source even with ground-based 1m class telescopes. LO observations are limited to brighter objects because they require high signal to noise ratio (S/N ~ 40) for proper extraction of angular diameter values. Hence, methods to improve the S/N ratio by reducing noise using Fourier and Wavelet transforms have been explored in this study. A sample of 54 near-infrared LO light curves observed with IR Camera at Mt Abu observatory has been used. It is seen that both Fourier and Wavelet methods have shown improvement in S/N, compared to the original data. However, the application of wavelet transforms results in slight smoothening of the fringes resulting in a higher angular diameter value. Fourier transforms which reduce discrete noise frequencies do not distort the fringe. Fourier transform method seems to be effective in S/N improvement, as well as improved model fit particularly in the fainter...

  7. Statistical Analysis of the Parameters of Gamma-Ray Bursts with Known Redshifts and Peaked Optical Light Curves

    CERN Document Server

    Beskin, Gregory; Greco, Giuseppe; Karpov, Sergey

    2015-01-01

    We present the statistical analysis of the properties of gamma-ray bursts with measured host galaxy redshifts and peaked optical light curves in proper frames of reference. The optical transients are classified by comparing the time lag of the optical peak relative to the GRB trigger with the duration of the gamma-ray emission itself. The results of the correlation analysis of all possible pairs of energy, spectral, and temporal characteristics of both gamma-ray and optical emissions are given. We specify the pairs of the parameters with correlation coefficients greater than 50 % at significance levels better than 1 %. The following empirical relations, obtained for the first time, are specifically discussed: a correlation between the peak optical afterglow $R$ band luminosity and redshift $L_{R} \\propto (z+1)^{5.39 \\pm 0.74}$ and a correlation between the peak luminosity of the prompt optical emissions and the time of the peak $L_{R} \\propto T_{\\rm peak}^{-3.85 \\pm 1.22}$. We also analyze the similarity of t...

  8. K2SC: Flexible systematics correction and detrending of K2 light curves using Gaussian Process regression

    CERN Document Server

    Aigrain, Suzanne; Pope, Benjamin

    2016-01-01

    We present K2SC (K2 Systematics Correction), a Python pipeline to model instrumental systematics and astrophysical variability in light curves from the K2 mission. K2SC uses Gaussian process regression to model position-dependent systematics and time-dependent variability simultaneously, enabling the user to remove both (e.g., for transit searches) or to remove systematics while preserving variability (for variability studies). For periodic variables, K2SC automatically computes estimates of the period, amplitude and evolution timescale of the variability. We apply K2SC to publicly available K2 data from campaigns 3--5, showing that we obtain photometric precision approaching that of the original Kepler mission. We compare our results to other publicly available K2 pipelines, showing that we obtain similar or better results, on average. We use transit injection and recovery tests to evaluate the impact of K2SC on planetary transit searches in K2 PDC (Pre-search Data Conditioning) data, for planet-to-star radi...

  9. XMM-Newton observations of OY Car III: OM light curve modelling, X-ray timing and spectral studies

    CERN Document Server

    Hakala, P; Hakala, Pasi; Ramsay, Gavin

    2003-01-01

    We revisit the XMM-Newton observations of the dwarf nova OY Car taken in July 2000 which occured shortly after an outburst. Ramsay et al (2001a) found a prominent energy dependent modulation at a period of 2240 sec: this modulation was only seen for app. 1/3 of the observation duration. In our new analysis, we examine this time interval in greater detail. In addition to the 2240 sec period we find evidence for other periods, the most prominent being near 3500 sec. Both these modulations are most likely due to changes in photoelectric absorption over this period: this is supported by phase-resolved spectroscopy. This may indicate the presence of matter above the accretion disc or a presence of a magnetic accretion curtain. In this case the 2240 sec period could represent a spin period of the white dwarf and the 3500 sec period a beat period between the spin and orbital periods. We also model the B band and UV eclipse profiles and light curves using a new technique to map the spatial extent of the accretion dis...

  10. Multi-wavelength light curve evolution of Swift J1357.2-0933 during its 2011 outburst

    CERN Document Server

    Weng, Shan-Shan

    2015-01-01

    Swift J1357.2-0933 underwent an episodic accretion in 2011 and provided very regular temporal and spectral evolution, making it an ideal source for exploring the nature of very faint X-ray transients (VFXTs). In this work, we present a detailed analysis on both X-ray and near-ultraviolet (NUV) light curves. The fluxes at all wavelengths display a near-exponential decays in the early phase and transits to a faster-decay at late times. The e-folding decay time-scales monotonically decrease with photon energies, and the derived viscous time-scale is $\\tau_{\\rm \\dot{M}} \\sim 60$ days. The time-scale in the late faster-decay stage is about a few days. The high ratio of NUV luminosity to X-ray luminosity indicates that the irradiation is unimportant in this outburst, while the near-exponential decay profile and the long decay time-scales conflict with the disc thermal-viscous instability model. We thus suggest that the disc is thermally stable during the observations. Adopting the truncated disc model, we obtain a ...

