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Sample records for bright hii region

  1. HRM: HII Region Models

    Science.gov (United States)

    Wenger, Trey V.; Kepley, Amanda K.; Balser, Dana S.

    2017-07-01

    HII Region Models fits HII region models to observed radio recombination line and radio continuum data. The algorithm includes the calculations of departure coefficients to correct for non-LTE effects. HII Region Models has been used to model star formation in the nucleus of IC 342.

  2. Finding Distant Galactic HII Regions

    CERN Document Server

    Anderson, L D; Johnstone, B M; Bania, T M; Balser, Dana S; Wenger, Trey V; Cunningham, V

    2015-01-01

    The WISE Catalog of Galactic HII Regions contains $\\sim2000$ HII region candidates lacking ionized gas spectroscopic observations. All candidates have the characteristic HII region mid-infrared morphology of WISE $12\\,\\,\\mu\\,m$ emission surrounding $22\\,\\mu\\,m$ emission, and additionally have detected radio continuum emission. We here report Green Bank Telescope (GBT) hydrogen radio recombination line (RRL) and radio continuum detections at X-band (9GHz; 3cm) of 302 WISE HII region candidates (out of 324 targets observed) in the zone $225^{\\circ} > l > -20^{\\circ}$, $|b| \\le 6^{\\circ}$. Here we extend the sky coverage of our HII region Discovery Survey (HRDS), which now contains nearly 800 HII regions distributed across the entire northern sky. We provide LSR velocities for the 302 detections and kinematic distances for 131 of these. Of the 302 new detections, five have ($l, b, v$) coordinates consistent with the Outer Scutum-Centaurus Arm (OSC), the most distant molecular spiral arm of the Milky Way. Due to ...

  3. On the structure of giant HII regions and HII galaxies

    CERN Document Server

    Tenorio-Tagle, G; Pérez, E; Silich, S; Telles, E

    2006-01-01

    We review the structural properties of giant extragalactic HII regions and HII galaxies based on two dimensional hydrodynamic calculations, and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus exposed to the most important star-formation feedback mechanisms: photoionization and the cluster wind. The models show how the two feedback mechanisms compete with each other in the disruption of clouds and lead to two different hydrodynamic solutions: The storage of clouds into a long lasting ragged shell that inhibits the expansion of the thermalized wind, and the steady filtering of the shocked wind gas through channels carved within the cloud stratum that results into the creation of large-scale superbubbles. Both solutions are here claimed to be concurrently at work in giant HII regions and HII galaxies, causing their detailed inner structure. A full description of t...

  4. Determining the Hubble constant using HII regions and HII galaxies

    CERN Document Server

    Chavez, Ricardo; Terlevich, Roberto; Plionis, Manolis; Bresolin, Fabio; Basilakos, Spyros; Melnick, Jorge

    2012-01-01

    We report the first results of a long term program aiming to provide accurate independent estimates of the Hubble constant (H0) and the Dark Energy equation of state parameter (w) using the L(Hbeta)-velocity dispersion (sigma) distance estimator for Giant HII regions and HII galaxies. We have used VLT and Subaru high dispersion spectroscopic observations of a local sample of HII galaxies, identified in the SDSS DR7 catalogue in order to re-define and improve the L(Hbeta) - sigma distance indicator and to determine the Hubble constant. To this end we used as local calibration or 'anchor' of this correlation, giant HII regions in nearby galaxies which have accurate distance measurements determined via primary indicators. Using our best sample of 89 nearby HII galaxies and 23 Giant HII regions in 9 galaxies we obtain H0 = 73.9+- 2.7 (statistical)+- 2.9 (systematic) km s-1 Mpc-1, in excellent agreement with, and independently confirming, the most recent SNe Ia based results.

  5. The WISE Catalog of Galactic HII Regions

    CERN Document Server

    Anderson, L D; Balser, Dana S; Cunningham, V; Wenger, T V; Johnstone, B M; Armentrout, W P

    2013-01-01

    Using data from the all-sky Wide-Field Infrared Survey Explorer (WISE) satellite, we made a catalog of over 8000 Galactic HII regions and HII region candidates by searching for their characteristic mid-infrared (MIR) morphology. WISE has sufficient sensitivity to detect the MIR emission from HII regions located anywhere in the Galactic disk. We believe this is the most complete catalog yet of regions forming massive stars in the Milky Way. Of the ~8000 cataloged sources, ~1500 have measured radio recombination line (RRL) or H$\\alpha$ emission, and are thus known to be HII regions. This sample improves on previous efforts by resolving HII region complexes into multiple sources and by removing duplicate entries. There are ~2500 candidate HII regions in the catalog that are spatially coincident with radio continuum emission. Our group's previous RRL studies show that ~95% of such targets are HII regions. We find that ~500 of these candidates are also positionally associated with known HII region complexes, so th...

  6. Interstellar Bubbles in Two Young HII Regions

    CERN Document Server

    Naze, Y; Points, S D; Danforth, C W; Rosado, M; Chen, C H R; Naze, Yael; Chu, You-Hua; Points, Sean D.; Danforth, Charles W.; Rosado, Margarita

    2001-01-01

    Massive stars are expected to produce wind-blown bubbles in the interstellar medium; however, ring nebulae, suggesting the existence of bubbles, are rarely seen around main-sequence O stars. To search for wind-blown bubbles around main-sequence O stars, we have obtained high-resolution Hubble Space Telescope WFPC2 images and high-dispersion echelle spectra of two pristine HII regions, N11B and N180B, in the Large Magellanic Cloud. These HII regions are ionized by OB associations that still contain O3 stars, suggesting that the HII regions are young and have not hosted any supernova explosions. Our observations show that wind-blown bubbles in these HII regions can be detected kinematically but not morphologically because their expansion velocities are comparable to or only slightly higher than the isothermal sound velocity in the HII regions. Bubbles are detected around concentrations of massive stars, individual O stars, and even an evolved red supergiant (a fossil bubble). Comparisons between the observed bu...

  7. Integral field spectroscopy of HII regions in M33

    CERN Document Server

    López-Hernández, Jesús; Terlevich, Roberto; Rosa-González, Daniel; Díaz, Ángeles; Benito, Rubén García; Vílchez, José; Hägele, Guillermo

    2013-01-01

    Integral field spectroscopy (IFS) is presented for star forming regions in M33. A central area of 300 x 500 pc^2 and the external HII region IC 132, at a galactocentric distance {\\sim} 19arcmin (4.69 kpc) were observed with the Potsdam Multi Aperture Spectrophotometer (PMAS) instrument at the 3.5 m telescope of the Calar Alto Hispano- Alem\\'an observatory (CAHA). The spectral coverage goes from 3600 A to 1{\\mu}m to include from [OII]{\\lambda}3727 A to the near infrared lines required for deriving sulphur electron temperature and abundance diagnostics. Local conditions within individual HII regions are presented in the form of emission line fluxes and physical conditions for each spatial resolution element (spaxel) and for segments with similar H{\\alpha} surface brightness. A clear dichotomy is observed when comparing the central to outer disc HII regions. While the external HII region has higher electron temperature plus larger H{\\beta} equivalent width, size and excitation, the central region has higher exti...

  8. Extended emission associated with young HII regions

    CERN Document Server

    Ellingsen, S P; Kurtz, S E

    2004-01-01

    We have used the Australia Telescope Compact Array (ATCA) to make observations of a sample of eight young ultra-compact HII regions, selected on the basis that they have associated class II methanol maser emission. We have made observations sensitive to both compact and extended structures and find both to be present in most sources. The scale of the extended emission in our sample is in general less than that observed towards samples based on IRAS properties, or large single-dish flux densities. Our observations are consistent with a scenario where extended and compact radio continuum emission coexists within HII regions for a significant period of time. We suggest that these observations are consistent with a model where HII evolution takes place within hierarchically structured molecular clouds. This model is the subject of a companion paper (Shabala et al. 2005) and addresses both the association between compact and extended emission and UCHII region lifetime problem.

  9. Intergalactic HII Regions Discovered in SINGG

    CERN Document Server

    Ryan-Weber, E V; Freeman, K C; Putman, M E; Webster, R L; team., the SINGG

    2003-01-01

    A number of very small isolated HII regions have been discovered at projected distances up to 30 kpc from their nearest galaxy. These HII regions appear as tiny emission line objects in narrow band images obtained by the NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG). We present spectroscopic confirmation of four isolated HII regions in two systems, both systems have tidal HI features. The results are consistent with stars forming in interactive debris due to cloud-cloud collisions. The H-alpha luminosities of the isolated HII regions are equivalent to the ionizing flux of only a few O stars each. They are most likely ionized by stars formed in situ, and represent atypical star formation in the low density environment of the outer parts of galaxies. A small but finite intergalactic star formation rate will enrich and ionize the surrounding medium. In one system, NGC 1533, we calculate a star formation rate of 1.5e-3 msun/yr, resulting in a metal enrichment of ~1e-3 solar for the continuous formati...

  10. Identification of ten new Galactic HII regions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We discovered ten large HII regions in the Sino-German λ6 cm polarization survey of the Galactic plane. They have been identified according to their flat spectral indexes and the high ratio between the 60 μm infrared emission and the λ6 cm emission. The integrated flux densities as well as the sizes of these sources are given at 4800 MHz. Cross-identifications are made with other major radio catalogs.

  11. Python Program to Select HII Region Models

    Science.gov (United States)

    Miller, Clare; Lamarche, Cody; Vishwas, Amit; Stacey, Gordon J.

    2016-01-01

    HII regions are areas of singly ionized Hydrogen formed by the ionizing radiaiton of upper main sequence stars. The infrared fine-structure line emissions, particularly Oxygen, Nitrogen, and Neon, can give important information about HII regions including gas temperature and density, elemental abundances, and the effective temperature of the stars that form them. The processes involved in calculating this information from observational data are complex. Models, such as those provided in Rubin 1984 and those produced by Cloudy (Ferland et al, 2013) enable one to extract physical parameters from observational data. However, the multitude of search parameters can make sifting through models tedious. I digitized Rubin's models and wrote a Python program that is able to take observed line ratios and their uncertainties and find the Rubin or Cloudy model that best matches the observational data. By creating a Python script that is user friendly and able to quickly sort through models with a high level of accuracy, this work increases efficiency and reduces human error in matching HII region models to observational data.

  12. The size--density relation of extragalactic HII regions

    CERN Document Server

    Hunt, L K

    2009-01-01

    We investigate the size--density relation in extragalactic HII regions, with the aim of understanding the role of dust and different physical conditions in the ionized medium. First, we compiled several observational data sets for Galactic and extragalactic HII regions and confirm that extragalactic HII regions follow the same size (D)--density (n) relation as Galactic ones. Motivated by the inability of static models to explain this, we then modelled the evolution of the size--density relation of HII regions by considering their star formation history, the effects of dust, and pressure-driven expansion. The results are compared with our sample data whose size and density span roughly six orders of magnitude. We find that the extragalactic size--density relation does not result from an evolutionary sequence of HII regions but rather reflects a sequence with different initial gas densities (``density hierarchy''). Moreover, the size of many HII regions is limited by dust absorption of ionizing photons, rather ...

  13. Radio Recombination Lines in Galactic HII Regions

    CERN Document Server

    Quireza, C; Bania, T M; Rood, R T; Balser, Dana S.; Quireza, Cintia; Rood, Robert T.

    2006-01-01

    We report radio recombination line (RRL) and continuum observations of a sample of 106 Galactic HII regions made with the NRAO 140 Foot radio telescope in Green Bank, WV. We believe this to be the most sensitive RRL survey ever made for a sample this large. Most of our source integration times range between 6 and 90 hours which yield typical r.m.s. noise levels of 1.0--3.5 milliKelvins. Our data result from two different experiments performed, calibrated, and analyzed in similar ways. A CII survey was made at 3.5 cm wavelength to obtain accurate measurements of carbon radio recombination lines. When combined with atomic (CI) and molecular (CO) data, these measurements will constrain the composition, structure, kinematics, and physical properties of the photodissociation regions that lie on the edges of HII regions. A second survey was made at 3.5 cm wavelength to determine the abundance of 3He in the interstellar medium of the Milky Way. Together with measurements of the 3He+ hyperfine line we get high precis...

  14. The Morphology of HII Regions during Reionization

    CERN Document Server

    McQuinn, M; Zahn, O; Dutta, S; Hernquist, L; Zaldarriaga, M; Quinn, Matthew Mc; Lidz, Adam; Zahn, Oliver; Dutta, Suvendra; Hernquist, Lars; Zaldarriaga, Matias

    2006-01-01

    It is possible that the properties of HII regions during reionization depend sensitively on many poorly constrained quantities (the nature of the ionizing sources, the clumpiness of the gas in the IGM, the degree to which photo-ionizing feedback suppresses the abundance of low mass galaxies, etc.), making it extremely difficult to interpret upcoming observations of this epoch. We demonstrate that the actual situation is more encouraging, using a suite of radiative transfer simulations, post-processed on outputs from a 1024^3, 94 Mpc N-body simulation. Analytic prescriptions are used to incorporate small scale structures that affect reionization, yet remain unresolved in the N-body simulation. We show that the morphology of the HII regions is most dependent on the global ionization fraction x_i. This is not to say that the bubble morphology is completely independent of all parameters besides x_i. The next most important dependence is that of the nature of the ionizing sources. The rarer the sources, the larger...

  15. Molecular Counterparts of Ultracompact HII Regions with Extended Envelopes

    CERN Document Server

    Kim, K T; Kim, Kee-Tae; Koo, Bon-Chul

    2003-01-01

    We carried out 13CO J=1-0, CS, and C34S J=2-1 and J=3-2 line observations of molecular clouds associated with 16 ultracompact (UC) HII regions with extended envelopes. The molecular clouds are the ones that give birth to rich stellar clusters and/or very massive (O7-O4) stars. Our data show that the clouds are very clumpy and of irregular morphology. They usually have much larger masses, velocity dispersions, and fractions of dense gas than molecular clouds that form early B or late O stars. This is compatible with earlier findings that more massive stars form in more massive cores. 13CO cores are in general associated with compact HII regions regardless of the presence of UC HII regions therein. In contrast, CS cores are preferentially associated with compact HII regions that contain UC HII regions. As with the fact that the compact HII regions containing UC HII regions are more compact than those not associated with UC HII regions, these indicate that the former may be in an earlier evolutionary phase than ...

  16. X-ray observations of the Sagittarius D HII region toward the Galactic center with Suzaku

    NARCIS (Netherlands)

    Sawada, M.; Tsujimoto, M.; Koyama, K.; Law, C.J.; Tsuru, T.G.; Hyodo, Y.

    2009-01-01

    We present a Suzaku X-ray study of the Sagittarius D (Sgr D) HII region in the Galactic center region. Two 18' × 18' images by the X-ray Imaging Spectrometer (XIS) encompass the entire Sgr D complex. Thanks to the low background, XIS discovered two diffuse sources with low surface brightness and obt

  17. The HII Region of a Primordial Star

    CERN Document Server

    Abel, T; Bryan, G L; Abel, Tom; Wise, John H.; Bryan, Greg L.

    2006-01-01

    The concordance model of cosmology and structure formation predicts the formation of isolated very massive stars at high redshifts in dark matter dominated halos of 10^5 to 10^6 Msun. These stars photo-ionize their host primordial molecular clouds, expelling all the baryons from their halos. When the stars die, a relic HII region is formed within which large amounts of molecular hydrogen form which will allow the gas to cool efficiently when gravity assembles it into larger dark matter halos. The filaments surrounding the first star hosting halo are largely shielded and provide the pathway for gas to stream into the halo when the star has died. We present the first fully three dimensional cosmological radiation hydrodynamical simulations that follow all these effects. A novel adaptive ray casting technique incorporates the time dependent radiative transfer around point sources. This approach is fast enough so that radiation transport, kinetic rate equations, and hydrodynamics are solved self-consistently. It ...

  18. Detecting stellar-wind bubbles through infrared arcs in HII regions

    CERN Document Server

    Mackey, Jonathan; Gvaramadze, Vasilii V; Mohamed, Shazrene; Langer, Norbert; Harries, Tim J

    2015-01-01

    Mid-infrared arcs of dust emission are often seen near ionizing stars within HII regions. A possible explanations for these arcs is that they could show the outer edges of asymmetric stellar wind bubbles. We use two-dimensional, radiation-hydrodynamics simulations of wind bubbles within HII regions around individual stars to predict the infrared emission properties of the dust within the HII region. We assume that dust and gas are dynamically well-coupled and that dust properties (composition, size distribution) are the same in the HII region as outside it, and that the wind bubble contains no dust. We post-process the simulations to make synthetic intensity maps at infrared wavebands using the TORUS code. We find that the outer edge of a wind bubble emits brightly at 24um through starlight absorbed by dust grains and re-radiated thermally in the infrared. This produces a bright arc of emission for slowly moving stars that have asymmetric wind bubbles, even for cases where there is no bow shock or any corresp...

  19. Chemical distribution of HII regions towards the Galactic anticentre

    CERN Document Server

    Fernández-Martín, Alba; Vílchez, José Manuel; Mampaso, Antonio

    2016-01-01

    We study the physical and chemical properties of a sample of HII regions located at RG >11 kpc and present the radial distribution of abundances towards the Galaxy anticentre. We carried out optical spectroscopic observations of nine HII regions with the WHT. The sample was increased by searching the literature for optical observations of regions towards the Galactic anticentre, re-analysing them to obtain a single sample of 23 objects covering the Galactocentric radius from 11 kpc to 18 kpc to be processed in a homogeneous and consistent manner. Accurate electron densities and temperatures of several ionic species were derived in 13 HII regions. These physical parameters were applied to the spectra to determine direct total chemical abundances. For those regions without direct estimations of temperature, chemical abundances were derived by performing tailor-made photoionisation models and/or by using an empirical relation obtained from radio recombination and optical temperatures. We performed weighted least...

  20. Time Variability in Simulated Ultracompact and Hypercompact HII Regions

    CERN Document Server

    Galván-Madrid, Roberto; Keto, Eric; Mac Low, Mordecai-Mark; Banerjee, Robi; Klessen, Ralf S

    2011-01-01

    Ultracompact and hypercompact HII regions appear when a star with a mass larger than about 15 solar masses starts to ionize its own environment. Recent observations of time variability in these objects are one of the pieces of evidence that suggest that at least some of them harbor stars that are still accreting from an infalling neutral accretion flow that becomes ionized in its innermost part. We present an analysis of the properties of the HII regions formed in the 3D radiation-hydrodynamic simulations presented by Peters et al. (2010) as a function of time. Flickering of the HII regions is a natural outcome of this model. The radio-continuum fluxes of the simulated HII regions, as well as their flux and size variations are in agreement with the available observations. From the simulations, we estimate that a small but non-negligible fraction (~ 10 %) of observed HII regions should have detectable flux variations (larger than 10 %) on timescales of ~ 10 years, with positive variations being more likely to ...

  1. HII regions feeding the interstellar medium in M83

    CERN Document Server

    Blasco-Herrera, Javier; Beckman, John; Gutiérrez, Leonel; Lundgren, Andreas; Font, Joan; Hernandez, Olivier; Carignan, Claude

    2009-01-01

    We analyse the internal dynamics of star-forming HII regions and their efficiency in interacting with the ISM. We use GHaFaS (Fabry-Perot) data of the nearby spiral galaxy M83 to perform multiple-Gaussian fitting to the integrated Halpha emission line for 136 HII regions, advanced instrumental response subtraction and to study the Luminosity-velocity dispersion relation. We find that the best way of dealing with instrumental response effects is convolving its actual shape with the Gaussian before fitting and that in our data almost none of the regions need a secondary Gaussian.

  2. On the Form of the HII Region Luminosity Function

    CERN Document Server

    Oey, M S

    1997-01-01

    Observed variations in the HII region luminosity function (HII LF) seen in spiral arm vs. interarm regions, and different galactic Hubble type, can be explained simply by evolutionary effects and maximum number of ionizing stars per cluster. We present Monte Carlo simulations of the HII LF, drawing the number of ionizing stars N_* from a power-law distribution of constant slope, and the stellar masses from a Salpeter IMF with an upper-mass limit of 100 M_sol. We investigate the evolution of the HII LF, as determined by stellar main-sequence lifetimes and ionizing luminosities, for a single burst case and continuous creation of the nebular population. Shallower HII LF slopes measured for the arms of spiral galaxies can be explained as a composite slope, expected for a zero-age burst population, whereas the interarm regions tend to be dominated by evolved rich clusters described by a single, steeper slope. Steeper slopes in earlier-type galaxies can be explained simply by a lower maximum N_* cutoff found for th...

  3. Nonlinear Dynamics of Ionization Fronts in HII Regions

    Energy Technology Data Exchange (ETDEWEB)

    Mizuta, A; Kane, J O; Pound, M W; Remington, B A; Ryutov, D D; Takabe, H

    2006-04-20

    Hydrodynamic instability of an accelerating ionization front (IF) is investigated with 2D hydrodynamic simulations, including absorption of incident photoionizing photons, recombination in the HII region, and radiative molecular cooling. When the amplitude of the perturbation is large enough, nonlinear dynamics of the IF triggered by the separation of the IF from the cloud surface is observed. This causes the second harmonic of the imposed perturbation to appear on the cloud surfaces, whereas the perturbation in density of ablated gas in the HII region remains largely single mode. This mismatch of modes between the IF and the density perturbation in the HII region prevents the strong stabilization effect seen in the linear regime. Large growth of the perturbation caused by Rayleigh-Taylor-like instability is observed late in time.

  4. On the Size of HII Regions around High Redshift Quasars

    CERN Document Server

    Maselli, A; Ferrara, A; Choudhury, T R

    2006-01-01

    We investigate the possibility of constraining the ionization state of the Intergalactic Medium (IGM) close to the end of reionization (z ~ 6) by measuring the size of the HII regions in high-z quasars spectra. We perform a combination of multiphase SPH and 3D radiative transfer (RT) simulations to reliably predict the properties of typical high-z quasar HII regions, embedded in a partly neutral IGM. From the analysis of mock spectra along lines of sight through the simulated QSO environment we find that the HII region size derived from quasar spectra is on average 30 % smaller than the physical one. Additional maximum likelihood analysis shows that this offset induces an overestimate of the neutral hydrogen fraction, x_HI, by a factor ~ 3. By applying the same statistical method to a sample of observed QSOs our study favors a mostly ionized (x_HI < 0.06) universe at z=6.1.

  5. An Isolated HII Region near ESO 481-G017

    CERN Document Server

    Santiago-Figueroa, N; Werk, J; Ryan-Weber, E; Meurer, G

    2009-01-01

    We obtained VLA 21-cm observations of the galaxy ESO 481-G017 to determine the environment and trigger of remote star formation traced by a HII region found 43 kpc from the galaxy (in projection). ESO 481-G017 is an early type spiral galaxy with a HI mass of 1.1*10^9 Msun and a distance of 55 Mpc. The isolated HII region has a H-alpha luminosity of 10^38.1 erg s^-1 and minimal continuum emission suggesting that new stars have formed where little or no stars previously existed. The difference in velocity between the HI disk of ESO 481-G017 (3840-4000 km s^-1) and the isolated HII region (4701 +/- 80 km s^-1) indicates the origin of the HII region may be stars forming in a tidal feature or newly triggered star formation in a very low luminosity companion galaxy. The VLA observations shed light on the nature of this young object.

  6. 7 mm continuum observations of ultra compact HII regions

    Science.gov (United States)

    Leto, P.; Umana, G.; Trigilio, C.; Buemi, C. S.; Dolei, S.; Manzitto, P.; Cerrigone, L.; Siringo, C.

    2009-12-01

    Aims: Ultra compact HII (UCHII) regions are indicators of high-mass star formation sites and are distributed mainly in the Galactic plane. They exhibit a broad band spectrum with significant emission between near-IR and radio wavelengths. We intend to investigate the possible contribution of the forthcoming ESA Planck mission to the science of UCHII regions by evaluating the possibility of detecting UCHIIs that are bright in the radio regime. Methods: We performed new 7 mm observations of a sample of UCHII regions. The observations were designed to acquire high-frequency radio spectra. For each source in our sample, the free-free radio spectrum has been modeled. Along with far-IR measurements, our spectra allow us to estimate the flux densities of the sources in the millimeter and sub-millimeter bands. We extrapolated and summed the ionized-gas (free-free radio emission) and dust (thermal emission) contributions in the afore mentioned wavelength ranges. The possibility of Planck detecting the selected sources can be assessed by comparing the estimated flux densities to the expected sensitivity in each Planck channel. To obtain a realistic estimation of the noise produced by the Galactic emission, the Planck sky model software package was used. Results: For each target source, from our new 7 mm data and other radio measurements from the literature, important physical parameters such as electron density and their spatial distribution, source geometry and emission measure were derived. We conclude that, in the case of the present sample, located close to the Galactic center, Planck will have a very low detection rate. In contrast, assuming that our sample is representative of the whole UCHII-region population, we derive a very high probability of detecting this kind of source with Planck if located instead close to the anticenter. From the analysis of the ionized-gas properties, we suggest that the selected sample could also be contaminated by other kinds of Galactic

  7. Rotation of the Warm Molecular Gas Surrounding Ultracompact HII Regions

    CERN Document Server

    Klaassen, P D; Keto, E R; Zhang, Q

    2009-01-01

    We present molecular line and 1.4 mm continuum observations towards five massive star forming regions at arcsecond resolution using the Submillimeter Array (SMA). We find that the warm molecular gas surrounding each HII region (as traced by SO_2 and OCS) appears to be undergoing bulk rotation. From the molecular line emission and thermal component of the continuum emission, we independently derived gas masses for each region which are consistent with each other. From the free-free component of the continuum emission we estimate the minimum stellar mass required to power the HII region and find that this mass, when added to the derived gas mass, is a significant fraction of the dynamical mass for that region.

  8. On the feedback from super stellar clusters. I. The structure of giant HII regions and HII galaxies

    CERN Document Server

    Tenorio-Tagle, G; Pérez, E; Silich, S; Telles, E

    2006-01-01

    We review the structural properties of giant extragalactic HII regions and HII galaxies based on 2D hydrodynamic calculations, and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus exposed to the most important star-formation feedback mechanisms: photoionization and the cluster wind. The models show how the two feedback mechanisms compete in the disruption of clouds and lead to two different hydrodynamic solutions: The storage of clouds into a long lasting ragged shell that inhibits the expansion of the thermalized wind, and the steady filtering of the shocked wind gas through channels carved within the cloud stratum. Both solutions are claimed to be concurrently at work in giant HII regions and HII galaxies, causing their detailed inner structure. This includes multiple large-scale shells, filled with an X-ray emitting gas, that evolve to finally merge with each...

  9. Topology and Sizes of HII Regions during Cosmic Reionization

    CERN Document Server

    Friedrich, Martina M; Alvarez, Marcelo A; Shapiro, Paul R; Iliev, Ilian T

    2010-01-01

    We use the results of large-scale simulations of reionization to explore methods for characterizing the topology and sizes of HII regions during reionization. We use four independent methods for characterizing the sizes of ionized regions. Three of them give us a full size distribution: the friends-of-friends (FOF) method, the spherical average method (SPA) and the power spectrum (PS) of the ionized fraction. These latter three methods are complementary: While the FOF method captures the size distribution of the small scale H~II regions, which contribute only a small amount to the total ionization fraction, the spherical average method provides a smoothed measure for the average size of the H~II regions constituting the main contribution to the ionized fraction, and the power spectrum does the same while retaining more details on the size distribution. Our fourth method for characterizing the sizes of the H II regions is the average size which results if we divide the total volume of the H II regions by their...

  10. Dust Properties in HII Regions in M33

    CERN Document Server

    Relano, M; Lisenfeld, U; Verley, S; Hermelo, I; Boquien, M; Albrecht, M; Kramer, C; Braine, J; Perez-Montero, E; De Looze, I; Xilouris, M; Kovacs, A; Staguhn, J

    2016-01-01

    The conversion of the IR emission into star formation rate can be strongly dependent on the physical properties of the dust, which are affected by the environmental conditions where the dust is embedded. We study here the dust properties of a set of HII regions in the Local Group Galaxy M33 presenting different spatial configurations between the stars, gas and dust to understand the dust evolution under different environments. We model the SED of each region using the DustEM tool and obtain the mass relative to hydrogen for Very Small Grains (YVSG), Polycyclic Aromatic Hydrocarbons (YPAH) and Big Grains (YBG). The relative mass of the VSGs (YVSG/YTOT) is a factor of 1.7 higher for HII regions classified as filled and mixed than for regions presenting a shell structure. The enhancement of VSGs within NGC 604 and NGC 595 is correlated to expansive gas structures with velocities greater than 50 km/s. The gas-to-dust ratio derived for the HII regions in our sample exhibits two regimes related to the HI-H2 transit...

  11. Single Star HII Regions in nearby LEGUS Galaxies

    Science.gov (United States)

    Kayitesi, Bridget; Lee, Janice C.; Thilker, David A.; LEGUS Team

    2017-01-01

    It is believed that O stars typically form in clustered environments, however past observations have shown that there are a few O stars in the field that are fairly far from clusters and have low space velocities. The goal of this project is to determine whether these O stars can be born in situ or whether they are runaways ejected from their parent clusters due to binary supernova explosions or other dynamic interactions. To do this, we select candidate hot stars and compute an isolation metric based on distance from other hot stars and clusters. We then deploy Zooniverse citizen scientists to classify the isolated sources and their associated nebulae. The detected presence of an HII region allows us to confirm a candidate as a true O star. We use the Zooniverse classification system to study the morphology of these HII regions and determine the runaway status of the O stars.

  12. Realistic Models for Filling Factors in HII Regions

    Science.gov (United States)

    Spangler, Steven R.; Costa, Allison H.; Bergerud, Brandon M.; Beauchamp, Kara M.

    2017-01-01

    One of the parameters used to describe HII regions and other ionized parts of the interstellar medium is the filling factor, defined as the volume fraction of an HII region occupied by matter. The best observational evidence for the existence of a filling factor less than unity is a discrepancy between the electron density derived from density-sensitive line ratios and the root mean square density obtained from emission measure measurements. Following the early, influential study by Osterbrock and Flather (ApJ 129, 26, 1959), most investigations of HII regions envision these objects as a group of isolated cells of high gas density embedded in a vacuum. This picture is at serious odds with more direct measurements of other astrophysical plasmas like the solar wind, where the density follows a less extreme probability distribution function (pdf) such as an exponential or lognormal. We have carried out a set of simulations in which model HII regions are created with different density pdfs such as exponential and lognormal as well as the extreme case of two delta functions. We calculate the electron density as inferred from spectroscopic line ratios and emission measures for all lines of sight through the model nebulas. In the cases of exponential and lognormal pdfs, the spectroscopically derived densities are higher than those obtained by the emission measures by factors of 20 to 100 percent. These are considerably smaller than values often reported in the literature, which can be an order of magnitude or greater. We will discuss possible ways to reconcile realistic density pdfs such as measured in space and laboratory plasmas with the results from astronomical spectroscopic measurements. Finally, we point out that for the Orion Nebula, the density discrepancy is due to geometry, not filling factor (O'Dell, ARAA 39, 99, 2001).

  13. HII Region Metallicity Distribution in the Milky Way Disk

    CERN Document Server

    Balser, Dana S; Bania, T M; Anderson, L D

    2011-01-01

    The distribution of metals in the Galaxy provides important information about galaxy formation and evolution. HII regions are the most luminous objects in the Milky Way at mid-infrared to radio wavelengths and can be seen across the entire Galactic disk. We used the NRAO Green Bank Telescope (GBT) to measure radio recombination line and continuum emission in 81 Galactic HII regions. We calculated LTE electron temperatures using these data. In thermal equilibrium metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. Our HII region distribution covers a large range of Galactocentric radius (5 to 22 kpc) and samples the Galactic azimuth range 330 degree to 60 degree. Using our highest quality data (72 objects) we derived an O/H Galactocentric radial gradient of -0.0383 +/- 0.0074 dex/kpc. Combining these data with a similar survey made with the NRAO 140 Foot telescope we get a radial gradient of -0.0446 +/- 0.0049 dex/kpc for this larger sample of ...

  14. The Fine Structure Lines of Hydrogen in HII Regions

    CERN Document Server

    Dennison, B; Minter, A H; Dennison, Brian; Minter, Anthony H.

    2005-01-01

    The 2s_{1/2} state of hydrogen is metastable and overpopulated in HII regions. In addition, the 2p states may be pumped by ambient Lyman-alpha radiation. Fine structure transitions between these states may be observable in HII regions at 1.1 GHz (2s_{1/2}-2p_{1/2}) and/or 9.9 GHz (2s_{1/2}-2p_{3/2}), although the details of absorption versus emission are determined by the relative populations of the 2s and 2p states. The n=2 level populations are solved with a parameterization that allows for Lyman-alpha pumping of the 2p states. The density of Lyman-alpha photons is set by their creation rate, easily determined from the recombination rate, and their removal rate. Here we suggest that the dominant removal mechanism of Lyman-alpha radiation in HII regions is absorption by dust. This circumvents the need to solve the Lyman-alpha transfer problem, and provides an upper limit to the rate at which the 2p states are populated by Lyman-alpha photons. In virtually all cases of interest, the 2p states are predominantl...

  15. Modeling the Photoionized Interface in Blister HII Regions

    CERN Document Server

    Sankrit, R; Sankrit, Ravi

    2000-01-01

    We present a grid of photoionization models for the emission from photoevaporative interfaces between the ionized gas and molecular cloud in blister HII regions. For the density profiles of the emitting gas in the models, we use a general power law form calculated for photoionized, photoevaporative flows by Bertoldi (1989). We find that the spatial emission line profiles are dependent on the incident flux, the shape of the ionizing continuum and the elemental abundances. In particular, we find that the peak emissivity of the [SII] and [NII] lines are more sensitive to the elemental abundances than are the total line intensities. The diagnostics obtained from the grid of models can be used in conjunction with high spatial resolution data to infer the properties of ionized interfaces in blister HII regions. As an example, we consider a location at the tip of an ``elephant trunk'' structure in M16 (the Eagle Nebula) and show how narrow band HST-WFPC2 images constrain the HII region properties. We present a photo...

  16. New calibrations for abundance determinations in HII regions

    CERN Document Server

    Pilyugin, L S

    2016-01-01

    Simple relations for deriving the oxygen abundance in HII regions with intensities of the three strong emission lines R_2, R_3, and N_2 (R calibration) or S_2, R_3, and N_2 (S calibration) in their spectra are suggested. A sample of 313 reference HII regions of the counterpart method is used as calibrating data points. Relations for the determination of nitrogen abundances, the R calibration, are also constructed. We find that the oxygen and nitrogen abundances in high-metallicity HII regions can be estimated using the intensities of the two strong lines R_2 and N_2 (or S_2 and N_2 for oxygen) only. The corresponding two-dimensional relations are provided. There are considerable advantages of the suggested calibration relations as compared to the existing ones. First, the oxygen and nitrogen abundances estimated through the suggested calibrations agree with the Te-based abundances within ~0.1 dex over the whole metallicity range, i.e., the relative accuracy of the calibration-based abundances is 0.1 dex. Alth...

  17. PAH 8μm Emission as a Diagnostic of HII Region Optical Depth

    Science.gov (United States)

    Oey, M. S.; Lopez-Hernandez, J.; Kellar, J. A.; Pellegrini, E. W.; Gordon, Karl D.; Jameson, Katherine; Li, Aigen; Madden, Suzanne C.; Meixner, Margaret; Roman-Duval, Julia; Bot, Caroline; Rubio, Monica; Tielens, A. G. G. M.

    2017-01-01

    PAHs are easily destroyed by Lyman continuum radiation and so in optically thick Stromgren spheres, they tend to be found only on the periphery of HII regions, rather than in the central volume. We therefore expect that in HII regions that are optically thin to ionizing radiation, PAHs would be destroyed beyond the primary nebular structure. Using data from the Spitzer SAGE survey of the Magellanic Clouds, we test whether 8 μm emission can serve as a diagnostic of optical depth in HII regions. We find that 8 μm emission does provide valuable constraints in the Large Magellanic Cloud, where objects identified as optically thick by their atomic ionization structure have 6 times higher median 8 μm surface brightness than optically thin objects. However, in the Small Magellanic Cloud, this differentiation is not observed. This appears to be caused by extremely low PAH production in this low-metallicity environment, such that any differentiation between optically thick and thin objects is washed out by stochastic variations, likely driven by the interplay between dust production and UV destruction. Thus, PAH emission is sensitive to nebular optical depth only at higher metallicities.

  18. Comparative internal kinematics of the HII regions in interacting and isolated galaxies: implications for massive star formation modes

    CERN Document Server

    Zaragoza-Cardiel, Javier; Font, Joan; García-Lorenzo, Begoña; Camps-Fariña, Artemi; Fathi, Kambiz; James, Philip A; Erroz-Ferrer, Santiago; Barrera-Ballesteros, Jorge; Cisternas, Mauricio

    2015-01-01

    We have observed 10 interacting galaxy pairs using the Fabry-Perot interferometer GH$\\alpha$FaS (Galaxy H$\\alpha$ Fabry-Perot system) on the $4.2\\rm{m}$ William Herschel Telescope (WHT) at the Observatorio del Roque de los Muchachos, La Palma. We present here the H$\\alpha$ surface brightness, velocity and velocity dispersion maps for the 10 systems we have not previously observed using this technique, as well as the physical properties (sizes, H$\\alpha$ luminosities and velocity dispersion) of 1259 HII regions from the full sample. We also derive the physical properties of 1054 HII regions in a sample of 28 isolated galaxies observed with the same instrument in order to compare the two populations of HII regions. We find a population of the brightest HII regions for which the scaling relations, for example the relation between the H$\\alpha$ luminosity and the radius, are clearly distinct from the relations for the regions of lower luminosity. The regions in this bright population are more frequent in the inte...

  19. The Fragmenting Superbubble Associated with the HII Region W4

    CERN Document Server

    West, J L; Normandeau, M; Landecker, T L; West, Jennifer L.; English, Jayanne; Normandeau, Magdalen

    2006-01-01

    New observations at high latitudes above the HII region W4 show that the structure formerly identified as a chimney candidate, an opening to the Galactic halo, is instead a superbubble in the process of fragmenting and possibly evolving into a chimney. Data at high Galactic latitudes (b > 5 degrees) above the W3/W4 star forming region at 1420 and 408 MHz Stokes I (total power) and 1420 MHz Stokes Q and U (linear polarization) reveal an egg-shaped structure with morphological correlations between our data and the H-alpha data of Dennison, Topasna, & Simonetti. Polarized intensity images show depolarization extending from W4 up the walls of the superbubble, providing strong evidence that the radio continuum is generated by thermal emission coincident with the H-alpha emission regions. We conclude that the parts of the HII region hitherto known as W4 and the newly revealed thermal emission are all ionized by the open cluster OCl 352. Assuming a distance of 2.35 kpc, the ovoid structure is 164 pc wide and ext...

  20. ATLASGAL --- properties of compact HII regions and their natal clumps

    CERN Document Server

    Urquhart, J S; Moore, T J T; Purcell, C R; Hoare, M G; Schuller, F; Wyrowski, F; Csengeri, T; Menten, K M; Lumsden, S L; Kurtz, S; Walmsley, C M; Bronfman, L; Morgan, L K; Eden, D J; Russeil, D

    2013-01-01

    We present a complete sample of molecular clumps containing compact and ultra-compact (UC) HII regions between \\ell=10\\degr and 60\\degr\\ and $|b|<1\\degr, identified by combining the the ATLASGAL submm and CORNISH radio continuum surveys with visual examination of archival infrared data. Our sample is complete to optically thin, compact and UCHII regions driven by a zero age main sequence star of spectral type B0 or earlier embedded within a 1,000 Msun clump. In total we identify 213 compact and UCHII regions, associated with 170 clumps. Unambiguous kinematic distances are derived for these clumps and used to estimate their masses and physical sizes, as well as the Lyman continuum fluxes and sizes of their embedded HII regions. We find a clear lower envelope for the surface density of molecular clumps hosting massive star formation of 0.05 g cm^{-2}, which is consistent with a similar sample of clumps associated with 6.7 GHz masers. The mass of the most massive embedded stars is closely correlated with the ...

  1. The environs of the HII region Gum31

    CERN Document Server

    Cappa, C; Amorin, R; Vasquez, J

    2007-01-01

    We analyze the distribution of the interstellar matter in the environs of the \\hii region Gum 31, excited by the open cluster NGC 3324, located in the complex Carina region, with the aim of investigating the action of the massive stars on the surrounding neutral material. We use 21cm-line data, radio continuum images at 0.843, 2.4 and 4.9 GHz, $^{12}${\\bf CO(1-0)} observations, and IRAS and MSX infrared data. Adopting a distance of 3 kpc for the \\hii\\ region and the ionizing cluster, we have derived an electron density of 33$\\pm$3 cm$^{-3}$ and an ionized mass of (3.3$\\pm$1.1)$\\times10^3$ M$_{\\odot}$ based on the radio continuum data at 4.9 GHz. The \\hi 21-cm line images revealed an \\hi shell surrounding the H {\\sc ii} region. The \\hi structure is 10.0$\\pm$1.7 pc in radius, has a neutral mass of 1500$\\pm$500 M$_{\\odot}$, and is expanding at 11 km s$^{-1}$. The associated molecular gas amounts to (1.5$\\pm$0.5)$\\times10^5$ M$_{\\odot}$, being its volume density of about 500 cm^{-3}. This molecular material proba...