  11. Discovery of the 2010 Eruption and the Pre-Eruption Light Curve for Recurrent Nova U Scorpii

    CERN Document Server

    Schaefer, Bradley E; Xiao, Limin; Darnley, Matthew J; Bode, Michael F; Harris, Barbara G; Dvorak, Shawn; Menke, John; Linnolt, Michael; Templeton, Matthew; Henden, Arne A; Pojmański, Grzegorz; Pilecki, Bogumil; Szczygiel, Dorota M; Watanabe, Yasunori

    2010-01-01

    We report the discovery by B. G. Harris and S. Dvorak on JD 2455224.9385 (2010 Jan 28.4385 UT) of the predicted eruption of the recurrent nova U Scorpii (U Sco). We also report on 815 magnitudes (and 16 useful limits) on the pre-eruption light curve in the UBVRI and Sloan r' and i' bands from 2000.4 up to 9 hours before the peak of the January 2010 eruption. We found no significant long-term variations, though we did find frequent fast variations (flickering) with amplitudes up to 0.4 mag. We show that U Sco did not have any rises or dips with amplitude greater than 0.2 mag on timescales from one day to one year before the eruption. We find that the peak of this eruption occurred at JD 2455224.69+-0.07 and the start of the rise was at JD 2455224.32+-0.12. From our analysis of the average B-band flux between eruptions, we find that the total mass accreted between eruptions is consistent with being a constant, in agreement with a strong prediction of nova trigger theory. The date of the next eruption can be ant...

  12. Secondary eclipses in the CoRoT light curves: A homogeneous search based on Bayesian model selection

    CERN Document Server

    Parviainen, Hannu; Belmonte, Juan Antonio

    2012-01-01

    We aim to identify and characterize secondary eclipses in the original light curves of all published CoRoT planets using uniform detection and evaluation critetia. Our analysis is based on a Bayesian model selection between two competing models: one with and one without an eclipse signal. The search is carried out by mapping the Bayes factor in favor of the eclipse model as a function of the eclipse center time, after which the characterization of plausible eclipse candidates is done by estimating the posterior distributions of the eclipse model parameters using Markov Chain Monte Carlo. We discover statistically significant eclipse events for two planets, CoRoT-6b and CoRoT-11b, and for one brown dwarf, CoRoT-15b. We also find marginally significant eclipse events passing our plausibility criteria for CoRoT-3b, 13b, 18b, and 21b. The previously published CoRoT-1b and CoRoT-2b eclipses are also confirmed.

  13. MIARMA: An information preserving method for filling gaps in time series. Application to CoRoT light curves

    CERN Document Server

    Pascual-Granado, J; Suárez, J C

    2014-01-01

    The method here presented intends to minimize the effect of the gaps in the power spectra by gap-filling preserving the original information, that is, in the case of asteroseismology, the stellar oscillation frequency content. We make use of a forward-backward predictor based on autoregressive moving average modelling (ARMA) in the time domain. The method MIARMA is particularly suitable for replacing invalid data such as those present in the light curves of the CoRoT satellite due to the pass through the South Atlantic Anomaly, and eventually for the data gathered by the NASA planet hunter Kepler. We select a sample of stars from the ultra-precise photometry collected by the asteroseismic camera on board the CoRoT satellite: the {\\delta} Scuti star HD 174966, showing periodic variations of the same order as the CoRoT observational window, the Be star HD 51193, showing longer time variations, and the solar-like HD 49933, with rapid time variations. We showed that in some cases linear interpolations are less re...

  14. Impacts of different SNLS3 light-curve fitters on cosmological consequences of interacting dark energy models

    CERN Document Server

    Hu, Yazhou; Li, Nan; Wang, Shuang

    2015-01-01

    Aims: We explore the cosmological consequences of interacting dark energy (IDE) models using the Supernova Legacy Survey three-year (SNLS3) data sets. In particular, we focus on the impacts of different SNLS3 light-curve fitters (LCF) (corresponding to the "SALT2", the "SiFTO", and the "Combined" supernova sample). Methods: Firstly, making use of the three SNLS3 data sets, as well as the observational data from the cosmic microwave background (CMB), the galaxy clustering (GC) and the direct measurement of Hubble constant $H_0$, we constrain the parameter spaces of three IDE models. Then, we plot the cosmic evolutions of Hubble diagram $H(z)$, deceleration diagram $q(z)$ and statefinder hierarchy $\\{S^{(1)}_3, S^{(1)}_4\\}$, and check whether or not these dark energy (DE) diagnosis can distinguish the differences among the results of different LCF. At last, we perform high-redshift cosmic age test using three old high redshift objects (OHRO), and explore the fate of the Universe. Results: For all the IDE models...

  15. On the Photometric Error Calibration for the Differential Light Curves of Point-like Active Galactic Nuclei

    Indian Academy of Sciences (India)

    Arti Goyal; Mukul Mhaskey; Gopal-Krishna; Paul J. Wiita; C. S. Stalin; Ram Sagar

    2013-09-01

    It is important to quantify the underestimation of rms photometric errors returned by the commonly used APPHOT algorithm in the IRAF software, in the context of differential photometry of point-like AGN, because of the crucial role it plays in evaluating their variability properties. Published values of the underestimation factor, , using several different telescopes, lie in the range 1.3–1.75. The present study aims to revisit this question by employing an exceptionally large data set of 262 differential light curves (DLCs) derived from 262 pairs of non-varying stars monitored under our ARIES AGN monitoring program for characterizing the intra-night optical variability (INOV) of prominent AGN classes. The bulk of these data were taken with the 1-m Sampurnanad Telescope (ST). We find = 1.54 ± 0.05 which is close to our recently reported value of = 1.5. Moreover, this consistency holds at least up to a brightness mismatch of 1.5 mag between the paired stars. From this we infer that a magnitude difference of at least up to 1.5 mag between a point-like AGN and comparison star(s) monitored simultaneously is within the same CCD chip acceptable, as it should not lead to spurious claims of INOV.

  16. M dwarfs in the b201 tile of the VVV survey: Colour-based Selection, Spectral Types and Light Curves

    CERN Document Server

    Rojas-Ayala, Bárbara; Minniti, Dante; Saito, Roberto K; Surot, Francisco

    2014-01-01

    The intrinsically faint M dwarfs are the most numerous stars in the Galaxy, have main-sequence lifetimes longer than the Hubble time, and host some of the most interesting planetary systems known to date. Their identification and classification throughout the Galaxy is crucial to unravel the processes involved in the formation of planets, stars and the Milky Way. The ESO Public Survey VVV is a deep near-IR survey mapping the Galactic bulge and southern plane. The VVV b201 tile, located in the border of the bulge, was specifically selected for the characterisation of M dwarfs. We used VISTA photometry to identify M dwarfs in the VVV b201 tile, to estimate their subtypes, and to search for transit-like light curves from the first 26 epochs of the survey. UKIDSS photometry from SDSS spectroscopically identified M dwarfs was used to calculate their expected colours in the $YJHK_s$ VISTA system. A colour-based spectral subtype calibration was computed. Possible giants were identified by a $(J-K_s, H_{J})$ reduced ...

  17. CCD Photometry of the globular cluster NGC 5466. RR Lyrae light curve decomposition and the distance scale

    CERN Document Server

    Ferro, A Arellano; Giridhar, Sunetra; Bramich, D M

    2007-01-01

    We report the results of CCD V and r photometry of the globular cluster NGC 5466. The difference image analysis technique adopted in this work has resulted in accurate time series photometry even in crowded regions of the cluster enabling us to discover five probably semi-regular variables. We present new photometry of three previously known eclipsing binaries and six SX Phe stars. The light curves of the RR Lyrae stars have been decomposed in their Fourier harmonics and their fundamental physical parameters have been estimated using semi-empirical calibrations. The zero points of the metallicity, luminosity and temperature scales are discussed and our Fourier results are transformed accordingly. The average iron abundance and distance to the Sun derived from individual RR Lyrae stars, indicate values of [Fe/H]=-1.91 +- 0.19 and D = 16.0 +- 0.6 kpc, or a true distance modulus of 16.02 +- 0.09 mag, for the parent cluster. These values are respectively in the Zinn & West metallicity scale and in agreement w...

  18. CUORE and beyond: bolometric techniques to explore inverted neutrino mass hierarchy

    CERN Document Server

    Artusa, D R; Azzolini, O; Balata, M; Banks, T I; Bari, G; Beeman, J; Bellini, F; Bersani, A; Biassoni, M; Brofferio, C; Bucci, C; Cai, X Z; Camacho, A; Canonica, L; Cao, X G; Capelli, S; Carbone, L; Cardani, L; Carrettoni, M; Casali, N; Chiesa, D; Chott, N; Clemenza, M; Copello, S; Cosmelli, C; Cremonesi, O; Creswick, R J; Dafinei, I; Dally, A; Datskov, V; De Biasi, A; Deninno, M M; Di Domizio, S; di Vacri, M L; Ejzak, L; Fang, D Q; Farach, H A; Faverzani, M; Fernandes, G; Ferri, E; Ferroni, F; Fiorini, E; Franceschi, M A; Freedman, S J; Fujikawa, B K; Giachero, A; Gironi, L; Giuliani, A; Goett, J; Gorla, P; Gotti, C; Gutierrez, T D; Haller, E E; Han, K; Heeger, K M; Hennings-Yeomans, R; Huang, H Z; Kadel, R; Kazkaz, K; Keppel, G; Kolomensky, Yu G; Li, Y L; Ligi, C; Liu, X; Ma, Y G; Maiano, C; Maino, M; Martinez, M; Maruyama, R H; Mei, Y; Moggi, N; Morganti, S; Napolitano, T; Nisi, S; Nones, C; Norman, E B; Nucciotti, A; O'Donnell, T; Orio, F; Orlandi, D; Ouellet, J L; Pallavicini, M; Palmieri, V; Pattavina, L; Pavan, M; Pedretti, M; Pessina, G; Pettinacci, V; Piperno, G; Pira, C; Pirro, S; Previtali, E; Rampazzo, V; Rosenfeld, C; Rusconi, C; Sala, E; Sangiorgio, S; Scielzo, N D; Sisti, M; Smith, A R; Taffarello, L; Tenconi, M; Terranova, F; Tian, W D; Tomei, C; Trentalange, S; Ventura, G; Vignati, M; Wang, B S; Wang, H W; Wielgus, L; Wilson, J; Winslow, L A; Wise, T; Woodcraft, A; Zanotti, L; Zarra, C; Zhu, B X; Zucchelli, S

    2014-01-01

    The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of $^{130}$Te. With 741 kg of TeO$_2$ crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is $1.6\\times 10^{26}$ y at $1\\sigma$ ($9.5\\times10^{25}$ y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40--100 meV (50--130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with $^{130}$Te and possibly other double beta decay candidate nuclei.