  2. Anomalous Microwave Emission from the HII region RCW175

    CERN Document Server

    Dickinson, C; Allison, J R; Bond, J R; Casassus, S; Cleary, K; Davis, R J; Jones, M E; Mason, B S; Myers, S T; Pearson, T J; Readhead, A C S; Sievers, J L; Taylor, A C; Todorovic, M; White, G J; Wilkinson, P N

    2008-01-01

    We present evidence for anomalous microwave emission in the RCW175 \\hii region. Motivated by 33 GHz $13\\arcmin$ resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of $4\\arcmin$. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio. The integrated flux density is $5.97\\pm0.30$ Jy at 31 GHz, in good agreement with the VSA. The 31 GHz flux density is $3.28\\pm0.38$ Jy ($8.6\\sigma$) above the expected value from optically thin free-free emission based on lower frequency radio data and thermal dust constrained by IRAS and WMAP data. Conventional emission mechanisms such as optically thick emission from ultracompact \\hii regions cannot easily account for this excess. We interpret the excess as evidence for electric dipole emission from small spinning dust grains, which does provide an adequate fit to the data.

  3. Effective temperature of ionizing stars of extragalactic HII regions

    CERN Document Server

    Dors, O L; Cardaci, M V; Krabbe, A C

    2016-01-01

    The effective temperature (Teff) of the radiation field of the ionizing star(s) of a large sample of extragalactic HII regions was estimated using the R= log([OII](3727)/[OIII]5007) index. We used a grid of photoionization models to calibrate the Teff-R relation finding that it has a strong dependence with the ionizing parameter while it shows a weak direct dependence with the metallicity (variations in Z imply variations in U) of both the stellar atmosphere of the ionizing star and the gas phase of the HII region. Since the R index varies slightly with the Teff for values larger than 40 kK, the R index can be used to derive the Teff in 30-40 kK range. A large fraction of the ionization parameter variation is due to differences in the temperature of the ionizing stars and then the use of the (relatively) low Teff dependent S2=[S II](6717+31)/Ha emission-line ratio to derive the ionization parameter is preferable over others in the literature. We propose linear metallicity dependent relationships between S2 an...

  4. Photoionization models of the CALIFA HII regions. I. Hybrid models

    CERN Document Server

    Morisset, C; Sánchez, S F; Galbany, L; Garcia-Benito, R; Husemann, B; Marino, R A; Mast, D; Roth, M M; Colaboration, CALIFA

    2016-01-01

    Photoionization models of HII regions require as input a description of the ionizing SED and of the gas distribution, in terms of ionization parameter U and chemical abundances (e.g. O/H and N/O). A strong degeneracy exists between the hardness of the SED and U, which in turn leads to high uncertainties in the determination of the other parameters, including abundances. One way to resolve the degeneracy is to fix one of the parameters using additional information. For each of the ~ 20000 sources of the CALIFA HII regions catalog, a grid of photoionization models is computed assuming the ionizing SED being described by the underlying stellar population obtained from spectral synthesis modeling. The ionizing SED is then defined as the sum of various stellar bursts of different ages and metallicities. This solves the degeneracy between the shape of the ionizing SED and U. The nebular metallicity (associated to O/H) is defined using the classical strong line method O3N2 (which gives to our models the status of "h...

  5. Forming a Primordial Star in a Relic HII Region

    CERN Document Server

    O'Shea, B W; Whalen, D; Norman, M L; Shea, Brian W. O'; Abel, Tom; Whalen, Dan; Norman, Michael L.

    2005-01-01

    There has been considerable theoretical debate over whether photoionization and supernova feedback from the first Population III stars facilitate or suppress the formation of the next generation of stars. We present results from an Eulerian adaptive mesh refinement simulation demonstrating the formation of a primordial star within a region ionized by an earlier nearby star. Despite the higher temperatures of the ionized gas and its flow out of the dark matter potential wells, this second star formed within 23 million years of its neighbor's death. The enhanced electron fraction within the HII region catalyzes rapid molecular hydrogen formation that leads to faster cooling in the subsequent star forming halos than in the first halos. This ``second generation'' primordial protostar has a much lower accretion rate because, unlike the first protostar, it forms in a rotationally supported disk of approximately 10-100 solar masses. In contrast to unpreprocessed regions, such configurations may allow binaries or mul...

  6. Line Emission from Radiation-Pressurized HII Region II: Dynamics and Population Synthesis

    CERN Document Server

    Verdolini, Silvia; Krumholz, Mark R; Matzner, Christopher D; Tielens, Alexander G G M

    2013-01-01

    Optical and infrared emission lines from HII regions are an important diagnostic used to study galaxies, but interpretation of these lines requires significant modeling of both the internal structure and dynamical evolution of the emitting regions. Most of the models in common use today assume that HII region dynamics are dominated by the expansion of stellar wind bubbles, and have neglected the contribution of radiation pressure to the dynamics, and in some cases also to the internal structure. However, recent observations of nearby galaxies suggest that neither assumption is justified, motivating us to revisit the question of how HII region line emission depends on the physics of winds and radiation pressure. In a companion paper we construct models of single HII regions including and excluding radiation pressure and winds, and in this paper we describe a population synthesis code that uses these models to simulate galactic collections of HII regions with varying physical parameters. We show that the choice...

  7. A Large Scale, Low Frequency Murchison Widefield Array Survey of Galactic HII regions between 260< l <\\340

    CERN Document Server

    Hindson, L; Hurley-Walker, N; Callingham, J R; Su, H; Morgan, J; Bell, M; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Deshpande, A A; Dwarakanath, K S; For, B -Q; Gaensler, B M; Greenhill, L J; Hancock, P; Hazelton, B J; Kapinska, A D; Kaplan, D L; Lenc, E; Lonsdale, C J; Mckinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Offringa, A; Ord, S M; Procopio, P; Prabu, T; UdayaShankar, N; Srivani, K S; Staveley-Smith, L; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L; Wu, C; Zheng, Q

    2016-01-01

    We have compiled a catalogue of HII regions detected with the Murchison Widefield Array (MWA) between 72 and 231MHz. The multiple frequency bands provided by the MWA allow us identify the characteristic spectrum generated by the thermal Bremsstrahlung process in HII regions. We detect 306 HII regions between 260 < l < 340 and report on the positions, sizes, peak, integrated flux density, and spectral indices of these HII regions. By identifying the point at which HII regions transition from the optically thin to thick regime we derive the physical properties including the electron density, ionised gas mass and ionising photon flux, towards 61 HII regions. This catalogue of HII regions represents the most extensive and uniform low frequency survey of HII regions in the Galaxy to date.

  8. Spectral line survey of the ultracompact HII region Monoceros R2

    NARCIS (Netherlands)

    Ginard, D.; Gonzalez-Garcia, M.; Fuente, A.; Cernicharo, J.; Alonso-Albi, T.; Pilleri, P.; Gerin, M.; Garcia-Burillo, S.; Ossenkopf, V.; Rizzo, J. R.; Kramer, C.; Goicoechea, J. R.; Pety, J.; Berne, O.; Joblin, C.

    2012-01-01

    Context. Ultracompact (UC) HII regions constitute one of the earliest phases in the formation of a massive star and are characterized by extreme physical conditions (G(0) > 10(5) Habing field and n > 10(6) cm(-3)). The UC HII Mon R2 is the closest example and an excellent target to study the chemist

  9. Distinguishing between HII regions and planetary nebulae with Hi-GAL, WISE, MIPSGAL, and GLIMPSE

    CERN Document Server

    Anderson, Loren D; Barlow, M J; Garcia-Lario, P; Noriega-Crespo, A

    2011-01-01

    HII regions and planetary nebulae (PNe) both emit at radio and infrared (IR) wavelengths, and angularly small HII regions can be mistaken for PNe. This problem of classification is most severe for HII regions in an early evolutionary stage, those that are extremely distant, or those that are both young and distant. Using data from the Herschel Hi-GAL survey, as well as WISE and the Spitzer MIPSGAL and GLIMPSE surveys, we wish to establish characteristic IR colors that can be used to distinguish between HII regions and PNe. We perform aperture photometry measurements for a sample of 126 HII regions and 43 PNe at wavelengths from 8.0 micron to 500 micron. We find that HII regions and PNe have distinct IR colors. The most robust discriminating color criteria are [F12/F8] 1.3, and [F160/F24] > 0.8 (or alternately [F160/F22] > 0.8), where the brackets indicate the log of the flux ratio. All three of these criteria are individually satisfied by over 98% of our sample of HII regions and by about 10% of our sample o...

  10. Evolution of Blister-Type HII Regions in a Magnetized Medium

    CERN Document Server

    Gendelev, Leo

    2011-01-01

    We use the three-dimensional Athena ionizing radiation-magnetohydrodynamics (IRMHD) code to simulate blister-type HII regions driven by stars on the edge of magnetized gas clouds. We compare these to simulations of spherical HII regions where the star is embedded deep within a cloud, and to non-magnetized simulations of both types, in order to compare their ability to drive turbulence and influence star formation. We find that magnetized blister HII regions can be very efficient at injecting energy into clouds. This is partly a magnetic effect: the magnetic energy added to a cloud by an HII region is comparable to or larger than the kinetic energy, and magnetic fields can also help collimate the ejected gas, increasing its energy yield. As a result of these effects, a blister HII region expanding into a cloud with a magnetic field perpendicular to its edge injects twice as much energy by 5 Myr as a non-magnetized blister HII region driven by a star of the same luminosity. Blister HII regions are also more eff...

  11. Deuteration around the ultracompact HII region Mon R2

    CERN Document Server

    Treviño-Morales, S P; Fuente, A; Kramer, C; Roueff, E; González-García, M; Cernicharo, J; Gerin, M; Goicoechea, J R; Pety, J; Berné, O; Ossenkopf, V; Ginard, D; García-Burillo, S; Rizzo, J R; Viti, S

    2014-01-01

    The massive star-forming region Mon R2 hosts the closest ultra-compact HII region that can be spatially resolved with current single-dish telescopes. We used the IRAM-30m telescope to carry out an unbiased spectral survey toward two important positions (namely IF and MP2), in order to studying the chemistry of deuterated molecules toward Mon R2. We found a rich chemistry of deuterated species at both positions, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO, NH2D, and N2D+ and their corresponding hydrogenated species and isotopologs. Our high spectral resolution observations allowed us to resolve three velocity components: the component at 10 km/s is detected at both positions and seems associated with the layer most exposed to the UV radiation from IRS 1; the component at 12 km/s is found toward the IF position and seems related to the molecular gas; finally, a component at 8.5 km/s is only detected toward the MP2 position, most likely related to a low-UV irradiated PDR. We derived the column density of ...

  12. Untangling the Recombination Line Emission from HII Regions with Multiple Velocity Components

    CERN Document Server

    Anderson, L D; Wenger, T V; Bania, T M; Balser, Dana S

    2015-01-01

    HII regions are the ionized spheres surrounding high-mass stars. They are ideal targets for tracing Galactic structure because they are predominantly found in spiral arms and have high luminosities at infrared and radio wavelengths. In the Green Bank Telescope HII Region Discovery Survey (GBT HRDS) we found that >30% of first Galactic quadrant HII regions have multiple hydrogen radio recombination line (RRL) velocities, which makes determining their Galactic locations and physical properties impossible. Here we make additional GBT RRL observations to determine the discrete HII region velocity for all 117 multiple-velocity sources within 18deg. < l < 65deg. The multiple-velocity sources are concentrated in the zone 22deg. < l < 32deg., coinciding with the largest regions of massive star formation, which implies that the diffuse emission is caused by leaked ionizing photons. We combine our observations with analyses of the electron temperature, molecular gas, and carbon recombination lines to determ...

  13. Imaging HII Regions from Galaxies and Quasars During Reionisation with SKA

    CERN Document Server

    Wyithe, Stuart; Kim, Hansik

    2015-01-01

    The ionisation structure of the Intergalactic Medium (IGM) during reionisation is sensitive to the unknown galaxy formation physics that prevailed at that time. This structure introduces non-Gaussian statistics into the redshifted 21 cm fluctuation amplitudes that can only be studied through tomographic imaging, which will clearly discriminate between different galaxy formation scenarios. Imaging the ionisation structure and cosmological HII regions during reionisation is therefore a key goal for the SKA. For example, the SKA1-LOW baseline design with a 1 km diameter core will resolve HII regions expected from galaxy formation models which include strong feedback on low-mass galaxy formation. Imaging the smaller HII regions that result from galaxy formation in the absence of SNe feedback will also be possible for SKA1-LOW in the later stages of reionisation, but may require the greater sensitivity of SKA early in the reionisation era. In addition to having baselines long enough to resolve the HII regions, the...

  14. The Discovery of Raman Scattering in HII Regions

    CERN Document Server

    Dopita, Michael A; Sutherland, Ralph S; Kewley, Lisa J; Groves, Brent A

    2016-01-01

    We report here on the discovery of faint extended wings of H\\alpha\\ observed out to an apparent velocity of ~ 7600 km/s in the Orion Nebula (M42) and in five HII regions in the Large and the Small Magellanic Clouds. We show that, these wings are caused by Raman scattering of both the O I and Si II resonance lines and stellar continuum UV photons with H I followed by radiative decay to the H I n=2 level. The broad wings also seen in H\\beta\\ and in H\\gamma\\ result from Raman scattering of the UV continuum in the H I n=4 and n=5 levels respectively.The Raman scattering fluorescence is correlated with the intensity of the narrow permitted lines of O I and Si II. In the case of Si II, this is explained by radiative pumping of the same 1023.7\\AA\\ resonance line involved in the Raman scattering by the Ly\\beta\\ radiation field. The subsequent radiative cascade produces enhanced Si II 5978.9, 6347.1$ and 6371.4\\AA\\ permitted transitions. Finally we show that in O I, radiative pumping of the 1025.76\\AA\\ resonance line ...

  15. High-velocity gas associated ultracompact HII regions

    Institute of Scientific and Technical Information of China (English)

    XU; Ye(徐烨); JIANG; Dongrong(蒋栋荣); YANG; Chuanyi(杨传义); ZHENG; Xingwu(郑兴武); GU; Minfeng(顾敏峰); PEI; Chunchuan(裴春传)

    2002-01-01

    We present the results of a survey for high-velocity 12CO (1-0) emission associated H2O masers and ultracompact (UC) HII regions. The aim is to investigate the relationship between H2O masers, CO high-velocity gas (HVG) and their associated infrared sources. Our sample satisfies Wood & Churchwell criterion. Almost 70 % of the sources have full widths (FWs) greater than 15 km@ s?1 at T*a = 100 mK and 15 % have FWs greater than 30 km@ s?1. In most of our objects there is excess high velocity emission in the beam. There is a clear correlation between CO line FWs and far-infrared luminosities: the FW increases with the FIR luminosity. The relation suggests that more luminous sources are likely to be more energetic and able to inject more energy into their surroundings. As a result, larger FW of the CO line could be produced. In most of our sources, the velocities of peak of the H2O emission are in agreement with those of the CO cloud, but a number of them have a large blueshift with respect to the CO peak. These masers might stem from the amplifications of a background source, which may amplify some unobservable weak masers to an observable level.

  16. A Protostellar Jet Emanating from a Hypercompact HII Region

    CERN Document Server

    Guzmán, Andrés E; Rodríguez, Luis F; Contreras, Yanett; Dougados, Catherine; Cabrit, Sylvie

    2016-01-01

    We present radio continuum observations of the high-mass young stellar object (HMYSO) G345.4938+01.4677 made using the Australia Telescope Compact Array (ATCA) at 5, 9, 17, and 19 GHz. These observations provide definite evidence that the outer and inner pairs of radio lobes consist of shock ionized material being excited by an underlying collimated and fast protostellar jet emanating from a hypercompact HII region. By comparing with images taken 6 yr earlier at 5 and 9 GHz using the same telescope, we assess the proper motions of the radio sources. The outer West and East lobes exhibit proper motions of $64\\pm12$ and $48\\pm13$ milliarcsec yr$^{-1}$, indicating velocities projected in the plane of the sky and receding from G345.4938+01.4677 of $520$ and $390$ km s$^{-1}$, respectively. The internal radio lobes also display proper motion signals consistently receding from the HMYSO, with magnitudes of $17\\pm11$ and $35\\pm10$ milliarcsec yr$^{-1}$ for the inner West and East lobes, respectively. The morphology ...

  17. The Green Bank Telescope HII Region Discovery Survey: III. Kinematic Distances

    CERN Document Server

    Anderson, L D; Balser, Dana S; Rood, Robert T

    2012-01-01

    Using the HI Emission/Absorption method, we resolve the kinematic distance ambiguity and derive distances for 149 of 182 (82%) HII regions discovered by the Green Bank Telescope HII Region Discovery Survey (GBT HRDS). The HRDS is an X-band (9GHz, 3cm) GBT survey of 448 previously unknown HII regions in radio recombination line and radio continuum emission. Here we focus on HRDS sources from 67deg. > l > 18deg., where kinematic distances are more reliable. The 25 HRDS sources in this zone that have negative recombination line velocities are unambiguously beyond the orbit of the Sun, up to 20kpc distant. They are the most distant HII regions yet discovered. We find that 61% of HRDS sources are located at the far distance, 31% at the tangent point distance, and only 7% at the near distance. "Bubble" HII regions are not preferentially at the near distance (as was assumed previously) but average 10kpc from the Sun. The HRDS nebulae, when combined with a large sample of HII regions with previously known distances, ...

  18. CHEMICAL ABUNDANCES AND PHYSICAL PARAMETERS OF HII REGIONS IN THE MAGELLANIC CLOUDS

    Directory of Open Access Journals (Sweden)

    R. E. Carlos Reyes

    2015-01-01

    Full Text Available Usamos datos en la región ultravioleta, visible e infrarroja de 11 regiones HII en las Nubes de Magallanes, a fin de determinar sus parámetros físicos y abundancias químicas. Así, hacemos un modelo de fotoionización de seis regiones HII en la Gran Nube de Magallanes (GNM y cinco regiones HII en la Pequeña Nube de Magallanes (PNM, lo cual nos permite calcular las abundancias de He, G, N, O, Ne, S y Ar. Los valores calculados se comparan con los encontrados en la literatura para regiones HII, nebulosas planetarias y estrellas. Obtuvimos los valores de las abundancias ajustando modelos del código CLOUDY para las intensidades de línea observadas. Además, las observaciones en el Observatorio Pico dos Dias de [S II] λ6717/λ6731 para regiones HII en la PNM nos permiten determinar la densidad electrónica. Los datos IUE de las líneas [C III] λ1909 se usan para determinar la abundancia de C de seis y cinco regiones HII en la GNM y en la PNM, respectivamente.

  19. Modelling Carbon Radio Recombination Line observation towards the Ultra-Compact HII region W48A

    CERN Document Server

    Jeyakumar, S

    2013-01-01

    We model Carbon Recombination Line (CRL) emission from the Photo Dissociation Region (PDR) surrounding the Ultra-Compact (UC) HII region W48A. Our modelling shows that the inner regions ($A_V \\sim 1$) of the CII layer in the PDR contribute significantly to the CRL emission. The dependence of line ratios of CRL emission with the density of the PDR and the far ultra-violet (FUV) radiation incident on the region is explored over a large range of these parameters that are typical for the environments of UCHII regions. We find that by observing a suitable set of CRLs it is possible to constrain the density of the PDR. If the neutral density in the PDR is high ($\\gtrsim 10^7$ \\cmthree) CRL emission is bright at high frequencies ($\\gtrsim 20$ GHz), and absorption lines from such regions can be detected at low frequencies ($\\lesssim 10$ GHz). Modelling CRL observations towards W48A shows that the UCHII region is embedded in a molecular cloud of density of about $4 \\times$ 10$^7$ \\cmthree.

  20. A New Interpretation of the Bipolar HII Region S106 from HCN J = 3 - 2 Mapping Observations

    Institute of Scientific and Technical Information of China (English)

    Sheng-Li Qin; Jun-Jie Wang; Gang Zhao; Martin Miller

    2005-01-01

    The first mapping observations of the bipolar HII region S106 in HCN J = 3-2 line were made by KOSMA submillimeter telescope in April, 2004. The results show that there is a bipolar cloud core is perpendicular to the IRS4 and that the flat structure of molecular cloud core is perpendicular to the axis of the outflow. This image roughly corresponds to the optical image where a dark lane bisects the bipolar HII region. Together with the optical, infrared and radio data, we conclude that the central UC HII region, and that a neutral disk is responsible for the bipolar HII region and the outflow.

  1. The Green Bank Telescope HII Region Discovery Survey II. The Source Catalog

    CERN Document Server

    Anderson, L D; Balser, Dana S; Rood, Robert T

    2011-01-01

    The Green Bank Telescope HII Region Discovery Survey has doubled the number of known HII regions in the Galactic zone 343deg.\\leql\\leq67deg. with |b|\\leq1deg. We detected 603 discrete hydrogen radio recombination line (RRL) components at 9GHz (3cm) from 448 targets. Our targets were selected based on spatially coincident mid-infrared and 20cm radio continuum emission. Such sources are almost invariably HII regions; we detected hydrogen RRL emission from 95% of our target sample. The sensitivity of the Green Bank Telescope and the power of its spectrometer together made this survey possible. Here we provide a catalog of the measured properties of the RRL and continuum emission from the survey nebulae. The derived survey completeness limit, 180mJy at 9GHz, is sufficient to detect all HII regions ionized by single O-stars to a distance of 12kpc. These recently discovered nebulae share the same distribution on the sky as does the previously known census of Galactic HII regions. On average, however, the new nebula...

  2. Line Emission from Radiation-Pressurized HII Regions I: Internal Structure and Line Ratios

    CERN Document Server

    Yeh, Sherry C C; Krumholz, Mark R; Matzner, Christopher D; Tielens, Alexander G G M

    2013-01-01

    The emission line ratios [OIII]5007/H-beta and [NII]6584/H-alpha have been adopted as an empirical way to distinguish between the fundamentally different mechanisms of ionization in emission-line galaxies. However, detailed interpretation of these diagnostics requires calculations of the internal structure of the emitting HII regions, and these calculations depend on the assumptions one makes about the relative importance of radiation pressure and stellar winds. In this paper we construct a grid of quasi-static HII region models to explore how choices about these parameters alter HII regions' emission line ratios. We find that, when radiation pressure is included in our models, HII regions reach a saturation point beyond which further increases in the luminosity of the driving stars does not produce any further increase in effective ionization parameter, and thus does not yield any further alteration in an HII region's line ratio. We also show that, if stellar winds are assumed to be strong, the maximum possi...

  3. Dusty Cradles in a Turbulent Nursery: The Sgr A East HII Region Complex at the Galactic Center

    Science.gov (United States)

    Lau, Ryan M.; Herter, Terry; Morris, Mark; Adams, Joseph

    2015-08-01

    We present high spatial resolution (FWHM ~ 3.2’’ - 3.8’’) imaging performed by the FORCAST instrument on SOFIA at 19, 25, 31, and 37 μm of the compact HII region complex G-0.02-0.07, the site of the most recent confirmed star formation within ~10 pc of the Galactic center. G-0.02-0.07 contains three compact HII regions (A, B, and C) and one ultra-compact HII region (D). Using this multiband imaging along with DustEM, we constrain the gas-to-dust mass ratios (~45 - 65) and the relative mass abundances of large grains, very small grains, and PAHs in the emitting dust from each region. Combining the inferred stellar luminosities, the expected and observed 1.90 μm fluxes and the observed dust thermal structure, the previously suggested heating sources for regions A, B, and C are confirmed. However, for region D, the observed fluxes at 1.87 and 1.90 μm of the previously proposed ionizing star are a factor of ~40 times too bright to be the heating source. We find that the location of the Region A heating source and the morphology of surrounding dust emission is consistent with that of a bow-shock, which suggests the heating source may have been ejected from its initial birth site rather than forming in-situ. In the ejection scenario for the Region A heating source, we estimate a lower limit on its age of ~104 yrs based on the size of the bow-shock.

  4. 20-CM radio-continuum study of the SMC: Part III - Compact HII Regions

    CERN Document Server

    Wong, G F; Crawford, E J; Tothill, N F H; De Horta, A Y; Galvin, T J

    2012-01-01

    We present and discuss a new catalogue of 52 compact HII regions in the Small Magellanic Cloud (SMC) and a newly created deep 1420 MHz (\\lambda=20 cm) radio-continuum image of the N19 region located in the southwestern part of the SMC. The new images were created by merging 1420 MHz radio-continuum archival data from the Australian Telescope Compact Array. The majority of these detected radio compact HII regions have rather flat spectral indices which indicates, as expected, that the dominant emission mechanism is of thermal nature.

  5. CHAOS I: Direct Chemical Abundances for HII Regions in NGC 628

    CERN Document Server

    Berg, Danielle A; Skillman, Evan D; Pogge, Richard W; Moustakas, John; Groh-Johnson, Mara

    2015-01-01

    The CHemical Abundances of Spirals (CHAOS) project leverages the combined power of the Large Binocular Telescope (LBT) with the broad spectral range and sensitivity of the Multi Object Double Spectrograph (MODS) to measure "direct" abundances in large samples of HII regions in spiral galaxies. We present LBT MODS observations of 62 HII regions in the nearby NGC628. We measure one or more auroral lines ([OIII] 4363, [NII] 5755, [SIII] 6312, or [OII] 7320,7330) in a large number of HII regions (40). Comparing derived temperatures from multiple auroral line measurements, we find: a strong correlation between temperatures based on [SIII] and [NII]; and large discrepancies for some temperatures based on [OII] and [OIII]. These trends are consistent with other observations in the literature, yet, given the widespread use and acceptance of [OIII] as a temperature determinant, the magnitude of the T[OIII] discrepancies still came as a surprise. Based on these results, we conduct a uniform abundance analysis using the...

  6. Extraplanar HII regions in the edge-on spiral galaxies NGC 3628 and NGC 4522

    Science.gov (United States)

    Stein, Y.; Bomans, D. J.; Ferguson, A. M. N.; Dettmar, R.-J.

    2017-08-01

    Context. Gas infall and outflow are critical for determining the star formation rate and chemical evolution of galaxies but direct measurements of gas flows are difficult to make. Young massive stars and Hii regions in the halos of galaxies are potential tracers for accretion and/or outflows of gas. Aims: Gas phase abundances of three Hii regions in the lower halos of the edge-on galaxies NGC 3628 and NGC 4522 are determined by analyzing optical long-slit spectra. The observed regions have projected distances to the midplane of their host from 1.4 to 3 kpc. Methods: With the measured flux densities of the optical nebular emission lines, we derived the oxygen abundance 12 + log(O/H) for the three extraplanar Hii regions. The analysis was based on one theoretical and two empirical strong-line calibration methods. Results: The resulting oxygen abundances of the extraplanar Hii regions are comparable to the disk Hii regions in one case and are a little lower in the other case. Since our results depend on the accuracy of the metallicity determinations, we critically discuss the difference of the calibration methods we applied and confirm previously noted offsets. From our measurements, we argue that these three extraplanar Hii regions were formed in the disk or at least from disk material. We discuss the processes that could transport disk material into the lower halo of these systems and conclude that gravitational interaction with a companion galaxy is most likely for NGC 3628 while ram pressure is favored in the case of NGC 4522. Based on observations gathered as part of observing program 64.N-0208(A), 3.6 m telescope with European Southern Observatory (ESO) Faint Object Spectrograph and Camera (EFOSC2) at ESO, La Silla observatory.

  7. An Alternative to Spinning Dust for the Microwave Emission of LPH 201.663+1.643 an Ultracompact HII Region

    CERN Document Server

    McCullough, P R

    2002-01-01

    The microwave spectral energy distribution of the dusty, diffuse H II region LPH 201.663+1.643 has been interpreted by others as tentative evidence for microwave emission from spinning dust grains. We present an alternative interpretation for that particular object; specifically, that an ultracompact H II region embedded within the dust cloud would explain the available observations as well or better than spinning dust. Parameters for the size, surface brightness, and flux density of the putative ultracompact HII region, derived from the microwave observations, are within known ranges. A possible candidate for such an ultracompact H II region is IRAS 06337+1051, based upon its infrared colors. However, IRAS 06337+1051's infrared flux appears to be too small to be consistent with the microwave flux required for this alternative model to explain the observations.

  8. The giant HII region NGC 588 as a benchmark for 2D photoionisation models

    CERN Document Server

    Perez-Montero, Enrique; Relano, Monica; Vilchez, Jose M; Kehrig, Carolina; Morisset, Christophe

    2014-01-01

    We use optical integral field spectroscopy and 8 and 24 micron mid-IR observations of the giant HII region NGC 588 in the disc of M33 as input and constraints for two-dimensional tailor-made photoionisation models. Two different geometrical approaches are followed for the modelling structure: i) Each spatial element of the emitting gas is studied individually using models which assume that the ionisation structure is complete in each element to look for azimuthal variations across gas and dust. ii) A single model is considered, and the two-dimensional structure of the gas and the dust are assumed to be due to the projection of an emitting sphere onto the sky. The models in both assumptions reproduce the radial profiles of Hbeta surface brightness, the observed number of ionising photons, and the strong optical emission-line relative intensities. The first approach produces a constant-density matter-bounded thin shell of variable thickness and dust-to-gas ratio, while the second gives place to a radiation-boun...

  9. NEBU_3D afast pseudo-3D photoionization code for aspherical planetary nebulae and HII regions

    CERN Document Server

    Morisset, C; Peña, M

    2005-01-01

    We describe a pseudo-3D photoionization code, NEBU_3D and its associated visualization tool, VIS_NEB3D, which are able to easily and rapidly treat a wide variety of nebular geometries, by combining models obtained with a 1D photoionization code. We also present a tool, VELNEB_3D, which can be applied to the results of 1D or 3D photoionization codes to generate emission line profiles, position-velocity maps and 3D maps in any emission line by assuming an arbitrary velocity field. As examples of the capabilities of these new tools, we consider three very different theoretical cases. The first one is a blister HII region, for which we have also constructed a spherical model (the spherical impostor) which has exactly the same Hbeta surface brightness distribution as the blister model and the same ionizing star. The second example shows how complex line profiles can be obtained even with a simple expansion law if the nebula is bipolar and the slit slightly off-center. The third example shows different ways to prod...

  10. A Study of Molecular Cloud Associated with the HII Region Sh156

    Science.gov (United States)

    Kang, Meejoo; Lee, Youngung

    2005-06-01

    We have conducted observations toward the molecular cloud associated with the HII region Sh 156 in tcocom (J=1-0), ȩocom(J=1-0), and CS(J=2-1) using the TRAO 14 m telescope. Combining with existing \\cocom(J=1-0) data of the Outer Galaxy Survey, we delineated the physical properties of the cloud. We found that there is a significant sign of interaction between the HII region and the molecular gas. We estimated the masses of the molecular cloud, using three different techniques; the most plausible mass is estimated to be 1.37 × 105 M⊙, using a conversion factor of X=1.9 × 1020 \\conf, and this is similar to virial mass estimate. This implies that the cloud is gravitationally bound and in virial equilibrium even though it is closely associated with the HII region. In addition to existing outflow, we found several MSX and IRAS point sources associated with dense core regions. Thus, more star forming activities other than the existing HII region are also going on in this region.

  11. Scaling Relations of Star-Forming Regions: from kpc-size clumps to HII regions

    CERN Document Server

    Wisnioski, Emily; Blake, Chris; Poole, Gregory B; Green, Andrew W; Wyder, Ted; Martin, Chris

    2012-01-01

    We present the properties of 8 star-forming regions, or 'clumps,' in 3 galaxies at z~1.3 from the WiggleZ Dark Energy Survey, which are resolved with the OSIRIS integral field spectrograph. Within turbulent discs, \\sigma~90 km/s, clumps are measured with average sizes of 1.5 kpc and average Jeans masses of 4.2 x 10^9 \\Msolar, in total accounting for 20-30 per cent of the stellar mass of the discs. These findings lend observational support to models that predict larger clumps will form as a result of higher disc velocity dispersions driven-up by cosmological gas accretion. As a consequence of the changes in global environment, it may be predicted that star-forming regions at high redshift should not resemble star-forming regions locally. Yet despite the increased sizes and dispersions, clumps and HII regions are found to follow tight scaling relations over the range z=0-2 for size, velocity dispersion, luminosity, and mass when comparing >2000 HII regions locally and 30 clumps at z>1 (\\sigma \\propto r^{0.42+/-...

  12. Properties of the giant HII regions and bar in the nearby spiral galaxy NGC5430

    CERN Document Server

    Brière, É; Spekkens, K

    2012-01-01

    In order to better understand the impact of the bar on the evolution of spiral galaxies, we measure the properties of giant HII regions and the bar in the SB(s)b galaxy NGC5430. We use two complementary data sets, both obtained at the Observatoire du Mont-M\\'egantic: a hyperspectral data cube from the imaging Fourier transform spectrograph SpIOMM, and high-resolution spectra across the bar from a long-slit spectrograph. We flux-calibrate SpIOMM spectra for the first time, and produce H{\\alpha} and [NII]{\\lambda}6584\\r{A} intensity maps from which we identify 51 giant HII regions in the spiral arms and bar. We evaluate the type of activity, the oxygen abundance and the age of the young populations contained in these giant HII regions and in the bar. Thus, we confirm that NGC5430 does not harbour a strong AGN, and that its Wolf-Rayet knot shows a pure HII region nature. We find no variation in abundance or age between the bar and spiral arms, nor as a function of galactocentric radius. These results are consist...

  13. The chemical composition of planetary nebulae and HII regions in NGC 3109

    CERN Document Server

    Pena, Miriam; Richer, Michael

    2007-01-01

    We present deep spectrophotometry for a sample of 8 PNe and 12 HII regions in the irregular galaxy NGC 3109, to analyze the chemical composition of both types of nebulae. We present line intensities and the physical conditions and the abundances of He, O, Ne, N, S and Ar are derived, using the classical T_e-based method. We confirm our previous identification of PNe and HII regions based on photometry, except for one object that we argue is a compact HII region rather than a PN. We find that the chemical composition of the ISM in NGC 3109, as sampled by its HII regions, is remarkably uniform. The oxygen abundance is log O/H + 12 = 7.77 \\pm 0.07 in this galaxy, as compared to 8.05 \\pm 0.09 for the SMC. PNe show significantly higher oxygen abundances in NGC 3109: log O/H + 12 = 8.16 \\pm 0.19. We argue that, similarly to what has been suggested for some of the PNe in the Magellanic Clouds and other metal-poor galaxies, oxygen in the PNe in NGC 3109 is affected by dredge up in their progenitors. This could be als...

  14. ON THE 21-MU-M FEATURE IN HII-REGIONS

    NARCIS (Netherlands)

    OUDMAIJER, RD; DEWINTER, D

    1995-01-01

    It has recently become possible to reduce the raw IRAS Low Resolution Spectrograph (LRS) data in an interactive way. In this paper several problems concerning the LRS data of extended objects are addressed. We investigate the presence of the 21 mum emission feature in HII regions as reported by Cox

  15. The Pa{\\alpha} Luminosity Function of HII Regions in Nearby Galaxies from HST/NICMOS

    CERN Document Server

    Liu, Guilin; Kennicutt, Robert C; Schinnerer, Eva; Sofue, Yoshiaki; Komugi, Shinya; Egusa, Fumi; Scoville, Nicholas Z

    2013-01-01

    The HII region luminosity function (LF) is an important tool for deriving the birthrates and mass distribution of OB associations, and is an excellent tracer of the newly formed massive stars and associations. To date, extensive work (predominantly in H{\\alpha}) has been done from the ground, which is hindered by dust extinction and the severe blending of adjacent (spatially or in projection) HII regions. Reliably measuring the properties of HII regions requires a linear resolution <40 pc, but analyses satisfying this requirement have been done only in a handful of galaxies, so far. As the first space-based work using a galaxy sample, we have selected 12 galaxies from our HST NICMOS Pa{\\alpha} survey and studied the luminosity function and size distribution of HII regions both in individual galaxies and cumulatively, using a virtually extinction-free tracer of the ionizing photon rate. The high angular resolution and low sensitivity to diffuse emission of NICMOS also offer an advantage over ground-based im...

  16. Dust dynamics and evolution in expanding HII regions. I. Radiative drift of neutral and charged grains

    CERN Document Server

    Akimkin, V V; Pavlyuchenkov, Ya N; Wiebe, D S

    2015-01-01

    We consider dust drift under the influence of stellar radiation pressure during the pressure-driven expansion of an HII region using the chemo-dynamical model MARION. Dust size distribution is represented by four dust types: conventional polycyclic aromatic hydrocarbons (PAHs), very small grains (VSGs), big grains (BGs) and also intermediate-sized grains (ISGs), which are larger than VSGs and smaller than BGs. The dust is assumed to move at terminal velocity determined locally from the balance between the radiation pressure and gas drag. As Coulomb drag is an important contribution to the overall gas drag, we evaluate a grain charge evolution within the HII region for each dust type. BGs are effectively swept out of the HII region. The spatial distribution of ISGs within the HII region has a double peak structure, with a smaller inner peak and a higher outer peak. PAHs and VSGs are mostly coupled to the gas. The mean charge of PAHs is close to zero, so they can become neutral from time to time because of char...

  17. Hard X-rays from Ultra-Compact HII Regions in W49A

    CERN Document Server

    Tsujimoto, M; Feigelson, E D; Getman, K V; Broos, P S

    2006-01-01

    We report the Chandra detection of hard X-ray emission from the Welch ring in W49A, an organized structure of ultra-compact (UC) HII regions containing a dozen nascent early-type stars. Two UC HII regions are associated with hard X-ray emission in a deep Advanced CCD Imaging Spectrometer image exposed for 96.7 ks. One of the two X-ray sources has no near-infrared counterpart and is extended by ~5 arcsec, or ~0.3 pc, at a distance of ~11.4 kpc, which is spatially aligned with the cometary radio continuum emission associated with the UC HII region. The X-ray spectrum of the emission, when fit with a thermal model, indicates a heavily absorbed plasma with extinction of \\~5x10^{23}/cm^{2}, temperature of ~7 keV, and X-ray luminosity in the 3.0-8.0 keV band of ~3x10^{33} ergs/s. Both the luminosity and the size of the emission resemble the extended hard emission found in UC HII regions in Sagittarius B2, yet they are smaller by an order of magnitude than the emission found in massive star clusters such as NGC 3603...

  18. The effect of Galactic foreground subtraction on redshifted 21-cm observations of quasar HII regions

    CERN Document Server

    Geil, Paul M; Petrovic, Nada; Oh, Peng

    2008-01-01

    We assess the impact of Galactic synchrotron foreground removal on the observation of high-redshift quasar HII regions in redshifted 21-cm emission. We consider the case where a quasar is observed in an intergalactic medium (IGM) whose ionisation structure evolves slowly relative to the light crossing time of the HII region, as well as the case where the evolution is rapid. The latter case is expected towards the end of the reionisation era where the highest redshift luminous quasars will be observed. In the absence of foregrounds the fraction of neutral hydrogen in the IGM could be measured directly from the contrast between the HII region and surrounding IGM. However, we find that foreground removal lowers the observed contrast between the HII region and the IGM. This indicates that measurement of the neutral fraction would require modelling to correct for this systematic effect. On the other hand, foreground removal does not modify the most prominent features of the 21-cm maps. Using a simple algorithm we ...

  19. The metallicity gradient of M 33: chemical abundances of HII regions

    CERN Document Server

    Magrini, L; Mampaso, A; Corradi, R L M; Leisy, P

    2007-01-01

    We present spectroscopic observations of a sample of 72 emission-line objects, including mainly HII regions, in the spiral galaxy M 33. Spectra were obtained with the multi-object, wide field spectrograph AF2/WYFFOS at the 4.2m WHT telescope. Line intensities, extinction, and electron density were determined for the whole sample of objects. The aim of the present work was to derive chemical and physical parameters of a set of HII regions, and from them the metallicity gradient. Electron temperatures and chemical abundances were derived for the 14 HII regions where both [OII] and [OIII] emission line fluxes were measured, including the electron temperature sensitive emission line [OIII] 436.3 nm and in a few cases [NII] 575.5 nm. The ionization correction factor (ICF) method was used to derive the total chemical abundances. The presence of abundance gradients was inferred from the radial behaviour of several emission-line ratios, and accurately measured from chemical abundances directly derived in 14 HII regio...

  20. Unveiling the birth and evolution of the HII region Sh2-173

    CERN Document Server

    Cichowolski, S; Ortega, M E; Cappa, C E; Vasquez, J

    2008-01-01

    Based on a multiwavelength study, the ISM around the HII region Sh2-173 has been analyzed. The ionized region is clearly detected in the optical and in the radio continuum images. The analysis of the HI data shows a region of low emissivity that has an excellent morphological correlation with the radio continuum emission. The HII region is partially bordered by a photodissociation region, which, in turn, is encircled by a molecular structure. Taking into account the presence of noncircular motions in the Perseus spiral arm, together with previous distance estimates for the region, we adopt a distance of 2.5 +- 0.5 kpc for Sh2-173. Seven hot stars were identified in the field of Sh2-173, being only one an O-type star. The amount of energetic photons emitted by this star is enough to keep the region ionized and heat the dust. Given that an expanding HII region may trigger star formation, a search for YSO candidates was made using different infrared point source catalogues. A population of 46 YSO candidates was ...

  1. A multiwavelength study of star formation in the vicinity of Galactic HII region Sh2-100

    OpenAIRE

    Samal, M. R.; Pandey, A. K.; Ojha, D. K.; Ghosh, S K; Kulkarni, V. K.; Kusakabe, N.; Tamura, M.; Bhatt, B. C.; Thompson, M A; Sagar, R

    2010-01-01

    We present multiwavelength investigation of morphology, physical-environment, stellar contents and star formation activity in the vicinity of star-forming region Sh 2-100. It is found that the Sh 2-100 region contains seven HII regions of ultracompact and compact nature. The present estimation of distance for three HII regions, along with the kinematic distance for others, suggests that all of them belong to the same molecular cloud complex. Using NIR photometry, we identified the most probab...