  19. Young and middle age pulsar light-curve morphology: Comparison of Fermi observations with gamma-ray and radio emission geometries

    CERN Document Server

    Pierbattista, M; Gonthier, P L; Grenier, I A

    2016-01-01

    Thanks to the huge amount of gamma-ray pulsar photons collected by the Fermi Large Area Telescope since June 2008, it is now possible to constrain gamma-ray geometrical models by comparing simulated and observed light-curve morphological characteristics. We assumed vacuum-retarded dipole pulsar magnetic field and tested simulated and observed morphological light-curve characteristics in the framework of two pole emission geometries, Polar Cap (PC), radio, and Slot Gap (SG), and Outer Gap (OG)/One Pole Caustic (OPC) emission geometries. We compared simulated and observed/estimated light-curve morphological parameters as a function of observable and non-observable pulsar parameters. The PC model gives the poorest description of the LAT pulsar light-curve morphology. The OPC best explains both the observed gamma-ray peak multiplicity and shape classes. The OPC and SG models describe the observed gamma-ray peak-separation distribution for low- and high-peak separations, respectively. This suggests that the OPC ge...

  20. Secular Light Curves of Comets C/2011 L4 Panstarrs and C/2012 S1 ISON Compared to 1P/Halley

    CERN Document Server

    Ferrin, Ignacio

    2013-01-01

    We used 1329 observations of comet C/2011 L4 Panstarrs and 1897 observations of C/2012 S1 ISON to create the Secular Light Curves (SLCs), and to compare them to comet 1P/Halley (3172 observations). These comets are at the present time approaching perihelion. Thus the information contained in this report is preliminary.

  1. Inferring supernova IIb/Ib/Ic ejecta properties from light curves and spectra: Correlations from radiative-transfer models

    CERN Document Server

    Dessart, Luc; Woosley, Stan; Livne, Eli; Waldman, Roni; Yoon, Sung-Chul; Langer, Norbert

    2016-01-01

    We present 1-D non-Local-Thermodynamic-Equilibrium time-dependent radiative-transfer simulations for a large grid of supernovae (SNe) IIb/Ib/Ic that result from the terminal explosion of the mass donor in a close-binary system. Our sample covers ejecta masses $M_{\\rm e}$ of 1.7$-$5.2M$_\\odot$, kinetic energies $E_{\\rm kin}$ of 0.6$-$5.0$\\times$10$^{51}$erg, and $^{56}$Ni masses of 0.05$-$0.30M$_\\odot$. We find a strong correlation between the $^{56}$Ni mass and the photometric properties at maximum, and between the rise time to bolometric maximum and the post-maximum decline rate. We confirm the small scatter in ($V-R$) at 10d past $R$-band maximum. The quantity $V_{\\rm m} \\equiv \\sqrt{2E_{\\rm kin}/M_{\\rm e}}$ is comparable to the Doppler velocity measured from HeI 5875\\AA\\ at maximum in SNe IIb/Ib, although some scatter arises from the uncertain level of chemical mixing. The OI7772\\AA\\ line may be used for SNe Ic, but the correspondence deteriorates with higher ejecta mass/energy. We identify a temporal reve...

  2. Impacts of different SNLS3 light-curve fitters on cosmological consequences of interacting dark energy models

    Science.gov (United States)

    Hu, Yazhou; Li, Miao; Li, Nan; Wang, Shuang

    2016-08-01

    We explore the cosmological consequences of interacting dark energy (IDE) models using the SNLS3 supernova samples. In particular, we focus on the impacts of different SNLS3 light-curve fitters (LCF; referred to in this paper as SALT2, SiFTO and combined sample). Firstly, making use of the three SNLS3 data sets, as well as the Planck distance priors data and the galaxy clustering data, we constrain the parameter spaces of three IDE models. Then, we study the cosmic evolutions of Hubble parameter H(z), deceleration diagram q(z), statefinder hierarchy S(1)3(z) and S(1)4(z), and check whether or not these dark energy diagnosis can distinguish the differences among the results of different SNLS3 LCF. Finally, we perform a high redshift cosmic age test using three old high redshift objects (OHRO), and explore the fate of the Universe. We find that the impacts of different SNLS3 LCF are rather small, and can not be distinguished using H(z), q(z), S(1)3(z), S(1)4(z), and the age data of OHRO. In addition, we infer, from the current observations, how far we are from a cosmic doomsday in the worst case, and find that the combined sample always gives the largest 2σ lower limit of the time interval between "big rip" and today, while the results given by the SALT2 and the SiFTO sample are similar. These conclusions are insensitive to a specific form of dark sector interaction. Our method can be used to distinguish the differences among various cosmological observations.

  3. Aeolus: A Markov--Chain Monte Carlo code for mapping ultracool atmospheres. An application on Jupiter and brown dwarf HST light curves

    CERN Document Server

    Karalidi, Theodora; Schneider, Glenn; Hanson, Jake R; Pasachoff, Jay M

    2015-01-01

    Deducing the cloud cover and its temporal evolution from the observed planetary spectra and phase curves can give us major insight into the atmospheric dynamics. In this paper, we present Aeolus, a Markov-Chain Monte Carlo code that maps the structure of brown dwarf and other ultracool atmospheres. We validated Aeolus on a set of unique Jupiter Hubble Space Telescope (HST) light curves. Aeolus accurately retrieves the properties of the major features of the jovian atmosphere such as the Great Red Spot and a major 5um hot spot. Aeolus is the first mapping code validated on actual observations of a giant planet over a full rotational period. For this study, we applied Aeolus to J and H-bands HST light curves of 2MASSJ21392676+0220226 and 2MASSJ0136565+093347. Aeolus retrieves three spots at the top-of-the-atmosphere (per observational wavelength) of these two brown dwarfs, with a surface coverage of 21+-3% and 20.3+-1.5% respectively. The Jupiter HST light curves will be publicly available via ADS/VIZIR.

  4. VARLET and PHALET two wavelet based filter methods to separate stellar variation, orbital disturbances and instrumental effects from transit events in stellar light curves.

    Science.gov (United States)

    Grziwa, S.; Korth, J.; Pätzold, M.

    2014-04-01

    The space telescopes CoRoT and Kepler provided a huge number of high-resolution stellar light curves. The light curves are searched for transit signals which may be produced by planets when passing in front of the stellar disc. Various flux variations by star spots, pulsation, flares, glitches, hot pixels etc., however, dominate the stellar light curves and mask faint transit signals in particular of small exoplanets, which may lead to missed candidates or a high rate of false detections. Full automated filtering and detection algorithms only make it possible to manage the huge number of stellar light curves to search for transits. This will become even more important in the future missions PLATO and TESS. The Rheinisches Institut für Umweltforschung (RIUPF) as one of the CoRoT detection teams has developed two model independent wavelet based filter techniques VARLET and PHALET to reduce the flux variability in light curves in order to improve the search for transits. The VARLET filter separates faint transit signals from stellar variations without using a-priori information of the target star. VARLET distinguishes variations by frequency, amplitude and shape. VARLET separates the large-scale variations from the white noise. The transit feature, however, is not extracted and still contained in the noise time series which makes it now much easier to search for transits by the search routine EXOTRANS (Grziwa, S. et al.2012 [1]). The PHALET filter is used to separate periodic features with well-known periods independent of their shape. With PHALET it is possible to separate detected diluting binaries and other periodic effects (e.g. disturbances caused by the spacecraft motion in the Earth orbit). The main purpose, however, is to separate already detected transits to search for transits from additional planets in the stellar systems. RIU-PF searched all Kepler light curves for planetary transits by including VARLET and PHALET in the processing pipeline. The results

  5. Present and future of double-beta decay searches with bolometric detectors

    Science.gov (United States)

    Cardani, L.

    2016-01-01

    Thanks to the excellent energy resolution, high efficiency and versatility, bolometric detectors are primed for the search of neutrinoless double-beta decay (0 ν DBD). The most advanced bolometric experiment, CUORE, is studying the 0 ν DBD of 130Te using a 741kg array of TeO2 crystals. CUORE points to a 90% CL sensitivity on the half-life of 0 ν DBD of 9.5×1025 yr in 5yr, corresponding to an upper limit on the neutrino Majorana mass of 50-130meV. This sensitivity will allow to touch, but not to explore, the region corresponding to the inverted hierarchy mass scenario. In this document I present the status of CUORE and the possible upgrades of the bolometric technology in view of a next generation experiment.

  6. Rejection of Alpha Surface Background in Non-scintillating Bolometric Detectors: The ABSuRD Project

    Science.gov (United States)

    Biassoni, M.; Brofferio, C.; Bucci, C.; Canonica, L.; di Vacri, M. L.; Gorla, P.; Pavan, M.; Yeh, M.

    2016-08-01

    Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation-based technique for the rejection of surface alpha background in non-scintillating bolometric experiments is proposed in this work. The idea is to combine a scintillating and a high sensitivity photon detector with a non-scintillating absorber. We present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.

  7. Photometric observations and light curve solutions of the W UMa stars NSVS 2244206, NSVS 908513, CSS J004004.7+385531 and VSX J062624.4+570907

    Science.gov (United States)

    Kjurkchieva, Diana Petrova; Popov, Velimir Angelov; Vasileva, Doroteya Lyubenova; Petrov, Nikola Ivanov

    2016-09-01

    Photometric observations in Sloan g‧ and i‧ bands of four W UMa stars, NSVS 2244206, NSVS 908513, CSS J004004.7+385531 and VSX J062624.4+570907, are presented. The light curve solutions reveal that all targets have overcontact configurations with fillout factors within 0.15–0.26. Their components are G-K spectral types and are almost in thermal contact. They are also relatively close in size and luminosity: the radius ratios r2/r1 are within 0.75–0.90 the luminosity ratios l2/l1 are within 0.53–0.63. The results of the light curve solution of CSS J004004.7+385531 imply the weak limb-darkening effect of its primary component and possible presence of additional absorbing features in the system.