  2. A nebula in your computer: simulating the physics and chemistry of an HII region

    CERN Document Server

    Bisbas, Thomas G

    2012-01-01

    In this contribution we discuss about numerical modeling of nebulae. In particular we emphasize on the dynamical evolution of an HII region and the chemical structure of a Photodissociation region. We do this using the Smoothed Particles Hydrodynamics code SEREN and the recently developed astrochemistry code 3D-PDR, respectively. We show an example application by simulating a cometary globule using these two codes.

  3. The Orion HII Region and the Orion Bar in the Mid-Infrared

    CERN Document Server

    Salgado, F; Adams, J D; Herter, T L; Tielens, A G G M

    2016-01-01

    We present mid-infrared photometry of the Orion Bar obtained with FORCAST aboard SOFIA at 6.4, 6.6, 7.7, 19.7, 31.5 and 37.1 \\um. By complementing this observations with archival FORCAST and \\emph{Herschel}/PACS images we are able to construct a complete infrared spectral energy distribution of the Huygens region in the Orion nebula By comparing the infrared images with gas tracers, we find that PACS maps trace the molecular cloud, while the FORCAST data trace the photodissociation region (PDR) and HII region. Analysis of the energetics of the region reveal that the PDR extends for 0.28~pc along the line-of-sight and that the Bar is inclined at an angle of $4\\degr$. The infrared and submillimeter images reveal that the Orion Bar represents a swept up shell with a thickness of 0.1~pc. The mass of the shell implies a shock velocity of $\\simeq 3$ km/s and an age of $\\simeq 10^5$ yr for the HII region. Our analysis shows that the UV and infrared dust opacities in the HII region and the PDR are a factor 5 to 10 lo...

  4. Spitzer--IRAC Imagery and Photometry of Ultracompact HII Regions With Extended Emission

    CERN Document Server

    De la Fuente-Acosta, E; Grave, J M C; Kumar, M S N; Trinidad, M A; Kurtz, S; Kemp, S; Franco, J; Quevedo, G

    2008-01-01

    We present the results of a morphological study performed to a sample of Ultracompact (UC) HII regions with Extended Emission (EE) using Spitzer--IRAC imagery and 3.6 cm VLA conf. D radio-continuum (RC) maps. Some examples of the comparison between maps and images are presented. Usually there is an IR point source counterpart to the peak(s) of RC emission, at the position of the UC source. We find that the predominant EE morphology is the cometary, and in most cases is coincident with IR emission at 8.0 $\\mu$m. Preliminary results of Spitzer--IRAC photometry of a sub-sample of 13 UC HII regions with EE based on GLIMPSE legacy data are also presented. Besides, individual IRAC photometry was performed to 19 UC sources within these 13 regions. We show that UC sources lie on specific locus, both in IRAC color-color and AM-product diagnostic diagrams. Counts of young stellar sources are presented for each region, and we conclude that a proportion of ~ 2%, ~10%, and ~88% of sources in the UC HII regions with EE are...

  5. From Ultracompact to Extended HII Regions. II: Cloud Gravity and Stellar Motion

    CERN Document Server

    Franco, J; Kurtz, S; Franco, Jose; Garcia-Segura, Guillermo; Kurtz, Stan

    2005-01-01

    The dynamical evolution of HII regions with and without stellar motion in dense, structured molecular clouds is studied. Clouds are modeled in hydrostatic equilibrium, with gaussian central cores and external halos that obey r**-2 and r**-3 density power laws. The cloud gravity is included as a time-independent, external force. Stellar velocities of 0, 2, 8, and 12 km/s are considered. When stellar motion is included, stars move from the central core to the edge of the cloud, producing transitions from ultracompact to extended HII regions as the stars move into lower density regions. The opposite behavior occurs when stars move toward the cloud cores. The main conclusion of our study is that ultracompact HII regions are pressure-confined entities while they remain embedded within dense cores. The confinement comes from ram and/or ambient pressures. The survival of ultracompact regions depends on the position of the star with respect to the core, the stellar life-time, and the core crossing time. Stars with ve...

  6. Primordial 4He abundance: a determination based on the largest sample of HII regions with a methodology tested on model HII regions

    CERN Document Server

    Izotov, Y I; Guseva, N G

    2013-01-01

    We verified the validity of the empirical method to derive the 4He abundance used in our previous papers by applying it to CLOUDY (v13.01) models. Using newly published HeI emissivities, for which we present convenient fits as well as the output CLOUDY case B hydrogen and HeI line intensities, we found that the empirical method is able to reproduce the input CLOUDY 4He abundance with an accuracy of better than 1%. The CLOUDY output data also allowed us to derive the non-recombination contribution to the intensities of the strongest Balmer hydrogen Halpha, Hbeta, Hgamma, and Hdelta emission lines and the ionisation correction factors for He. With these improvements we used our updated empirical method to derive the 4He abundances and to test corrections for several systematic effects in a sample of 1610 spectra of low-metallicity extragalactic HII regions, the largest sample used so far. From this sample we extracted a subsample of 111 HII regions with Hbeta equivalent width EW(Hbeta) > 150A, with excitation p...

  7. Revealing deuterium Balmer lines in HII regions with VLT-UVES

    CERN Document Server

    Hébrard, G; Walsh, J R; Vidal-Madjar, A; Ferlet, R

    2000-01-01

    The search for deuterium Balmer lines with VLT-UVES is reported in HII regions of the Galaxy and the Magellanic Clouds. The DI lines appear as faint, narrow emission features in the blue wings of the HI Balmer lines and can be distinguished from high-velocity HI emission. The previous identification to deuterium is re-inforced beyond doubt. The detection of D-alpha and D-beta in Orion (Hebrard et al. 2000) is confirmed and deuterium lines are now detected up to at least D-eta. The UVES observations provide the first detection of Balmer DI lines in four new HII regions (M 8, M 16, M 20, and DEM S 103 in SMC), demonstrating that these lines are of common occurence.

  8. Sh2-205: Three independent HII regions or only one?

    Science.gov (United States)

    Romero, G. A.; Cappa, C. E.

    Resumen: We present a study of the HII region Sh2-205 and its environs, based on data obtained from the CGPS, 12CO observations and MSX. We find that Sh2-205 can be separated in three independent optical structures: SH149.25-0.0, SH148.83-0.67, and LBN148.11-0.45. The derived spectral indices show the thermal nature of SH148.83-0.67 and LBN148.11-0.45. The morphology of SH148.83-0.67, both in optical and in radio, along with the energetic requirements indicate that this feature is an interstellar bubble powered by the UV photons of HD24431 (O9 III). LBN148.11-0.45 has the morphology of a classical HII region and their ionizing sources remain uncertain. Dust and molecular gas are found related to LBN148.11-0.45. Particularly, a photodissociation region is detected surrounding the central part of this HII region at infrared wavelengths.

  9. An Analysis of IRAS Identified Hii Regions and their Radio Properties

    CERN Document Server

    Hughes, V A

    1993-01-01

    To try and confirm the types of object in the list of 2298 potential HII regions identified by Hughes \\& MacLeod from the IRAS Point Source Catalog, we selected a sample of 82 for observing at the VLA. We selected half with values of Y = log(F$_{25}$/F$_{12}$) $\\geq$ 0.8, and for control purposes, half with values of 0.3 $\\leq$ log(F$_{25}$/F$_{12}$) $\\leq$ 0.5. 78 radio sources were detected, and of all the objects, 72\\% had at least one associated radio source. Most of the radio sources had diameters of $<$ 3\\arcsec, which was the limit to the angular resolving power of the survey. Those with larger values of Y had significantly larger values of peak radio, integrated radio, and 100$\\mu$m flux densities than those with smaller Y. Also, they generally had associated masers, and thus were most likely young compact HII regions containing star forming regions. Those with smaller Y tended not to have associated maser activity and are probably older HII regions, or stars with high IR and ionizing radiation...

  10. Study of young stellar groupings in HII regions based on the spectral and photometric data

    CERN Document Server

    Gusev, A S; Piskunov, A E; Kharchenko, N V; Pilyugin, L S; Ezhkova, O V; Khramtsova, M S; Guslyakova, S A; Bruevich, V V; Dodonov, S N; Lang, V; Shimanovskaya, E V; Efremov, Yu N

    2016-01-01

    We studied 102 star forming regions in seven spiral galaxies (NGC 628, NGC 783, NGC 2336, NGC 6217, NGC 6946, NGC 7331, and NGC 7678) on the basis of complex spectroscopic, photometric (UBVRI) and spectrophotometric (H alpha line) observations. Using data on the chemical composition and absorption in HII regions, obtained from spectroscopic observations, and using evolutionary models, we estimated physical parameters (ages and masses) of young stellar groupings embedded in HII regions. We found that the gas extinction, A(gas), which determined from the Balmer decrement, does not correspond in some cases to the absorption A(stars) in the young stellar associations (complexes). This is due to the spatial offset relative HII cloud the stellar group related to him. It has been found that the condition A(gas) = A(stars) does not satisfied for the star forming regions, in which: 1) the contribution to the total emission of gas in the B and/or V bands is higher than 40%, and 2) EW(H alpha) > 1500A. Extinction A(V) i...

  11. The impact of new ionizing fluxes on ISO observations of HII regions and starbursts

    CERN Document Server

    Schärer, D; Schaerer, Daniel; Stasinska, Grazyna

    1998-01-01

    Extensive grids of photoionization models have been calculated for single star HII regions and evolving starbursts. We illustrate the predictions for IR fine structure lines which are used to analyse the stellar content, and derive properties such as the age and IMF. The impact of recent ionizing fluxes on the IR lines are shown. First comparisons of our starburst models with IR-diagnostics and the ISO observations of Genzel et al. (1998) are also presented.

  12. Discovery of radiatively excited molecular hydrogen in the giant extragalactic HII region complex NGC 604

    NARCIS (Netherlands)

    Israel, F.P.; Hawarden, T.G.; Wade, R.S.; Geballe, T.R.; Dishoeck, van E.F.

    1989-01-01

    The 1-0S(1), 2-1S(1), 1-0S(0) and 1-0Q branch transitions of molecular hydrogen (H2) towards the giant emission nebula (HII region) NGC 604 in M33 have been detected. The line ratios are incompatible with shock-excited H2, but indicate the widespread presence of fluorescent H2 at a mean temperature

  13. Chemical behavior of the Dwarf Irregular Galaxy NGC 6822. Its PN and HII region abundances

    CERN Document Server

    Hernandez-Martinez, Liliana; Carigi, Leticia; Garcia-Rojas, Jorge

    2009-01-01

    We aim to derive the chemical behavior of a significant sample of PNe and HII regions in the irregular galaxy NGC 6822 The selected objects are distributed in different zones of the galaxy. Due to the faintness of PNe and HII regions in NGC 6822, to gather spectroscopic data with large telescopes is necessary. We obtained a well suited sample of spectra by employing VLT-FORS 2 and Gemini-GMOS spectrographs. Ionic and total abundances are calculated for the objects where electron temperatures can be determined through the detection of [OIII] \\lambda 4363 or/and [NII] \\lambda 5755 lines. A "simple" chemical evolution model has been developed and the observed data are used to compute a model for NGC 6822 in order to infer a preliminary chemical history in this galaxy. Confident determinations of He, O, N, Ne, S and Ar abundances were derived for a sample of 11 PNe and one HII region. We confirm that the present ISM is chemically homogeneous, at least in the central 2 kpc of the galaxy, showing a value 12+log O/H...

  14. A multiwavelength investigation of the HII region S311: Young stellar population and star formation

    CERN Document Server

    Yadav, Ram Kesh; Sharma, Saurabh; Ojha, D K; Samal, M R; Mallick, K K; Jose, J; Ogura, K; Richichi, Andrea; Irawati, Puji; Kobayashi, N; Eswaraiah, C

    2016-01-01

    We present a multiwavelength investigation of the young stellar population and star formation activities around the \\hii region Sharpless 311. Using our deep near-infrared observations and archival {\\it Spitzer}-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of $\\sim$86 arcmin$^2$. The YSOs sample include 8 Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSOs sample is estimated to be 1.0 \\msun. The ages and masses of the majority of the candidate YSOs are estimated to be in the range of $\\sim$0.1$-$5 Myr and $\\sim$0.3$-$6 \\msun, respectively. The 8 \\mum image of S311 displays an approximately spherical cavity around the ionizing source which is possibly created due to the expansion of the \\hii region. The spatial distribution of the candidate YSOs reveals that a significant number of them are distributed systematically along the 8 $\\mu$m emission with a majority clustered around the eastern border of the \\hii region. Four clumps/com...

  15. Spitzer and Herschel multiwavelength characterization of the dust content of evolved HII regions

    CERN Document Server

    Paladini, R; Veneziani, M; Noriega-Crespo, A; Anderson, L D; Piacentini, F; Goncalves, D Pinheiro; Paradis, D; Tibbs, C T; Bernard, J -P; Natoli, P

    2012-01-01

    We have analyzed a uniform sample of 16 evolved HII regions located in a 2 deg X 2 deg Galactic field centered at (l,b) = (30 deg, 0 deg) and observed as part of the Herschel Hi-GAL survey. The evolutionary stage of these HII regions was established using ancillary radio continuum data. By combining Hi-GAL PACS (70 micron, 160 micron) and SPIRE (250 micron, 350 micron and 500 micron) measurements with MIPSGAL 24 micron data, we built Spectral Energy Distributions (SEDs) of the sources and showed that a 2-component grey-body model is a good representation of the data. In particular, wavelengths > 70 micron appear to trace a cold dust component, for which we estimated an equilibrium temperature of the Big Grains (BGs) in the range 20 - 30 K, while for lambda < 70 micron, the data indicated the presence of a warm dust component at temperatures of the order of 50 - 90 K. This analysis also revealed that dust is present in the interior of HII regions, although likely not in a large amount. In addition, the data...

  16. Identification and multi-filter photometry of HII regions from nearby galaxies with J-PLUS

    Science.gov (United States)

    Logroño-García, R.; Vilella-Rojo, G.; López-Sanjuan, C.; Varela, J.; Muniesa, D.; Lamadrid, J. L.; Cenarro, A. J.; J-PLUS, T.

    2017-03-01

    The Javalambre Photometric Local Universe Survey (J-PLUS) has already started the data acquisition phase at the Observatorio Astrofísico de Javalambre (OAJ) in Teruel, Spain. Benefiting from the large field of view (2 deg^2) and the 12 filters set of the T80Cam at the T80/JAST telescope, we aim to study the properties of HII regions in nearby galaxies (z J-PLUS bands using as reference the Hα+NII detection image. (5) Constructs the photo-spectra for each identified HII region. We demonstrate the capabilities of this method by comparing synthetic aperture photometry from SDSS spectra with the Hα flux measured with J-PLUS data. Such comparison can be found in the poster by Vilella-Rojo et al. Once the pipeline is implemented, we will generate a catalog of nearby HII regions at zJ-PLUS. With this catalog, we will study the impact of environment in the 2D star formation properties of nearby galaxies, taking advantage of the unprecedented large contiguous area that J-PLUS will offer.

  17. The HII region G35.673-00.847: another case of triggered star formation?

    CERN Document Server

    Paron, S; Ortega, M E

    2010-01-01

    As part of a systematic study that we are performing with the aim to increase the observational evidence of triggered star formation in the surroundings of HII regions, we analyze the ISM around the HII region G35.673-00.847, a poorly studied source. Using data from large-scale surveys: Two Micron All Sky Survey, Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), MIPSGAL, Galactic Ring Survey (GRS), VLA Galactic Plane Survey (VGPS), and NRAO VLA Sky Survey (NVSS) we performed a multiwavelength study of G35.673-00.847 and its surroundings. The mid IR emission, shows that G35.673-00.847 has an almost semi-ring like shape with a cut towards the galactic west. The radius of this semi-ring is about 1.5' (~1.6 pc, at the distance of ~3.7 kpc). The distance was estimated from an HI absorption study and from the analysis of the molecular gas. Indeed, we find a molecular shell composed by several clumps distributed around the HII region, suggesting that its expansion is collecting the surrounding mate...

  18. Enrichment of the ISM by metal-rich droplets and the abundance bias in HII regions

    CERN Document Server

    Stasinska, Grazyna; Rodriguez, Monica; Henney, William J

    2007-01-01

    We critically examine a scenario for the enrichment of the interstellar medium (ISM) in which supernova ejecta follow a long (10^8 yr) journey before falling back onto the galactic disk in the form of metal-rich ``droplets'', These droplets do not become fully mixed with the interstellar medium until they become photoionized in HII regions. We investigate the hypothesis that the photoionization of these highly metallic droplets can explain the observed ``abundance discrepancy factors'' (ADFs), which are found when comparing abundances derived from recombination lines and from collisionally excited lines, both in Galactic and extragalactic HII regions. We derive bounds of 10^{13}--10^{15} cm on the droplet sizes inside HII regions in order that (1) they should not have already been detected by direct imaging of nearby nebulae, and (2) they should not be too swiftly destroyed by diffusion in the ionized gas. From photoionization modelling we find that, if this inhomogeneous enrichment scenario holds, then the r...

  19. Re-analysis of the radio luminosity function of Galactic HII regions

    CERN Document Server

    Paladini, R; Noriega-Crespo, A; Carey, S J

    2009-01-01

    We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic HII regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and super-giant HII regions, a significant number of sub-giant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered HII regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23+/-0.07 (fourth quadrant) and to -1.85+/-0.11 (first quadrant). We also find margina...

  20. Type II supernovae as probes of environment metallicity: observations of host HII regions

    CERN Document Server

    Anderson, J P; Dessart, L; Hamuy, M; Galbany, L; Morrell, N I; Stritzinger, M D; Phillips, M M; Folatelli, G; Boffin, H M J; de Jaeger, T; Kuncarayakti, H; Prieto, J L

    2016-01-01

    Spectral modelling of SNII atmospheres indicates a clear dependence of metal line strengths on progenitor metallicity. This motivates further work to evaluate the accuracy with which these SNe can be used as metallicity indicators. To assess this accuracy we present a sample of SNII HII-region spectroscopy, from which environment abundances are derived. These environment abundances are compared to the observed strength of metal lines in SN spectra. Combining our sample with measurements from the literature, we present oxygen abundances of 119 host HII regions, by extracting emission line fluxes and using abundance diagnostics. Then, following Dessart et al., these abundances are compared to equivalent widths of Fe 5018 A at various time and colour epochs. Our distribution of inferred SNII host HII-region abundances has a range of ~0.6 dex. We confirm the dearth of SNeII exploding at metallicities lower than those found (on average) in the Large Magellanic Cloud. The equivalent width of Fe 5018 A at 50 days po...

  1. The population of planetary nebulae and HII regions in M81. A study of radial metallicity gradients and chemical evolution

    CERN Document Server

    Stanghellini, Letizia; Villaver, Eva; Galli, Daniele

    2010-01-01

    We analyze the chemical abundances of planetary nebulae and HII regions in the M81 disk for insight on galactic evolution, and compare it with that of other galaxies, including the Milky Way. We acquired Hectospec/MMT spectra of 39 PNe and 20 HII regions, with 33 spectra viable for temperature and abundance analysis. Our PN observations represent the first PN spectra in M81 ever published, while several HII region spectra have been published before, although without a direct electron temperature determination. We determine elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon in PNe and HII regions, and determine their averages and radial gradients. The average O/H ratio of PNe compared to that of the HII regions indicates a general oxygen enrichment in M81 in the last ~10 Gyr. The PN metallicity gradient in the disk of M81 is -0.055+-0.02 dex/kpc. Neon and sulfur in PNe have a radial distribution similar to that of oxygen, with similar gradient slopes. If we combine our HII sample with th...

  2. A radio continuum and infrared study of Galactic HII regions

    NARCIS (Netherlands)

    Martin-Hernandez, NL; van der Hulst, JM; Tielens, AGGM

    2003-01-01

    We present observations of the 4.8 and 8.6 GHz continuum emission towards 11 southern H II regions made with the Australian Telescope Compact Array. The observed objects were selected from the Infrared Space Observatory (ISO) spectral catalogue of compact H II regions (Peeters et al. 2002b). The mor

  3. Hydrodynamic Instability of Ionization Fronts in HII Regions

    Energy Technology Data Exchange (ETDEWEB)

    Mizuta, A; Kane, J; Ryutov, D; Remington, B; Takabe, H; Pound, M

    2003-08-21

    The authors investigate hydrodynamic instability of accelerating ionization fronts with two dimensional hydrodynamic simulations. When recombination in the ionized region is turned off, Rayleigh-Taylor instability is effective. Perturbation grows up with classical Rayleigh-Taylor growth rate. In the case with recombination, the local difference of absorption profile works to smooth the surface. The perturbation does not grow and the amplitude follows a damped oscillations with time.

  4. Hii regions in ngc 5055. ii. physical properties

    Directory of Open Access Journals (Sweden)

    M. Rozas

    2008-01-01

    Full Text Available En este artículo usamos las observaciones presentadas en Rozas (2007 de la galaxia NGC 5055 en las líneas Hα y Hβ, junto con observaciones CCD con filtros estrechos en las líneas [OII], [OIII], [SII] y S[III] para calcular las anchuras equivalentes, excitación, grados de ionización, parámetros de ionización y metalicidades de las regiones catalogadas en Rozas (2007.

  5. The Molecular Cloud Associated with the HII Region RCW:34

    Science.gov (United States)

    Pagani, L.; Heydari-Malayeri, M.; Castets, A.

    1993-08-01

    We present millimetric multi-line observations of the molecular cloud associated with the H II region RCW 34. We believe we are able to present a coherent description of the cloud: a molecular bar on top of the H II region is divided into three elements: a dense, heated part situated in the post-shock trail, a cold, less dense part besides, left unperturbed and a diffuse component either in front of the dense parts or possibly mixed with them if the dense parts are clumpy. This diffuse component has a density of a few hundreds per cm-3, a temperature in the range 30-60 K and its opacity in 12CO is close to or less than unity. We show that this diffuse component, the existence of which is controversial, is the best explanation to the large 12CO (J: 1 → 0)/(J: 2 → 1) ratio we have observed. A simple-minded model is presented to approach its properties. The cloud is on top and partly in front of the H II region and can explain the 4.2 mag of visual extinction measured by one of us (Heydari-Malayeri 1988). The very high velocity flow detected in Hα by Heydari-Malayeri has no counterpart in radio but could be a direct visualisation of the so-called "Champagne effect" (Tonorio-Tagle 1979).

  6. The Spitzer Survey of the Small Magellanic Cloud: Discovery of Embedded Protostars in the HII Region NGC 346

    CERN Document Server

    Simon, Joshua D; Whitney, Barbara A; Robitaille, Thomas P; Shah, Ronak Y; Makovoz, David; Stanimirovic, Snezana; Barba, Rodolfo H; Rubio, Monica

    2007-01-01

    We use Spitzer Space Telescope observations from the Spitzer Survey of the Small Magellanic Cloud (S3MC) to study the young stellar content of N66, the largest and brightest HII region in the SMC. In addition to large numbers of normal stars, we detect a significant population of bright, red infrared sources that we identify as likely to be young stellar objects (YSOs). We use spectral energy distribution (SED) fits to classify objects as ordinary (main sequence or red giant) stars, asymptotic giant branch stars, background galaxies, and YSOs. This represents the first large-scale attempt at blind source classification based on Spitzer SEDs in another galaxy. We firmly identify at least 61 YSOs, with another 50 probable YSOs; only one embedded protostar in the SMC was reported in the literature prior to the S3MC. We present color selection criteria that can be used to identify a relatively clean sample of YSOs with IRAC photometry. Our fitted SEDs indicate that the infrared-bright YSOs in N66 have stellar mas...

  7. HII Region Ionization of the Interstellar Medium: A Case Study of NGC 7538

    CERN Document Server

    Luisi, Matteo; Balser, Dana S; Bania, T M; Wenger, Trey V

    2016-01-01

    Using data from the Green Bank Telescope, we analyze the radio continuum (free-free) and radio recombination line (RRL) emission of the compact HII region NGC 7538 (Sharpless 158). We detect extended radio continuum and hydrogen RRL emission beyond the photodissociation region (PDR) toward the north and east, but a sharp decrease in emission toward the south and west. This indicates that a non-uniform PDR morphology is affecting the amount of radiation "leaking" through the PDR. The strongest carbon RRL emission is found in the western PDR that appears to be dense. We compute a leaking fraction $f_R = 15 \\pm 5$ % of the radio continuum emission measured in the plane of the sky which represents a lower limit when accounting for the three-dimensional geometry of the region. We detect an average $^4\\textrm{He}^+/\\textrm{H}^+$ abundance ratio by number of $0.088 \\pm 0.003$ inside the HII region and a decrease in this ratio with increasing distance from the region beyond the PDR. Using Herschel Space Observatory d...

  8. An MSX Infrared Analysis of the Superbubble around Giant HII Region NGC3603

    CERN Document Server

    Wang, Jia

    2009-01-01

    Using the MSX mid-infrared observation, we reveal a 100 pc-scale superbubble surrounding the giant HII region NGC3603. We suggest that the diffuse surrounding infrared emission in bands A, C, and D is dominated by that of PAH and the emission in band E is dominated by that of dust grains. The fitted dust temperature is consistent with the heating by the central cluster's UV photons. The derived gas-to-dust mass ratio for the bubble shell is of order 10^2.

  9. VizieR Online Data Catalog: SN II in host HII regions (Anderson+, 2016)

    Science.gov (United States)

    Anderson, J. P.; Gutierrez, C. P.; Dessart, L.; Hamuy, M.; Galbany, L.; Morrell, N. I.; Stritzinger, M. D.; Phillips, M. M.; Folatelli, G.; Boffin, H. M. J.; de Jaeger, T.; Kuncarayakti, H.; Prieto, J. L.

    2016-07-01

    The data analysed in this publication comprise two distinct types of observations. The first is of SN II optical spectroscopy obtained during their photospheric phases, i.e. from discovery to at most ~100 days post explosion. These data are used to extract absorption line pEW measurements. The second data set is emission line spectral observations of host HII regions of SNe II. These are used to estimate SN II environment oxygen abundances, which can be used as metallicity proxies. In the course of this work we compare our observational results with the predictions from the spectral models of Dessart et al. (2014MNRAS.440.1856D). (2 data files).

  10. New radio observations of anomalous microwave emission in the HII region RCW175

    CERN Document Server

    Battistelli, E S; Cruciani, A; de Bernardis, P; Genova-Santos, R; Masi, S; Naldi, A; Paladini, R; Piacentini, F; Tibbs, C T; Verstraete, L; Ysard, N

    2015-01-01

    We have observed the HII region RCW175 with the 64m Parkes telescope at 8.4GHz and 13.5GHz in total intensity, and at 21.5GHz in both total intensity and polarization. High angular resolution, high sensitivity, and polarization capability enable us to perform a detailed study of the different constituents of the HII region. For the first time, we resolve three distinct regions at microwave frequencies, two of which are part of the same annular diffuse structure. Our observations enable us to confirm the presence of anomalous microwave emission (AME) from RCW175. Fitting the integrated flux density across the entire region with the currently available spinning dust models, using physically motivated assumptions, indicates the presence of at least two spinning dust components: a warm component with a relatively large hydrogen number density n_H=26.3/cm^3 and a cold component with a hydrogen number density of n_H=150/cm^3. The present study is an example highlighting the potential of using high angular-resolutio...

  11. Spectral line survey of the ultracompact HII region Mon R2

    CERN Document Server

    Ginard, D; Fuente, A; Cernicharo, J; Alonso-Albi, T; Pilleri, P; Gerin, M; García-Burillo, S; Ossenkopf, V; Rizzo, J R; Kramer, C; Goicoechea, J R; Pety, J; Berné, O; Joblin, C

    2012-01-01

    Ultracompact (UC) HII regions constitute one of the earliest phases in the formation of a massive star and are characterized by extreme physical conditions (Go>10^5 Habing field and n>10^6 cm^-3). The UC HII Mon R2 is the closest one and therefore an excellent target to study the chemistry in these complex regions. We carried out a 3mm and 1mm spectral survey using the IRAM 30-m telescope towards three positions that represent different physical environments in Mon R2: (i) the ionization front (IF) at (0",0"); two peaks in the molecular cloud (ii) MP1 at the offset (+15",-15") and (iii) MP2 at the farther offset (0",40"). In addition, we carried out extensive modeling to explain the chemical differences between the three observed regions. We detected more than thirty different species. We detected SO+ and C4H suggesting that UV radiation plays an important role in the molecular chemistry of this region. We detected the typical PDR molecules CN, HCN, HCO, C2H, and c-C3H2. While the IF and the MP1 have a chemis...

  12. Constraining the escape fraction of ionizing photons from HII regions within NGC 300: A concept paper

    CERN Document Server

    Niederhofer, Florian; Bastian, Nate; Ercolano, Barbara

    2016-01-01

    Using broadband photometry from the Hubble Space Telescope in combination with Very Large Telescope narrowband Halpha observations of the nearby spiral galaxy NGC 300, we explore a method for estimating the escape fractions of hydrogen-ionizing photons from HII regions within this galaxy. Our goal in this concept study is to evaluate the spectral types of the most massive stars using the broadband data and estimating their ionizing photon output with the help of stellar atmosphere models. A comparison with the Halpha flux that gives the amount of ionized gas in the HII region provides a measure of the escape fraction of ionizing photons from that region. We performed some tests with a number of synthetic young clusters with varying parameters to assess the reliability of the method. However, we found that the derived stellar spectral types and consequently the expected ionizing photon luminosity of a region is highly uncertain. The tests also show that on one hand we tended to overestimate the integrated phot...

  13. Interaction Between HII Region and AFGL333-Ridge: Implications to the Star Formation Scenario

    CERN Document Server

    Nakano, Makoto; Chibueze, James O; Nagayama, Takumi; Omodaka, Toshihiro; Handa, Toshihiro; Sunada, Kazuyuki; Kamezaki, Tatsuya; Burns, Ross A

    2016-01-01

    We investigated the star formation activities in the AFGL333 region, which is in the vicinity of the W4 expanding bubble, by conducting NH3 (1,1), (2,2), and (3,3) mapping observations with the 45 m Nobeyama Radio Telescope at an angular resolution of 75". The morphology of the NH3 (1,1) map shows a bow-shape structure with the size of 2.0 x 0.6 pc as seen in the dust continuum. At the interface between the W4 bubble and the dense NH3 cloud, the compact HII region G134.2+0.8, associated with IRAS02245+6115, is located. Interestingly, just north and south of G134.2+0.8 we found NH3 emission exhibiting large velocity widths of ~ 2.8 km/s, compared to 1.8 km/s at the other positions. As the possibility of mechanical energy injection through the activity of YSO(s) is low, we considered the origin of the large turbulent gas motion as indication of interaction between the compact HII region and the periphery of the dense molecular cloud. We also found expanding motion of the CO emission associated with G134.2+0.8. ...

  14. A single HII region model of the strong interstellar scattering towards Sgr A*

    Science.gov (United States)

    Sicheneder, Egid; Dexter, Jason

    2017-01-01

    Until recently, the strong interstellar scattering observed towards the Galactic center (GC) black hole, Sgr A*, was thought to come from dense gas within the GC region. The pulse broadening towards the transient magnetar SGR J1745-2900 near Sgr A* has shown that the source of the scattering is instead located much closer to Earth, possibly in a nearby spiral arm. We show that a single HII region along the line of sight, 1.5 - 4.8 kpc away from Earth with density ne of a few ˜eq 100 cm^{-3} and radius R ≃ 1.8 - 3.2 pc can explain the observed angular broadening of Sgr A*. Clouds closer to the GC overproduce the observed DM, providing an independent location constraint that agrees with that from the magnetar pulse broadening. Our model predicts that sources within ≲ 10 pc should show the same scattering origin as the magnetar and Sgr A*, while the nearest known pulsars with separations >20 pc should not. The radio spectrum of Sgr A* should show a cutoff from free-free absorption at 0.2 ≲ ν ≲ 1 GHz. For a magnetic field strength B ˜eq 15 - 70 {μ}G, the HII region could produce the rotation measure of the magnetar, the largest of any known pulsar, without requiring the gas near Sgr A* to be strongly magnetised.

  15. S7 : Probing the physics of Seyfert Galaxies through their ENLR & HII Regions

    CERN Document Server

    Dopita, Michael A; Scharwachter, Julia; Kewley, Lisa J; Davies, Rebecca; Sutherland, Ralph; Kharb, Preeti; Jose, Jessy; Bhatt, Harish; Ramya, S; Hampton, Elise; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; Srivastava, Shweta; James, Bethan

    2014-01-01

    Here we present the first results from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) which aims to investigate the physics of ~140 radio-detected southern active Galaxies with z<0.02 through Integral Field Spectroscopy using the Wide Field Spectrograph (WiFeS). This instrument provides data cubes of the central 38 x 25 arc sec. of the target galaxies in the waveband 340-710nm with the unusually high resolution of R=7000 in the red (530-710nm), and R=3000 in the blue (340-560nm). These data provide the morphology, kinematics and the excitation structure of the extended narrow-line region, probe relationships with the black hole characteristics and the host galaxy, measures host galaxy abundance gradients and the determination of nuclear abundances from the HII regions. From photoionisation modelling, we may determine the shape of the ionising spectrum of the AGN, discover whether AGN metallicities differ from nuclear abundances determined from HII regions, and probe grain destruction...

  16. Properties of compact HII regions and their host clumps in the inner vs outer Galaxy - early results from SASSy

    Science.gov (United States)

    Djordjevic, Julie; Thompson, Mark; Urquhart, James S.

    2017-01-01

    We present a catalog of compact and ultracompact HII regions for all Galactocentric radii. Previous catalogs focus on the inner Galaxy (Rgal ≤ 8 kpc) but the recent SASSy 870 µm survey allows us to identify regions out to ~20 kpc. Early samples are also filled with false classifications leading to uncertainty when deriving star formation efficiencies in Galactic models. These objects have similar mid-IR colours to HII regions. Urquhart et al. (2013) found that they could use mid-IR, submm, and radio data to identify the genuine compact HII regions, avoiding confusion. They used this method on a small portion of the Galaxy (10 < l < 60), identifying 213 HII regions embedded in 170 clumps. We use ATLASGAL and SASSy, crossmatched with RMS, to sample the remaining galactic longitudes out to Rgal = 20 kpc. We derive the properties of the identified compact HII regions and their host clumps while addressing the implications for recent massive star formation in the outer Galaxy. Observations towards nearby galaxies are biased towards massive stars, affecting simulations and overestimating models for galactic evolution and star formation rates. The Milky Way provides the ideal template for studying factors affecting massive star formation rates and efficiencies at high resolution, thus fine-tuning those models. We find that there is no significant change in the rate of massive star formation in the outer vs inner Galaxy. Despite some peaks in known complexes and possible correlation with spiral arms, the outer Galaxy appears to produce massive stars as efficiently as the inner regions. However, many of the potential star forming SASSy clumps have no available radio counterpart to confirm the presence of an HII region or other star formation tracer. Follow-up observations will be required to verify this conclusion and are currently in progress.

  17. New 20-cm radio-continuum study of the small Magellanic cloud - part III: Compact Hii regions

    Directory of Open Access Journals (Sweden)

    Wong G.F.

    2012-01-01

    Full Text Available We present and discuss a new catalogue of 48 compact Hii regions in the Small Magellanic Cloud (SMC and a newly created deep 1420 MHz (λ=20 cm radio-continuum image of the N19 region located in the southwestern part of the SMC. The new images were created by merging 1420 MHz radiocontinuum archival data from the Australian Telescope Compact Array. The majority of these detected radio compact Hii regions have rather flat spectral indices which indicates, as expected, that the dominant emission mechanism is of thermal nature.

  18. Detection of reactive ions in the ultracompact HII regions Mon R2 and G29.96-0.02

    CERN Document Server

    Rizzo, J R; Rodríguez-Franco, A; García-Burillo, S

    2003-01-01

    We report the first detection of the reactive ions CO+ and HOC+ towards ultracompact (UC) HII regions, particularly in Mon R2 and G29.96-0.02. We have observed two positions in Mon R2, namely the peak of the UC HII region and a position in the high density molecular cloud which bounds it. CO+ and HOC+ were detected at the UC HII region but not at the molecular cloud, as expected if the CO$^+$ and HOC$^+$ emissions arise in the PDR surrounding the \\uch. The measured CO$^+$ and HOC$^+$ column densities are of the order of 10$^{11}$ cm$^{-2}$ in both sources, which yields a strikingly low [HCO$^+$]/[HOC$^+$] abundance ratio of 460 in Mon R2. These values are similar to those found in some other well-known PDRs, like NGC 7023 and the Orion Bar. We briefly discuss the chemical implications of these results.

  19. A multi-wavelength investigation of RCW175: an HII region harboring spinning dust emission

    CERN Document Server

    Tibbs, C T; Compiegne, M; Dickinson, C; Alves, M I R; Flagey, N; Shenoy, S; Noriega-Crespo, A; Carey, S; Casassus, S; Davies, R D; Davis, R J

    2012-01-01

    Using infrared, radio continuum and spectral observations, we performed a detailed investigation of the HII region RCW175. We determined that RCW175, which actually consists of two separate HII regions, G29.1-0.7 and G29.0-0.6, is located at a distance of 3.2+/-0.2 kpc. Based on the observations we infer that the more compact G29.0-0.6 is less evolved than G29.1-0.7 and was possibly produced as a result of the expansion of G29.1-0.7 into the surrounding interstellar medium. We compute a star formation rate for RCW175 of (12.6+/-1.9)x10^{-5} M_{\\sun}/yr, and identified 6 possible young stellar object candidates within its vicinity. Additionally, we estimate that RCW175 contains a total dust mass of 215+/-53 M_{\\sun}. RCW175 has previously been identified as a source of anomalous microwave emission (AME), an excess of emission at cm wavelengths often attributed to electric dipole radiation from the smallest dust grains. We find that the AME previously detected in RCW175 is not correlated with the smallest dust ...

  20. Two physical regimes for the Giant HII Regions and Giant Molecular Clouds in the Antennae Galaxies

    CERN Document Server

    Zaragoza-Cardiel, Javier; Beckman, John E; García-Lorenzo, Begoña; Erroz-Ferrer, Santiago; Gutiérrez, Leonel

    2014-01-01

    We have combined observations of the Antennae galaxies from the radio interferometer ALMA (Atacama Large Millimetre/submillimetre Array) and from the optical interferometer GH$\\alpha$FaS (Galaxy Halpha Fabry-Perot System). The two sets of observations have comparable angular and spectral resolutions, enabling us to identify 142 giant molecular clouds and 303 HII regions. We have measured, and compare, their basic physical properties (radius, velocity dispersion, luminosity). For the HII regions we find two physical regimes, one for masses $>10^{5.4} \\mathrm{M_{\\odot}}$ of ionized gas, which the gas density increases with gas mass, the other for masses $<10^{5.4} \\mathrm{M_{\\odot}}$ of ionized gas where the gas density decreases with gas mass. For the GMCs we find, in contrast to previous studies in other galaxies over a generally lower mass range of clouds, that the gas density increases with the total gas mass, hinting at two regimes for these clouds if we consider both sources of data. We also find that ...

  1. StarBench: The D-type expansion of an HII region

    CERN Document Server

    Bisbas, T G; Williams, R J R; Mackey, J; Tremblin, P; Raga, A C; Arthur, S J; Baczynski, C; Dale, J E; Frostholm, T; Geen, S; Haugboelle, T; Hubber, D; Iliev, I T; Kuiper, R; Rosdahl, J; Sullivan, D; Walch, S; Wuensch, R

    2015-01-01

    StarBench is a project focused on benchmarking and validating different star-formation and stellar feedback codes. In this first StarBench paper we perform a comparison study of the D-type expansion of an HII region. The aim of this work is to understand the differences observed between the twelve participating numerical codes against the various analytical expressions examining the D-type phase of HII region expansion. To do this, we propose two well-defined tests which are tackled by 1D and 3D grid- and SPH- based codes. The first test examines the `early phase' D-type scenario during which the mechanical pressure driving the expansion is significantly larger than the thermal pressure of the neutral medium. The second test examines the `late phase' D-type scenario during which the system relaxes to pressure equilibrium with the external medium. Although they are mutually in excellent agreement, all twelve participating codes follow a modified expansion law that deviates significantly from the classical Spit...

  2. Unresolved wind-driven shells and the supersonic velocity dispersion in giant HII regions

    CERN Document Server

    Tenorio-Tagle, G; Fernandes, R C; Fernandes, R Cid

    1995-01-01

    The presence of giant shells or loops in giant HII regions are clear witness of the mechanical energy input from massive stars. Here we evaluate the impact that winds may have on the structure of giant nebulae and on their supersonic velocity dispersion. We follow the suggestion from Chu \\& Kennicutt (1994) to see if a combination of a large number of unresolved wind-driven shells caused by massive stars could produce the integrated broad Gaussian profiles typical of giant HII regions. The results, accounting for a wide range of energies, densities and velocity or age of the expanding shells, show that supersonic Gaussian profiles may arise only from a collection of unresolved wind-driven shells if the shells present a peculiar velocity distribution which implies a strongly peaked age distribution leading to an awkward star formation history. On the other hand, a uniform distribution of ages originates profiles with a flat-topped core defined by the terminal shell velocity and a steep decay as v^{-6} up t...

  3. On the Origin of the HII Regions Associated with Massive and Compact Superstar Clusters

    Science.gov (United States)

    Silich, Sergiy; Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana

    This contribution to the IV Korea-Mexico meeting deals with the hydrodynamics of the matter reinserted within super star clusters (SSCs) by both stellar winds and supernova explosions, results recently printed in The Astrophysical Journal (Silich et al. 2007). The motivation of such a project arose from the persistent presence of the small mass and compact HII regions that sit right on top of many massive and compact SSCs, from which one expects a large mechanical energy power. The data used for our calculations appear only recently (see Smith et al. 2006) for the massive and compact SSC M82-A1. We presented in our paper the calculated flow, derived through analytical and semi-analytical methods, which led to almost identical results. We have found out that the only way of accommodating a compact HII region (4.5 pc in radius, in the case of M82-A1) on top of a 6.3 Myr old and massive (> 10^6 M_{⊙}) SSC with a half light radius of 3 pc, requires of two assumptions: a very low heating efficiency (Tagle et al. 2007) and a high pressure in the surrounding medium.

  4. The Role of Stellar Feedback in the Dynamics of HII Regions

    CERN Document Server

    Lopez, Laura A; Bolatto, Alberto D; Prochaska, J Xavier; Ramirez-Ruiz, Enrico; Castro, Daniel

    2013-01-01

    Stellar feedback is often cited as the biggest uncertainty in galaxy formation models today. This uncertainty stems from a dearth of observational constraints as well as the great dynamic range between the small scales (1 kpc) that are shaped by this feedback. To bridge this divide, in this paper we aim to assess observationally the role of stellar feedback at the intermediate scales of HII regions. In particular, we employ multiwavelength data to examine several stellar feedback mechanisms in a sample of 32 HII regions in the Large and Small Magellanic Clouds (LMC and SMC, respectively). Using optical, infrared, radio, and X-ray images, we measure the pressures exerted on the shells from the direct stellar radiation, the dust-processed radiation, the warm ionized gas, and the hot X-ray emitting gas. We find that the warm ionized gas dominates over the other terms in all of the sources, although two have comparable dust-processed radiation pressures to their warm gas pressures. The hot gas pressures are compa...

  5. HII REGIONS IN HYDROSTATIC BALANCE BETWEEN GAS PRESSURE, RADIATION PRESSURE AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. C. Raga

    2015-01-01

    Full Text Available Estudiamos las soluciones de una versión modificada de la ecuación de Lane-Emden isotérmica, la cual incorpora el efecto de la presión de radiación (dirigida hacia afuera asociada a las fotoionizaciones. Estas soluciones son relevantes para regiones HII alrededor de un cúmulo con ≈500 estrellas O, que puede fotoionizar el gas hasta distancias de ≈ pc (siendo n0 la densidad central del gas, donde son importantes los efectos tanto de la autogravedad como de la presión de radiación. Encontramos que las soluciones tienen una transición de un régimen "dominado por gravedad" (en el que las soluciones convergen a radios grandes a la solución de la esfera isotérmica autogravitante no singular a uno "dominado por presión de radiación" (en el que la densidad diverge a un radio finito para regiones HII con densidades centrales mayores que ncrit = 100 cm -3. Argumentamos que las soluciones con densidades centrales altas, dominadas por presión de radiación, no ocurrirán en muchas de las situaciones astrofísicamente relevantes, dada la ausencia de un posible medio confinador de presión suficientemente alta.

  6. Fossil HII Regions: Self-Limiting Star Formation at High Redshift

    CERN Document Server

    Oh, S P; Haiman, Zoltan

    2003-01-01

    Recent results by the WMAP satellite suggest that the intergalactic medium was significantly reionized at redshifts as high as z~17. At this early epoch, the first ionizing sources likely appeared in the shallow potential wells of mini-halos with virial temperatures T < 10^4 K. Once such an ionizing source turns off, its surrounding HII region Compton cools and recombines. Nonetheless, we show that the ``fossil'' HII regions left behind remain at high adiabats, prohibiting gas accretion and cooling in subsequent generations of mini-halos. Thus, early star formation is self-limiting. We quantify this effect to show that star formation in mini-halos cannot account for the bulk of the electron scattering opacity measured by WMAP, which must be due to more massive objects. We argue that gas entropy, rather than IGM metallicity, regulates the evolution of the global ionizing emissivity, and impedes full reionization until lower redshifts. We discuss several important consequences of this early entropy floor for...

  7. Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons

    CERN Document Server

    Nicholls, David C; Sutherland, Ralph S

    2012-01-01

    The measurement of electron temperatures and metallicities in H ii regions and Planetary Nebulae (PNe) has-for several decades-presented a problem: results obtained using different techniques disagree. What it worse, they disagree consistently. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In this paper, we explore the possibility that electrons in H ii regions and PNe depart from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a "kappa-distribution" for the electron energies. Such distributions are widely found in Solar System plasmas, where they can be directly measured. This simple assumption is able to explain the temperature and metallicity discrepancies in H ii regions and PNe arising from the different measurement techniques. We find that the energy distribution does not need to depart dramatically from an equilibrium distribution. From an examination of data from Hii regions and PNe it appears that kappa ~ ...

  8. GMRT and VLA Observations at 49 cm and 20 cm of the HII Region near = 24.8°, = 0.1°

    Indian Academy of Sciences (India)

    N. G. Kantharia; W. M. Goss; D. Anish Roshi; Niruj R. Mohan; Francois Viallefond

    2007-03-01

    We report multi-frequency radio continuum and hydrogen radio recombination line observations of HII regions near = 24.8°, = 0.1° using the Giant Metrewave Radio Telescope(GMRT) at 1.28 GHz ( = 172), 0.61 GHz ( = 220) and the Very Large Array (VLA) at 1.42 GHz ( = 166). The region consists of a large number of resolved HII regions and a few compact HII regions as seen in our continuum maps, many of which have associated infrared (IR) point sources. The largest HII region at = 24.8° and = 0.1° is a few arcmins in size and has a shell-type morphology. It is a massive HII region enclosing ∼ 550 M⊙ with a linear size of 7 pc and an rms electron density of ∼ 110 cm-3 at a kinematic distance of 6 kpc. The required ionization can be provided by a single star of spectral type O5.5. We also report detection of hydrogen recombination lines from the HII region at = 24.8° and = 0.1° at all observed frequencies near = 100 km s-1. We model the observed integrated line flux density as arising in the diffuse HII region and find that the best fitting model has an electron density comparable to that derived from the continuum.We also report detection of hydrogen recombination lines from two other HII regions in the field.

  9. Small-spatial scale variations of nebular properties and the abundance discrepancy in three Galactic HII regions

    CERN Document Server

    Mesa-Delgado, A

    2010-01-01

    We present results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic HII regions: M8, M17 and NGC7635. We study the spatial distributions of a large number of nebular parameters such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of O^{2+}, ADF(O^{2+}), defined as the logarithmic difference of the O^{2+} abundances derived from collisionally excited and recombination lines. We find that the ADF(O^{2+}) remains fairly constant along the slit positions of M8 and M17. In the case of NGC7635, we only detect the OII recombination lines in the integrated spectrum along the whole slit, where the ADF(O^{2+}) reaches a remarkably high value of about 0.59 dex. We compare our results with previous ones obtained for the Orion Nebula. We f...

  10. The Ionizing Stars of the Galactic Ultra-Compact HII Region G45.45+0.06

    CERN Document Server

    Blum, Robert D

    2008-01-01

    Using the NIFS near-infrared integral-field spectrograph behind the facility adaptive optics module, ALTAIR, on Gemini North, we have identified several massive O-type stars that are responsible for the ionization of the Galactic Ultra-Compact HII region G45.45+0.06. The sources ``m'' and ``n'' from the imaging study of Feldt et a. 1998 are classified as hot, massive O-type stars based on their K-band spectra. Other bright point sources show red and/or nebular spectra and one appears to have cool star features that we suggest are due to a young, low-mass pre-main sequence component. Still two other embedded sources (``k'' and ``o'' from Feldt et al.) exhibit CO bandhead emission that may arise in circumstellar disks which are possibly still accreting. Finally, nebular lines previously identified only in higher excitation planetary nebulae and associated with KrIII and SeIV ions are detected in G45.45+0.06.

  11. The Genesis of Super Star Clusters as Self-Gravitating HII Regions

    CERN Document Server

    Tan, J C; Tan, Jonathan C.; Kee, Christopher F. Mc

    2000-01-01

    We examine the effects of ionization, radiation pressure and main sequence winds from massive stars on self-gravitating, clumpy molecular clouds, thereby modeling the formation and pre-supernova feedback of massive star clusters. We find the process of ``turbulent mass loading'' is effective in confining HII regions. Extrapolating typical Galactic high-mass star forming regions to greater initial gas cloud masses and assuming steady star formation rates, we determine the timescales for cloud disruption. We find that a dense n_c ~ 2 x 10^5 cm^-3 cloud with initial mass M_c ~ 4 x 10^5 M_sun is able to form ~2 x 10^5 M_sun of stars (50% efficiency) before feedback disperses the gas after ~3 Myr. This mass and age are typical of young, optically visible super star clusters (SSCs). The high efficiency permits the creation of a bound stellar system.

  12. Extinction and PAH intensity variations across the HII region IRAS 12063-6259

    Science.gov (United States)

    Stock, D.; Peeters, E.; Tielens, X.; Otaguro, J.; Bik, A.

    The spatial variations in polycyclic aromatic hydrocarbon (PAH) band intensities are generally attributed to variations of the physical conditions in the environment hosting the emitting PAH molecules. However, in recent years, it has been suggested that such variations are caused mainly by extinction. To resolve this question, we have obtained near-infrared (NIR), mid-infrared (MIR) and radio observations of the compact HII region IRAS 12063-6259. We use these data to construct multiple independent extinction maps and to measure the main PAH feature intensities (6.2, 7.7, 8.6 and 11.2 µ m). Three extinction maps are derived: the first using the NIR hydrogen lines and case B recombination theory; the second combining the NIR data, radio data and case B recombination; and the third making use of the Spitzer/IRS MIR observations to measure the 9.8 µ m silicate absorption feature intensity using the Spoon method and PAHFIT. We conclude that different areas of IRAS 12063-6259 possess markedly different extinction properties, with some regions displaying both silicate absorption and corresponding NIR extinction, and other regions displaying NIR extinction and no corresponding silicate absorption. While such breakdowns of the relationship between the NIR extinction and the silicate absorption strength have been observed in molecular clouds, they have never been observed for HII regions. We then compare the PAH intensity variations in the Spitzer/IRS data after dereddening to those found in the original data. Generally it was found that the PAH band intensity variations persist even after dereddening, implying that extinction is not the main cause of the PAH band intensity variations.

  13. Spitzer Analysis of HII Region Complexes in the Magellanic Clouds: Determining a Suitable Monochromatic Obscured Star Formation Indicator

    CERN Document Server

    Lawton, Brandon; Babler, Brian; Block, Miwa; Bolatto, Alberto D; Bracker, Steve; Carlson, Lynn R; Engelbracht, Charles W; Hora, Joseph L; Indebetouw, Remy; Madden, Suzanne C; Meade, Marilyn; Meixner, Margaret; Misselt, Karl; Oey, M S; Oliveira, Joana M; Robitaille, Thomas; Sewilo, Marta; Shiao, Bernie; Vijh, Uma P; Whitney, Barbara

    2010-01-01

    HII regions are the birth places of stars, and as such they provide the best measure of current star formation rates (SFRs) in galaxies. The close proximity of the Magellanic Clouds allows us to probe the nature of these star forming regions at small spatial scales. We aim to determine the monochromatic IR band that most accurately traces the bolometric IR flux (TIR), which can then be used to estimate an obscured SFR. We present the spatial analysis, via aperture/annulus photometry, of 16 LMC and 16 SMC HII region complexes using the Spitzer IRAC and MIPS bands. UV rocket data and SHASSA H-alpha data are also included. We find that nearly all of the LMC and SMC HII region SEDs peak around 70um, from ~10 to ~400 pc from the central sources. As a result, the sizes of HII regions as probed by 70um is approximately equal to the sizes as probed by TIR (about 70 pc in radius); the radial profile of the 70um flux, normalized by TIR, is constant at all radii (70um ~ 0.45 TIR); the 1-sigma standard deviation of the 7...

  14. Predictions of the extent of self-enrichment in oxygen of giant metal-poor HII regions

    CERN Document Server

    Wofford, Aida

    2009-01-01

    In general, HII regions do not show clear signs of self-enrichment in products from massive stars (M > 8 M_sun). In order to explore why, I modeled the contamination with Wolf-Rayet star ejecta of metal-poor (Z=0.001) HII regions, ionised either by a 10^6 M_sun cluster of coeval stars (cluster 1), or a cluster resulting from continuous star formation at a rate of 1 M_sun yr^-1 (cluster 2). The clusters have Z=0.001 and a Salpeter initial mass function (IMF) from 0.1 to 120 M_sun. Independent one dimensional constant density simulations of the emission-line spectra of unenriched HII regions were computed at the discrete ages 1, 2, 3, 4, and 5 Myr, with the photoionisation code CLOUDY, using as input, radiative and mechanical stellar feedbacks predicted by the evolutionary synthesis code STARBURST99. Each HII region was placed at the outer radius of the adiabatically expanding superbubble of Mac Low and McCray (1988). For models with thermal and ionisation balance time-scales of less than 1 Myr, and with oxygen...

  15. Amplification of Magnetic Fields in a Primordial HII Region and Supernova

    CERN Document Server

    Koh, Daegene

    2016-01-01

    Magnetic fields permeate the Universe on all scales and play a key role during star formation. We study the evolution of magnetic fields around a massive metal-free (Population III) star at $z \\sim 15$ during the growth of its HII region and subsequent supernova explosion by conducting three cosmological magnetohydrodynamic simulations with radiation transport. Given the theoretical uncertainty and weak observational constraints of magnetic fields in the early universe, we initialize the simulations with identical initial conditions only varying the seed field strength. We find that magnetic fields grow as $\\rho^{2/3}$ during the gravitational collapse preceding star formation, as expected from ideal spherical collapse models. Massive Population III stars can expel a majority of the gas from the host halo through radiative feedback, and we find that the magnetic fields are not amplified above the spherical collapse scaling relation during this phase. However, afterwards when its supernova remnant can radiativ...

  16. THE INNER GALACTIC STRUCTURE TRACED BY MOLECULAR CLOUDS ASSOCIATED WITH ULTRA-COMPACT HII REGIONS

    Directory of Open Access Journals (Sweden)

    A. Luna

    2008-01-01

    Full Text Available Estamos sometiendo a pruebas un método para determinar las distancias para una muestra de regiones HII ultracompactas con colores en IRAS y con detección de CS(J=2-1. La ambigüedad de las distancias cinem aticas se resuelve mediante simulaciones Monte Carlo. Utilizando nubes moleculares sintéticas simulamos las distribuciones longitud heliocéntrica-radio (l-R sobre el plano galáctico, y las proyecciones asociadas longitudvelocidad LSR (l-VLSR. Se escoge la mejor distribución galáctica por comparación con los mapas observados de CO. Se presentan resultados preliminares para el IV cuadrante galáctico.

  17. Extragalactic Ultracompact HII Regions: Probing the Birth Environments of Super Star Clusters

    CERN Document Server

    Johnson, K E

    2004-01-01

    In recent years, a number of extragalactic massive star clusters that are still deeply embedded in their birth material have been discovered. These objects represent the youngest stage of massive star cluster evolution yet observed, and the most massive and dense of these may be proto globular clusters. Their properties appear to be similar to those of ultracompact HII regions in the Galaxy, but scaled up in total mass and luminosity. In many cases, these clusters are only visible at mid-IR to radio wavelengths, and they have typically been detected as ``inverted'' spectrum radio sources. However, the set of existing observations is anemic, and our current physical model for these natal clusters in simplistic. This article will overview what we think we know about these objects based on existing observations and outline some of the most significant gaps in our current understanding.

  18. Formation of Population III Stars in Fossil HII Regions: Significance of HD

    CERN Document Server

    Nagakura, T; Nagakura, Takanori; Omukai, Kazuyuki

    2005-01-01

    We study the evolution of gas in HII regions around the first stars after the death of the exciting stars. If the first star in a small halo dies without supernova (SN), subsequent star formation is possible in the same halo. We thus investigate the effect of ionization of the gas on subsequent star formation within small halos in the early universe using one-dimensional hydrodynamics with spherical symmetry along with non-equilibrium primordial gas chemistry. We find that the enhanced electron fraction facilitates the formation of molecular hydrogen at the cores of these halos. The low temperature circumstances produced by the H_2 cooling is suitable for HD formation and the resultant cooling further drops the temperature below 100 K. Consequently, low-mass stars with primordial abundances can form even in a small halo. After accreting the interstellar metals, these stars might resemble low-mass ultra metal-poor stars discovered in the present Galactic halo.

  19. Radiation-MHD simulations of pillars and globules in HII regions

    CERN Document Server

    Mackey, Jonathan

    2012-01-01

    Implicit and explicit raytracing-photoionisation algorithms have been implemented in the author's radiation-magnetohydrodynamics code. The algorithms are described briefly and their efficiency and parallel scaling are investigated. The implicit algorithm is more efficient for calculations where ionisation fronts have very supersonic velocities, and the explicit algorithm is favoured in the opposite limit because of its better parallel scaling. The implicit method is used to investigate the effects of initially uniform magnetic fields on the formation and evolution of dense pillars and cometary globules at the boundaries of HII regions. It is shown that for weak and medium field strengths an initially perpendicular field is swept into alignment with the pillar during its dynamical evolution, matching magnetic field observations of the`Pillars of Creation' in M16. A strong perpendicular magnetic field remains in its initial configuration and also confines the photoevaporation flow into a bar-shaped, dense, ioni...

  20. The Elephant Trunk Nebula and the Trumpler 37 cluster: Contribution of triggered star formation to the total population of an HII region

    CERN Document Server

    Getman, Konstantin V; Sicilia-Aguilar, Aurora; Broos, Patrick S; Kuhn, Michael A; Garmire, Gordon P

    2012-01-01

    Rich young stellar clusters produce HII regions whose expansion into the nearby molecular cloud is thought to trigger the formation of new stars. However, the importance of this mode of star formation is uncertain. This investigation seeks to quantify triggered star formation (TSF) in IC 1396A (a.k.a., the Elephant Trunk Nebula), a bright rimmed cloud (BRC) on the periphery of the nearby giant HII region IC 1396 produced by the Trumpler 37 cluster. X-ray selection of young stars from Chandra X-ray Observatory data is combined with existing optical and infrared surveys to give a more complete census of the TSF population. Over 250 young stars in and around IC 1396A are identified; this doubles the previously known population. A spatio-temporal gradient of stars from the IC 1396A cloud toward the primary ionizing star HD 206267 is found. We argue that the TSF mechanism in IC 1396A is the radiation-driven implosion process persisting over several million years. Analysis of the X-ray luminosity and initial mass f...

  1. The filling factor - radius relation for 58 HII regions across the disk of NGC6946

    CERN Document Server

    Cedrés, B; Bongiovanni, A; Cepa, J; Ramos, A Asensio; Giammanco, C; Cabrera-Lavers, A; Alfaro, E

    2013-01-01

    Using the OSIRIS tunable narrow band imager on the 10.4m GTC (La Palma) we have mapped the SAB(rs)cd galaxy NGC 6946 over a 7.3x7.5 square arcminutes field in the emission lines of the [SII]\\lambda\\lambda, 6717, 6731 doublet, and in H\\alpha. From these maps we have produced catalogs of the H\\alpha luminosities and effective radii of 557 HII regions across the disk, and derived the [SII] emission line ratios of 370 of these. The H\\alpha observations were used to derive the mean luminosity-weighted electron densities for the regions of the sample, while the [SII] line ratios allowed us to derive values of the in situ electron densities in the denser zones from which the major fraction of the radiation in these lines is emitted, for 58 of the regions. This is by far the largest data set of its kind for a single galaxy. A classical two phase model is used to derive the filling factors of the regions. We find that although the mean electron density decreases with the square root of the radius of the regions, the i...

  2. Dusty Cradles in a Turbulent Nursery: The Sgr A East HII Region Complex at the Galactic Center

    CERN Document Server

    Lau, Ryan; Morris, Mark; Adams, Joe

    2014-01-01

    We present imaging at 19, 25, 31, and 37 {\\mu}m of the compact HII region complex G-0.02-0.07 located 6 pc in projection from the center of the Galaxy obtained with SOFIA using FORCAST. G-0.02-0.07 contains three compact HII regions (A, B, and C) and one ultra-compact HII region (D). Our observations reveal the presence of two faint, infrared sources located 23'' and 35'' to the east of region C (FIRS 1 and 2) and detect dust emission in two of the three "ridges" of ionized gas west of region A. The 19/37 color temperature and 37 {\\mu}m optical depth maps of regions A - C are used to characterize the dust energetics and morphology. Regions A and B exhibit average 19/37 color temperatures of ~105 K, and regions C and D exhibit color temperatures of ~115 K and ~130 K, respectively. Using the DustEM code we model the SEDs of regions A - D and FIRS 1, all of which require populations of very small, transiently heated grains and large, equilibrium-heated grains. We also require the presence of polycyclic aromatic ...

  3. Spectral line survey of the ultracompact HII region Monoceros R2

    Science.gov (United States)

    Ginard, D.; González-García, M.; Fuente, A.; Cernicharo, J.; Alonso-Albi, T.; Pilleri, P.; Gerin, M.; García-Burillo, S.; Ossenkopf, V.; Rizzo, J. R.; Kramer, C.; Goicoechea, J. R.; Pety, J.; Berné, O.; Joblin, C.

    2012-07-01

    Context. Ultracompact (UC) Hii regions constitute one of the earliest phases in the formation of a massive star and are characterized by extreme physical conditions (G0 > 105 Habing field and n > 106 cm-3). The UC Hii Mon R2 is the closest example and an excellent target to study the chemistry in these complex regions. Aims: Our goal is to investigate the chemistry of the molecular gas around UC Hii Mon R2 and the variations caused by the different local physical conditions. Methods: We carried out 3 mm and 1 mm spectral surveys using the IRAM 30-m telescope towards three positions that represent different physical environments in Mon R2: (i) the ionization front (IF) at (0″, 0″), and two peaks in the molecular cloud; (ii) molecular Peak 1 (hereafter MP1) at the offset (+15″, -15″); and (iii) molecular Peak 2 (hereafter MP2) at the farther offset (0″, 40″). In addition, we carried out extensive modeling to explain the chemical differences between the three observed regions. Results: We detected more than 30 different species (including isotopologues and deuterated compounds). In particular, we detected SO+ and C4H confirming that ultraviolet (UV) radiation plays an important role in the molecular chemistry of this region. In agreement with this interpretation, we detected the typical photo-dissociation region (PDR) molecules CN, HCN, HCO, C2H, and c-C3H2. There are chemical differences between the observed positions. While the IF and the MP1 have a chemistry similar to that found in high UV field and dense PDRs such as the Orion Bar, the MP2 is similar to lower UV/density PDRs such as the Horsehead nebula. Our chemical modeling supports this interpretation. In addition to the PDR-like species, we detected complex molecules such as CH3CN, H2CO, HC3N, CH3OH, and CH3C2H that are not usually found in PDRs. The sulfur compounds CS, HCS+, C2S, H2CS, SO, and SO2 and the deuterated species DCN and C2D were also identified. The origin of these complex species

  4. A bright-rimmed cloud sculpted by the H ii region Sh2-48

    CERN Document Server

    Ortega, M E; Giacani, E; Rubio, M; Dubner, G

    2013-01-01

    To characterize a bright-rimmed cloud embedded in the HII region Sh2-48 searching for evidence of triggered star formation. We carried out observations towards a region of 2'x2' centered at RA=18h 22m 11.39s, dec.=-14deg 35m 24.81s (J2000) using the Atacama Submillimeter Telescope Experiment (ASTE; Chile) in the 12CO J=3-2,13CO J=3-2, HCO+ J=4-3, and CS J=7-6 lines with an angular resolution of about 22". We also present radio continuum observations at 5 GHz carried out with the Jansky Very Large Array (JVLA; EEUU) interferometer with a synthetized beam of 7"x5". The analysis of our molecular observations reveals the presence of a relatively dense clump with n(H_2)~3x10^3 cm^-3, located in projection onto the interior of the HII region Sh2-48. The emission distribution of the four observed molecular transitions has, at VLSR~38 kms^-1, morphological anti-correlation with the bright-rimmed cloud as seen in the optical emission. From the new radio continuum observations we identify a thin layer of ionized gas lo...

  5. Study of morphology and stellar content of the Galactic HII region IRAS 16148-5011

    CERN Document Server

    Mallick, K K; Tamura, M; Linz, H; Samal, M R; Ghosh, S K

    2014-01-01

    An investigation of the IRAS 16148-5011 region - a cluster at a distance of 3.6 kpc - is presented here, carried out using multiwavelength data in near-infrared (NIR) from the 1.4m Infrared Survey Facility telescope, mid-infrared (MIR) from the archival Spitzer GLIMPSE survey, far-infrared (FIR) from the Herschel archive, and low-frequency radio continuum observations at 1280 and 843 MHz from the Giant Metrewave Radio Telescope (GMRT) and Molonglo Survey archive, respectively. A combination of NIR and MIR data is used to identify 7 Class I and 133 Class II sources in the region. Spectral Energy Distribution (SED) analysis of selected sources reveals a 9.6 Msolar, high-mass source embedded in nebulosity. However, Lyman continuum luminosity calculation using radio emission - which shows a compact HII, region - indicates the spectral type of the ionizing source to be earlier than B0-O9.5. Free-free emission SED modelling yields the electron density as 138 cm^{-3}, and thus the mass of the ionized hydrogen as ~16...

  6. Star formation towards the southern Cometary HII region IRAS 17256-3631

    CERN Document Server

    Veena, V S; Tej, A; Varricatt, W P; Ghosh, S K; Chandrasekhar, T; Ashok, N M

    2015-01-01

    IRAS 17256-3631 is a southern Galactic massive star forming region located at a distance of 2 kpc. In this paper, we present a multiwavelength investigation of the embedded cluster, the HII region, as well as the parent cloud. Radio images at 325, 610 and 1372 MHz were obtained using GMRT, India while the near-infrared imaging and spectroscopy were carried out using UKIRT and Mt. Abu Infrared Telescope, India. The near-infrared K-band image reveals the presence of a partially embedded infrared cluster. The spectral features of the brightest star in the cluster, IRS-1, spectroscopically agrees with a late O or early B star and could be the driving source of this region. Filamentary H_2 emission detected towards the outer envelope indicates presence of highly excited gas. The parent cloud is investigated at far-infrared to millimeter wavelengths and eighteen dust clumps have been identified. The spectral energy distributions (SEDs) of these clumps have been fitted as modified blackbodies and the best-fit peak t...

  7. Triggered massive star formation associated with the bubble Hii region Sh2-39 (N5)

    Science.gov (United States)

    Duronea, N. U.; Cappa, C. E.; Bronfman, L.; Borissova, J.; Gromadzki, M.; Kuhn, M. A.

    2017-09-01

    Aims: We perform a multiwavelength analysis of the bubble Hii region Sh2-39 (N5) and its environs with the aim of studying the physical properties of Galactic IR bubbles and exploring their impact in triggering massive star formation. Methods: To analyze the molecular gas, we used CO(3-2) and HCO+(4-3) line data obtained with the on-the-fly technique from the ASTE telescope. To study the distribution and physical characteristics of the dust, we made use of archival data from ATLASGAL, Herschel, and MSX, while the ionized gas was studied making use of an NVSS image. We used public WISE, Spitzer, and MSX point source catalogs to search for infrared candidate young stellar objects (YSOs) in the region. To investigate the stellar cluster [BDS2003]6 we used IR spectroscopic data obtained with the ARCoIRIS spectrograph, mounted on Blanco 4 m Telescope at CTIO, and new available IR Ks band observations from the VVVeXtended ESO Public Survey (VVVX). Results: The new ASTE observations allowed the molecular gas component in the velocity range from 30 km s-1 to 46 km s-1, associated with Sh2-39, to be studied in detail. The morphology of the molecular gas suggests that the ionized gas is expanding against its parental cloud. We identified four molecular clumps, which were likely formed by the expansion of the ionization front, and determined some of their physical and dynamical properties. Clumps with HCO+ and 870 μm counterparts show evidence of gravitational collapse. We identified several candidate YSOs across the molecular component. Their spatial distribution and the fragmentation time derived for the collected layers of the molecular gas suggest that massive star formation might have been triggered by the expansion of the nebula via the collect and collapse mechanism. The spectroscopical distance obtained for the stellar cluster [BDS2003]6, placed over one of the collapsing clumps in the border of the Hii region, reveals that this cluster is physically associated with

  8. The environment and star formation of HII region Sh2-163: a multi-wavelength study

    CERN Document Server

    Yu, Naiping; Li, Nan

    2016-01-01

    To investigate the environment of HII region Sh2-163 and search for evidence of triggered star formation in this region, we performed a multi-wavelength study of this HII region. Most of our data were taken from large-scale surveys: 2MASS, CGPS, MSX and SCUBA. We also made CO molecular line observations, using the 13.7-m telescope. The ionized region of Sh2-163 is detected by both the optical and radio continuum observations. Sh2-163 is partially bordered by an arc-like photodissociation region (PDR), which is coincident with the strongest optical and radio emissions, indicating interactions between the HII region and the surrounding interstellar medium. Two molecular clouds were discovered on the border of the PDR. The morphology of these two clouds suggests they are compressed by the expansion of Sh2-163. In cloud A, we found two molecular clumps. And it seems star formation in clump A2 is much more active than in clump A1. In cloud B, we found new outflow activities and massive star(s) are forming inside. ...

  9. Formation of Pillars at the Boundaries between HII Regions and Molecular Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Mizuta, A; Kane, J O; Pound, M W; Remington, B A; Ryutov, D D; Takabe, H

    2006-04-20

    We investigate numerically the hydrodynamic instability of an ionization front (IF) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes. When the initial amplitude is small, the imposed perturbation is completely stabilized and does not grow. When the initial perturbation amplitude is large enough, roughly the ratio of the initial amplitude to wavelength is greater than 0.02, portions of the IF temporarily separate from the molecular cloud surface, locally decreasing the ablation pressure. This causes the appearance of a large, warm HI region and triggers nonlinear dynamics of the IF. The local difference of the ablation pressure and acceleration enhances the appearance and growth of a multimode perturbation. The stabilization usually seen at the IF in the linear regimes does not work due to the mismatch of the modes of the perturbations at the cloud surface and in density in HII region above the cloud surface. Molecular pillars are observed in the late stages of the large amplitude perturbation case. The velocity gradient in the pillars is in reasonably good agreement with that observed in the Eagle Nebula. The initial perturbation is imposed in three different ways: in density, in incident photon number flux, and in the surface shape. All cases show both stabilization for a small initial perturbation and large growth of the second harmonic by increasing amplitude of the initial perturbation above a critical value.

  10. Anomalous Microwave Emission in HII regions: is it really anomalous? The case of RCW 49

    CERN Document Server

    Paladini, Roberta; Agliozzo, Claudia; Tibbs, Christopher T; Noriega-Crespo, Alberto; Umana, Grazia; Dickinson, Clive; Trigilio, Corrado

    2015-01-01

    The detection of an excess of emission at microwave frequencies with respect to the predicted free-free emission has been reported for several Galactic HII regions. Here, we investigate the case of RCW 49, for which the Cosmic Background Imager tentatively (~ 3 sigma) detected Anomalous Microwave Emission at 31 GHz on angular scales of 7'. Using the Australia Telescope Compact Array, we carried out a multi-frequency (5 GHz, 19 GHz and 34 GHz) continuum study of the region, complemented by observations of the H109$\\alpha$ radio recombination line. The analysis shows that: 1) the spatial correlation between the microwave and IR emission persists on angular scales from 3.4' to 0.4", although the degree of the correlation slightly decreases at higher frequencies and on smaller angular scales, 2) the spectral indices between 1.4 and 5 GHz are globally in agreement with optically thin free-free emission, however, ~ 30% of these are positive and much greater than -0.1, consistently with a stellar wind scenario, 3) n...

  11. The Stellar Content of Obscured Galactic Giant HII Regions. VII. W3

    CERN Document Server

    Navarete, F; Damineli, A; Moisés, A P; Blum, R D; Conti, P S

    2011-01-01

    Spectrophotometric distances in the K band have been reported by different authors for a number of obscured Galactic HII regions. Almost 50% of them show large discrepancies compared to the classical method using radial velocities measured in the radio spectral region. In order to provide a crucial test of both methods, we selected a target which does not present particular difficulty for any method and which has been measured by as many techniques as possible. The W3 star forming complex, located in the Perseus arm, offers a splendid opportunity for such a task. We used the NIFS spectrograph on the Frederick C. Gillett Gemini North telescope to classify candidate "naked photosphere" OB stars based on 2MASS photometry. Two of the targets are revealed to be mid O-type main sequence stars leading to a distance of d = 2.20 kpc. This is in excellent agreement with the spectrophotometric distance derived in the optical band (d = 2.18 kpc, Humphreys 1978) and with a measurement of the W3 trigonometric parallax (d =...

  12. The RMS Survey: Resolving kinematic distance ambiguities towards a sample of compact HII regions using HI absorption

    CERN Document Server

    Urquhart, J S; Lumsden, S L; Oudmaijer, R D; Moore, T J T; Mottram, J C; Cooper, H D B; Mottram, M; Rogers, H C

    2011-01-01

    We present high-resolution HI data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact HII regions from the Red MSX Source (RMS) survey. The high resolution data are complemented with lower resolution archival HI data extracted from the Southern and VLA Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the HI absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1,000 massive young stellar objects and compact HII regions, is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined.

  13. The relation between radio flux density and ionizing ultra-violet flux for HII regions and supernova remnants in the Large Magellanic cloud

    Directory of Open Access Journals (Sweden)

    Filipović M.D.

    2003-01-01

    Full Text Available We present a comparison between the Parkes radio surveys (Filipović et al 1995 and Vacuum Ultra-Violet (VUV surveys (Smith et al. 1987 of the Large Magellanic Clouds (LMC. We have found 72 sources in common in the LMC which are known HII regions (52 and supernova remnants (SNRs (19. Some of these radio sources are associated with two or more UV stellar associations. A comparison of the radio flux densities and ionizing UV flux for HII regions shows a very good correlation, as expected from theory. Many of the Magellanic Clouds (MCs SNRs are embedded in HII regions, so there is also a relation between radio and UV which we attribute to the surrounding HII regions.

  14. Radiation-MHD models of elephant trunks and globules in HII regions

    Science.gov (United States)

    Mackey, Jonathan; Lim, Andrew J.

    2011-01-01

    We study the formation and evolution of pillars of dense gas, known as elephant trunks, at the boundaries of HII regions, formed by shadowing of ionising radiation by dense clumps. The effects of magnetic fields on this process are investigated using 3D radiation-magnetohydrodynamics simulations. For a simulation in which an initially uniform magnetic field of strength \\vert B\\vert≃50 μG is oriented perpendicular to the radiation propagation direction, the field is swept into alignment with the pillar during its dynamical evolution, in agreement with observations of the ``Pillars of Creation'' in M16, and of some cometary globules. This effect is significantly enhanced when the simulation is re-run with a weaker field of ≃18 μG. A stronger field with \\vert B\\vert≃ 160 μG is sufficient to prevent this evolution completely, also significantly affecting the photoionisation process. Using a larger simulation domain it is seen that the pillar formation models studied in Mackey & Lim (2010) ultimately evolve to cometary structures in the absence of dense gas further from the star.

  15. Detailed Numerical Simulations on the Formation of Pillars around HII-regions

    CERN Document Server

    Gritschneder, Matthias; Naab, Thorsten; Walch, Stefanie

    2010-01-01

    We study the structural evolution of turbulent molecular clouds under the influence of ionizing radiation emitted from a nearby massive star by performing a high resolution parameter study with the iVINE code. The temperature is taken to be 10K or 100K, the mean number density is either 100cm^3 or 300cm^3. Besides, the turbulence is varied between Mach 1.5 and Mach 12.5 and the main driving scale between 1pc and 8pc. We vary the ionizing flux by an order of magnitude. In our simulations the ionizing radiation enhances the initial turbulent density distribution and thus leads to the formation of pillar-like structures observed adjacent to HII regions in a natural way. Gravitational collapse occurs regularly at the tips of the structures. We find a clear correlation between the initial state of the turbulent cold cloud and the final morphology and physical properties of the structures formed. The most favorable regime for the formation of pillars is Mach 4-10. Structures and therefore stars only form if the ini...

  16. Heavy elements in Galactic and Magellanic Cloud HII regions recombination-line versus forbidden-line abundances

    CERN Document Server

    Tsamis, Y G; Liu, X W; Danziger, I J; Storey, P J; Tsamis, Yiannis G.

    2003-01-01

    We have obtained deep optical, long-slit spectrophotometry of the Galactic HII regions M 17, NGC 3576 and of the Magellanic Cloud HII regions 30 Doradus, LMC N11B and SMC N66, recording the optical recombination lines (ORLs) of CII, NII and OII. Temperature-insensitive ORL C2+/O2+ and N2+/O2 ratios are obtained for all nebulae except SMC N66. The ORL C2+/O2+ ratios show remarkable agreement within each galactic system, while also being in agreement with the corresponding CEL ratios. For all five nebulae, the O2+/H+ abundance derived from multiple OII ORLs is found to be higher than the corresponding value derived from the strong [OIII] 4959, 5007A CELs, by factors of 1.8--2.7 for four of the nebulae. The LMC N11B nebula exhibits a more extreme discrepancy factor for the O2+ ion, ~5. Thus these HII regions exhibit ORL/CEL abundance discrepancy factors that are similar to those previously encountered amongst planetary nebulae. Our optical CEL O2+/H+ abundances agree to within 20-30 per cent with published O2+/H...

  17. ISO Mid-Infrared Observations of Giant HII Regions in M33

    Science.gov (United States)

    Skelton, B. P.; Waller, W. H.; Hodge, P. W.; Boulanger, F.; Cornett, R. H.; Fanelli, M. N.; Lequeux, J.; Stecher, T. P.; Viallefond, F.; Hui, Y.

    1999-01-01

    We present Infrared Space Observatory Camera (ISOCAM) Circular Variable Filter scans of three giant HII regions in M33. IC 133, NGC 595, and CC 93 span a wide range of metallicity, luminosity, nebular excitation, and infrared excess; three other emission regions (CC 43, CC 99, and a region to the northeast of the core of NGC 595) are luminous enough in the mid-infrared to be detected in the observed fields. ISOCAM CVF observations provide spatially resolved observations (5'') of 151 wavelengths between 5.1 and 16.5 microns with a spectral resolution R = 35 to 50. We observe atomic emission lines ([Ne II], [Ne III], and [S IV]), several "unidentified infrared bands" (UIBs; 6.2, 7.7, 8.6, 11.3, 12.0, and 12.7 microns), and in some cases a continuum which rises steeply at longer wavelengths. We conclude that the spectra of these three GHRs are well explained by combinations of ionized gas, PAHs, and very small grains in various proportions and with different spatial distributions. Comparisons between observed ratios of the various UIBs with model ratios indicate that the PAHs in all three of the GHRs are dehydrogenated and that the small PAHs have been destroyed in IC 133 but have survived in NGC 595 and CC 93. The [Ne III]/[Ne II] ratios observed in IC 133 and NGC 595 are consistent with their ages of 5 and 4.5 Myr, respectively; the deduced ionization parameter is higher in IC 133, consistent with its more compact region of emission.

  18. ISO Mid-Infrared Observations of Giant HII Regions in M33

    Science.gov (United States)

    Skelton, B. P.; Waller, W. H.; Hodge, P. W.; Boulanger, F.; Cornett, R. H.; Fanelli, M. N.; Lequeux, J.; Stecher, T. P.; Viallefond, F.; Hui, Y.

    1999-01-01

    We present Infrared Space Observatory Camera (ISOCAM) Circular Variable Filter scans of three giant HII regions in M33. IC 133, NGC 595, and CC 93 span a wide range of metallicity, luminosity, nebular excitation, and infrared excess; three other emission regions (CC 43, CC 99, and a region to the northeast of the core of NGC 595) are luminous enough in the mid-infrared to be detected in the observed fields. ISOCAM CVF observations provide spatially resolved observations (5'') of 151 wavelengths between 5.1 and 16.5 microns with a spectral resolution R = 35 to 50. We observe atomic emission lines ([Ne II], [Ne III], and [S IV]), several "unidentified infrared bands" (UIBs; 6.2, 7.7, 8.6, 11.3, 12.0, and 12.7 microns), and in some cases a continuum which rises steeply at longer wavelengths. We conclude that the spectra of these three GHRs are well explained by combinations of ionized gas, PAHs, and very small grains in various proportions and with different spatial distributions. Comparisons between observed ratios of the various UIBs with model ratios indicate that the PAHs in all three of the GHRs are dehydrogenated and that the small PAHs have been destroyed in IC 133 but have survived in NGC 595 and CC 93. The [Ne III]/[Ne II] ratios observed in IC 133 and NGC 595 are consistent with their ages of 5 and 4.5 Myr, respectively; the deduced ionization parameter is higher in IC 133, consistent with its more compact region of emission.

  19. Oxygen abundance distributions in six late-type galaxies based on SALT spectra of HII regions

    CERN Document Server

    Zinchenko, I A; Grebel, E K; Pilyugin, L S

    2015-01-01

    Spectra of 34 H II regions in the late-type galaxies NGC1087, NGC2967, NGC3023, NGC4030, NGC4123, and NGC4517A were observed with the South African Large Telescope (SALT). In all 34 H II regions, oxygen abundances were determined through the "counterpart" method (C method). Additionally, in two H II regions in which the auroral lines were detected oxygen abundances were measured through the classic Te method. We also estimated the abundances in our H II regions using the O3N2 and N2 calibrations and compared those with the C-based abundances. With these data we examined the radial abundance distributions in the disks of our target galaxies. We derived surface-brightness profiles and other characteristics of the disks (the surface brightness at the disk center and the disk scale length) in three photometric bands for each galaxy using publicly available photometric imaging data. The radial distributions of the oxygen abundances predicted by the relation between abundance and disk surface brightness in the W1 b...