  8. 128 x 128 pixel uncooled bolometric FPA for IR detection and imaging

    Science.gov (United States)

    Jerominek, Hubert; Pope, Timothy D.; Alain, Christine; Zhang, Rose; Lehoux, Mario; Picard, Francis; Fuchs, R. Wayne; Grenier, Carol; Rouleau, Yves; Cayer, Felix; Savard, Simon; Bilodeau, Ghislain; Couillard, Jean-Francois; Larouche, Carl; Ngo, Linh P.

    1998-10-01

    An uncooled IR camera making use of a 128 X 128 pixel bolometric FPA is presented. The reconfigurable bolometric focal plane array consist of 50 micrometer X 50 micrometer pixels and simple on-chip CMOS readout electronics which can be operated in random access, independent row and column clocking, and self-scanning modes. Depending on the selected pixel format and frame rate, the FPA's NETD varies from 0.52 degrees Celsius down to 0.10 degrees Celsius. The modular IR camera is software configured and provides RS170A analog video and 12-bit TTL format digital outputs.

  9. Design, fabrication, and calibration of curved integral coils for measuring transfer function, uniformity, and effective length of LBL ALS [Lawrence Berkeley Laboratory Advanced Light Source] Booster Dipole Magnets

    International Nuclear Information System (INIS)

    A matched pair of curved integral coils has been designed, fabricated and calibrated at Lawrence Berkeley Laboratory for measuring Advanced Light Source (ALS) Booster Dipole Magnets. Distinctive fabrication and calibration techniques are described. The use of multifilar magnet wire in fabrication integral search coils is described. Procedures used and results of AC and DC measurements of transfer function, effective length and uniformity of the prototype booster dipole magnet are presented in companion papers. 8 refs

  10. Four-colour photometry of eclipsing binaries. XLI uvby light curves for AD Bootis, HW Canis Majoris, SW Canis Majoris, V636 Centauri, VZ Hydrae, and WZ Ophiuchi

    CERN Document Server

    Clausen, J V; García, J M; Giménez, A; Helt, B E; Olsen, E H; Andersen, J

    2008-01-01

    CONTEXT: Accurate mass, radius, and abundance determinations from binaries provide important information on stellar evolution, fundamental to central fields in modern astrophysics and cosmology. AIMS: Within the long-term Copenhagen Binary Project, we aim to obtain high-quality light curves and standard photometry for double-lined detached eclipsing binaries with late A, F, and G type main-sequence components, needed for the determination of accurate absolute dimensions and abundances, and for detailed comparisons with results from recent stellar evolutionary models. METHODS: Between March 1985 and July 2007, we carried out photometric observations of AD Boo, HW CMA, SW CMa, V636 Cen, VZ Hya, and WZ Oph at the Str"omgren Automatic Telescope at ESO, La Silla. RESULTS: We obtained complete uvby light curves, ephemerides, and standard uvby\\beta indices for all six systems.For V636 Cen and HW CMa, we present the first modern light curves, whereas for AD Boo, SW CMa, VZ Hya, and WZ Oph, they are both more accurate...

  11. GALEX and Optical Light Curves of WX LMi, SDSSJ103100.5+202832.2 and SDSSJ121209.31+013627.7

    CERN Document Server

    Linnell, Albert P; Plotkin, Richard M; Holtzman, Jon; Seibert, Mark; Harrison, Thomas E; Howell, Steve B

    2010-01-01

    {\\it GALEX} near ultraviolet (NUV) and far-ultraviolet (FUV) light curves of three extremely low accretion rate polars show distinct modulations in their UV light curves. While these three systems have a range of magnetic fields from 13 to 70 MG, and of late type secondaries (including a likely brown dwarf in SDSSJ121209.31+013627.7), the accretion rates are similar, and the UV observations imply some mechanism is operating to create enhanced emission zones on the white dwarf. The UV variations match in phase to the two magnetic poles viewed in the optical in WX LMi and to the single poles evident in the optical in SDSSJ1212109.31+013627.7 and SDSSJ103100.55+202832.2. Simple spot models of the UV light curves show that if hot spots are responsible for the UV variations, the temperatures are on the order of 10,000-14,000K. For the single pole systems, the size of the FUV spot must be smaller than the NUV and in all cases, the geometry is likely more complicated than a simple circular spot.