  20. The galaxy-wide distributions of mean electron density in the HII regions of M51 and NGC 4449

    CERN Document Server

    Gutiérrez, Leonel

    2010-01-01

    Using ACS-HST images to yield continuum subtracted photometric maps in H\\alpha of the Sbc galaxy M51 and the dwarf irregular galaxy NGC 4449, we produced extensive (over 2000 regions for M51, over 200 regions for NGC4449) catalogues of parameters of their HII regions: their H\\alpha luminosities, equivalent radii and coordinates with respect to the galaxy centers. From these data we derived, for each region, its mean luminosity weighted electron density, , determined from the H\\alpha luminosity and the radius, R, of the region. Plotting these densities against the radii of the regions we find excellent fits for varying as R^{-1/2}. This relatively simple relation has not, as far as we know, been predicted from models of HII region structure, and should be useful in constraining future models. Plotting the densities against the galactocentric radii, r, of the regions we find good exponential fits, with scale lengths of close to 10 kpc for both galaxies. These values are comparable to the scale lengths of the H...

  1. INDUCED STAR FORMATION IN THE HII REGION SH2-54

    Directory of Open Access Journals (Sweden)

    J. Vasquez

    2011-01-01

    Full Text Available En este trabajo presentamos un estudio multifrecuencia del medio interstelar en el entorno de la región HII Sh2-54. El gas molecular y el polvo se han analizado y descripto por medio de las observaciones milimétricas e infrarrojas, respectivamente. La emisión en 8.0 ¿Êm de Spitzer-IRAC presenta una compleja estructura filamentaria de gas fotodisociado, evidenciando la interacción entre la región HII y el gas molecular. Numerosos candidatos a objetos estelares jóvenes se encuentran proyectados sobre Sh2-54 y sus alrededores. Analizamos si la presencia de estos objetos puede ser explicada dentro de un escenario de formación estelar inducida.

  2. The interstellar medium and the massive stellar content toward the SNR G18.1-0.1 and neighboring HII regions

    CERN Document Server

    Paron, S; Ortega, M E; Colombo, J F Albacete; Pichel, A

    2013-01-01

    We perform a multiwavelength study toward the SNR G18.1-0.1 and nearby several HII regions (infrared dust bubbles N21 and N22, and the HII regions G018.149-00.283 and G18.197-00.181). Our goal is to provide observational evidence supporting that massive stars usually born in clusters from the same molecular cloud, which then produce, along their evolution, different neighboring objects such as HII regions, interstellar bubbles and supernova remnants. We suggest that the objects analysed in this work belong to a same complex located at the distance of about 4 kpc. Using molecular data we inspected the interstellar medium toward this complex and from optical and X-ray observations we looked for OB-type stars in the region. Analysing public 13CO J=1--0 data we found several molecular structures very likely related to the HII region/SNR complex. We suggest that the molecular gas is very likely being swept and shaped by the expansion of the HII regions. From spectroscopic optical observations obtained with the 2.1...

  3. Bipolar HII regions - Morphology and star formation in their vicinity - I - G319.88$+$00.79 and G010.32$-$00.15

    CERN Document Server

    Deharveng, L; Samal, M R; Anderson, L D; LeLeu, G; Brevot, D; Duarte-Cabral, A; Molinari, S; Pestalozzi, M; Foster, J B; Rathborne, J M; Jackson, J M

    2015-01-01

    Our goal is to identify bipolar HII regions and to understand their morphology, their evolution, and the role they play in the formation of new generations of stars. We use the Spitzer and Herschel Hi-GAL surveys to identify bipolar HII regions. We search for their exciting star(s) and estimate their distances using near-IR data. Dense clumps are detected using Herschel-SPIRE data. MALT90 observations allow us to ascertain their association with the central HII region. We identify Class 0/I YSOs using their Spitzer and Herschel-PACS emissions. These methods will be applied to the entire sample of candidate bipolar HII regions. This paper focuses on two bipolar HII regions, one interesting in terms of its morphology, G319.88$+$00.79, and one in terms of its star formation, G010.32$-$00.15. Their exciting clusters are identified and their photometric distances estimated to be 2.6 kpc and 1.75 kpc, respectively. We suggest that these regions formed in dense and flat structures that contain filaments. They have a...

  4. The first CO+ image. I. Probing the HI/H2 layer around the ultracompact HII region Mon R2

    Science.gov (United States)

    Treviño-Morales, S. P.; Fuente, A.; Sánchez-Monge, Á.; Pilleri, P.; Goicoechea, J. R.; Ossenkopf-Okada, V.; Roueff, E.; Rizzo, J. R.; Gerin, M.; Berné, O.; Cernicharo, J.; Gónzalez-García, M.; Kramer, C.; García-Burillo, S.; Pety, J.

    2016-09-01

    The CO+ reactive ion is thought to be a tracer of the boundary between a Hii region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the Hii region. We compared the CO+ distribution with other species present in photon-dominated regions (PDR), such as [Cii] 158 μm, H2 S(3) rotational line at 9.3 μm, polycyclic aromatic hydrocarbons (PAHs), and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [Cii] emission. This confirms that the CO+ emission arises from a narrow dense layer of the Hi/H2 interface. We determined the CO+ fractional abundance relative to C+ toward three positions. The abundances range from 0.1 to 1.9 × 10-10 and are in good agreement with the previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO+ linewidth is larger than those found in molecular gas tracers, and their central velocity are blueshifted with respect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photoevaporating clump surfaces.

  5. The first CO+ image: Probing the HI/H2 layer around the ultracompact HII region Mon R2

    CERN Document Server

    Trevino-Morales, S P; Sanchez-Monge, A; Pilleri, P; Goicoechea, J R; Ossenkopf-Okada, V; Roueff, E; Rizzo, J R; Gerin, M; Berne, O; Cernicharo, J; Gonzalez-Garcia, M; Kramer, C; Garcia-Burillo, S; Pety, J

    2016-01-01

    The CO+ reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. We compare the CO+ distribution with other species present in photon-dominated regions (PDR), such as [CII] 158 mm, H2 S(3) rotational line at 9.3 mm, polycyclic aromatic hydrocarbons (PAHs) and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [CII] emission. This confirms that the CO+ emission arises from a narrow dense layer of the HI/H2 interface. We have determined the CO+ fractional abundance, relative to C+ toward three positions. The abundances range from 0.1 to 1.9x10^(-10) and are in good agreement with previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO...

  6. Near-IR integral field spectroscopy of ionizing stars and young stellar objects on the borders of HII regions

    CERN Document Server

    Martins, F; Deharveng, L; Zavagno, A; Bouret, J -C

    2009-01-01

    We present near-IR SINFONI observations of three Galactic HII regions: RVW79, RCW82 and RCW120. We identify the ionizing stars of each region: they are early to late O stars, close to the main sequence. We derive their stellar and wind properties using atmosphere models computed with the code CMFGEN. The cluster ionizing RCW~79 formed 2.3+/-0.5 Myr ago. Similar ages are estimated, albeit with a larger uncertainty, for the ionizing stars of the other two regions. In RCW79 the mechanical wind luminosity represents only 0.1% of the ionizing luminosity, questioning the influence of stellar winds on the dynamics of the the HII region. The young stellar objects show four main types of spectral features: H2 emission, Br gamma emission, CO bandheads emission and CO bandheads absorption. These features are typical of young stellar objects surrounded by disks and/or envelopes. The radial velocities of most YSOs are consistent with that of the ionized gas, firmly establishing that star formation is taking place on the b...

  7. HII region G46.5-0.2: the interplay between ionizing radiation, molecular gas and star formation

    CERN Document Server

    Paron, S; Dubner, G; Yuan, Jing-Hua; Petriella, A; Giacani, E; Li, Jin Zeng; Wu, Yuefang; Liu, Hongli; Huang, Ya Fang; Zhang, Si-Ju

    2015-01-01

    HII regions are particularly interesting because they can generate dense layers of gas and dust, elongated columns or pillars of gas pointing towards the ionizing sources, and cometary globules of dense gas, where triggered star formation can occur. Understanding the interplay between the ionizing radiation and the dense surrounding gas is very important to explain the origin of these peculiar structures, and hence to characterize triggered star formation. G46.5-0.2 (G46), a poorly studied galactic HII region located at about 4 kpc, is an excellent target to perform this kind of studies. Using public molecular data extracted from the Galactic Ring Survey (13CO J=1-0) and from the James Clerk Maxwell Telescope data archive (12CO, 13CO, C18O J=3-2, HCO+ and HCN J=4-3), and infrared data from the GLIMPSE and MIPSGAL surveys, we perform a complete study of G46, its molecular environment and the young stellar objects placed around it. We found that G46, probably excited by an O7V star, is located close to the edge...

  8. H$\\alpha$ tail, intracluster HII regions and star-formation: ESO137-001 in Abell 3627

    CERN Document Server

    Sun, M; Voit, G M

    2007-01-01

    We present the discovery of a 40 kpc H-alpha tail and at least 29 emission-line objects downstream of a star-forming galaxy ESO 137-001 in a rich, nearby cluster A3627. The galaxy is known to possess a dramatic 70 kpc X-ray tail. The detected H-alpha tail coincides positionally with the X-ray tail. The H-alpha emission in the galaxy is sharply truncated on the front and the sides near the nucleus, indicating significant ram pressure stripping. ESO 137-001 is thus the first cluster late-type galaxy known with both an X-ray tail and an H-alpha tail. The emission-line objects are all distributed downstream of the galaxy, with projected distance up to 39 kpc from the galaxy. From the analysis on the H-alpha_{off} frame and the estimate of the background emission-line objects, we conclude that it is very likely all these 29 emission-line objects are HII regions associated with ESO 137-001. The high surface number density and luminosities of these HII regions (up to 10^40 ergs/s) largely dwarf the previously known ...

  9. On the relative importance of different microphysics on the D-type expansion of galactic HII regions

    CERN Document Server

    Haworth, Thomas J; Acreman, David M; Bisbas, Thomas G

    2015-01-01

    Radiation hydrodynamics (RHD) simulations are used to study many astrophysical phenomena, however they require the use of simplified radiation transport and thermal prescriptions to reduce computational cost. In this paper we present a systematic study of the importance of microphysical processes in RHD simulations using the example of D-type HII region expansion. We compare the simplest hydrogen-only models with those that include: ionisation of H, He, C, N, O, S and Ne, different gas metallicity, non-LTE metal line blanketed stellar spectral models of varying metallicity, radiation pressure, dust and treatment of photodissociation regions. Each of these processes are explicitly treated using modern numerical methods rather than parameterisation. In line with expectations, changes due to microphysics in either the effective number of ionising photons or the thermal structure of the gas lead to differences in D-type expansion. In general we find that more realistic calculations lead to the onset of D-type exp...

  10. Flickering of 1.3 cm Sources in Sgr B2: Towards a Solution to the Ultracompact HII Region Lifetime Problem

    CERN Document Server

    De Pree, C G; Mac Low, M -M; Wilner, D J; Goss, W M; Galván-Madrid, R; Keto, E R; Klessen, R S; Monsrud, A

    2013-01-01

    Accretion flows onto massive stars must transfer mass so quickly that they are themselves gravitationally unstable, forming dense clumps and filaments. These density perturbations interact with young massive stars, emitting ionizing radiation, alternately exposing and confining their HII regions. As a result, the HII regions are predicted to flicker in flux density over periods of decades to centuries rather than increasing monotonically in size as predicted by simple Spitzer solutions. We have recently observed the Sgr B2 region at 1.3 cm with the VLA in its three hybrid configurations (DnC, CnB and BnA) at a resolution of 0.25''. These observations were made to compare in detail with matched continuum observations from 1989. At 0.25'' resolution, Sgr B2 contains 41 UC HII regions, 6 of which are hypercompact. The new observations of Sgr B2 allow comparison of relative peak flux densites for the HII regions in Sgr B2 over a 23 year time baseline (1989-2012) in one of the most source-rich massive star forming...

  11. Populations of High-Luminosity Density-Bounded HII Regions in Spiral Galaxies? Evidence and Implications

    Science.gov (United States)

    Beckman, J. E.; Rozas, M.; Zurita, A.; Watson, R. A.; Knapen, J. H.

    2000-01-01

    In this paper we present evidence that the H II regions of high luminosity in disk galaxies may be density bounded, so that a significant fraction of the ionizing photons emitted by their exciting OB stars escape from the regions. The key piece of evidence is the presence, in the Ha luminosity functions (LFs) of the populations of H iI regions, of glitches, local sharp peaks at an apparently invariant luminosity, defined as the Stromgren luminosity Lstr), LH(sub alpha) = Lstr = 10(sup 38.6) (+/- 10(sup 0.1)) erg/ s (no other peaks are found in any of the LFs) accompanying a steepening of slope for LH(sub alpha) greater than Lstr This behavior is readily explicable via a physical model whose basic premises are: (a) the transition at LH(sub alpha) = Lstr marks a change from essentially ionization bounding at low luminosities to density bounding at higher values, (b) for this to occur the law relating stellar mass in massive star-forming clouds to the mass of the placental cloud must be such that the ionizing photon flux produced within the cloud is a function which rises more steeply than the mass of the cloud. Supporting evidence for the hypothesis of this transition is also presented: measurements of the central surface brightnesses of H II regions for LH(sub alpha) less than Lstr are proportional to L(sup 1/3, sub H(sub alpha)), expected for ionization bounding, but show a sharp trend to a steeper dependence for LH(sub alpha) greater than Lstr, and the observed relation between the internal turbulence velocity parameter, sigma, and the luminosity, L, at high luminosities, can be well explained if these regions are density bounded. If confirmed, the density-bounding hypothesis would have a number of interesting implications. It would imply that the density-bounded regions were the main sources of the photons which ionize the diffuse gas in disk galaxies. Our estimates, based on the hypothesis, indicate that these regions emit sufficient Lyman continuum not only to

  12. Combined stellar structure and atmosphere models for massive stars; 4, The impact on the ionization structure of single star HII regions

    CERN Document Server

    Stasinska, G; Stasinska, Grazyna; Schaerer, Daniel

    1996-01-01

    We study the impact of modern stellar atmospheres that take into account the effects of stellar winds, departures from LTE and line blanketing ("CoStar" models) on the ionization structure of HII regions. Results from a large grid of photoionization models are presented. Due to a flatter energy distribution in the HeI continuum, compared to the widely used Kurucz models, generally higher ionic ratios are obtained. We find that N+/O+ and Ne++/O++ can be safely used as direct indicators of N/O and Ne/O abundance ratios in HII regions, over a wide range of astrophysical situations. The roughly constant observed value of Ne++/O++ ionic ratios in Galactic HII regions is naturally reproduced by photoionization models using CoStar fluxes, while Kurucz models at solar metallicity fail to reproduce this behaviour. This gives support to ionizing fluxes from non-LTE atmospheres including stellar winds and line blanketing. However, we also point out that tests of stellar atmosphere models from observations of HII regions...

  13. A Herschel and BIMA study of the sequential star formation near the W48A HII region

    CERN Document Server

    Rygl, K L J; Polychroni, D; Wyrowski, F; Motte, F; Elia, D; Nguyen-Luong, Q; Didelon, P; Pestalozzi, M; Benedettini, M; Molinari, S; Andre, Ph; Fallscheer, C; Gibb, A; di Giorgio, A M; Hill, T; Konyves, V; Marston, A; Pezzuto, S; Rivera-Ingraham, A; Schisano, E; Schneider, N; Spinoglio, L; Ward-Thompson, D; White, G J

    2014-01-01

    We present the results of Herschel HOBYS photometric mapping combined with BIMA observations and additional archival data, and perform an in-depth study of the evolutionary phases of the star-forming clumps in W 48A and their surroundings. Age estimates for the compact sources were derived from bolometric luminosities and envelope masses, which were obtained from the dust continuum emission, and agree within an order of magnitude with age estimates from molecular line and radio data. The clumps in W 48A are linearly aligned by age (east-old to west-young): we find a ultra compact (UC) HII region, a young stellar object (YSO) with class II methanol maser emission, a YSO with a massive outflow, and finally the NH_2D prestellar cores from Pillai et al. This remarkable positioning reflects the (star) formation history of the region. We find that it is unlikely that the star formation in the W 48A molecular cloud was triggered by the UCHII region and discuss the Aquila supershell expansion as a mayor influence on ...

  14. A young stellar cluster within the RCW41 HII region: deep NIR photometry and Optical/NIR polarimetry

    CERN Document Server

    Santos, Fábio P; Franco, Gabriel A P

    2012-01-01

    The RCW41 star-forming region is embedded within the Vela Molecular Ridge, hosting a massive stellar cluster surrounded by a conspicuous HII region. Understanding the role of interstellar magnetic fields and studying the newborn stellar population is crucial to build a consistent picture of the physical processes acting on this kind of environment. We have carried out a detailed study of the interstellar polarization toward RCW41, with data from an optical and near-infrared polarimetric survey. Additionally, deep near-infrared images from the NTT 3.5m telescope have been used to study the photometric properties of the embedded young stellar cluster, revealing several YSO's candidates. By using a set of pre-main sequence isochrones, a mean cluster age in the range 2.5 - 5.0 million years was determined, and evidence of sequential star formation were revealed. An abrupt decrease in R-band polarization degree is noticed toward the central ionized area, probably due to low grain alignment efficiency caused by the...

  15. High Angular Resolution Imaging Spectroscopy of the Galactic Ultra-Compact HII Region K3-50A

    CERN Document Server

    Blum, Robert D

    2009-01-01

    Gemini North adaptive optics imaging spectroscopy is presented for the Galactic ultra-compact HII (UCHII) region K3-50A. Data were obtained in the K-band using the Near-infrared Integral Field Spectrograph (NIFS) behind the facility adaptive optics module ALTAIR in natural guide star mode. The NIFS data cube reveals a complex spatial morphology across the 0.1 pc scale of the 3'' UCHII region. Comparison of the nebular emission to Cloudy ionization models shows that the central source must have an effective temperature between about 37000 K and 45000 K with preferred values near 40000 K. Evidence is presented for sharp density variations in the nebula which are interpreted as a clearing of material nearest the central source. High excitation lines of FeIII and SeIV show that the ionization of the nebula clearly changes with distance from the central source. A double lobed kinematic signature (+/- 25 kms) is evident in the Br gamma line map which may be related to the larger scale ionized flow detailed in earli...

  16. Abundance determination of multiple star-forming regions in the HII galaxy SDSS J165712.75+321141.4

    CERN Document Server

    Hagele, Guillermo F; Perez-Montero, Enrique; Diaz, Angeles I; Cardaci, Monica V; Firpo, Veronica; Terlevich, Elena; Terlevich, Roberto

    2011-01-01

    We analyze high signal-to-noise spectrophotometric observations acquired simultaneously with TWIN, a double-arm spectrograph, from 3400 to 10400 \\AA of three star-forming regions in the HII galaxy SDSS J165712.75+321141.4. We have measured four line temperatures: Te([OIII]), Te([SIII]), Te([OII]), and Te([SII]), with high precision, rms errors of order 2%, 5%, 6% and 6%, respectively, for the brightest region, and slightly worse for the other two. The temperature measurements allowed the direct derivation of ionic abundances of oxygen, sulphur, nitrogen, neon and argon. We have computed CLOUDY tailor-made models which reproduce the O2+ measured thermal and ionic structures within the errors in the three knots, with deviations of only 0.1 dex in the case of O+ and S2+ ionic abundances. In the case of the electron temperature and the ionic abundances of S+/H+, we find major discrepancies which could be consequence of the presence of colder diffuse gas. The star formation history derived using STARLIGHT shows a ...

  17. Integral field spectroscopy of the two complexes of HII regions in the main galaxy of the minor merger AM2306-721

    Science.gov (United States)

    Hernandez-Jimenez, J. A.; Pastoriza, G.; Sanmartim, D.; Winge, C.; Bonatto, C.; Krabbe, A. C.; Rodrigues, I.

    2017-07-01

    We present a study of two complexes of HII regions in the main galaxy of minor merger AM 2306-721. The observations were obtained with the GMOS-IFU on the Gemini South telescope. By using different discrimination criteria, we determined that shock-ionized gas fraction ranges between 0% and 35%, which are in good agreement with numerical models. Thus, we conclude that almost all the mechanical energy from stellar winds and supernovae is being irradiated.

  18. Denser Sampling of the Rosette Nebula with Faraday Rotation Measurements: Improved Estimates of Magnetic Fields in HII Regions

    CERN Document Server

    Costa, Allison H; Sink, Joseph R; Brown, Shea; Mao, Sui Ann

    2015-01-01

    We report Faraday rotation measurements of 11 extragalactic radio sources with lines of sight through the Rosette Nebula, a prominent HII region associated with the star cluster NGC 2244. It is also a prototypical example of a "stellar bubble" produced by the winds of the stars in NGC 2244. The goal of these measurements is to better determine the strength and structure of the magnetic field in the nebula. We calculate the rotation measure (RM) through two methods, a least-squares fit to $\\chi$( $\\lambda^2$) and Rotation Measure Synthesis. In conjunction with our results from Savage et al. (2013), we find an excess RM due to the shell of the nebula of +40 to +1200 rad m$^{-2}$ above a background RM of +147 rad m$^{-2}$. We discuss two forms of a simple shell model intended to reproduce the magnitude of the observed RM as a function of distance from the center of the Rosette Nebula. The models represent different physical situations for the magnetic field within the shell of the nebula. The first assumes that ...

  19. Helium in natal HII regions: the origin of the X-ray absorption in gamma-ray burst afterglows

    CERN Document Server

    Watson, Darach; Andersen, Anja C; Fynbo, Johan P U; Gorosabel, Javier; Hjorth, Jens; Jakobsson, Páll; Krühler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele

    2012-01-01

    Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that He in the GRB's host HII region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_Hx) is correlated with both the neutral gas column density and with the optical afterglow extinction (Av). This correlation explains the connection between dark bursts and bursts with high N_Hx values. From these correlations we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e. the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorpt...

  20. VizieR Online Data Catalog: IRX-β relation of HII regions in NGC628 (Ye+, 2016)

    Science.gov (United States)

    Ye, C.; Zou, H.; Lin, L.; Lian, J.; Hu, N.; Kong, X.

    2016-10-01

    NGC 628 has been observed by the PPAK IFS Nearby Galaxies Survey (PINGS) performed by the 3.5m telescope of the Calar Alto Observatory. The IFU provides a sampling of 2.7", an optical wavelength range of 3700-7000Å with a spectral resolution of ~8Å. The final data set comprises 11094 individual spectra, and the typical spatial resolution is about 3.5"-4". The slice image at the Hα wavelength is used to determine HII regions. FUV and near-UV (NUV) images of NGC 628 were taken by the Galaxy Evolution Explorer (GALEX), which are centered at wavelengths of 1516 and 2267Å. IR images were taken by Spitzer IRAC (3.6um, 8.0um) and MIPS (24um). The spatial resolutions of UV and IR images are 4.3", 5.3", 1.9", 2.8", and 6.4", respectively. We obtain these images from the data release website of Local Volume Legacy (LVL) survey DR5 (Dale+, 2009, J/ApJ/703/517; http://irsa.ipac.caltech.edu/data/SPITZER/LVL/). (2 data files).

  1. ISO spectroscopy of compact HII regions in the Galaxy - II. Ionization and elemental abundances

    NARCIS (Netherlands)

    Martin-Hernandez, NL; Peeters, E; Morisset, C; Tielens, AGGM; Cox, P; Roelfsema, PR; Baluteau, JP; Schaerer, D; Mathis, JS; Damour, F; Churchwell, E; Kessler, MF

    2002-01-01

    Based on the ISO spectral catalogue of compact H II regions by Peeters et al. (2002), we present a first analysis of the hydrogen recombination and atomic fine-structure lines originated in the ionized gas. The sample consists of 34 H II regions located at galactocentric distances between R-Gal = 0

  2. The Orion HII Region and the Orion Bar in the Mid-infrared

    Science.gov (United States)

    Salgado, F.; Berné, O.; Adams, J. D.; Herter, T. L.; Keller, L. D.; Tielens, A. G. G. M.

    2016-10-01

    We present mid-infrared photometry of the Orion bar obtained with the Faint Object infraRed Camera for the SOFIA Telescope (FORCAST) on board SOFIA at 6.4, 6.6, 7.7, 19.7, 31.5, and 37.1 μm. By complementing this observation with archival FORCAST and Herschel/PACS images, we are able to construct a complete infrared spectral energy distribution of the Huygens region in the Orion nebula. Comparing the infrared images with gas tracers, we find that PACS maps trace the molecular cloud, while the FORCAST data trace the photodissociation region (PDR) and the H ii region. Analysis of the energetics of the region reveal that the PDR extends for 0.28 pc along the line of sight and that the bar is inclined at an angle of 4°. The infrared and submillimeter images reveal that the Orion bar represents a swept-up shell with a thickness of 0.1 pc. The mass of the shell implies a shock velocity of ≃3 km s-1 and an age of ≃105 years for the H ii region. Our analysis shows that the UV and infrared dust opacities in the H ii region and the PDR are a factor 5 to 10 lower than in the diffuse interstellar medium. In the ionized gas, Lyα photons are a major source of dust heating at distances larger than ≃0.06 pc from θ 1 Ori C. Dust temperatures can be explained if the size of the grains is between 0.1 and 1 μm. We derive the photoelectric heating efficiency of the atomic gas in the Orion bar. The results are in good qualitative agreement with models and the quantitative differences indicate a decreased polycyclic aromatic hydrocarbon abundance in this region.

  3. Different structures formed at HII boundaries

    Science.gov (United States)

    Miao, Jingqi; Cornwall, Paul; Kinnear, Tim

    2015-03-01

    Hydrodynamic simulations on the evolution of molecular clouds (MCs) at HII boundaries are used to show that radiation driven implosion (RDI) model can create almost all of the different morphological structures, such as a single bright-rimmed cloud (BRC), fragment structure and multiple elephant trunk (ET) structures.

  4. VizieR Online Data Catalog: Radio observations of Galactic WISE HII regions (Anderson+, 2015)

    Science.gov (United States)

    Anderson, L. D.; Armentrout, W. P.; Johnstone, B. M.; Bania, T. M.; Balser, D. S.; Wenger, T. V.; Cunningham, V.

    2016-01-01

    We draw our targets from the MIR objects in the WISE catalog of Anderson+, 2014, J/ApJS/212/1. We also include in our sample Sharpless H II regions (Sharpless 1959, VII/20). See section 2 for further details. Our observations were made with the GBT 100m telescope from 2012 July through 2014 August. There are seven radio recombination lines (RRLs) that can be cleanly observed simultaneously with the GBT in the X-band: H87α to H93α. We average these seven RRLs (each at two orthogonal polarizations) to create a single average RRL spectrum. We followed the same GBT observational procedure as in the original HRDS (Green Bank Telescope H II Region Discovery Survey (GBT HRDS; Bania et al. 2010ApJ...718L.106B). (3 data files).

  5. Star clusters and the structure of the ISM Tunnels and wakes in giant extragalactic HII regions

    CERN Document Server

    Tenorio-Tagle, G; Tenorio-Tagle, Guillermo; Tanco, Gustavo Medina

    1998-01-01

    Several structures have been discovered embedded in regions of recent or ongoing star formation, which point to the importance of the interaction between fast moving wind-blowing stars and their environment. Using hydrodynamic simulations, we investigate the passage through the interstellar medium of a supersonic stellar wind source, and show how it can naturally lead to the formation of tubes, channels and swamps of globules as interfaces are crossed. The results are in excellent agreement with observation of 30 Doradus.

  6. Production of Elephant Trunks in HII Regions by Radiation-Magnetohydrodynamic Instabilities

    OpenAIRE

    Fierlinger, Katharina; Krumholz, Mark; Grittschneder, Matthias

    2010-01-01

    Recent SPH and grid code simulations showed, that ionizing radiation can amplify overdensities in turbulent molecular clouds and produce molecular pillars. The relevance of magnetic fields for the structure and stability of molecular clouds is still under discussion. We investigate whether an ionization front hitting a medium with small distortions of the magnetic field can produce the observed pillar-like structures in star forming regions (e.g. Eagle Nebula). Numerical MHD simulations with ...

  7. Physical properties of the Sh2-104 HII region as seen by Herschel

    CERN Document Server

    Rodón, J A; Baluteau, J -P; Anderson, L D; Polehampton, E; Abergel, A; Motte, F; Bontemps, S; Ade, P; André, P; Arab, H; Beichman, C; Bernard, J -P; Blagrave, K; Boulanger, F; Cohen, M; Compiegne, M; Cox, P; Dartois, E; Davis, G; Emery, R; Fulton, T; Gry, C; Habart, E; Halpern, M; Huang, M; Joblin, C; Jones, S C; Kirk, J; Lagache, G; Lin, T; Madden, S; Makiwa, G; Martin, P; Miville-Deschênes, M -A; Molinari, S; Moseley, H; Naylor, D; Okumura, K; Orieux, F; Gonçalvez, D Pinheiro; Rodet, T; Russeil, D; Saraceno, P; Sidher, S; Spencer, L; Swinyard, B; Ward-Thompson, D; White, G

    2010-01-01

    Context: Sh2-104 is a Galactic H ii region with a bubble morphology, detected at optical and radio wavelengths. It is considered the first observational confirmation of the collect-and-collapse model of triggered star-formation. Aims: We aim to analyze the dust and gas properties of the Sh2-104 region to better constrain its effect on local future generations of stars. In addition, we investigate the relationship between the dust emissivity index {\\beta} and the dust temperature, T_dust. Methods: Using Herschel PACS and SPIRE images at 100, 160, 250, 350 and 500 {\\mu}m we determine T_dust and {\\beta} throughout Sh2-104, fitting the spectral energy distributions (SEDs) obtained from aperture photometry. With the SPIRE Fourier transform spectrometer (FTS) we obtained spectra at different positions in the Sh2-104 region. We detect J-ladders of CO and 13CO, with which we derive the gas temperature and column density. We also detect proxies of ionizing flux as the [NII] 3P1-3P0 and [CI] 3P2-3P1 transitions. Result...

  8. A radiation driven implosion model for the enhanced luminosity of protostars near HII regions

    CERN Document Server

    Motoyama, K; Shang, H

    2007-01-01

    Context. Molecular clouds near the H II regions tend to harbor more luminous protostars. Aims. Our aim in this paper is to investigate whether or not radiation-driven implosion mechanism enhances luminosity of protostars near regions of high-ionizing fluxes. Methods. We performed numerical simulations to model collapse of cores exposed to UV radiation from O stars. We investigated dependence of mass loss rates on the initial density profiles of cores and variation of UV fluxes. We derived simple analytic estimates of accretion rates and final masses of protostars. Results. Radiation-driven implosion mechanism can increase accretion rates of protostars by 1-2 orders of magnitude. On the other hand, mass loss due to photo-evaporation is not large enough to have a significant impact on the luminosity. The increase of accretion rate makes luminosity 1-2 orders higher than those of protostars that form without external triggering. Conclusions. Radiation-driven implosion can help explain the observed higher luminos...

  9. Optical Recombination Lines of Heavy-elements in Giant Extragalactic HII Regions

    CERN Document Server

    Esteban, C; Torres-Peimbert, S; Rodríguez, M

    2002-01-01

    We present high resolution observations of the giant extragalactic H II regions NGC 604, NGC 2363, NGC 5461 and NGC 5471, based on observations taken with the ISIS spectrograph on the William Herschel Telescope. We have detected -by the first time- C II and O II recombination lines in these objects. We find that recombination lines give larger C^{++} and O^{++} abundances than collisionallly excited lines, suggesting that temperature variations can be present in the objects. We detect [Fe IV] lines in NGC 2363 and NGC 5471, the most confident detection of optical lines of this kind in H II regions. Considering the temperature structure we derive their H, He, C, N, O, Ne, S, Ar, and Fe abundances. From the recombination lines of NGC 5461 and NGC 5471 we determine the presence of C/H and O/H gradients in M101. We calculate the Delta Y/Delta O and Delta Y/Delta Z values considering the presence of temperature variations and under the assumption of constant temperature. We obtain a better agreement with models of...

  10. An HST/NICMOS view of the prototypical giant HII region NGC604 in M33

    CERN Document Server

    Barba, Rodolfo H; Perez, Enrique; Rubio, Monica; Bolatto, Alberto; Farina, Cecilia; Bosch, Guillermo; Walborn, Nolan R

    2009-01-01

    We present the first high-spatial resolution near-infrared (NIR) imaging of NGC 604, obtained with the NICMOS camera aboard the Hubble Space Telescope (HST). These NICMOS broadband images reveal new NIR point sources, clusters, and diffuse structures. We found an excellent spatial correlation between the 8.4 GHz radio continuum and the 2.2mu-m nebular emission. Moreover, massive young stellar object candidates appear aligned with these radio peaks, reinforcing the idea that those areas are star-forming regions. Three different scaled OB associations are recognized in the NICMOS images. The brightest NIR sources in our images have properties that suggest that they are red supergiant stars, of which one of them was previously known. This preliminary analysis of the NICMOS images shows the complexity of the stellar content of the NGC 604 nebula.

  11. Physical and chemical properties of Red MSX Sources in the southern sky: HII regions

    CERN Document Server

    Yu, Naiping; Li, Nan

    2016-01-01

    We have studied the physical and chemical properties of 18 southern Red Midcourse Space Experiment Sources (RMSs), using archival data taken from the Atacama Pathfinder Experiment (APEX) Telescope Large Area Survey of the Galaxy, the Australia Telescope Compact Array, and the Millimeter Astronomy Legacy Team Survey at 90 GHz. Most of our sources have simple cometary/unresolved radio emissions at 4.8 and/or 8.6GHz. The large number of Lyman continuum fluxes (NL) indicates they are probably massive O- or early B-type star formation regions. Archival IRAS infrared data are used to estimate the dust temperature, which is about 30 K of our sources. Then, the H2 column densities and the volume-averaged H2 number densities are estimated using the 0.87 mm dust emissions. Large-scale infall and ionized accretions may be occurring in G345.4881+00.3148. We also attempt to characterize the chemical properties of these RMSs through molecular line (N2H+ (1-0) and HCO+ (1-0)) observations. Most of the detected N2H+ and HCO+...

  12. The Herschel view of HII regions in M 33 (HERM33ES)

    Science.gov (United States)

    Verley, S.; Relaño, M.; Kramer, C.; Xilouris, E. M.; Boquien, M.; Calzetti, D.; Combes, F.; Buchbender, C.; Braine, J.; Quintana-Lacaci, G.; Tabatabaei, F. S.; Lord, S.; Israel, F.; Stacey, G.; van der Werf, P.

    2010-12-01

    Within the framework of the HERM33ES Key Project (Kramer et al. 2010), using the high resolution and sensitivity of the Herschel photometric data, we study the compact emission in the Local Group spiral galaxy M 33. We present a catalogue of 159 compact emission sources in M 33 identified by SExtractor in the 250 μm SPIRE band which is the one that provides the best spatial resolution. We measure fluxes at 24 μm and Hα for those 159 extracted sources. We find a very strong Pearson correlation coefficient with the MIPS 24 μm emission (r24 = 0.94) and a rather strong correlation with the Hα emission, although with more scatter (rHα = 0.83). Due to the very strong link between the 250 μm compact emission and the 24 μm and Hα emissions, by recovering the star formation rate from standard recipes for H II regions, we are able to provide star formation rate calibrations based on the 250 μm compact emission alone. Finally, the morphological study of a set of three Hα shells shows that there is a displacement between far-ultraviolet and the SPIRE bands, while the Hα structure is in general much more coincident with the cool dust.

  13. The HI dominated Low Surface Brightness Galaxy KKR17

    CERN Document Server

    Lam, Man I; Yang, Ming; Zhou, Zhi-Min; Du, Wei; Zhu, Yi-Nan

    2014-01-01

    We present new narrow-band (H$\\alpha$ and [OIII]) imagings and optical spectrophotometry of HII regions for a gas-rich low surface brightness irregular galaxy, KKR 17. The central surface brightness of the galaxy is $\\mu_0(B)$ = 24.15 $\\pm$0.03 mag~sec$^{-2}$. The galaxy was detected by \\emph{Arecibo Legacy Fast ALFA survey} (ALFALFA), and its mass is dominated by neutral hydrogen (HI) gas. In contrast, both the stellar masses of the bright HII and diffuse stellar regions are small. In addition, the fit to the spectral energy distribution to each region shows the stellar populations of HII and diffuse regions are different. The bright HII region contains a large fraction of O-type stars, revealing the recent strong star formation, whereas the diffuse region is dominated by median age stars, which has a typical age of $\\sim$ 600 Myrs. Using the McGaugh's abundance model, we found that the average metallicity of KKR 17 is 12 + (O/H) = 8.0 $\\pm$ 0.1. The star formation rate of KKR 17 is 0.21$\\pm$0.04 M$_{\\odot}$...

  14. A molecular outflow evidencing star formation activity in the vicinity of the HII region G034.8-0.7 and the SNR W44

    CERN Document Server

    Paron, S; Rubio, M; Dubner, G

    2009-01-01

    This work aims at investigating the molecular gas component in the vicinity of two young stellar object (YSO) candidates identified at the border of the HII region G034.8-0.7 that is evolving within a molecular cloud shocked by the SNR W44. The purpose is to explore signatures of star forming activity in this complex region. We performed a near and mid infrared study towards the border of the HII region G034.8-0.7 and observed a 90" X 90" region near 18h 56m 48s, +01d 18' 45" (J2000) using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3--2, 13CO J=3--2, HCO+ J=4--3 and CS J=7--6 lines with an angular resolution of 22". Based on the infrared study we propose that the source 2MASS 18564827+0118471 (IR1 in this work) is a YSO candidate. We discovered a bipolar 12CO outflow in the direction of the line of sight and a HCO+ clump towards IR1, confirming that it is a YSO. From the detection of the CS J=7--6 line we infer the presence of high density (>10^7 cm^-3) and warm (>60 K) gas towards IR...

  15. An In-Depth View of the Mid-Infrared Properties of Point Sources and the Diffuse ISM in the SMC Giant HII Region, N66

    CERN Document Server

    Whelan, David G; Galliano, Frederic; Peeters, Els; Bernard-Salas, Jeronimo; Johnson, Kelsey E; Indebetouw, Remy; Brandl, Bernhard

    2013-01-01

    (abridged)The focus of this work is to study mid-infrared point sources and the diffuse interstellar medium (ISM) in the low-metallicity (~0.2 solar) giant HII region N66 using the Spitzer Space Telescope's Infrared Spectrograph. We study 14 targeted infrared point sources as well as spectra of the diffuse ISM that is representative of both the photodissociation regions (PDRs) and the HII regions. Among the point source spectra, we spectroscopically confirm that the brightest mid-infrared point source is a massive embedded young stellar object, we detect silicates in emission associated with two young stellar clusters, and we observe spectral features of a known B[e] supergiant that are more commonly associated with Herbig Be stars. In the diffuse ISM, we provide additional evidence that the very small grain population is being photodestroyed in the hard radiation field. The 11.3 um PAH complex emission exhibits an unexplained centroid shift in both the point source and ISM spectra that should be investigated...

  16. The oxygen abundance in the inner HII regions of M101. Implications for the calibration of strong-line metallicity indicators

    CERN Document Server

    Bresolin, F

    2006-01-01

    I present deep spectroscopy of four HII regions in the inner, metal-rich zone of the spiral galaxy M101 obtained with the LRIS spectrograph at the Keck telescope. From the analysis of the collisionally excited lines in two of the target HII regions, H1013 and H493, I have obtained oxygen abundances 12+log(O/H)=8.52 and 12+log(O/H)=8.74, respectively. These measurements extend the determination of the oxygen abundance gradient of M101 via the direct method to only 3 kpc from the center. The intensity of the CII 4267 line in H1013 leads to a carbon abundance 12+log(C/H)=8.66, corresponding to nearly twice the solar value. From a comparison of the continuum temperature derived from the Balmer discontinuity, T(Bac)=5000 K, and the line temperature derived from [OIII]4363/5007, T[OIII]=7700 K, an average temperature T0=5500 K and a mean square temperature fluctuation t^2=0.06 have been derived. Accounting for the spatial inhomogeneity in temperature raises the oxygen abundance obtained from the oxygen auroral line...

  17. The evolution of emission lines in HII galaxies

    CERN Document Server

    Stasinska, G; Leitherer, C; Stasinska, Grazyna; Schaerer, Daniel; Leitherer, Claus

    2001-01-01

    We constructed diagnostic diagrams using emission line ratios and equivalent widths observed in several samples of HII galaxies. The diagrams are compared to predictions from new photoionization models for evolving starbursts. We find that HII galaxies from objective-prism surveys are not reproduced by models of instantaneous starbursts surrounded by constant density, ionization bounded HII regions. The observed relations between emission line ratios and Hb equivalent width (W(Hb)) can be understood if older stellar populations are not negligible in HII galaxies. Also, different dust obscuration for stars and gas and leakage of Lyman continuum photons from the observed HII regions can be important. As a result, HII galaxies selected from objective-prism surveys are unlikely to contain many objects in which the most recent starburst is older than about 5~Myr. The observed increase of [OI]/Hb with decreasing W(Hb) can result from the dynamical effects of winds and supernovae. This interpretation provides also a...

  18. Stripped gas as fuel for newly formed HII regions in the encounter between VCC1249 and M49: a unified picture from NGVS and GUViCS

    CERN Document Server

    Battaia, Fabrizio Arrigoni; Fumagalli, Michele; Boselli, Alessandro; Boissier, Samuel; Cortese, Luca; Heinis, Sebastien; Ferrarese, Laura; Côté, Patrick; Mihos, J Christopher; Cuillandre, Jean Charles; Duc, Pierre-Alain; Durrell, Patrick; Gwyn, Stephen; Jordán, Andrés; Liu, Chengze; Peng, Eric

    2012-01-01

    Context: We study the peculiar interacting galaxy system of VCC1249/M49 located in the core of the Virgo B subcluster. Owing to a recent interaction between the dwarf galaxy VCC1249 and the halo gas of the gE M49, neutral hydrogen has been displaced from the interstellar medium of this dwarf into the Virgo ICM. Observations also reveal multiple compact star-forming regions that are embedded in this HI cloud, with a projected separation up to 13 kpc from VCC1249 in the northwest direction. Aims: Motivated by recent NUV imaging from GUViCS of the VCC1249/M49 system that shows significant ongoing/recent star formation in the compact regions, we aim to constrain the origin of these outlying HII regions with a multi-wavelength approach. Methods: Using deep optical (u, g, i, z) imaging from NGVS and new Halpha imaging obtained at the San Pedro Martir observatory together with Keck long-slit spectroscopy, we characterize the SFR, ages, and metallicity of VCC1249 and its outlying compact regions. Moreover, we analyze...

  19. On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS

    CERN Document Server

    Skogsrud, H; De Pontieu, B

    2015-01-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolution. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1-m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si IV 1394 and 1403 {\\AA} lines, reveal ubiquitous bright "grains" which are short-lived (2-5 min) bright roundish small patches of sizes 0.5-1.7" that generally move limbward with velocities up to about 30 km s$^{-1}$. In this paper we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in H{\\alpha}. We find that the grains show ...

  20. Deep near-infrared adaptive optics observations of a young embedded cluster at the edge of the RCW 41 HII region

    CERN Document Server

    Neichel, B; Plana, H; Zavagno, A; Bernard, A; Fusco, T

    2015-01-01

    We investigate the star formation activity in a young star forming cluster embedded at the edge of the RCW 41 HII region. As a complementary goal, we aim at demonstrating the gain provided by Wide-Field Adaptive Optics instruments to study young clusters. We used deep, JHKs images from the newly commissioned Gemini-GeMS/GSAOI instrument, complemented with Spitzer IRAC observations, in order to study the photometric properties of the young stellar cluster. GeMS is an AO instrument, delivering almost diffraction limited images over a field of 2' across. The exquisite angular resolution allows us to reach a limiting magnitude of J = 22 for 98% completeness. The combination of the IRAC photometry with our JHKs catalog is used to build color-color diagrams, and select Young Stellar Objects (YSOs) candidates. We detect the presence of 80 Young Stellar Object (YSO) candidates. Those YSOs are used to infer the cluster age, which is found to be in the range 1 to 5 Myr. We find that 1/3 of the YSOs are in a range betwe...

  1. An O2If*/WN6 Star Catch in the Act in a Compact Hii region in the Starburst Cluster NGC 3603

    CERN Document Server

    Roman-Lopes, A

    2013-01-01

    In this paper I report the discovery of an O2If*/WN6 star probably still partially embedded in its parental cocoon in the star-burst cluster NGC 3603. From the observed size of the associated compact Hii region, it was possible to derive a probable dynamic age of no more than 600,000 years. Using the computed visual extinction value Av ~ 6 magnitudes, an absolute visual magnitude Mv =-5.7 mag is obtained, which for the assumed heliocentric distance of 7.6 kpc results in a bolometric luminosity of ~ 8x10^5 Lsun. Also from the V magnitude and the V-I color of the new star, and previous models for NGC3603's massive star population, we estimate its mass for the binary (O2If*/WN6 + O3If) and the single-star case (O2If*/WN6). In the former, it was found that the initial mass of each component possibly exceeded 80 Msun and 40 Msun, while in the latter MTT 58's initial mass possibly was in excess of 100 Msun.

  2. Modeling and predicting the shape of the far-infrared/submillimeter emission in ultra-compact HII regions and cold clumps

    CERN Document Server

    Paradis, D; Noriega-Crespo, A; Paladini, R; Bernard, J -P; Bot, C; Cambrésy, L; Demyk, K; Gromov, V; Rivera-Ingraham, A; Veneziani, M

    2014-01-01

    Dust properties are likely affected by the environment in which dust grains evolve. For instance, some analyses of cold clumps (7 K- 17 K) lead to favor the aggregation process in dense environments. However, the study of warm (30 K-40 K) dust emission at long wavelength ($\\lambda$$>$300 $\\mu$m) has been limited by the difficulty in combining far infred-millimeter (FIR-mm) spectral coverage and high angular resolution to observe warm dust grains. Using Herschel data from 70 to 500 $\\mu$m, as part of the Herschel infrared Galactic (Hi-GAL) survey associated to 1.1 mm data from the Bolocam Galactic Plane Survey (BGPS), we compare emission in two types of environments: ultra-compact HII (UCHII) regions and cold molecular clumps (denoted as cold clumps). This comparison allows us to test models of dust emission in the FIR-mm domain used to reproduce emission in the diffuse medium, in these environments, and to check their ability to predict the dust emission in our Galaxy. We determine the emission spectra in twe...

  3. Extragalactic chemical abundances: do HII regions and young stars tell the same story? The case of the spiral galaxy NGC 300

    CERN Document Server

    Bresolin, Fabio; Kudritzki, Rolf-Peter; Pietrzynski, Grzegorz; Urbaneja, Miguel A; Carraro, Giovanni

    2009-01-01

    (Abridged) We have obtained new spectrophotometric data for 28 HII regions in the spiral galaxy NGC 300, a member of the nearby Sculptor Group. The detection of auroral lines, including [OIII]4363, [SIII]6312 and [NII]5755, has allowed us to measure electron temperatures and direct chemical abundances for the whole sample. We determine for the first time in this galaxy a radial gas-phase oxygen abundance gradient based solely on auroral lines, and obtain the following least-square solution: 12+log(O/H)=8.57-0.41 R/R25, where the galactocentric distance is expressed in terms of the isophotal radius R25. The gradient corresponds to -0.077 dex/kpc, and agrees very well with the galactocentric trend in metallicity obtained for 29 B and A supergiants in the same galaxy. The intercept of the regression for the nebular data virtually coincides with the intercept obtained from the stellar data. This allows little room for depletion of nebular oxygen onto dust grains, although in this kind of comparison we are somewha...

  4. ON THE ACTIVE REGION BRIGHT GRAINS OBSERVED IN THE TRANSITION REGION IMAGING CHANNELS OF IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Skogsrud, H.; Voort, L. Rouppe van der; Pontieu, B. De [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

    2016-02-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5–1.″7 that generally move limbward with velocities up to about 30 km s{sup −1}. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

  5. Gas Kinematics in the HII regions G351.69-1.15 and G351.63-1.25

    CERN Document Server

    Veena, V S; Tej, A; Kantharia, N G; Ghosh, S K

    2016-01-01

    We probe the structure and kinematics of two neighbouring H II regions identified as cometary and bipolar, using radio recombination lines (RRL). The H172{\\alpha} RRLs from these H II regions: G351.6-1.15 and G351.6-1.25, are mapped using GMRT, India. We also detect carbon RRLs C172{\\alpha} towards both these regions. The hydrogen RRLs display the effects of pressure and dynamical broadening in the line profiles, with the dynamical broadening (15 km/s) playing a major role in the observed profile of G351.6-1.15. We investigate the kinematics of molecular gas species towards this H II region from the MALT90 pilot survey. The molecular gas is mostly distributed towards the north and north-west of the cometary head. The molecular line profiles indicate signatures of turbulence and outflow in this region. The ionized gas at the cometary tail is blue shifted by 8 km/s with respect to the ambient molecular cloud, consistent with the earlier proposed champagne flow scenario. The relative velocity of 5 km/s between t...

  6. First science results from SOFIA/FORCAST: The mid-infrared view of the compact HII region W3A

    CERN Document Server

    Salgado, F; Adams, J D; Herter, T L; Gull, G; Schoenwald, J; Keller, L D; De Buizer, J M; Vacca, W D; Becklin, E E; Shuping, R Y; M., A G G; Tielens,; Zinnecker, H

    2012-01-01

    The massive star forming region W3 was observed with the faint object infrared camera for the SOFIA telescope (FORCAST) as part of the Short Science program. The 6.4, 6.6, 7.7, 19.7, 24.2, 31.5 and 37.1 \\um bandpasses were used to observe the emission of Polycyclic Aromatic Hydrocarbon (PAH) molecules, Very Small Grains and Big Grains. Optical depth and color temperature maps of W3A show that IRS2 has blown a bubble devoid of gas and dust of $\\sim$0.05 pc radius. It is embedded in a dusty shell of ionized gas that contributes 40% of the total 24 \\um emission of W3A. This dust component is mostly heated by far ultraviolet, rather than trapped Ly$\\alpha$ photons. This shell is itself surrounded by a thin ($\\sim$0.01 pc) photodissociation region where PAHs show intense emission. The infrared spectral energy distribution (SED) of three different zones located at 8, 20 and 25\\arcsec from IRS2, show that the peak of the SED shifts towards longer wavelengths, when moving away from the star. Adopting the stellar radi...

  7. HII galaxies in 4D

    CERN Document Server

    Telles, Eduardo

    2014-01-01

    HII galaxies are clumpy and their gas kinematics can be mapped to show the global turbulent motions and the effect of massive star evolution. The distribution of their physical conditions is homogeneous and oxygen abundance is uniform. The presence of nebular HeII 4868 line seems to be higher in a low abundance galaxy, implying a harder ionization power probably due to stars in low metallicity. Innovative methods of data cube analysis, namely PCA tomography (nicknamed 4D), seem promising in revealing additional information not detected with the standard methods. I review some of our own recent work on the 3D spectroscopy of HII galaxies.

  8. Evolution of Prolate Molecular Clouds at Hii Boundaries: II. Formation of BRCs of asymmetrical morphology

    CERN Document Server

    Kinnear, T M; White, G J; Sugitani, K; Goodwin, S

    2015-01-01

    A systematic investigation on the evolution of a prolate cloud at an Hii boundary is conducted using Smoothed Particle Hydrodynamics (SPH) in order to understand the mechanism for a variety of irregular morphological structures found at the boundaries of various Hii regions. The prolate molecular clouds in this investigation are set with their semi-major axes at inclinations between 0 and 90 degrees to a plane parallel ionizing radiation flux. A set of 4 parameters, the number density n, the ratio of major to minor axis gamma, the inclination angle phi and the incident flux F_EUV, are used to define the initial state of the simulated clouds. The dependence of the evolution of a prolate cloud under Radiation Driven Implosion (RDI) on each of the four parameters is investigated. It is found that: i) in addition to the well studied standard type A, B or C Bright Rimmed Clouds (BRCs), many other types such as asymmetrical BRCs, filamentary structures and irregular horse-head structures could also be developed at ...

  9. The outer regions of galaxy clusters: Chandra constraints on the X-ray surface brightness

    CERN Document Server

    Ettori, S

    2008-01-01

    (Abridged version) We study the properties of the X-ray surface brightness profiles in a sample of galaxy clusters that are observed with Chandra and have emission detectable with a signal-to-noise ratio larger than 2 at a radius beyond R500 ~ 0.7 R200. Our study aims at measuring the slopes of the X-ray surface brightness and of the gas density profiles in the outskirts of massive clusters. These constraints are then compared to similar results obtained from observations and numerical simulations of the temperature and dark matter density profiles with the intention to present a consistent picture of the outer regions of galaxy clusters. We extract the surface brightness profiles S_b(r) from X-ray exposures obtained with Chandra of 52 X-ray luminous galaxy clusters at z>0.3. We estimate R200 both using a beta-model to reproduce the surface brightness profile and scaling relations from the literature, showing that the two methods converge to comparable values. We evaluate then the radius, R_S2N, at which the ...

  10. Application of satellite microwave remote sensed brightness temperature in the regional soil moisture simulation

    Directory of Open Access Journals (Sweden)

    X. K. Shi

    2009-02-01

    Full Text Available As the satellite microwave remote sensed brightness temperature is sensitive to land surface soil moisture (SM and SM is a basic output variable in model simulation, it is of great significance to use the brightness temperature data to improve SM numerical simulation. In this paper, the theory developed by Yan et al. (2004 about the relationship between satellite microwave remote sensing polarization index and SM was used to estimate the land surface SM from AMSR-E (Advanced Microwave Scanning Radiometer – Earth Observing System brightness temperature data. With consideration of land surface soil texture, surface roughness, vegetation optical thickness, and the AMSR-E monthly SM products, the regional daily land surface SM was estimated over the eastern part of the Qinghai-Tibet Plateau. The results show that the estimated SM is lower than the ground measurements and the NCEP (American National Centers for Environmental Prediction reanalysis data at the Maqu Station (33.85° N, 102.57° E and the Tanglha Station (33.07° N, 91.94° E, but its regional distribution is reasonable and somewhat better than that from the daily AMSR-E SM product, and its temporal variation shows a quick response to the ground daily precipitations. Furthermore, in order to improve the simulating ability of the WRF (Weather Research and Forecasting model to land surface SM, the estimated SM was assimilated into the Noah land surface model by the Newtonian relaxation (NR method. The results indicate that, by fine tuning of the quality factor in NR method, the simulated SM values are improved most in desert area, followed by grassland, shrub and grass mixed zone. At temporal scale, Root Mean Square Error (RMSE values between simulated and observed SM are decreased 0.03 and 0.07 m3/m3 by using the NR method in the Maqu Station and the Tanglha Station, respectively.

  11. Molecular clouds associated with compact HII regionsin Galactic plane

    Institute of Scientific and Technical Information of China (English)

    孙锦; 沈家健; 孙艳春; 张燕平

    2002-01-01

    13CO (J = 1 - 0) emission of massive star forming region including 15 ultracompact and 4compact HII regions in Galactic plane was mapped with the 13.7 m millimeter wave telescope of Purple Mountain Observatory. The present observations provide the first complete structure of the clouds in 13CO with a higher spatial resolution and a wide-field coverage of 28′×45′. Combined with the images of far-infrared emission and dust color temperature obtained from ISSA, various possible dynamical connections between the compact HII regions and associated clouds were found. We presente some reasons to explain the formation of new dense cold core and molecular emission cavity in the massive star formation and early evolution. The luminosities of excitation stars for all HII regions and the main parameters of associated clouds are also derived. The results show that the newborn stars' luminosities are correlated with the 13CO column densities, masses (in 55"beam) and 13CO velocity widths obviously.``

  12. Ha AND [OIII] EMISSION LINE MAPS OF MRK 1318 AND TOL 1358-328. CHARACTERISING THE STAR FORMATION IN HII GALAXIES

    Directory of Open Access Journals (Sweden)

    A. Torres-Campos

    2011-01-01

    Full Text Available Usando im genes en los filtros H y [OIII] h5007 tomadas con el telescopio SOAR de 4.1 m hemos creado un cat logo de regiones HII en las galaxias HII Tol 1358-328 y Mrk 1318. Este cat logo es el primer paso de un trabajo que pretende caracterizar la formaci n estelar y el impacto que tiene en el medio interestelar (MIE que lo rodea en galaxias HII extremadamente j venes.

  13. Mäesuitsu hiis / Ahto Kaasik

    Index Scriptorium Estoniae

    Kaasik, Ahto, 1969-

    2014-01-01

    Tartumaal Võnnu vallas Terikese külas asuvast Mäesuitsu hiiest, mida on nimetatud ka Suitsumäe hiis, Suitsumägi, Salumägi, Härja hiie mägi, Ohvrimägi, Ohvrimäe hiis, Ukumägi ning taluomaniku järgi ka Ääre-, Ääru- ja Ääro mägi

  14. Multi-wavelength Study of Transition Region Penumbral Subarcsecond Bright Dots Using IRIS and NST

    CERN Document Server

    Deng, Na; Tian, Hui; Kleint, Lucia; Liu, Chang; Xu, Yan; Wang, Haimin

    2016-01-01

    Using high-resolution transition region (TR) observations taken by the Interface Region Imaging Spectrograph (IRIS) mission, Tian et al. (2014b) revealed numerous short-lived subarcsecond bright dots (BDs) above sunspots (mostly located in the penumbrae), which indicate yet unexplained small-scale energy releases. Moreover, whether these subarcsecond TR brightenings have any signature in the lower atmosphere and how they are formed are still not fully resolved. This paper presents a multi-wavelength study of the TR penumbral BDs using a coordinated observation of a near disk-center sunspot with IRIS and the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory. NST provides high-resolution chromospheric and photospheric observations with narrow-band H-alpha imaging spectroscopy and broad-band TiO images, respectively, complementary to IRIS TR observations. A total of 2692 TR penumbral BDs are identified from a 37-minute time series of IRIS 1400 A slitjaw images. Their locations tend to be associat...

  15. Mid-Infrared diagnostics of metal-rich HII regions from VLT and Spitzer Spectroscopy of Young Massive Stars in W31

    CERN Document Server

    Furness, JP; Morris, PW; Barbosa, CL; Blum, RD; Conti, PS; van Dyk, SD

    2009-01-01

    We present near-IR VLT/ISAAC and mid-IR Spitzer/IRS spectroscopy of the young massive cluster in the W31 star-forming region. H-band spectroscopy provides refined classifications for four cluster members O stars with respect to Blum et al. In addition, photospheric features are detected in the massive Young Stellar Object (mYSO) #26. Spectroscopy permits estimates of stellar temperatures and masses, from which a cluster age of ~0.6 Myr and distance of 3.3 kpc are obtained, in excellent agreement with Blum et al. IRS spectroscopy reveals mid-infrared fine structure line fluxes of [Ne II-III] and [S III-IV] for four O stars and five mYSOs. In common with previous studies, stellar temperatures of individual stars are severely underestimated from the observed ratios of fine-structure lines, despite the use of contemporary stellar atmosphere and photoionization models. We construct empirical temperature calibrations based upon the W31 cluster stars of known spectral type, supplemented by two inner Milky Way ultrac...

  16. Cosmological HII Bubble Growth During Reionization

    CERN Document Server

    Shin, Min-Su; Cen, Renyue

    2007-01-01

    We present general properties of ionized hydrogen (HII) bubbles and their growth based on a state-of-the-art large-scale (100 Mpc/h) cosmological radiative transfer simulation. The simulation resolves all halos with atomic cooling at the relevant redshifts and simultaneously performs radiative transfer and dynamical evolution of structure formation. Our major conclusions include: (1) for significant HII bubbles, the number distribution is peaked at a volume of ~ 0.6 Mpc^3/h^3 at all redshifts. But, at z 10 even the largest HII bubbles have a balanced ionizing photon contribution from Pop II and Pop III stars, while at z < 8 Pop II stars start to dominate the overall ionizing photon production for large bubbles, although Pop III stars continue to make a non-negligible contribution. (6) The relationship between halo number density and bubble size is complicated but a strong correlation is found between halo number density and bubble size for for large bubbles.

  17. 3D OPTICAL AND IR SPECTROSCOPY OF EXCEPTIONAL HII GALAXIES

    Directory of Open Access Journals (Sweden)

    E. Telles

    2009-01-01

    Full Text Available In this contribution I will very brie y summarize some recent results obtained applying 3D spectroscopy to observations of the well known HII galaxy II Zw 40, both in the optical and near-IR. I have studied the distribution of the dust in the starburst region, the velocity and velocity dispersion, and the geometry of the molecular hydrogen and ionized gas. I found a clear correlation between the component of the ISM and the velocity eld suggesting that the latter has a fundamental role in de ning the modes of the star formation process.

  18. The L-σ relation for HII galaxies in green

    Science.gov (United States)

    Melnick, J.; Telles, E.; Bordalo, V.; Chávez, R.; Fernández-Arenas, D.; Terlevich, E.; Terlevich, R.; Bresolin, F.; Plionis, M.; Basilakos, S.

    2017-03-01

    The correlation between emission-line luminosity (L) and profile-width (σ) for HII galaxies provides a powerful method to measure the distances to galaxies over a wide range of redshifts. In this paper, we use SDSS spectrophotometry to explore the systematics of the correlation using the [OIII]5007 lines instead of Hα or Hβ to measure luminosities and line widths. We also examine possible systematic effects involved in measuring the profile-widths and the luminosities through different apertures. We find that the green L-σ relation, defined using [OIII]5007 luminosities, is significantly more sensitive than Hβ to the effects of age and the physical conditions of the nebulae, which more than offsets the advantage of the higher strength of the [OIII]5007 lines. We then explore the possibility of mixing [OIII]5007 profile-widths with SDSS Hβ luminosities using the Hubble constant H0 to quantify the possible systematic effects. We find the mixed L(Hβ) - σ[OIII] relation to be at least as powerful as the canonical L-σ relation as a distance estimator, and we show that evolutionary corrections do not change the slope and the scatter of the correlation and, therefore, do not bias the L-σ distance indicator at high redshifts. Locally, however, the luminosities of the giant HII regions that provide the zero-point calibrators are sensitive to evolutionary corrections and may bias the Hubble constant if their mean ages, as measured by the equivalent widths of Hβ, are significantly different from the mean age of the HII galaxies. Using a small sample of 16 ad-hoc zero point calibrators we obtain a value of H0 = 66.4+ 5.0-4.5km s-1 Mpc-1 for the Hubble constant, which is fully consistent with the best modern determinations, and which is not biased by evolutionary corrections.

  19. Relationship of magnetic field strength and brightness of fine-structure elements in the solar temperature minimum region

    Science.gov (United States)

    Cook, J. W.; Ewing, J. A.

    1990-01-01

    A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B.

  20. THE STAR FORMATION REGION NGC 6334

    Directory of Open Access Journals (Sweden)

    M. Tapia

    2009-01-01

    Full Text Available The bright nebular complex NGC 6334 contains some of the most active sites of massive star formation known in our Galaxy. It is located at a distance from the Sun of 1.62 kpc and has a total mass of a few 105M . The physical characteristics of the active spots range widely, from well developed expanding HII regions to deeply embedded, still contracting, young objects detected only as millimeter sources, thus at their earliest observable stage of their evolution. The oldest optically visible round HII regions with central O-type stars are found in the southern parts, and the youngest along a molecular ridge. On the latter, no clear spatial evolutionary correlation is apparent.

  1. DR Tau: Temporal variability of the brightness distribution in the potential planet-forming region

    CERN Document Server

    Brunngräber, Robert; Ratzka, Thorsten; Ober, Florian

    2016-01-01

    We investigate the variability of the brightness distribution and the changing density structure of the protoplanetary disk around DR Tau, a classical T Tauri star. DR Tau is known for its peculiar variations from the ultraviolet (UV) to the mid-infrared (MIR). Our goal is to constrain the temporal variation of the disk structure based on photometric and MIR interferometric data. We observed DR Tau with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) at three epochs separated by about nine years, two months, respectively. We fit the spectral energy distribution and the MIR visibilities with radiative transfer simulations. We are able to reproduce the spectral energy distribution as well as the MIR visibility for one of the three epochs (third epoch) with a basic disk model. We were able to reproduce the very different visibility curve obtained nine years earlier with a very similar baseline (first epoch), using the same disk model with a smaller scale heigh...

  2. Star formation in bright-rimmed clouds and cluster associated with W5 E H{\\sc ii} region

    CERN Document Server

    Chauhan, Neelam; Ogura, K; Jose, J; Ojha, D K; Samal, M R; Mito, H

    2011-01-01

    The aim of this paper is to present the results of photometric investigations of the central cluster of the W5 E region as well as a follow-up study of the triggered star formation in and around bright-rimmed clouds (BRCs). We have carried out wide field $UBVI_c$ and deep $VI_c$ photometry of the W5 E H{\\sc ii} region. A distance of $\\sim$2.1 kpc and a mean age of $\\sim$1.3 Myr have been obtained for the central cluster. The young stellar objects (YSOs) associated with the region are identified on the basis of near-infrared and mid-infrared observations. We confirmed our earlier results that the average age of the YSOs lying on/inside the rim are younger than those lying outside the rim. The global distribution of the YSOs shows an aligned distribution from the ionising source to the BRCs. These facts indicate that a series of radiation driven implosion processes proceeded from near the central ionising source towards the periphery of the W5 E H{\\sc ii} region. We found that, in general, the age distributions...

  3. Starburst in the interacting HII galaxy II Zw 40 and in non-interacting HII galaxies

    CERN Document Server

    Telles, Eduardo

    2009-01-01

    I summarize the results of our integral field spectroscopic observations of the nearby prototype of HII galaxies, II Zw 40. Observations with GMOS-IFU on GEMINI-North in the optical allowed us to make a detailed kinematic picture of the central starburst, while SINFONI with adaptive optics on the ESO-VLT gave us a near-IR view of the interplay between the ISM phases. Here, I also address the question that not all starbursts require an external trigger such as a galaxy-galaxy encounter, as it seems to be the case for a fraction of low luminosity HII galaxies. We speculate that these may form stars spontaneously like "pop-corn in a pan".

  4. Extremely-bright submillimeter galaxies beyond the Lupus-I star-forming region

    CERN Document Server

    Tamura, Y; Shimajiri, Y; Tsukagoshi, T; Nakajima, Y; Oasa, Y; Wilner, D J; Chandler, C J; Saigo, K; Tomida, K; Yun, M S; Taniguchi, A; Kohno, K; Hatsukade, B; Aretxaga, I; Austermann, J E; Dickman, R; Ezawa, H; Goss, W M; Hayashi, M; Hughes, D H; Hiramatsu, M; Inutsuka, S; Ogasawara, R; Ohashi, N; Oshima, T; Scott, K S; Wilson, G W

    2015-01-01

    We report detections of two candidate distant submillimeter galaxies (SMGs), MM J154506.4$-$344318 and MM J154132.7$-$350320, which are discovered in the AzTEC/ASTE 1.1 mm survey toward the Lupus-I star-forming region. The two objects have 1.1 mm flux densities of 43.9 and 27.1 mJy, and have Herschel/SPIRE counterparts as well. The Submillimeter Array counterpart to the former SMG is identified at 890 $\\mu$m and 1.3 mm. Photometric redshift estimates using all available data from the mid-infrared to the radio suggest that the redshifts of the two SMGs are $z_{\\rm photo} \\simeq$ 4-5 and 3, respectively. Near-infrared objects are found very close to the SMGs and they are consistent with low-$z$ ellipticals, suggesting that the high apparent luminosities can be attributed to gravitational magnification. The cumulative number counts at $S_{\\rm 1.1mm} \\ge 25$ mJy, combined with other two 1.1-mm brightest sources, are $0.70 ^{+0.56}_{-0.34}$ deg$^{-2}$, which is consistent with a model prediction that accounts for ...

  5. Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets

    Science.gov (United States)

    Samanta, Tanmoy; Tian, Hui; Banerjee, Dipankar; Schanche, Nicole

    2017-02-01

    Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph, we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with the formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.

  6. Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface

    CERN Document Server

    Kirk, J; Louden, T; Littlefair, S P; Copperwheat, C M; Armstrong, D J; Marsh, T R; Dhillon, V S

    2016-01-01

    We have measured the transmission spectrum of the extremely inflated hot Jupiter WASP-52b using simultaneous photometric observations in SDSS u', g' and a filter centred on the sodium doublet (NaI) with the ULTRACAM instrument mounted on the 4.2m William Herschel Telescope. We find that Rayleigh scattering is not the dominant source of opacity within the planetary atmosphere and find a transmission spectrum more consistent with wavelength-independent opacity such as from clouds. We detect an in-transit anomaly that we attribute to the presence of stellar activity and find that this feature can be more simply modelled as a bright region on the stellar surface akin to Solar faculae rather than spots. A spot model requires a significantly larger planet/star radius ratio than that found in previous studies. Our results highlight the precision that can be achieved by ground-based photometry with errors in the scaled planetary radii of less than one atmospheric scale height, comparable to HST observations.

  7. The Radio Properties of Composite LINER/HII Galaxies

    CERN Document Server

    Filho, M E; Ho, L C; Filho, Mercedes E.; Barthel, Peter D.; Ho, Luis C.

    2002-01-01

    Arcsec-resolution VLA observations -- newly obtained as well as published -- of 40 nearby galaxies are discussed, completing a study of the radio properties of a magnitude-limited sample of nearby galaxies of the composite LINER/HII type. Our results reveal an overall detection rate of at least 25% AGN candidates among these composite sources. The general properties of these AGN candidates, as compared to non-AGN composite sources and HII galaxies, are discussed.

  8. Direct measurement of lensing amplification in Abell S1063 using a strongly lensed high redshift HII Galaxy

    CERN Document Server

    Terlevich, Roberto; Terlevich, Elena; Chavez, Ricardo; Telles, Eduardo; Bresolin, Fabio; Plionis, Manolis; Basilakos, Spyros; Arenas, David Fernandez; Moran, Ana Luisa Gonzalez; Diaz, Angeles I; Aretxaga, Itziar

    2016-01-01

    ID11 is an actively star forming extremely compact galaxy and Ly alpha emitter at z=3.117 that is gravitationally magnified by a factor of ~17 by the cluster of galaxies Hubble Frontier Fields AS1063. Its observed properties resemble those of low luminosity HII galaxies or Giant HII regions like 30-Doradus in the LMC. Using the tight correlation correlation between the Balmer-line luminosities and the width of the emission lines (typically L(Hbeta)-sigma(Hbeta)) valid for HII galaxies and Giant HII regions to estimate its total luminosity, we are able to measure the lensing amplification of ID11. We obtain an amplification of 23 +- 11 similar within errors to the value of ~17 estimated or predicted by the best lensing models of the massive cluster Abell S1063. We also compiled from the literature luminosities and velocity dispersions for a set of lensed compact starforming regions. There is more scatter in the L-sigma correlation for these lensed systems but on the whole the results tend to support the lensin...

  9. Doppler Imaging of Young Late-Type Stars: HII 686, HII 3163, and P1724

    Science.gov (United States)

    Stout-Batalha, Natalie Marie

    Maximum entropy image reconstruction (Doppler imaging) is applied to HII 686 (K4V, v sin i=64 km s-1) and HII 3163 (K0, v sin i=70 km s-1), two zero-age main sequence stars of the Pleiades cluster, and the weak-lined T Tauri star Parenago 1724 (K0, v sin i=71 km s-1). Their surface temperature distributions are determined in order to study the nature of magnetic activity in young ultra-fast rotators. Specific intensity line profiles used in the DI algorithm are synthesized. The sensitivity of the reconstructions to the choice of input stellar and atomic data is investigated. The quality of the fit to the average disk integrated line profile is found to be more important to DI analysis than the exact parameters used to generate the fit when the shape of the disk integrated line profile is dominated by rotational broadening. Fifteen absorption lines are used to generate fifteen individual reconstructions of each Pleiades target. Averaging reduces noise in the reconstructions. However, spurious features can persist at sub-observer longitudes. Such 'phase-ghosting' can largely be eliminated by including broad-band photometric observations in the analysis. Using the large number of reconstructions for a given star, uncertainties in the images are estimated. HII 686 shows one predominant feature at 77o latitude which is 700 K cooler than the surrounding photosphere. HII 3163 also shows one predominant feature centered at approximately 70o latitude. A spot temperature 1000 K cooler than the photosphere best reproduces the observations. P1724 shows a predominant feature (or features) centered at 30o latitude which is 800 K cooler than its photosphere. These results are discussed in light of recent theoretical observations and existing image reconstructions of similar objects. No correlations are found among reconstructions which could be attributed to line characteristics: equivalent width, excitation potential or depth of formation. This is also true for the LiI and KI

  10. A substellar companion to Pleiades HII 3441

    Science.gov (United States)

    Konishi, Mihoko; Matsuo, Taro; Yamamoto, Kodai; Samland, Matthias; Sudo, Jun; Shibai, Hiroshi; Itoh, Yoichi; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki; Hashimoto, Jun; Kuzuhara, Masayuki; Kusakabe, Nobuhiko; Abe, Lyu; Akiyama, Eiji; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph C.; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R.; Kwon, Jungmi; McElwain, Michael W.; Mede, Kyle; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martín, Amaya; Nishimura, Tetsuo; Oh, Daehyeon; Pyo, Tae-Soo; Serabyn, Eugene; Schlieder, Joshua E.; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H.; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John P.; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2016-09-01

    We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0{^''.}49 ± 0{^''.}02 (66 ± 2 au) and a mass of 68 ± 5 MJ based on three observations in the J-, H-, and Ks-bands. The spectral type is estimated to be M7 (˜2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0^{+26.1}_{-8.8}%. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

  11. A Substellar Companion to Pleiades HII 3441

    CERN Document Server

    Konishi, Mihoko; Yamamoto, Kodai; Samland, Matthias; Sudo, Jun; Shibai, Hiroshi; Itoh, Yoichi; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki; Hashimoto, Jun; Kuzuhara, Masayuki; Kusakabe, Nobuhiko; Abe, Lyu; Akiyama, Eiji; Brandner, Wolfgang; Brandt, Timothy D; Carson, Joseph C; Feldt, Markus; Goto, Miwa; Grady, Carol A; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S; Henning, Thomas; Hodapp, Klaus W; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R; Kwon, Jungmi; Mcelwain, Michael W; Mede, Kyle; Miyama, Shoken; Morino, Jun-Ichi; Moro-Mart'in, Amaya; Nishimura, Tetsuo; Oh, Daehyeon; Pyo, Tae-Soo; Serabyn, Eugene; Schlieder, Joshua E; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L; Watanabe, Makoto; Wisniewski, John P; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2016-01-01

    We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0".49 +/- 0".02 (66 +/- 2 AU) and a mass of 68 +/- 5 M_J based on three observations in the J-, H-, and K_S-band. The spectral type is estimated to be M7 (~2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0 +26.1/-8.8 %. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

  12. A substellar companion to Pleiades HII 3441

    Science.gov (United States)

    Konishi, Mihoko; Matsuo, Taro; Yamamoto, Kodai; Samland, Matthias; Sudo, Jun; Shibai, Hiroshi; Itoh, Yoichi; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki; Hashimoto, Jun; Kuzuhara, Masayuki; Kusakabe, Nobuhiko; Abe, Lyu; Akiyama, Eiji; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph C.; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R.; Kwon, Jungmi; McElwain, Michael W.; Mede, Kyle; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martín, Amaya; Nishimura, Tetsuo; Oh, Daehyeon; Pyo, Tae-Soo; Serabyn, Eugene; Schlieder, Joshua E.; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H.; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John P.; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2016-12-01

    We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0{^''.}49 ± 0{^''.}02 (66 ± 2 au) and a mass of 68 ± 5 MJ based on three observations in the J-, H-, and Ks-bands. The spectral type is estimated to be M7 (˜2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0^{+26.1}_{-8.8}%. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

  13. Impact of initial models and variable accretion rates on the pre-main-sequence evolution of massive and intermediate-mass stars and the early evolution of HII regions

    CERN Document Server

    Haemmerlé, Lionel

    2016-01-01

    Massive star formation requires the accretion of gas at high rate while the star is already bright. Its actual luminosity depends sensitively on the stellar structure. We compute pre-main-sequence tracks for massive and intermediate-mass stars with variable accretion rates and study the evolution of stellar radius, effective temperature and ionizing luminosity, starting at $2\\,M_\\odot$ with convective or radiative structures. The radiative case shows a much stronger swelling of the protostar for high accretion rates than the convective case. For radiative structures, the star is very sensitive to the accretion rate and reacts quickly to accretion bursts, leading to considerable changes in photospheric properties on timescales as short as 100 - 1000 yr. The evolution for convective structures is much less influenced by the instantaneous accretion rate, and produces a monotonically increasing ionizing flux that can be many orders of magnitude smaller than in the radiative case. For massive stars, it results in ...

  14. The L-sigma Relation of Local HII Galaxies

    CERN Document Server

    Bordalo, Vinicius

    2011-01-01

    We present for the first time a new data set of emission line widths for 118 star-forming regions in HII galaxies (HIIGs). This homogeneous set is used to investigate the L-sigma relation in conjunction with optical spectrophotometric observations. Peculiarities in the line profiles such as sharp lines, wings, asymmetries, and in some cases more than one component in emission were verified. From a new independent homogeneous set of spectrophotometric data we derived physical condition parameters and performed the statistical principal component analysis. We have investigated the potential role of metallicity (O/H), Hbeta equivalent width (WHbeta) and ionization ratio [OIII]/[OII] to account for the observational scatter of L-sigma relation. Our results indicate that the L-sigma relation for HIIGs is more sensitive to the evolution of the current starburst event (short-term evolution) and dated by WHbeta or even the [OIII]/[OII] ratio. The long-term evolution measured by O/H also plays a potential role in dete...

  15. Constraining the Dark Energy Equation of State with HII Galaxies

    CERN Document Server

    Chávez, Ricardo; Basilakos, Spyros; Terlevich, Roberto; Terlevich, Elena; Melnick, Jorge; Bresolin, Fabio; González-Morán, Ana Luisa

    2016-01-01

    We use the HII galaxies $L - \\sigma$ relation and the resulting Hubble expansion cosmological probe of a sample of just 25 high-$z$ (up to $z \\sim 2.33$) HII galaxies, in a joint likelihood analysis with other well tested cosmological probes (CMB, BAOs) in an attempt to constrain the dark energy equation of state (EoS). The constraints, although still weak, are in excellent agreement with those of a similar joint analysis using the well established SNIa Hubble expansion probe. Interestingly, even with the current small number of available high redshift HII galaxies, the HII/BAO/CMB joint analysis gives a 13% improvement of the quintessence dark energy cosmological constraints compared to the BAO/CMB joint analysis. We have further performed extensive Monte Carlo simulations, with a realistic redshift sampling, to explore the extent to which the use of the $L - \\sigma$ relation, observed in HII galaxies, can constrain effectively the parameter space of the dark energy EoS. The simulations predict substantial i...

  16. Relationship Between Solar Coronal X-Ray Brightness and Active Region Magnetic Fields: A Study Using High Resolution Observations

    CERN Document Server

    Hazra, Soumitra; Ravindra, B

    2014-01-01

    By utilizing high resolution observations of nearly co-temporal and co-spatial SOT spectropolarimeter and XRT coronal X-ray data onboard Hinode, we revisit the contentious issue of the relationship between global magnetic quantities and coronal X-ray intensity. Co-aligned vector magnetogram and X-ray data are used for this study. We find that there is no pixel-to-pixel correlation between the observed loop brightness and magnetic quantities. However, the X-ray brightness is well correlated with the integrated magnetic quantities such as total unsigned magnetic flux, total unsigned vertical current, area integrated square of the vertical magnetic field and horizontal magnetic fields. Comparing all these quantities we find that the total magnetic flux correlates well with the observed integrated X-ray brightness, though there is some differences in the strength of the correlation when we use the X-ray data from different filters. While we get a good correlation between X-ray brightness and total unsigned vertic...

  17. Diabetes insipidus in pediatric germinomas of the suprasellar region: characteristic features and significance of the pituitary bright spot.

    Science.gov (United States)

    Kilday, John-Paul; Laughlin, Suzanne; Urbach, Stacey; Bouffet, Eric; Bartels, Ute

    2015-01-01

    The pituitary bright spot is acknowledged to indicate functional integrity of the posterior pituitary gland, whilst its absence supports a diagnosis of central diabetes insipidus (DI). This feature was evaluated, together with the incidence and clinical characteristics of DI in children with suprasellar/neurohypophyseal germinomas. We performed a review of all suprasellar (SS) or bifocal (BF) germinoma pediatric patients treated in Toronto since 2000. Demographics, symptomatology, treatment outcome and imaging were evaluated. Nineteen patients fulfilled inclusion criteria (10 SS, 9 BF; median age 12.5 years (6.2-16.8 years)). All remained alive at 6.4 years median follow-up (1.2-13.7 years) after receiving chemotherapy and radiotherapy (13 focal/ventricular, four whole brain, two neuraxis), with only one progression. All had symptoms of DI at presentation with a symptom interval above one year in eight cases (42 %). Desmopressin was commenced and maintained in 16 patients (84 %). The pituitary bright spot was lost in most diagnostic interpretable cases, but was appreciated in three patients (18 %) who had normal serum sodium values compared to 'absent' cases (p = 0.013). For two such cases, spots remained visible until last follow-up (range 0.4-3.3 years), with one still receiving desmopressin. No case of bright spot recovery was observed following therapy. Protracted symptom intervals for germinoma-induced central DI may reflect poor clinical awareness. Explanations for persistence of the pituitary bright spot in symptomatic patients remain elusive. Desmopressin seldom reverses the clinical features of germinoma-induced DI to allow discontinuation, nor does treatment cause bright spot recovery.