  12. Blue and IR Light Curves of the Mysterious Pre-Main Sequence Star V582 Mon (KH 15D) from 1955 to 1970

    CERN Document Server

    Maffei, P; Tosti, G; Maffei, Paolo; Ciprini, Stefano; Tosti, Gino

    2004-01-01

    In recent years, an increasing number of publications have been addressed to the peculiar and mysterious pre-main sequence star V582 Mon, also known as KH 15D. This extraordinary T Tauri star, located in the young star cluster NGC 2264, appears as to be an eclipsing variable. In the present paper, we report a unique and self-consistent set of light curves in the blue and near-infrared bands, spanning a 15-year interval (epoch 1955-1970). Our photometric data show clearly the beginning of the eclipse stage occurred in early 1958 in the blue, and perhaps around four years later in the infrared. The light curve period turns out to be the same reported by recent observations (about 48.3 days), so that no evidence for a period change results. On the other hand, in our data the light curve shape appears as sinusoidal and is therefore different from the one displayed today. The photometric behaviour, determined with time-series and colour-index analysis, suggests that V582 Mon (KH 15D) could be initially surrounded ...

  13. Optical light curve of GRB 121011A: a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium

    CERN Document Server

    Xin, Li-Ping; Qiu, Yu-Lei; Deng, Jin-Song; Wang, Jing; Han, Xu-Hui

    2016-01-01

    We reported the optical observations of GRB 121011A by 0.8-m TNT telescope at Xinglong observatory, China. The light curve of optical afterglow shows a smooth and featureless bump during the epoch of $\\sim$130 sec and $\\sim$5000 sec with a rising index of $1.57\\pm0.28$ before the break time of $539\\pm44$ sec, and a decaying index of about $1.29\\pm0.07$ up to the end of our observations. Meanwhile, the X-ray light curve decays in a single power-law with a slop of about $1.51\\pm0.03$ observed by $XRT$ onboard ${\\rm} Swift$ from 100 sec to about 10000 sec after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysi...

  14. The prompt-afterglow connection in Gamma-Ray Bursts: a comprehensive statistical analysis of Swift X-ray light-curves

    CERN Document Server

    Margutti, R; Bernardini, M G; Chincarini, G; Pasotti, F; Guidorzi, C; Angelini, L; Burrows, D N; Capalbi, M; Evans, P A; Gehrels, N; Kennea, J; Mangano, V; Moretti, A; Nousek, J; Osborne, J P; Page, K L; Perri, M; Racusin, J; Romano, P; Sbarufatti, B; Stafford, S; Stamatikos, M

    2012-01-01

    We present a comprehensive statistical analysis of Swift X-ray light-curves of Gamma-Ray Bursts (GRBs), collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the rest-frame X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time scales and the energetics of the different light-curve phases, with the final aim of distinguishing between competing models. Variability episodes superimposed on smooth light-curve decays are also studied and their properties constrained. Two fundamental questions drive this effort: i) Does the X-ray emission retain any kind of "memory" of the prompt gamma-ray phase? ii) Where is the dividing line between long and short GRB X-ray properties? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs in the X-rays, but are interestingly characterized by very similar intrinsic absorption. We furthermore reveal the existence of a nu...

  15. TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

    International Nuclear Information System (INIS)

    We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a given supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty

  16. The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric interferometer (MBI)

    Science.gov (United States)

    Timbie, P. T.; Tucker, G. S.; Ade, P. A. R.; Ali, S.; Bierman, E.; Bunn, E. F.; Calderon, C.; Gault, A. C.; Hyland, P. O.; Keating, B. G.; Kim, J.; Korotkov, A.; Malu, S. S.; Mauskopf, P.; Murphy, J. A.; O'Sullivan, C.; Piccirillo, L.; Wandelt, B. D.

    2006-12-01

    We provide an overview of a mission concept study underway for the Einstein Inflation Probe (EIP). Our study investigates the advantages and tradeoffs of using an interferometer (EPIC) for the mission. We also report on the status of the millimeter-wave bolometric interferometer (MBI), a ground-based pathfinder optimized for degree-scale CMB polarization measurements at 90 GHz.

  17. Piecing together the X-ray background: bolometric corrections for active galactic nuclei

    Science.gov (United States)

    Vasudevan, R. V.; Fabian, A. C.

    2007-11-01

    The X-ray background can be used to constrain the accretion history of supermassive black holes (SMBHs) in active galactic nuclei (AGN), with the SMBH mass density related to the energy density due to accretion. A knowledge of the hard X-ray bolometric correction, κ2-10keV, is a vital input into these studies, as it allows us to constrain the parameters of the accretion responsible for SMBH growth. Earlier studies assumed a constant bolometric correction for all AGN, and more recent work has suggested accounting for a dependence on AGN luminosity. Until recently, the variations in the disc emission in the ultraviolet (UV) have not been taken into account in this calculation; we show that such variations are important by construction of optical-to-X-ray spectral energy distributions for 54 AGN. In particular, we use Far Ultraviolet Spectroscopic Explorer (FUSE) UV and X-ray data from the literature to constrain the disc emission as well as possible. We find evidence for very significant spread in the bolometric corrections, with no simple dependence on luminosity being evident. Populations of AGN such as narrow-line Seyfert 1 nuclei, radio-loud and X-ray-weak AGN may have bolometric corrections which differ systematically from the rest of the AGN population. We identify other sources of uncertainty including intrinsic extinction in the optical-UV, X-ray and UV variability and uncertainties in SMBH mass estimates. Our results suggest a more well-defined relationship between the bolometric correction and Eddington ratio in AGN, with a transitional region at an Eddington ratio of ~0.1, below which the bolometric correction is typically 15-25, and above which it is typically 40-70. We consider the potential-implied parallels with the low/hard and high/soft states in Galactic black hole (GBH) accretion, and present bolometric corrections for the GBH binary GX 339-4 for comparison. Our findings reinforce previous studies proposing a multistate description of AGN

  18. Chlorophyll a fluorescence responses of temperate Phaeophyceae under submersion and emersion regimes: a comparison of rapid and steady-state light curves.

    Science.gov (United States)

    Nitschke, Udo; Connan, Solène; Stengel, Dagmar B

    2012-10-01

    The potential of algae to acclimate to environmental stress is commonly assessed using chlorophyll a fluorescence, with changes in parameters of photosynthesis versus irradiance (P/E) curves measured either as rapid light curves (RLC) or steady-state light curves (LC). Here, effects of emersion on primary photosynthesis of four brown macroalgae (Ascophyllum nodosum, Fucus serratus, Sargassum muticum, Laminaria digitata) were compared by applying both RLC and LC. When LC were used, photosynthetic performance was enhanced during emersion in A. nodosum and F. serratus as shown by increases in q(P), rETR(max) and E(k). By contrast, emersion had no impact on photosynthetic parameters of S. muticum and L. digitata. Relative changes in the NPQ-rETR relationship were reduced in A. nodosum, F. serratus and S. muticum, but remained unaffected in L. digitata. As none of the species developed their potential NPQ(max), corresponding values could not be determined from RLC. Using RLC, observed photosynthetic performance of F. serratus and L. digitata was reduced upon emersion, whilst values for NPQ(max) were enhanced. Only results derived from LC provide evidence for a potential physiological adaptation of brown macroalgae to their natural habitat; it is recommended using the LC protocol to detect environmental impacts on photosynthesis. PMID:22915336

  19. Candidates of eclipsing multiples based on extraneous eclipses on binary light curves: KIC 7622486, KIC 7668648, KIC 7670485 and KIC 8938628

    CERN Document Server

    Zhang, Jia; He, Jian-Duo

    2016-01-01

    Four candidates of eclipsing multiples, based on new extraneous eclipses found on Kepler binary light curves, are presented and studied. KIC 7622486 is a double eclipsing binary candidate with orbital period of 2.2799960 days and 40.246503 days. The two binary systems do not eclipse each other in the line of sight, but there is mutual gravitational influence between them which leads to the small but definite eccentricity 0.0035(0.0022) on the short 2.2799960 days period orbit. KIC 7668648 is hierarchical quadruple system candidate, with two sets of solid 203(+-5) days period extraneous eclipses and another independent set of extraneous eclipses. A clear and credible extraneous eclipse is found on the binary light curve of KIC 7670485 which made it a triple system candidates. Two sets of extraneous eclipse of about 390 days and 220 days period are found on KIC 8938628 binary curves, which not only confirms the previous conclusion of $388.5(+-0.3) triple system, but also proposed a new additional objects that m...

  20. Column Store for GWAC: A High-cadence, High-density, Large-scale Astronomical Light Curve Pipeline and Distributed Shared-nothing Database

    Science.gov (United States)

    Wan, Meng; Wu, Chao; Wang, Jing; Qiu, Yulei; Xin, Liping; Mullender, Sjoerd; Mühleisen, Hannes; Scheers, Bart; Zhang, Ying; Nes, Niels; Kersten, Martin; Huang, Yongpan; Deng, Jinsong; Wei, Jianyan

    2016-11-01

    The ground-based wide-angle camera array (GWAC), a part of the SVOM space mission, will search for various types of optical transients by continuously imaging a field of view (FOV) of 5000 degrees2 every 15 s. Each exposure consists of 36 × 4k × 4k pixels, typically resulting in 36 × ∼175,600 extracted sources. For a modern time-domain astronomy project like GWAC, which produces massive amounts of data with a high cadence, it is challenging to search for short timescale transients in both real-time and archived data, and to build long-term light curves for variable sources. Here, we develop a high-cadence, high-density light curve pipeline (HCHDLP) to process the GWAC data in real-time, and design a distributed shared-nothing database to manage the massive amount of archived data which will be used to generate a source catalog with more than 100 billion records during 10 years of operation. First, we develop HCHDLP based on the column-store DBMS of MonetDB, taking advantage of MonetDB’s high performance when applied to massive data processing. To realize the real-time functionality of HCHDLP, we optimize the pipeline in its source association function, including both time and space complexity from outside the database (SQL semantic) and inside (RANGE-JOIN implementation), as well as in its strategy of building complex light curves. The optimized source association function is accelerated by three orders of magnitude. Second, we build a distributed database using a two-level time partitioning strategy via the MERGE TABLE and REMOTE TABLE technology of MonetDB. Intensive tests validate that our database architecture is able to achieve both linear scalability in response time and concurrent access by multiple users. In summary, our studies provide guidance for a solution to GWAC in real-time data processing and management of massive data.