  18. Daylight photodynamic therapy - Experience and safety in treatment of actinic keratoses of the face and scalp in low latitude and high brightness region*

    Science.gov (United States)

    Galvão, Luiz Eduardo Garcia; Gonçalves, Heitor de Sá; Botelho, Karine Paschoal; Caldas, Juliana Chagas

    2017-01-01

    Daylight photodynamic therapy has been used in countries with high latitudes during the summer for actinic keratoses treatment with reports of similar efficacy to conventional photodynamic therapy. We evaluate its safety in 20 patients in the city of Fortaleza, a local with low latitude and high brightness. Sixteen patients did not report any discomfort due to the procedure. Daylight photodynamic therapy is an easy application method with great tolerability by the patient and has the possibility of being performed throughout the year in these regions. It can mean a promising tool in the control of skin cancer. PMID:28225978

  19. Wind-Blown Bubbles and HII Regions around Massive Stars

    Directory of Open Access Journals (Sweden)

    S. J. Arthur

    2007-01-01

    Full Text Available La evoluci on de las estrellas muy masivas est a dominada por su p erdida de masa, aunque las tasas de p erdida de masa no se conocen con mucha precisi on, particularmente una vez que la estrella sale de la secuencia principal. Los estudios de las nebulosas de anillo y de las cascarones de HI que rodean a muchas estrellas Wolf-Rayet (WR y variables azules luminosas (LBV proporcionan algo de informaci on acerca de la historia de la p erdida de masa en las etapas previas. Durante la secuencia principal y la fase WR los vientos estelares hipers onicos forman burbujas en el medio circunestelar e interestelar. Estas dos fases est an separadas por una etapa en donde la estrella pierde masa a una tasa muy alta pero a baja velocidad. Por lo tanto, el ambiente presupernova es determinado por la estrella progenitora misma, a un hasta distancias de algunas decenas de parsecs de la estrella. En este art culo, se describen las diferentes etapas en la evoluci on del medio circunestelar alrededar de una estrella de masa 40 M mediante simulaciones num ericas

  20. Thermally induced fluid reversed hexagonal (H(II)) mesophase.

    Science.gov (United States)

    Amar-Yuli, Idit; Wachtel, Ellen; Shalev, Deborah E; Moshe, Hagai; Aserin, Abraham; Garti, Nissim

    2007-12-06

    In the present study we characterized the microstructures of the Lc and HII phases in a glycerol monooleate (GMO)/tricaprylin (TAG)/water mixture as a function of temperature. We studied the factors that govern the formation of a low-viscosity HII phase at relatively elevated temperatures (>35 degrees C). This phase has very valuable physical characteristics and properties. The techniques used were differential scanning calorimetry (DSC), wide- and small-angle X-ray scattering (WAXS and SAXS, respectively), NMR (self-diffusion and (2)H NMR), and Fourier transform infrared (FTIR) spectroscopies. The reverse hexagonal phase exhibited relatively rapid flow of water in the inner channels within the densely packed cylindrical aggregates of GMO with TAG molecules located in the interstices. The existence of two water diffusion peaks reflects the existence of both mobile water and hydration water at the GMO-water interface (hydrogen exchange between the GMO hydroxyls and water molecules). Above 35 degrees C, the sample became fluid yet hexagonal symmetry was maintained. The fluidity of the HII phase is explained by a significant reduction in the domain size and also perhaps cylinder length. This phenomenon was characterized by higher mobility of the GMO, lower mobility of the water, and a significant dehydration process.

  1. Novel high-brightness tunneling-regenerated multi-active-region AlGaInP light-emitting diode

    Institute of Scientific and Technical Information of China (English)

    郭霞; 沈光地; 王国宏; 王学忠; 杜金玉; 高国; 王康隆

    2003-01-01

    In order to resolve the prevailing problems in conventional light-emitting diodes (LEDs), novel high-efficiency tunneling-regenerated multi-active-region (TRMAR) LEDs are proposed, which have such advantages as low heat generation, carrier overflow level and non-radiation recombination rate and whose quantum efficiency and the output optical power can be scaled with the number of the active regions. Experiments show that the on-axis luminous intensity of TRMAR LEDs increases linearly with the number of active regions. The novel LEDs have high quantum efficiency under low current injection and their maximum on-axis luminous intensity exceeds 5 candelas at 20 mA current injection at the peak wavelength of 625 nm with a 15° angle cap.

  2. Star formation and the interstellar medium in low surface brightness galaxies; 1, Oxygen abundances and abundance gradients in low surface brightness disk galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; Hulst, J. M. van der

    1998-01-01

    Submitted to: Astron. Astrophys. Abstract: We present measurements of the oxygen abundances in 64 HII regions in 12 LSB galaxies. We find that oxygen abundances are low. No regions with solar abundance have been found, and most have oxygen abundances $sim 0.5$ to 0.1 solar. The oxygen abundance appe

  3. MAGIC Upper Limits for two Milagro-detected, Bright Fermi Sources in the Region of SNR G65.1+0.6

    CERN Document Server

    Aleksić, J; Antoranz, P; Backes, M; Barrio, J A; Bastieri, D; González, J Becerra; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnoli, G; Bordas, P; Tridon, D Borla; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Camara, M; Carmona, E; Carosi, A; Colin, P; Contreras, J L; Cortina, J; Covino, S; Dazzi, F; De Angelis, A; del Pozo, E De Cea; De Lotto, B; De Maria, M; De Sabata, F; DelgadoMendez, C; Ortega, A Diago; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fonseca, M V; Font, L; López, R J García; Garczarczyk, M; Gaug, M; Giavitto, G; Godinović, N; Hadasch, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Jogler, T; Klepser, S; Krähenbühl, T; Kranich, D; Krause, J; La Barbera, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moralejo, A; Nieto, D; Nilsson, K; Orito, R; Oya, I; Paoletti, R; Paredes, J M; Partini, S; Pasanen, M; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Pochon, J; Prada, F; Moroni, P G Prada; Prandini, E; Puchades, N; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rissi, M; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Sánchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shayduk, M; Shore, S N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Spiro, S; Stamerra, A; Steinke, B; Storz, J; Strah, N; Struebig, J C; Suric, T; Takalo, L; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Torres, D F; Vankov, H; Wagner, R M; Weitzel, Q; Zabalza, V; Zandanel, F; Zanin, R

    2010-01-01

    We report on the observation of the region around supernova remnant G65.1+0.6 with the stand-alone MAGIC-I telescope. This region hosts the two bright GeV gamma-ray sources 1FGL J1954.3+2836 and 1FGL J1958.6+2845. They are identified as GeV pulsars and both have a possible counterpart detected at about 35 TeV by the Milagro observatory. MAGIC collected 25.5 hours of good quality data, and found no significant emission in the range around 1 TeV. We therefore report differential flux upper limits, assuming the emission to be point-like (<0.1 deg) or within a radius of 0.3 deg. In the point-like scenario, the flux limits around 1 TeV are at the level of 3 % and 2 % of the Crab Nebula flux, for the two sources respectively. This implies that the Milagro emission is either extended over a much larger area than our point spread function, or it must be peaked at energies beyond 1 TeV, resulting in a photon index harder than 2.2 in the TeV band.

  4. MAGIC Upper Limits for Two Milagro-detected Bright Fermi Sources in the Region of SNR G65.1+0.6

    Science.gov (United States)

    Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Bordas, P.; Borla Tridon, D.; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Contreras, J. L.; Cortina, J.; Covino, S.; Dazzi, F.; De Angelis, A.; De Cea del Pozo, E.; De Lotto, B.; De Maria, M.; De Sabata, F.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Errando, M.; Ferenc, D.; Fonseca, M. V.; Font, L.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giavitto, G.; Godinović, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; Krause, J.; La Barbera, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Lorenz, E.; Majumdar, P.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, L.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Struebig, J. C.; Suric, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.

    2010-12-01

    We report on the observation of the region around supernova remnant G65.1+0.6 with the stand-alone MAGIC-I telescope. This region hosts the two bright GeV gamma-ray sources 1FGL J1954.3+2836 and 1FGL J1958.6+2845. They are identified as GeV pulsars and both have a possible counterpart detected at about 35 TeV by the Milagro observatory. MAGIC collected 25.5 hr of good quality data and found no significant emission in the range around 1 TeV. We therefore report differential flux upper limits, assuming the emission to be point-like (<=0fdg1) or within a radius of 0fdg3. In the point-like scenario, the flux limits around 1 TeV are at the level of 3% and 2% of the Crab Nebula flux for the two sources, respectively. This implies that the Milagro emission is either extended over a much larger area than our point-spread function or it must be peaked at energies beyond 1 TeV, resulting in a photon index harder than 2.2 in the TeV band.

  5. The bright lights of city regions: Assumptions, realities and implications of changing population dynamics: Zooming in on the Gauteng city region

    CSIR Research Space (South Africa)

    Pieterse, A

    2014-10-01

    Full Text Available to assumptions of migration and urbanisation. Firstly, even though poverty has been perceived as largely a rural issue, the urbanisation of poverty is in fact occurring at a large scale and city regions, particularly the Gauteng city region, is dealing...

  6. The bright lights of city regions - Assumptions, realities and implications of changing population dynamics: Zooming in on the Gauteng city region

    CSIR Research Space (South Africa)

    Pieterse, A

    2014-09-01

    Full Text Available It is well known that the city regions attract migrants from across the country because of their roles as economic engines and job baskets in South Africa. To address urbanisation implications it is imperative to better understand some...

  7. Hubble Space Telescope Hx Imaging of Star-forming Galaxies at z approximately equal to 1-1.5: Evolution in the Size and Luminosity of Giant H II Regions

    Science.gov (United States)

    Livermore, R. C.; Jones, T.; Richard, J.; Bower, R. G.; Ellis, R. S.; Swinbank, A. M.; Rigby, J. R.; Smail, Ian; Arribas, S.; Rodriguez-Zaurin, J.; hide

    2013-01-01

    We present Hubble Space Telescope/Wide Field Camera 3 narrow-band imaging of the Ha emission in a sample of eight gravitationally lensed galaxies at z = 1-1.5. The magnification caused by the foreground clusters enables us to obtain a median source plane spatial resolution of 360 pc, as well as providing magnifications in flux ranging from approximately 10× to approximately 50×. This enables us to identify resolved star-forming HII regions at this epoch and therefore study their Ha luminosity distributions for comparisons with equivalent samples at z approximately 2 and in the local Universe. We find evolution in the both luminosity and surface brightness of HII regions with redshift. The distribution of clump properties can be quantified with an HII region luminosity function, which can be fit by a power law with an exponential break at some cut-off, and we find that the cut-off evolves with redshift. We therefore conclude that 'clumpy' galaxies are seen at high redshift because of the evolution of the cut-off mass; the galaxies themselves follow similar scaling relations to those at z = 0, but their HII regions are larger and brighter and thus appear as clumps which dominate the morphology of the galaxy. A simple theoretical argument based on gas collapsing on scales of the Jeans mass in a marginally unstable disc shows that the clumpy morphologies of high-z galaxies are driven by the competing effects of higher gas fractions causing perturbations on larger scales, partially compensated by higher epicyclic frequencies which stabilize the disc.

  8. Observações em Radiofreqüências do complexo de Regiões HII Compactas RCW 95

    Science.gov (United States)

    Barres de Almeida, Ulisses

    2006-05-01

    In this work we studied the complex of compact HII (CHII) regions RCW 95. The cloud is about 10'x10' and was mapped on the radio continuum emission at 43 GHz; a survey of water lines was also conducted at 22.2 GHz, corresponding to the 616 - 523 rotational transition of this molecule. The observations were made with the 14-meter single-dish antennae of the Itaptinga radio observatory, in Atibaia, ruled by INPE (Nacional Institute for Space Research, Brazil). For the continuum observations we made several scans in right ascension throughout the whole of the source spaced by 1' in declination, that were following combined to produce a map of isotemperatures for the cloud. The study resulted on the identification of resolved radio continuum sources associated with all the three IRAS sources in the region: IRAS 15408-5356, 15411-5352 and 15412-5359, all with far-IR colours characteristics of CHII regions. The water line survey resulted on the positive identification of maser emission associated with the three IRAS sources, supporting the evidences for these regions to harbour massive young stars. Two other unresolved HII regions, unassociated with far-IR sources, were also discovered through detailed analyses of the profiles of the radio continuum scans. The regions associated to the IRAS sources 15408-5356 and 15411-5352 were already known to be regions of massive star formation, whilst the stellar population associated to IRAS 15412-5359 had not been studied before. The discovery of water lines and the presence of a thermal continuum source on this direction suggested that this region could also contain young stars. We then conducted a study of the stellar population inside a region of 2'2' around this IRAS source using near-IR (J, H and K) band images from 2MASS catalogue. Throught this we were able to identify a significant population of massive stars, including one O9V star and some early BV that were charged responsibility for the ionization of the gas in the

  9. Chandra observations of the HII complex G5.89-0.39 and TeV gamma-ray source HESSJ1800-240B

    CERN Document Server

    Hampton, E J; Hofmann, W; Horns, D; Uchiyama, Y; Wagner, S

    2016-01-01

    We present the results of our investigation, using a Chandra X-ray observation, into the stellar population of the massive star formation region G5.89-0.39, and its potential connection to the coincident TeV gamma-ray source HESSJ1800-240B. G5.89-0.39 comprises two separate HII regions G5.89-0.39A and G5.89-0.39B (an ultra-compact HII region). We identified 159 individual X-ray point sources in our observation using the source detection algorithm \\texttt{wavdetect}. 35 X-ray sources are associated with the HII complex G5.89-0.39. The 35 X-ray sources represent an average unabsorbed luminosity (0.3-10\\,keV) of $\\sim10^{30.5}$\\,erg/s, typical of B7-B5 type stars. The potential ionising source of G5.89-0.39B known as Feldt's star is possibly identified in our observation with an unabsorbed X-ray luminosity suggestive of a B7-B5 star. The stacked energy spectra of these sources is well-fitted with a single thermal plasma APEC model with kT$\\sim$5\\,keV, and column density N$_{\\rm H}=2.6\\times10^{22}$\\,cm$^{-2}$ (A...

  10. H(II) centers in natural silica under repeated UV laser irradiations

    OpenAIRE

    Messina, F.; Cannas, M.; Boscaino, R.

    2004-01-01

    We investigated the kinetics of H(II) centers (=Ge'-H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The...

  11. Water-soluble multidentate polymers compactly coating Ag2S quantum dots with minimized hydrodynamic size and bright emission tunable from red to second near-infrared region

    Science.gov (United States)

    Gui, Rijun; Wan, Ajun; Liu, Xifeng; Yuan, Wen; Jin, Hui

    2014-04-01

    Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in the bright fluorescent QDs with high PL quantum yields (QYs: 14.2-16.4%). Experimental results confirm that the QDs have high PL stability and ultralow cytotoxicity, as well as high PLQYs and small hydrodynamic sizes (4.5-5.6 nm) similar to fluorescent proteins (27-30 kDa), indicating the feasibility of highly effective PL imaging in cells and living animals.Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in

  12. An Old Supernova Remnant within an HII Complex at l {\\approx} 173{\\circ}: FVW 172.8+1.5

    CERN Document Server

    Kang, Ji-hyun; Salter, Chris

    2012-01-01

    We present the results of HI 21-cm line observations to explore the nature of the high-velocity (HV) HI gas at l ~ 173{\\circ} . In low-resolution Hi surveys this HV gas appears as faint, wing-like, HI emission that extends to velocities beyond those allowed by Galactic rotation. We designate this feature FVW (Forbidden Velocity Wing) 172.8+1.5. Our high-resolution (3.'4) Arecibo HI observations show that FVW 172.8+1.5 is composed of knots, filaments, and ring-like structures distributed over an area a few degrees in extent. These HV HI emission features are confined within the limits of the HII complex G173+1.5, which is composed of five Sharpless HII regions distributed along a radio continuum loop of size 4{\\circ}.4 {\\times} 3{\\circ}.4, or ~ 138 pc {\\times} 107 pc, at a distance of 1.8 kpc. G173+1.5 is one of the largest star-forming regions in the outer Galaxy. We demonstrate that the HV HI gas is well correlated with the radio continuum loop and that the two seem to trace an expanding shell. The expansion...

  13. Too large and overlooked? Extended free-free emission towards massive star formation regions

    CERN Document Server

    Longmore, S N; Keto, E; Kurtz, S; Walsh, A J

    2009-01-01

    We present Australia Telescope Compact Array observations towards 6 massive star formation regions which, from their strong 24 GHz continuum emission but no compact 8 GHz continuum emission, appeared good candidates for hyper-compact HII regions. However, the properties of the ionised gas derived from the 19 to 93 GHz continuum emission and H70 alpha + H57 alpha radio recombination line data show the majority of these sources are, in fact, regions of spatially-extended, optically-thin free-free emission. These extended sources were missed in the previous 8 GHz observations due to a combination of spatial-filtering, poor surface brightness sensitivity and primary beam attenuation. We consider the implications that a significant number of these extended HII regions may have been missed by previous surveys of massive star formation regions. If the original sample of 21 sources is representative of the population as a whole, the fact that 6 contain previously undetected extended free-free emission suggests a larg...

  14. HII mesophase as a drug delivery system for topical application of methyl salicylate.

    Science.gov (United States)

    Liang, Xin; Chen, Yu-Lin; Jiang, Xiao-Jing; Wang, Sheng-Mei; Zhang, Ji-Wen; Gui, Shuang-Ying

    2017-03-30

    The main objective of this study was to develop reversed hexagonal (HII) mesophase for transdermal delivery of methyl salicylate. The formulation was prepared, characterized and evaluated for its skin penetration in vitro and skin retention in vivo. Preliminary pharmacodynamics and skin irritation were also investigated. The formulation was identified as hexagonal structure. In vitro study exhibited that HII mesophase enhanced the skin permeation by delivering 2.61 times more methyl salicylate than the commercially available cream. Meanwhile, HII mesophase presented higher bioavailability as AUC(0-24) and AUC(0-∞) were 32.894μg·mL(-1) and 32.935μg·mL(-1) respectively, while the cream were 12.791μg·mL(-1) and 12.970μg·mL(-1). Preliminary pharmacodynamics studies demonstrated that HII mesophase possessed anti-inflammatory and analgesic effects for inhibiting paw edema, granuloma and pain. MeSa HII mesophase showed no skin irritation on the normal rat skin. Thus, HII mesophase was considered as an effective delivery system for MeSa.

  15. Star Cluster Complexes and the Host Galaxy in Three HII Galaxies: Mrk 36, UM 408, and UM 461

    CERN Document Server

    Lagos, Patricio; Nigoche-Netro, A; Carrasco, Eleazar Rodrigo

    2011-01-01

    We present a stellar population study of three HII galaxies (Mrk 36, UM 408, and UM 461) based on the analysis of new ground-based high resolution near-infrared J, H and Kp broad-band and Br narrow-band images obtained with Gemini/NIRI. We identify and determine relative ages and masses of the elementary star clusters and/or star cluster complexes of the starburst regions in each of these galaxies by comparing the colors with evolutionary synthesis models that include the contribution of stellar continuum, nebular continuum and emission lines. We found that the current star cluster formation efficiency in our sample of low luminosity HII galaxies is ~10%. Therefore, most of the recent star formation is not in massive clusters. Our findings seem to indicate that the star formation mode in our sample of galaxies is clumpy, and that these complexes are formed by a few massive star clusters with masses > 10^4 Mo. The age distribution of these star cluster complexes shows that the current burst started recently an...

  16. The HII Galaxy Hubble Diagram Strongly Favors $R_{\\rm h}=ct$ over $\\Lambda$CDM

    CERN Document Server

    Wei, Jun-Jie; Melia, Fulvio

    2016-01-01

    We continue to build support for the proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae. Using a sample of 25 high-redshift HIIGx, 107 local HIIGx, and 24 GEHR, we confirm that the correlation between the emission-line luminosity and ionized-gas velocity dispersion is a viable luminosity indicator, and use it to test and compare the standard model $\\Lambda$CDM and the $R_{\\rm h}=ct$ Universe by optimizing the parameters in each cosmology using a maximization of the likelihood function. For the flat $\\Lambda$CDM model, the best fit is obtained with $\\Omega_{\\rm m}= 0.40_{-0.09}^{+0.09}$. However, statistical tools, such as the Akaike (AIC), Kullback (KIC) and Bayes (BIC) Information Criteria favor $R_{\\rm h}=ct$ over the standard model with a likelihood of $\\approx 94.8\\%-98.8\\%$ versus only $\\approx 1.2\\%-5.2\\%$. For $w$CDM (the version of $\\Lambda$CDM with a dark-energy...

  17. Ultraluminous X-ray Source Correlations with Star-Forming Regions

    CERN Document Server

    Swartz, Douglas A; Soria, Roberto

    2009-01-01

    Maps of low-inclination nearby galaxies in Sloan Digitized Sky Survey u-g, g-r and r-i colors are used to determine whether Ultraluminous X-ray sources (ULXs) are predominantly associated with star-forming regions of their host galaxies. An empirical selection criterion is derived from colors of HII regions in M81 and M101 that differentiates between the young, blue stellar component and the older disk and bulge population. This criterion is applied to a sample of 58 galaxies of Hubble type S0 and later and verified through an application of Fisher's linear discriminant analysis. It is found that 60% (49%) of ULXs in optically-bright environments are within regions blueward of their host galaxy's HII regions compared to only 27% (0%) of a control sample according to the empirical (Fisher) criterion. This is an excess of 3-sigma above the 32% (27%) expected if the ULXs were randomly distributed within their galactic hosts. This indicates a ULX preference for young, approximately <10 Myr, OB associations. Ho...

  18. On the compact HII galaxy UM 408 as seen by GMOS-IFU: Physical conditions

    CERN Document Server

    Lagos, Patricio; Munoz-Tunon, Casiana; Carrasco, Eleazar R; Cuisinier, Francois; Tenorio-Tagle, Guillermo

    2009-01-01

    We present Integral Field Unit GMOS-IFU data of the compact HII galaxy UM408, obtained at Gemini South telescope, in order to derive the spatial distribution of emission lines and line ratios, kinematics, plasma parameters, and oxygen abundances as well the integrated properties over an area of 3"x4".4(~750x1100 pc) located in the central part of the galaxy. The starburst in this area is resolved into two giant regions of ~375 and 250pc diameter, respectively. The ages of these two regions, estimated using Hb equivalent widths, suggest that they are coeval events of ~5Myr with stellar masses of ~10^4M_o. We have also used [OIII]/Hb and [SII]/Ha ratio maps to explore the excitation mechanisms in this galaxy. The Ha emission line was used to measure the radial velocity and velocity dispersion. We derived an integrated oxygen abundance of 12+log(O/H)=7.87 summing over all spaxels in our field of view. An average value of 12+log(O/H)=7.77 and a difference of D(O/H)=0.47 between the minimum and maximum values (7.5...

  19. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millennium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  20. Star Formation in HII Galaxies. Properties of the ionized gas

    CERN Document Server

    Hägele, G F; Terlevich, E; Pérez-Montero, E; Terlevich, R; Cardaci, M V

    2009-01-01

    We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the XXI century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should superseed currently used ones based on very simple, and poorly tested, photo-ionization model sequences. Then, these observations are analysed applying a methodology designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen, neon, argon and iron in the ionsied gas. Four electron temperatures and one electron density are derived from the observed forbidden line ratios using the five-level atom approximation. For our best objects errors of 1% in T([OIII]), 3% in T([OII]) and 5% in T([SIII]) are achieved with a resulting accuracy between 5 and 9% in total oxygen abundances, O/H. These accuracies are expected to improve as better calibrations based on more precise me...

  1. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  2. Carbon gas in SMC low-metallicity star-forming regions

    CERN Document Server

    Requena-Torres, M A; Okada, Y; Guesten, R; Stutzki, J; Risacher, C; Simon, R; Zinnecker, H

    2016-01-01

    This paper presents [CII], [CI] and CO emission line maps of the star-forming regions N66, N25+N26, and N88 in the metal-poor Local Group dwarf galaxy SMC. The spatial and velocity structure of the large HII region N66 reveals an expanding ring of shocked molecular gas centered on the exciting star cluster NGC346, whereas a more distant dense molecular cloud is being eroded by UV radiation from the same cluster. In the N25+N26 and N88 maps, diffuse [CII] emission at a relatively low surface brightness extends well beyond the compact boundaries of the bright emission associated with the [CII] regions. In all regions, the distribution of this bright [CII] emission and the less prominent [CI] emission closely follows the outline of the CO complexes, but the intensity of the [CII] and [CI] emission is generally anticorrelated, which can be understood by the action of photodissociation and photoionization processes. Notwithstanding the overall similarity of CO and [CII] maps, the intensity ratio of these lines var...

  3. [Bright light therapy].

    Science.gov (United States)

    Poirrier, R; Cambron, L

    2007-01-01

    Bright light therapy is a treatment that emerged in the eighties of the last century. It can be used in different pathologies such as seasonal affective disorders, major depressions, and many disorders of the wake-sleep rhythm, whether they are of primary or secondary origin. Important progress made at the basic neuroscience levels, allows today a sound understanding of the bright light mode of action. Moreover, the main indications are now the subject of consensus reports and meta-analyses which show good levels of evidence-based medicine. Bright light therapy constitutes a first choice indication in seasonal affective disorder. It is also perfectly possible to prescribe bright light therapy in the major depression disorders. It has been demonstrated that the effect size is the same as with antidepressants of reference. It is admitted nowadays that bright light therapy may be at least, an adjunct to pharmacotherapy, in order to accelerate the antidepressant effect onset, or to prolong this effect after withdrawal of the drug. Bright light therapy can also be viewed as an alternative to the pharmacological approach especially when this one is impossible, not tolerated or not accepted by the patient. The contraindications are rare.

  4. High Brightness OLED Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, Jeffrey [OLEDWorks LLC; Kondakova, Marina [OLEDWorks LLC; Boroson, Michael [OLEDWorks LLC; Hamer, John [OLEDWorks LLC

    2016-05-25

    In this work we describe the technology developments behind our current and future generations of high brightness OLED lighting panels. We have developed white and amber OLEDs with excellent performance based on the stacking approach. Current products achieve 40-60 lm/W, while future developments focus on achieving 80 lm/W or higher.

  5. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies. RESULTS: Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI. CONCLUSIONS: The data suggest that perceptions

  6. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  7. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  8. The metallicity of circumnuclear star forming regions

    CERN Document Server

    Díaz, A I; Castellanos, M; Hägele, G F

    2006-01-01

    We present a spectrophotometric study of circumnuclear star forming regions (CNSFR) in the early type spiral galaxies: NGC 2903, NGC 3351 and NGC 3504, all of them of over solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is made after careful subtraction of the very prominent underlying stellar absorption. It is found that most regions show the highest abundances in HII region-like objects. The relative N/O and S/O abundances are discussed. In is also shown that CNSFR, as a class, segregate from the disk HII region family, clustering around smaller ``softness parameter" -- \\eta' -- values, and therefore higher ionizing temperatures.

  9. Studying the interstellar medium of HII/BCD galaxies using IFU spectroscopy

    CERN Document Server

    Lagos, Patricio

    2013-01-01

    We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of HII/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm that, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances, similar to other low-mass starburst galaxies. They also show He II 4686 emission with properties being suggestive of a mix of excitation sources, with Wolf-Rayet stars being excluded as the primary one. Finally, in this contribution we include a list of all HII/BCD galaxies studied thus far with integral-field unit spectroscopy.

  10. HII and H2 in the envelopes of cooling flow central galaxies

    CERN Document Server

    Jaffe, W; Baker, K

    2005-01-01

    We report observations of ionized and warm molecular gas in the extended regions of the central galaxies in several cooling flow clusters. These show that both gas phases are present in these clusters to large radii. We trace both Pa alpha and H2 lines to radii in excess of 20 kpc. The surface brightness profiles of the two phases trace each other closely. Apart from very close to the central AGN, line ratios in and between the phases vary only slowly with position. The kinematics of the phases are indistinguishable and away from the influence of the central AGN both the mean and dispersion in velocity are low (= 10^5 K.

  11. Time-resolved emission from bright hot pixels of an active region observed in the EUV band with SDO/AIA and multi-stranded loop modeling

    CERN Document Server

    Tajfirouze, E; Petralia, A; Testa, P

    2015-01-01

    Evidence for small amounts of very hot plasma has been found in active regions and might be the indication of an impulsive heating, released at spatial scales smaller than the cross section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 A and 335 A) from the Atmospheric Imaging Assembly on-board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from the random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels and using two independent methods: an artificial intelligent system (Probabilistic Neural Network, PNN) and a simple cross-correlation technique. We explore the space of the param...

  12. High mass star formation in the IRAS 17233-3606 region: a new nearby and bright hot core in the southern sky

    CERN Document Server

    Leurini, S; Thorwirth, S; Wyrowski, F; Schilke, P; Menten, K M; Guesten, R; Zapata, L

    2008-01-01

    We present molecular line observations of the massive star forming region IRAS 17233-3606 aimed at studying the molecular core associated with the source. The observations were made using the Atacama Pathfinder Experiment telescope in the CO (3-2) and HCO^+ (4-3) transitions, and in the CH_3OH (6_K-5_K), (7_K-6_K) and CH_3CN (16_K-15_K) bands. For the CO(3-2) and HCO^+ (4-3) transitions, we obtained maps with a size of 70''\\times 70''. The typical angular resolution of the data is ~18''. Our observations reveal an exceptionally rich molecular spectrum, a signpost of hot core activity. Comparisons with two other prominent southern hot cores were made through observations in the same frequency setups. We also detected a bipolar outflow in CO (3-2) and HCO^+ (4-3) lines. Modelling reveals a hot core of size ~3'' and a temperature of 150 K in the IRAS17233-3606 region. The parameters of the molecular outflow are derived through the analysis of the CO (3-2) emission, and are typical of outflows driven by high-mass...

  13. The interplay between ionized gas and massive stars in the HII galaxy IIZw70: integral field spectroscopy with PMAS

    CERN Document Server

    Kehrig, C; Sánchez, S F; Telles, E; Pérez-Montero, E; Martin-Gordon, D

    2007-01-01

    We performed an integral field spectroscopic study for the HII galaxy IIZw70 in order to investigate the interplay between its ionized interstellar medium (ISM) and the massive star formation (SF). Observations were taken in the optical spectral range (3700-6800 A) with the Potsdam Multi-Aperture Spectrophotometer (PMAS) attached to the 3.5 m telescope at CAHA. We created and analysed maps of spatially distributed emission-lines, continuum emission and properties of the ionized ISM (e.g. physical-chemical conditions, dust extinction, kinematics). We investigated the relation of these properties to the spatial distribution and evolutionary stage of the massive stars. For the first time we detected the presence of Wolf-Rayet (WR) stars in this galaxy. The peak of the ionized gas emission coincides with the location of the WR bump. The region of the galaxy with lower dust extinction corresponds to the region that shows the lowest values of velocity dispersion and radial velocity. The overall picture suggests tha...

  14. Time-resolved Emission from Bright Hot Pixels of an Active Region Observed in the EUV Band with SDO/AIA and Multi-stranded Loop Modeling

    Science.gov (United States)

    Tajfirouze, E.; Reale, F.; Petralia, A.; Testa, P.

    2016-01-01

    Evidence of small amounts of very hot plasma has been found in active regions and might be an indication of impulsive heating released at spatial scales smaller than the cross-section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 and 335 Å) from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from a random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels, and using two independent methods: an artificial intelligent system (Probabilistic Neural Network) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration, their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 minute) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 Å channel, are signatures of a heating excess that occurred a few minutes before.

  15. TIME-RESOLVED EMISSION FROM BRIGHT HOT PIXELS OF AN ACTIVE REGION OBSERVED IN THE EUV BAND WITH SDO/AIA AND MULTI-STRANDED LOOP MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Tajfirouze, E.; Reale, F.; Petralia, A. [Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, I-90134 (Italy); Testa, P., E-mail: aastex-help@aas.org [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-01-01

    Evidence of small amounts of very hot plasma has been found in active regions and might be an indication of impulsive heating released at spatial scales smaller than the cross-section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 and 335 Å) from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from a random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels, and using two independent methods: an artificial intelligent system (Probabilistic Neural Network) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration, their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 minute) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 Å channel, are signatures of a heating excess that occurred a few minutes before.

  16. Interpreting Central Surface Brightness and Color Profiles in Elliptical Galaxies

    Science.gov (United States)

    Silva, David R.; Wise, Michael W.

    1996-01-01

    Hubble Space Telescope imagery has revealed dust features in the central regions of many (50%--80%) nearby bright elliptical galaxies. If these features are an indication of an underlying smooth diffuse dust distribution, then the interpretation of central surface brightness and color profiles in elliptical galaxies becomes significantly more difficult. In this Letter, diagnostics for constraining the presence of such an underlying central dust distribution are presented. We show that easily detectable central color gradients and flattened central surface brightness profiles can be induced by even small amounts of smoothly distributed dust (~100 M⊙). Conversely, combinations of flat surface brightness profiles and flat color gradients or steep surface brightness profiles and steep color gradients are unlikely to be caused by dust. Taken as a whole, these results provide a simple observational tautology for constraining the existence of smooth diffuse dust distributions in the central regions of elliptical galaxies.

  17. How Bright Is the Sun?

    Science.gov (United States)

    Berr, Stephen

    1991-01-01

    Presents a sequence of activities designed to allow eighth grade students to deal with one of the fundamental relationships that govern energy distribution. Activities guide students to measure light bulb brightness, discover the inverse square law, compare light bulb light to candle light, and measure sun brightness. (two references) (MCO)

  18. Growth and Destruction of Disks: Combined HI and HII View

    CERN Document Server

    Bershady, Matthew; Crawford, Steven

    2008-01-01

    How large disk galaxies have evolved in, and out of, the blue cloud of actively star-forming galaxies as a function of environment and time is an outstanding question. Some of the largest disks become systems like M31, M33 and the Milky Way today. In denser environments, it appears they transform onto the red sequence. Tracking disk systems since z<0.5 as a function HI mass, dynamical mass, and environment should be possible in the coming decade. HI and optical data combined can sample outer and inner disk dynamics to connect halo properties with regions of most intense star-formation, and the gas reservoir to the consumption rate. We describe existing and future IFUs on 4-10m telescopes that complement upcoming HI surveys for studying disks at z<0.5. Multiple units, deployable over large fields-of-view, and with logarithmic sampling will yield kinematic and star-formation maps and properties of the stellar populations, resolving the core but retaining sensitivity to disk outskirts.

  19. Characterizing spiral arm and interarm star formation

    CERN Document Server

    Kreckel, K; Schinnerer, E; Groves, B; Adamo, A; Hughes, A; Meidt, S

    2016-01-01

    Interarm star formation contributes significantly to a galaxy's star formation budget, and provides an opportunity to study stellar birthplaces unperturbed by spiral arm dynamics. Using optical integral field spectroscopy of the nearby galaxy NGC 628 with VLT/MUSE, we identify 391 HII regions at 35pc resolution over 12 kpc^2. Using tracers sensitive to the underlying gravitational potential, we associate HII regions with either arm (271) or interarm (120) environments. We find that most HII region physical properties (luminosity, size, metallicity, ionization parameter) are independent of environment. We calculate the fraction of Halpha luminosity due to the diffuse ionized gas (DIG) background contaminating each HII region, and find the DIG surface brightness to be higher within HII regions compared to the surroundings, and slightly higher within arm HII regions. Use of the temperature sensitive [SII]/Halpha line ratio map instead of the Halpha surface brightness to identify HII region boundaries does not ch...

  20. Global View of the Bright Material on Vesta

    Science.gov (United States)

    Zambon, F.; DeSanctis, C.; Schroeder, S.; Tosi, F.; Li, J.-Y.; Longobardo, A.; Ammannito, E.; Blewett, D. T.; Palomba, E.; Capaccioni, F.; Frigeri, A.; Capria, M. T.; Fonte, S.; Mittlefehldt, D. W.; Nathues, A.; Pieters, C.; Russell, C. T.; Raymond, C. A.

    2014-01-01

    At 525 km in mean diameter, Vesta is the second-most massive and one of the brightest asteroids of the main-belt. Here we give a global view of the bright material (BM) units on Vesta. We classified the BMs according to the normal visual albedo. The global albedo map of Vesta allows to be divided the surface into three principal types of terrains: bright regions, dark regions and intermediate regions. The distribution of bright regions is not uniform. The mid-southern latitudes contain the most bright areas, while the northern hemisphere is poor in bright regions. The analysis of the spectral parameters and the normal visual albedo show a dependence between albedo and the strength (depth) of ferrous iron absorption bands, strong bands correspond with high albedo units. Vesta's average albedo is 0.38, but there are bright material whose albedo can exceed 0.50. Only the E-Type asteroids have albedos comparable to those of the BMs on Vesta. The Dawn mission observed a large fraction of Vesta's surface at high spatial resolution, allowing a detailed study of the morphology and mineralogy of it. In particular, reflectance spectra provided by the Visible and InfraRed spectrometer (VIR), confirmed that Vesta's mineralogy is dominated by pyroxenes. All Vesta spectra show two strong absorption bands at approx 0.9 and 1.9 micron, typical of the pyroxenes and associated with the howardite, eucrite and diogenite (HED) meteorites.

  1. VizieR Online Data Catalog: Spectrophotometric distances of HII regions (Moises+, 2011)

    Science.gov (United States)

    Moises, A. P.; Damineli, A.; Figueredo, E.; Blum, R. D.; Conti, P. S.; Barbosa, C. L.

    2011-11-01

    The J-band (λ1.28um, δλ=0.3um), H-band (λ1.63um, δλ=0.3um) and Ks-band (λ2.19um, δλ=0.4um) images were obtained on the nights of 1999 May 1, 4 and 20, 2000 May 19 and 21 and 2001 July 10 and 12, at the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco telescope, using the facility's infrared imager OSIRIS, which has a field of view (FOV) of 93x93arcsec2 and a pixel scale of 0.161arcsec/pixel. On the nights of 2005 Jult 3-6 and 11 and 2006 June 3-7, we obtained images using the facility's infrared imager ISPI (with a FOV of 10.25x10.25arcmin2 and a pixel scale of 0.3arcsec/pix), also at the 4-m Blanco telescope. Also, on the nights of 1998 August 28 and 29, we obtained images on the CTIO 4-m telescope using the facility's infrared imager CIRIM (with a FOV of 102x102arcsec2 and a pixel scale of 0.40arcsec/pix). (3 data files).

  2. Photoevaporation Flows in Blister HII Regions: I. Smooth Ionization Fronts and Application to the Orion Nebula

    CERN Document Server

    Henney, W J; Garcia-Diaz, M T; Garcia-Diaz, Ma. T.

    2005-01-01

    We present hydrodynamical simulations of the photoevaporation of a cloud with large-scale density gradients, giving rise to an ionized, photoevaporation flow. The flow is found to be approximately steady during the large part of its evolution, during which it can resemble a "champagne flow" or a "globule flow" depending on the curvature of the ionization front. The distance from source to ionization front and the front curvature uniquely determine the structure of the flow, with the curvature depending on the steepness of the lateral density gradient in the neutral cloud. We compare these simulations with both new and existing observations of the Orion nebula and find that a model with a mildly convex ionization front can reproduce the profiles of emission measure, electron density, and mean line velocity for a variety of emitting ions on scales of 10^{17} to 10^{18} cm. The principal failure of our model is that we cannot explain the large observed widths of the [O I] 6300 Angstrom line that forms at the ion...

  3. Properties of compact 250 \\mu m emission and HII regions in M33 (HERM33ES)

    CERN Document Server

    Verley, S; Kramer, C; Xilouris, E M; Boquien, M; Calzetti, D; Combes, F; Buchbender, C; Braine, J; Quintana-Lacaci, G; Tabatabaei, F S; Lord, S; Israel, F; Stacey, G; van der Werf, P

    2010-01-01

    Within the framework of the HERM33ES Key Project, using the high resolution and sensitivity of the Herschel photometric data, we study the compact emission in the Local Group spiral galaxy M33 to investigate the nature of the compact SPIRE emission sources. We extracted a catalogue of sources at 250um in order to investigate the nature of this compact emission. Taking advantage of the unprecedented Herschel resolution at these wavelengths, we also focus on a more precise study of some striking Halpha shells in the northern part of the galaxy. We present a catalogue of 159 compact emission sources in M33 identified by SExtractor in the 250um SPIRE band that is the one that provides the best spatial resolution. We also measured fluxes at 24um and Halpha for those 159 extracted sources. The morphological study of the shells also benefits from a multiwavelength approach including Halpha, far-UV from GALEX, and infrared from both Spitzer IRAC 8um and MIPS 24um in order to make comparisons. For the 159 compact sour...

  4. Bright Streaks and Dark Fans

    Science.gov (United States)

    2007-01-01

    The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below. The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans. Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide. Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

  5. Aftereffect of Adaptation to Illusory Brightness

    OpenAIRE

    Xinguang Cao; Hiroyuki Ito

    2011-01-01

    Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours) for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of t...

  6. Evolution of Prolate Molecular Clouds at HII Boundaries: I. Formation of fragment-core structures

    CERN Document Server

    Kinnear, Timothy M; White, Glenn J; Goodwin, Simon

    2014-01-01

    The evolution of a prolate cloud at an Hii boundary is investigated using Smoothed Particle Hydrodynamics (SPH). The prolate molecular clouds in our investigation are set with their semi-major axis perpendicular to the radiative direction of a plane parallel ionising Extreme Ultraviolet (EUV) flux. Simulations on three high mass prolate clouds reveal that EUV radiation can trigger distinctive high density core formation embedded in a final linear structure. This contrasts with results of the previous work in which only an isotropic Far Ultraviolet (FUV) interstellar background flux was applied. A systematic investigation on a group of prolate clouds of equal mass but different initial densities and geometric shapes finds that the distribution of the cores over the final linear structure changes with the initial conditions of the prolate cloud and the strength of the EUV radiation flux. These highly condensed cores may either scatter over the full length of the final linear structure or form two groups of high...

  7. HII 2407: A Low-Mass Eclipsing Binary Revealed by K2 Observations of the Pleiades

    CERN Document Server

    David, Trevor J; Hillenbrand, Lynne A; Cody, Ann Marie; Conroy, Kyle; Stassun, Keivan G; Pope, Benjamin; Aigrain, Suzanne; Gillen, Ed; Cameron, Andrew Collier; Barrado, David; Rebull, L M; Isaacson, Howard; Marcy, Geoffrey W; Zhang, Celia; Riddle, Reed L; Ziegler, Carl; Law, Nicholas M; Baranec, Christoph

    2015-01-01

    The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within $Kepler$/$K2$ photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main-sequence and we compare our results for the $M/M_\\odot$ and $R/R_\\odot$ values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.

  8. HII 2407: AN ECLIPSING BINARY REVEALED BY K2 OBSERVATIONS OF THE PLEIADES

    Energy Technology Data Exchange (ETDEWEB)

    David, Trevor J.; Hillenbrand, Lynne A.; Zhang, Celia; Riddle, Reed L. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Stauffer, John; Rebull, L. M. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cody, Ann Marie [NASA Ames Research Center, Mountain View, CA 94035 (United States); Conroy, Kyle; Stassun, Keivan G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Pope, Benjamin; Aigrain, Suzanne; Gillen, Ed [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Cameron, Andrew Collier [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom); Barrado, David [Centro de Astrobiología, INTA-CSIC, Dpto. Astrofísica, ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Isaacson, Howard; Marcy, Geoffrey W. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Ziegler, Carl; Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Baranec, Christoph, E-mail: tjd@astro.caltech.edu [Institute for Astronomy, University of Hawai‘i at Mānoa, Hilo, HI 96720-2700 (United States)

    2015-11-20

    The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within Kepler/K2 photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main sequence and we compare our results for the M/M{sub ⊙} and R/R{sub ⊙} values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.

  9. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  10. Bright Light Treatment in Psychiatry

    Directory of Open Access Journals (Sweden)

    Pinar Guzel Ozdemir

    2017-06-01

    Full Text Available Bright light treatment is a treatment modality that leads elevation of mood due to attenuation in depressive symptoms, regulation in circadian rhythm activity, increase the effect of antidepressants and amelioration in sleep quality. Bright light treatment is considered among the first-line treatments for seasonal affective disorder because of high response rates. Additionally, bright light treatment being extended to other conditions, including non-seasonal mood disorders, Alzheimer's disease, circadian rhythm sleep disorders, eating disorders, attention deficit hyperactivity disorder and other behavioral syndromes is likely to have a far reached use. Side effects are often temporary and can generally be overcome by reducing exposure time. The central focus on this paper is to review the action mechanisms, efficacy, usage areas, the ways of administration and side effects of the light treatment. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2017; 9(2.000: 177-188

  11. Near-Infrared Imaging Polarimetry of S106 Cluster-Forming Region with SIRPOL

    CERN Document Server

    Saito, Hiro; Kandori, Ryo; Kusakabe, Nobuhiko; Hashimoto, Jun; Nakajima, Yasushi; Sato, Yaeko; Nagata, Tetsuya; Nagayama, Takahiro; Kato, Daisuke

    2008-01-01

    We present the results of wide-field JHKs polarimetry toward the HII region S106 using the IRSF (Infrared Survey Facility) telescope. Our polarimetry data revealed an extended (up to ~ 5') polarized nebula over S106. We confirmed the position of the illuminating source of most of the nebula as consistent with S106 IRS4 through an analysis of polarization vectors. The bright portion of the polarized intensity is consistent with the red wing component of the molecular gas. Diffuse polarized intensity emission is distributed along the north--south molecular gas lanes. We found the interaction region between the radiation from S106 IRS4 and the dense gas. In addition, we also discovered two small polarization nebulae, SIRN1 and SIRN2, associated with a young stellar objects (YSO). Aperture polarimetry of point-like sources in this region was carried out for the first time. The regional magnetic field structures were derived using point-like source aperture polarimetry, and the magnetic field structure position an...

  12. T-cell compartment involvement in two high antibody responder lines of mice (HI and HII Biozzi mice) respectively susceptible and resistant to collagen-induced arthritis.

    Science.gov (United States)

    Lima, G C; Zyad, A; Decreusefond, C; Mevel, J C; Stiffel, C; Mouton, D; Couderc, J

    1993-08-01

    The T-cell compartment was investigated in two high antibody responder lines of mice respectively susceptible (HI) and resistant (HII) to chicken collagen (CII)-induced arthritis (CIA). Previous data had shown that both lines were high anti-CII Ab producers, without any TCR V-beta gene defect or membrane expression impairment. The present studies demonstrate that anti-CII proliferation is much lower in HII than in HI. These results are confirmed by the limiting dilution analysis of anti-CII T-precursor frequencies (1/991 in HI and 1/12175 in HII). The percentage of CD8+ T cells is constitutively higher in HII mice, this difference increasing after CII immunization. This finding suggests a suppressive effect accounting for resistance to CIA. However, no restoration of specific response was achieved by in-vivo or in-vitro depletion of CD8+ T cells. T clones specific for Chicken CII could be obtained only from primed HI mice. Four of five clones with CD8+ phenotype proliferated in vitro to native and denatured CII and showed cytotoxic function in an anti-CD3 redirected assay. The CD4+ clone was shown to proliferate on both HI and HII-pulsed APC, which rules out a major CII processing/presentation defect in HII.

  13. Consecutive Bright Pulses in the Vela Pulsar

    CERN Document Server

    Palfreyman, Jim L; Dickey, John M; Young, Timothy G; Hotan, Claire E; 10.1088/2041-8205/735/1/L17

    2011-01-01

    We report on the discovery of consecutive bright radio pulses from the Vela pulsar, a new phenomenon that may lead to a greater understanding of the pulsar emission mechanism. This results from a total of 345 hr worth of observations of the Vela pulsar using the University of Tasmania's 26 m radio telescope to study the frequency and statistics of abnormally bright pulses and sub-pulses. The bright pulses show a tendency to appear consecutively. The observations found two groups of six consecutive bright pulses and many groups of two to five bright pulses in a row. The strong radio emission process that produces the six bright pulses lasts between 0.4 and 0.6 s. The numbers of bright pulses in sequence far exceed what would be expected if individual bright pulses were independent random events. Consecutive bright pulses must be generated by an emission process that is long lived relative to the rotation period of the neutron star.

  14. Internetwork chromospheric bright grains observed with IRIS

    CERN Document Server

    Martínez-Sykora, Juan; Carlsson, Mats; De Pontieu, Bart; Pereira, Tiago M D; Boerner, Paul; Hurlburt, Neal; Kleint, Lucia; Lemen, James; Tarbell, Ted D; Title, Alan; Wuelser, Jean-Pierre; Hansteen, Viggo H; Golub, Leon; McKillop, Sean; Reeves, Kathy K; Saar, Steven; Testa, Paola; Tian, Hui; Jaeggli, Sarah; Kankelborg, Charles

    2015-01-01

    The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet sun. These bright grains are seen with the IRIS 1330 \\AA, 1400 \\AA\\ and 2796 \\AA\\ slit-jaw filters. We combine coordinated observations with IRIS and from the ground with the Swedish 1-m Solar Telescope (SST) which allows us to have chromospheric (Ca II 8542 \\AA, Ca II H 3968 \\AA, H\\alpha, and Mg II k 2796 \\AA), and transition region (C II 1334 \\AA, Si IV 1402) spectral imaging, and single-wavelength Stokes maps in Fe I 6302 \\AA at high spatial (0.33"), temporal and spectral resolution. We conclude that the IRIS slit-jaw grains are the counterpart of so-called acoustic grains, i.e., resulting from chromospheric acoustic waves in a non-magnetic environment. We compare slit-jaw images with spectra from the IRIS spectrograph. We conclude that the grain intensity in the 2796 \\AA\\ slit-jaw filter comes from both the Mg II k core and wings. The signal in the C II ...

  15. Brightness-equalized quantum dots

    Science.gov (United States)

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-10-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  16. Disentangling the metallicity and star formation history of HII galaxies through tailor-made models

    CERN Document Server

    Perez-Montero, Enrique; Hagele, Guillermo F; Diaz, Angeles I

    2010-01-01

    We present a self-consistent study of the stellar populations and the ionized gas in a sample of 10 HII galaxies with, at least, four measured electron temperatures and a precise determination of ionic abundances following the "direct method". We fitted the spectral energy distribution of the galaxies using the program STARLIGHT in order to quantify the contribution of the underlying stellar population to EW(Hbeta), which amounts to about 10% for most of the objects. We then studied the Wolf-Rayet stellar populations detected in seven of the galaxies. The presence of these populations and the corrected EW(Hbeta) values indicate that the ionizing stellar populations were created following a continuous star formation episode of 10 Myr duration, hence WR stars may be present in all of objects even if they are not detected in some of them. The derived stellar features, the number of ionizing photons and the relative intensities of the strongest emission lines were used as input parameters to compute tailored mode...

  17. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  18. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  19. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  20. Variations in the Fe mineralogy of bright Martian soil

    Science.gov (United States)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  1. Results of Satellite Brightness Modeling Using Kringing Optimized Interpolation

    Science.gov (United States)

    Weeden, C.; Hejduk, M.

    At the 2005 AMOS conference, Kriging Optimized Interpolation (KOI) was presented as a tool to model satellite brightness as a function of phase angle and solar declination angle (J.M Okada and M.D. Hejduk). Since November 2005, this method has been used to support the tasking algorithm for all optical sensors in the Space Surveillance Network (SSN). The satellite brightness maps generated by the KOI program are compared to each sensor's ability to detect an object as a function of the brightness of the background sky and angular rate of the object. This will determine if the sensor can technically detect an object based on an explicit calculation of the object's probability of detection. In addition, recent upgrades at Ground-Based Electro Optical Deep Space Surveillance Sites (GEODSS) sites have increased the amount and quality of brightness data collected and therefore available for analysis. This in turn has provided enough data to study the modeling process in more detail in order to obtain the most accurate brightness prediction of satellites. Analysis of two years of brightness data gathered from optical sensors and modeled via KOI solutions are outlined in this paper. By comparison, geo-stationary objects (GEO) were tracked less than non-GEO objects but had higher density tracking in phase angle due to artifices of scheduling. A statistically-significant fit to a deterministic model was possible less than half the time in both GEO and non-GEO tracks, showing that a stochastic model must often be used alone to produce brightness results, but such results are nonetheless serviceable. Within the Kriging solution, the exponential variogram model was the most frequently employed in both GEO and non-GEO tracks, indicating that monotonic brightness variation with both phase and solar declination angle is common and testifying to the suitability to the application of regionalized variable theory to this particular problem. Finally, the average nugget value, or

  2. Gemini GMOS--IFU spectroscopy of the compact HII galaxies Tol 0104-388 and Tol 2146-391: The dependence on the properties of the interstellar medium

    CERN Document Server

    Lagos, P; Nigoche-Netro, A; Carrasco, E R

    2012-01-01

    Using GMOS--IFU spectroscopic observations of the compact HII/BCD galaxies Tol 0104-388 and Tol 2146-391, we study the spatial distribution of emission lines, equivalent width EW(Hb), extinction c(Hb), ionization ratios ([OIII]5007/Hb, [SII]6717,6731/Ha and [NII]6584/Ha), kinematics, and the chemical pattern (O/H, N/H and N/O) of the warm interstellar medium in these galaxies. We also investigate a possible dependence of these properties on the I(HeII4686)/I(Hb) ratio and find no significant correlation between these variables. In fact, the oxygen abundances appear to be uniform in the regions where the HeII4686 emission line was measured. It can be interpreted in the sense that these correlations are related to global properties of the galaxies and not with small patches of the interstellar medium. Although a possible weak N/H gradient is observed in Tol 2146-391, the available data suggest that the metals from previous star-formation events are well mixed and homogeneously distributed through the optical ex...

  3. Star forming regions in gas-rich SO galaxies

    Science.gov (United States)

    Pogge, Richard W.; Eskridge, Paul B.

    1987-01-01

    The first results of an H alpha imaging survey of HI rich SO galaxies, which were searched for HII regions and other sources of emission, are presented. The charge coupled device H alpha interference filter images were made of 16 galaxies. Eight of these galaxies show evidence for on-going star formation, one has nuclear emission but no HII regions, and the remaining seven have no emissions detected within well defined upper limits. With the exception of one notably peculiar galaxy in which the emission from HII regions appears pervasive, the HII regions are either organized into inner-disk rings or randomly distributed throughout the disk. A few of these galaxies are found to be clearly not SO's; or peculiar objects atypical of the SO class. Using simple models star formation rates (SFRs) and gas depletion times from the observed H alpha fluxes were estimated. In general, the derived SFRs are much lower than those found in isolated field spiral galaxies and the corresponding gas depletion time scales are also longer.

  4. PROFFIT: Analysis of X-ray surface-brightness profiles

    Science.gov (United States)

    Eckert, Dominique

    2016-08-01

    PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

  5. The possible origin of facular brightness in the solar atmosphere

    Science.gov (United States)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  6. Using H-alpha Morphology and Surface Brightness Fluctuations to Age-Date Star Clusters in M83

    CERN Document Server

    Whitmore, Bradley C; Kim, Hwihyun; Kaleida, Catherine; Mutchler, Max; Calzetti, Daniela; Saha, Abhijit; O'Connell, Robert; Balick, Bruce; Bond, Howard E; Carollo, Marcella; Disney, Michael J; Dopita, Michael A; Frogel, Jay A; Hall, Donald N B; Holtzman, Jon A; Kimble, Randy A; McCarthy, Patrick J; Paresce, Francesco; Silk, Joseph I; Trauger, John T; Walker, Alistair R; Windhorst, Rogier A; Young, Erick T; 10.1088/0004-637X/729/2/78

    2011-01-01

    We use new WFC3 observations of the nearby grand design spiral galaxy M83 to develop two independent methods for estimating the ages of young star clusters. The first method uses the physical extent and morphology of Halpha emission to estimate the ages of clusters younger than tau ~10 Myr. It is based on the simple premise that the gas in very young (tau 10 Myr) clusters. A by-product of this study is the identification of 22 "single-star" HII regions in M83, with central stars having ages ~4 Myr.

  7. MS_RHII-RSD, a dual-function RNase HII-(p)ppGpp synthetase from Mycobacterium smegmatis.

    Science.gov (United States)

    Murdeshwar, Maya S; Chatterji, Dipankar

    2012-08-01

    In the noninfectious soil saprophyte Mycobacterium smegmatis, intracellular levels of the stress alarmones guanosine tetraphosphate and guanosine pentaphosphate, together termed (p)ppGpp, are regulated by the enzyme Rel(Msm). This enzyme consists of a single, bifunctional polypeptide chain that is capable of both synthesizing and hydrolyzing (p)ppGpp. The rel(Msm) knockout strain of M. smegmatis (Δrel(Msm)) is expected to show a (p)ppGpp null [(p)ppGpp(0)] phenotype. Contrary to this expectation, the strain is capable of synthesizing (p)ppGpp in vivo. In this study, we identify and functionally characterize the open reading frame (ORF), MSMEG_5849, that encodes a second functional (p)ppGpp synthetase in M. smegmatis. In addition to (p)ppGpp synthesis, the 567-amino-acid-long protein encoded by this gene is capable of hydrolyzing RNA·DNA hybrids and bears similarity to the conventional RNase HII enzymes. We have classified this protein as actRel(Msm) in accordance with the recent nomenclature proposed and have named it MS_RHII-RSD, indicating the two enzymatic activities present [RHII, RNase HII domain, originally identified as domain of unknown function 429 (DUF429), and RSD, RelA_SpoT nucleotidyl transferase domain, the SYNTH domain responsible for (p)ppGpp synthesis activity]. MS_RHII-RSD is expressed and is constitutively active in vivo and behaves like a monofunctional (p)ppGpp synthetase in vitro. The occurrence of the RNase HII and (p)ppGpp synthetase domains together on the same polypeptide chain is suggestive of an in vivo role for this novel protein as a link connecting the essential life processes of DNA replication, repair, and transcription to the highly conserved stress survival pathway, the stringent response.

  8. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  9. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  10. FORCAST Observations of a Bright ToO Comet

    Science.gov (United States)

    Wooden, Diane

    2014-10-01

    We propose to measure the dust and organics of an unknown bright comet or comet outburst with this CY3 Target-of-Opportunity (ToO) proposal. A 5-27 micron spectrum coupled with 11, 19, and 31 micron dual-band photometry of a ToO bright comet with FORCAST will address our two primary goals: 1) characterize the coma dust mineralogy; and 2) identify organics in the critical 5-8 micron region. The crystalline fraction of comet dust has become a benchmark for models of heating and radial transport in our protoplanetary disk. In addition, by measuring the wavelengths, relative intensities, and feature asymmetries of crystalline peaks at 11.2, 19, and 23.5, 27.5, and 33 micron, the shapes of forsterite crystals can be constrained and their condensation temperatures inferred by comparison with theoretical and experimental data. Observations of cometary organics probe the unknown precursor materials that were transformed by heat into 'macromolecular carbon' found ubiquitously in carbonaceous chondrite samples from primitive asteroids. Thermal models fitted to FORCAST observations of a bright ToO comet determine the dust properties and the comet's dust properties links to the physical and chemical conditions in the solar nebula, and help to fulfill the SOFIA Science Case for Evolution of Our Solar System. We define a CY3 ToO bright comet as an unpredictable cometary outburst event or a comet discovered after the CY3 submission deadline that produces a comet with an integrated brightness of Veye within 2 months of discovery. FORCAST 5--31.5 micron observations of a bright comet will enable the study of dust mineral compositions and organic materials, will enable the search for controversial species including PAHs, phyllosilicates and carbonates, and will add to 17 comets with model-constrained silicate crystalline fractions.

  11. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    Mikko Paavo Tulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  12. Aftereffect of Adaptation to Illusory Brightness

    Directory of Open Access Journals (Sweden)

    Xinguang Cao

    2011-05-01

    Full Text Available Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of the tested square area was physically unchanged. The results show that when the black surround inducing brightness contrast suddenly became gray (i.e., vanished, the center gray square tended to look darker than a control gray square. Similarly, after viewing a subjective square consisting of black-line terminations, the square area tended to look darker than the control even though the afterimage of the lines could not be seen. These results indicate that induced or illusory brightness causes an aftereffect in brightness regardless of the appearance of negative afterimages of the illusion-inducing components.

  13. Massive envelopes and filaments in the NGC 3603 star forming region

    CERN Document Server

    Hummel, C A; Galvan-Madrid, R; Koribalski, B S

    2015-01-01

    The formation of massive stars and their arrival on the zero-age main-sequence occurs hidden behind dense clouds of gas and dust. In the giant Hii region NGC 3603, the radiation of a young cluster of OB stars has dispersed dust and gas in its vicinity. At a projected distance of 2:5 pc from the cluster, a bright mid-infrared (mid-IR) source (IRS 9A) had been identified as a massive young stellar object (MYSO), located on the side of a molecular clump (MM2) of gas facing the cluster. We investigated the physical conditions in MM2, based on APEX sub-mm observations using the SABOCA and SHFI instruments, and archival ATCA 3 mm continuum and CS spectral line data. We resolved MM2 into several compact cores, one of them closely associated with IRS 9A. These are likely infrared dark clouds as they do not show the typical hot-core emission lines and are mostly opaque against the mid-IR background. The compact cores have masses of up to several hundred times the solar mass and gas temperatures of about 50 K, without ...

  14. Magnetic field structure of IC 63 and IC 59 associated to H II region - Sh 185

    CERN Document Server

    Soam, A; Lee, Chang Won; Neha, S; Andersson, B-G

    2016-01-01

    Bright-rimmed clouds (BRCs) are formed at the periphery of H$~$II regions as the radiation from the central star interacts with dense gas. The ionization and resulting compression of the clouds may lead to cloud disruption causing secondary star formation depending on the stellar and gas parameters. Here we use R-band polarimetry to probe the plane-of-the sky magnetic field in the two near-by BRCs IC\\,59 and IC\\,63. Both nebulae are illuminated by $\\gamma$ Cas with the direction of ionizing radiation being orientated parallel or perpendicular to the local magnetic field, allowing us to probe the importance of magnetic field pressure in the evolution of BRCs. Because of the proximity of the system ($\\sim$200pc) we have acquired a substantial sample of over 500 polarization measurements for stars background to the nebulae. On large scales, the magnetic field geometries of both clouds are anchored to the ambient magnetic field. For IC 63, the magnetic field is aligned parallel to the head-tail morphology of the ...

  15. The temperature and ionization structure of the emitting gas in HII galaxies: Implications for the accuracy of abundance determinations

    CERN Document Server

    Hägele, G F; Díaz, A I; Terlevich, E; Terlevich, R J; Haegele, Guillermo F.; Perez-Montero, Enrique; Diaz, Angeles I.; Terlevich, Elena; Terlevich, Roberto

    2006-01-01

    We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the XXI century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should superseed currently used ones based on very simple, and poorly tested, photo-ionization model sequences. As a first step to reach these goals we have obtained simultaneous blue to far red longslit spectra with the William Herschel Telescope (WHT) of three compact HII galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 2 (DR2) spectral catalog using the INAOE Virtual Observatory superserver. Our spectra cover the range from 3200 to 10500 \\AA, including the Balmer jump, the [OII]3727,29 \\AA lines, the [SIII]9069,9532 \\AA doublet as well as various weak auroral lines such as [OIII]4363 \\AA and [SIII]6312 \\AA. For the three objects we have measured at least four line...

  16. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  17. Bright Star Astrometry with URAT

    CERN Document Server

    Zacharias, Norbert

    2015-01-01

    The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) is observing the northern sky since April 2012 for an astrometric survey. Multiple overlaps per year are performed in a single bandpass (680$-$750 nm) using the "redlens" 20 cm aperture astrograph and a mosaic of large CCDs. Besides the regular, deep survey to magnitude 18.5, short exposures with an objective grating are taken to access stars as bright as 3rd magnitude. A brief overview of the program, observing and reductions is given. Positions on the 8 to 20 mas level are obtained of 66,202 Hipparcos stars at current epochs. These are compared to the Hipparcos Catalog to investigate its accuracy. About 20\\% of the observed Hipparcos stars are found to have inconsitent positions with the Hipparcos Catalog prediction on the 3 sigma level or over (about 75 mas or more discrepant position offsets). Some stars are now seen at an arcsec (or 25 sigma) off their Hipparcos Catalog predicted position.

  18. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  19. Bright stars and recent star formation in the irregular magellanic galaxy NGC2366

    CERN Document Server

    Aparicio, A; Gallart, C; Castaneda, H O; Chiosi, C; Bertelli, G; Muñoz-Tunón, C; Telles, E; Tenorio-Tagle, G; Díaz, A I; García-Vargas, M L; Garzón, F; González-Delgado, R M; Mas-Hesse, J M; Pérez, E; Rodríguez-Espinosa, J M; Terlevich, E; Terlevich, R J; Varela, A M; Vílchez, J M; Cepa, J; Gallart, C; Castaneda, H; Chiosi, C; Bertelli, G; Munoz-Tunon, Casiana; Telles, Eduardo; Tenorio-Tagle, G; Diaz, A I; Garcia-Vargas, M L; Garzon, F; Gonzalez-Delgado, R Ma; Mas-Hesse, M; Perez, E; Rodriguez-Espinosa, J M; Terlevich, E; Terlevich, R J; Varela, A M; Vilchez, J M

    1995-01-01

    The stellar content of the Im galaxy NGC 2366 is discussed on the basis of CCD BVR photometry. The three brightest blue and red stars have been used to estimate its distance, obtaining a balue of 2.9 Mpc. The spatial distribution of the young stellar population is discussed in the light of the integrated color indices and the color-magnitude diagrams of different zones of the galaxy. A generalized star formation burst seems to have taken place about 50 Myr ago. The youngest stars are preferentially formed in the South-West part of the bar, where the giant HII complex NGC 2363 is located, being younger and bluer. The bar seems to play a role favouring star formation in one of its extremes. Self-propagation however, does not seem to be triggering star formation at large scale. A small region, populated by very young stars has also been found at the East of the galaxy.

  20. Galaxy selection and the surface brightness distribution

    CERN Document Server

    McGaugh, S S; Schombert, J M

    1995-01-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (\\ie approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity ...

  1. AGN physics - The Jet-driven Outflow in the Radio Galaxy 3C305 and the Use of Hardness Ratio Maps to Constrain Spectral Parameters of Low Brightness Regions.

    NARCIS (Netherlands)

    Harris, D. E.; Hardcastle, M. J.; Massaro, F.; Baum, S. A.; Bianchi, S.; Chiaberge, M.; Morganti, R.; O'Dea, C. P.; Siemiginowska, A.

    2012-01-01

    From Chandra X-ray and VLA radio observations of the radio galaxy 3C305, we can make a self-consistent model in which the X-ray-emitting plasma is responsible for the depolarization of some regions of the radio emission from the jets and hotspots. On the assumption that the X-ray-emitting material,

  2. Using the VLT to analyze the compact photoionized regions in NGC 3109

    Directory of Open Access Journals (Sweden)

    M. Peña

    2007-01-01

    Full Text Available Veinte nebulosas planetarias (NP y numerosas regiones HII compactas fueron detectadas en la galaxia irregular NGC3109, mediante imágenes \\en-línea" y \\fuera de línea" en [O III] 5007 obtenidas con el ESO VLT. Las NPs fueron seleccionadas como objetos estelares que no mostraran continuo estelar. Espectroscopia obtenida con el VLT FORS1 en modo multi-objeto ha permitido confirmar la naturaleza de NP para varias candidatas. Se ha obtenido también espectroscopia para varias regiones HII compactas. Los espectros son profundos de manera que muchos objetos muestran [O III] 4363 y se puede determinar la temperatura de las regiones, permitiendo analizar la composición química de NPs y regiones HII. Encontramos que las regiones HII muestran una composición química (O/H muy homogénea (en promedio 12 + log O/H = 7.79_0.10, en tanto que las NPs muestran variaciones grandes de composición química y un aparente enriquecimiento en oxígeno.

  3. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  4. Space Brightness Evaluation for a Daylit Room

    Directory of Open Access Journals (Sweden)

    Takashi Maruyama

    2011-05-01

    Full Text Available One of the most important problems for lighting design is how to reduce an electric energy. One way to solve this problem is use of daylight, but little is known how to perceive a brightness of a room illuminated by daylight come in through a window and artificial light. Although the horizontal illuminance increases because of daylight, we would not perceive the room as bright as brightness estimated by the illuminance. The purpose of this study is to measure the space brightness for daylit room and to propose a evaluation method. The experiment was conducted with a couple of miniature office rooms, standard room and test room. Test room has several types of windows and standard room has no window. Subject was asked to evaluate the brightness of the test room relative to the standard room with method of magnitude estimation. It was found that brightness of daylit room did not increase simply with horizontal illuminance. Subject perceived a daylit room darker than a room illuminated only by the artificial light even if horizontal illuminance of these room was same. The effect of daylight on space brightness would vary with the window size and intensity of daylight or artificial light.

  5. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  6. From forced collapse to H ii region expansion in Mon R2: Envelope density structure and age determination with Herschel

    CERN Document Server

    Didelon, P; Tremblin, P; Hill, T; Hony, S; Hennemann, M; Hennebelle, P; Anderson, L D; Galliano, F; Schneider, N; Rayner, T; Rygl, K; Louvet, F; Zavagno, A; Konyves, V; Sauvage, M; Andre, Ph; Bontemps, S; Peretto, N; Griffin, M; Gonzalez, M; Lebouteiller, V; Arzoumanian, D; Benedettini, M; Di Francesco, J; Menshchikov, A; Minier, V; Luong, Q Nguyen; Bernard, J -P; Palmeirim, P; Pezzuto, S; Rivera-Ingraham, A; Russeil, D; Ward-Thompson, D; White, G J

    2015-01-01

    The surroundings of HII regions can have a profound influence on their development, morphology, and evolution. This paper explores the effect of the environment on H II regions in the MonR2 molecular cloud. We aim to investigate the density structure of envelopes surrounding HII regions and to determine their collapse and ionisation expansion ages. The Mon R2 molecular cloud is an ideal target since it hosts an H II region association. Column density and temperature images derived from Herschel data were used together to model the structure of HII bubbles and their surrounding envelopes. The resulting observational constraints were used to follow the development of the Mon R2 ionised regions with analytical calculations and numerical simulations. The four hot bubbles associated with H II regions are surrounded by dense, cold, and neutral gas envelopes. The radial density profiles are reminiscent of those of low-mass protostellar envelopes. The inner parts of envelopes of all four HII regions could be free-fal...

  7. First Detection of the [OIII] 88 micron Line at High Redshifts: Characterizing the Starburst and Narrow Line Regions in Extreme Luminosity Systems

    CERN Document Server

    Ferkinhoff, C; Nikola, T; Parshley, S C; Stacey, G J; Benford, D J; Staguhn, J G

    2010-01-01

    We have made the first detections of the 88 micron [OIII] line from galaxies in the early Universe, detecting the line from the lensed AGN/starburst composite systems APM 08279+5255 at z = 3.911 and SMM J02399-0136 at z = 2.8076. The line is exceptionally bright from both systems, with apparent (lensed) luminosities ~10^11 L_solar. For APM 08279, the [OIII] line flux can be modeled in a star formation paradigm, with the stellar radiation field dominated by stars with effective temperatures, Teff >36,000 K, similar to the starburst found in M82. The model implies ~35% of the total far-IR luminosity of the system is generated by the starburst, with the remainder arising from dust heated by the AGN. The 88 micron line can also be generated in the narrow line region of the AGN if gas densities are around a few 1000 cm-3. For SMM J02399 the [OIII] line likely arises from HII regions formed by hot (Teff >40,000 K) young stars in a massive starburst that dominates the far-IR luminosity of the system. The present wor...

  8. VizieR Online Data Catalog: HII regions and GMC in the Antennae (Zaragoza-Cardiel+, 2014)

    Science.gov (United States)

    Zaragoza-Cardiel, J.; Font, J.; Beckman, J. E.; Garcia-Lorenzo, B.; Erroz-Ferrer, S.; Gutierrez, L.

    2014-10-01

    We present two sets of observations of the Antennae: data cubes of emission in Hα from the ionized component of the interstellar medium and of emission in the CO(3-2) line from the molecular component. (4 data files).

  9. The ionizing radiation from massive stars and its impact on HII regions: results from modern model atmospheres

    CERN Document Server

    Simón-Díaz, S

    2008-01-01

    We present a detailed comparison of the ionizing spectral energy distributions (SEDs) predicted by four modern stellar atmosphere codes, TLUSTY, CMFGEN, WMbasic, and FASTWIND. We consider three sets of stellar parameters representing a late O-type dwarf (O9.5 V), a mid O-type (O7 V) dwarf, and an early O-type dwarf (O5.5 V). We explore two different possibilities for such a comparison, following what we called evolutionary and observational approaches: in the evolutionary approach one compares the SEDs of stars defined by the same values of Teff and logg; in the observational approach the models to be compared do not necessarily have the same Teff and logg, but produce similar H and HeI-II optical lines. We find that there is a better agreement, in terms of Q(H0), the ratio Q(He0)/Q(H0), and the shape of the SEDs predicted by the four codes in the spectral range between 13 and 30 eV, when models are compared following the observational approach. However, even in this case, large differences are found at highe...

  10. A search for precursors of Ultracompact HII Regions in a sample of luminous IRAS sources; 3, Circumstellar Dust Properties

    CERN Document Server

    Molinari, S; Cesaroni, R; Palla, Fabrizio; Molinari, Sergio; Brand, Jan; Cesaroni, Riccardo; Palla, Francesco

    2000-01-01

    The James Clerk Maxwell Telescope has been used to obtain submillimeter and millimeter continuum photometry of a sample of 30 IRAS sources previously studied in molecular lines and centimeter radio continuum. All the sources have IRAS colours typical of very young stellar objects (YSOs) and are associated with dense gas. In spite of their high luminosities (L>10000 solar units), only ten of these sources are also associated with a radio counterpart. In 17 cases we could identify a clear peak of millimeter emission associated with the IRAS source, while in 9 sources the millimeter emission was extended or faint and a clear peak could not be identified; upper limits were found in 4 cases only. Using simple greybody fitting model to the observed SED, we derive global properties of the circumstellar dust. The dust temperature varies from 24 K to 45 K, while the exponent of the dust emissivity vs frequency power-law spans a range 1.56

  11. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  12. The analogy between stereo depth and brightness.

    Science.gov (United States)

    Brookes, A; Stevens, K A

    1989-01-01

    Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

  13. Observations and diagnostics in high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Cianchi, A., E-mail: alessandro.cianchi@roma2.infn.it [University of Rome Tor Vergata and INFN-Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Anania, M.P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V. [INFN-LNF, Via Enrico Fermi 40, 00044 Frascati (Italy)

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  14. Subjective comparison of brightness preservation methods for local backlight dimming displays

    DEFF Research Database (Denmark)

    Korhonen, Jari; Mantel, Claire; Forchhammer, Søren

    2015-01-01

    Local backlight dimming is a popular technology in high quality Liquid Crystal Displays (LCDs). In those displays, the backlight is composed of contributions from several individually adjustable backlight segments, set at different backlight luminance levels in different parts of the screen......, according to the luma of the target image displayed on LCD. Typically, transmittance of the liquid crystal cells (pixels) located in the regions with dimmed backlight is increased in order to preserve their relative brightness with respect to the pixels located in the regions with bright backlight....... There are different methods for brightness preservation for local backlight dimming displays, producing images with different visual characteristics. In this study, we have implemented, analyzed and evaluated several different approaches for brightness preservation, and conducted a subjective study based on rank...

  15. Effect of Interior Chromaticness on Space Brightness

    Directory of Open Access Journals (Sweden)

    Hidenari Takada

    2011-05-01

    Full Text Available To design a lighting environment, horizontal illuminance is generally used as the brightness of a room. But it is reported that a subjective brightness does not always match the horizontal illuminance. For example, the room furnished with high saturated colored objects is perceived brighter than the room furnished with achromatic objects, even though the horizontal illuminance is the same. To investigate a effect of interior chromaticness on space brightness, we conducted the experiment in four miniature rooms that were different in terms of chromaticness of interior decorating surfaces, but kept lightness of surfaces constant. Subjects were asked to set the illuminance of reference room, that is furnished with achromatic objects, to equate the brightness of the test room, that is with chromatic objects. Four of seven subjects needed less illuminance to get the equality of space brightness if the test room had a saturated objects. The illuminance ratio of test to reference room was about 1.4. Other three subjects set the illuminance of reference room almost equal to test room. Thus, there are differences between individuals so further work would be needed to estimate the quantitative effect of interior chromaticness on space brightness.

  16. Giant Low Surface Brightness Galaxies: Evolution in Isolation

    Indian Academy of Sciences (India)

    M. Das

    2013-03-01

    Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in surface brightness. They often have bright bulges that are similar to those found in early type galaxies. The bulges can host low luminosity Active Galactic Nuclei (AGN) that have relatively low mass black holes. GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies. In fact many GLSB galaxies are found under dense regions close to the edges of voids. These galaxies have very massive dark matter halos that also contribute to their stability and lack of evolution. In this paper we briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive dark matter halos have led to the low star formation rates and the slower rate of evolution in these galaxies.

  17. South African night sky brightness during high aerosol epochs

    CERN Document Server

    Winkler, Hartmut; Marang, Fred

    2014-01-01

    Sky conditions in the remote, dry north-western interior of South Africa are now the subject of considerable interest in view of the imminent construction of numerous solar power plants in this area. Furthermore, the part of this region in which the core of the SKA is to be located (which includes SALT) has been declared an Astronomical Advantage Zone, for which sky brightness monitoring will now be mandatory. In this project we seek to characterise the sky brightness profile under a variety of atmospheric conditions. Key factors are of course the lunar phase and altitude, but in addition the sky brightness is also significantly affected by the atmospheric aerosol loading, as that influences light beam scattering. In this paper we chose to investigate the sky characteristics soon after the Mount Pinatubo volcanic eruption in 1991, which resulted in huge ash masses reaching the stratosphere (where they affected solar irradiance for several years). We re-reduced photometric sky measurements from the South Afric...

  18. Brightness/darkness induction and the genesis of a contour.

    Science.gov (United States)

    Roncato, Sergio

    2014-01-01

    Visual contours often result from the integration or interpolation of fragmented edges. The strength of the completion increases when the edges share the same contrast polarity (CP). Here we demonstrate that the appearance in the perceptual field of this integrated unit, or contour of invariant CP, is concomitant with a vivid brightness alteration of the surfaces at its opposite sides. To observe this effect requires some stratagems because the formation in the visual field of a contour of invariant CP normally engenders the formation of a second contour and then the rise of two streams of induction signals that interfere in different ways. Particular configurations have been introduced that allow us to observe the induction effects of one contour taken in isolation. I documented these effects by phenomenological observations and psychophysical measurement of the brightness alteration in relation to luminance contrast. When the edges of the same CP complete to form a contour, the background of homogeneous luminance appears to dim at one side and to brighten at the opposite side (in accord with the CP). The strength of the phenomenon is proportional to the local luminance contrast. This effect weakens or nulls when the contour of the invariant CP separates surfaces filled with different gray shades. These conflicting results stimulate a deeper exploration of the induction phenomena and their role in the computation of brightness contrast. An alternative perspective is offered to account for some brightness illusions and their relation to the phenomenal transparency. The main assumption asserts that, when in the same region induction signals of opposite CP overlap, the filling-in is blocked unless the image is stratified into different layers, one for each signal of the same polarity. Phenomenological observations document this "solution" by the visual system.

  19. Brightness/darkness induction and the genesis of a contour

    Directory of Open Access Journals (Sweden)

    Sergio eRoncato

    2014-10-01

    Full Text Available Visual contours often result from the integration or interpolation of fragmented edges.The strength of the completion increases when the edges share the same contrast polarity (CP. Here we demonstrate that the appearance in the perceptual field of this integrated unit, or contour of invariant CP, is concomitant with a vivid brightness alteration of the surfaces at its opposite sides. To observe this effect requires some stratagems because the formation in the visual field of a contour of invariant CP normally engenders the formation of a second contour and then the rise of two streams of induction signals that interfere in different ways. Particular configurations have been introduced that allow us to observe the induction effects of one contour taken in isolation. I documented these effects by phenomenological observations and psychophysical measurement of the brightness alteration in relation to luminance contrast. When the edges of the same CP complete to form a contour, the background of homogeneous luminance appears to dim at one side and to brighten at the opposite side (in accord with the CP. The strength of the phenomenon is proportional to the local luminance contrast. This effect weakens or nulls when the contour of the invariant CP separates surfaces filled with different grey shades.These conflicting results stimulate a deeper exploration of the induction phenomena and their role in the computation of brightness contrast. An alternative perspective is offered to account for some brightness illusions and their relation to the phenomenal transparency. The main assumption asserts that, when in the same region induction signals of opposite CP overlap, the filling-in are blocked unless the image is stratified into different layers, one for each signal of the same polarity. Phenomenological observations document this solution by the visual system

  20. Proxy magnetometry of the photosphere: why are G-band bright points so bright?

    NARCIS (Netherlands)

    Rutten, R.J.; Kiselman, Dan; Voort, Luc Rouppe van der; Plez, Bertrand

    2000-01-01

    We discuss the formation of G-band bright points in terms of standard uxtube modeling, in particular the 1D LTE models constructed by Solanki and coworkers. Combined with LTE spectral synthesis they explain observed G-band bright point contrasts quite well. The G-band contrast increase over the cont

  1. A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

    NARCIS (Netherlands)

    Nijboer, T.C.W.; Nys, G.M.S.; van der Smagt, M.J.; de Haan, E.H.F.

    2009-01-01

    We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level

  2. A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

    Science.gov (United States)

    Nijboer, Tanja C W; Nys, Gudrun M S; van der Smagt, Maarten J; de Haan, Edward H F

    2009-01-01

    We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

  3. Bright stars observed by FIMS/SPEAR

    CERN Document Server

    Jo, Young-Soo; Min, Kyoung-Wook; Choi, Yeon-Ju; Lim, Tae-Ho; Lim, Yeo-Myeong; Edelstein, Jerry; Han, Wonyong

    2015-01-01

    In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of 2--3 {\\AA} over the wavelength of 1370--1710 {\\AA}. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

  4. Brightness discrimination in budgerigars (Melopsittacus undulatus.

    Directory of Open Access Journals (Sweden)

    Olle Lind

    Full Text Available Birds have excellent spatial acuity and colour vision compared to other vertebrates while spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity describes the detection of gratings of varying spatial frequency. It is unclear whether bird brightness discrimination between large uniform fields is poor as well. Here we show that budgerigars (Melopsittacus undulatus need a Michelson contrast of 0.09 to discriminate between large spatially separated achromatic fields in bright light conditions. This is similar to the peak contrast sensitivity of 10.2 (0.098 Michelson contrast for achromatic grating stimuli established in earlier studies. The brightness discrimination threshold described in Weber fractions is 0.18, which is modest compared to other vertebrates.

  5. A brightness exceeding simulated Langmuir limit

    Energy Technology Data Exchange (ETDEWEB)

    Nakasuji, Mamoru [2-15-11, Serigaya-chou, Kounan-ku, Yokohama-shi, Kanagawa-ken (Japan)

    2013-08-15

    When an excitation of the first lens determines a beam is parallel beam, a brightness that is 100 times higher than Langmuir limit is measured experimentally, where Langmuir limits are estimated using a simulated axial cathode current density which is simulated based on a measured emission current. The measured brightness is comparable to Langmuir limit, when the lens excitation is such that an image position is slightly shorter than a lens position. Previously measured values of brightness for cathode apical radii of curvature 20, 60, 120, 240, and 480 μm were 8.7, 5.3, 3.3, 2.4, and 3.9 times higher than their corresponding Langmuir limits, respectively, in this experiment, the lens excitation was such that the lens and the image positions were 180 mm and 400 mm, respectively. From these measured brightness for three different lens excitation conditions, it is concluded that the brightness depends on the first lens excitation. For the electron gun operated in a space charge limited condition, some of the electrons emitted from the cathode are returned to the cathode without having crossed a virtual cathode. Therefore, method that assumes a Langmuir limit defining method using a Maxwellian distribution of electron velocities may need to be revised. For the condition in which the values of the exceeding the Langmuir limit are measured, the simulated trajectories of electrons that are emitted from the cathode do not cross the optical axis at the crossover, thus the law of sines may not be valid for high brightness electron beam systems.

  6. Dark Dunes Over-riding Bright Dunes

    Science.gov (United States)

    2000-01-01

    Some martian sand dunes may be more active than others. In this picture, wind has caused the dark and somewhat crescent-shaped dunes to advance toward the lower left. While their movement cannot actually be seen in this April 1998snapshot, the location of their steepest slopes--their slip faces--on their southwestern sides indicates the direction of movement. Oddly, these dark dunes have moved across and partly cover sets of smaller, bright ridges that also formed by wind action.This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image illustrates an intriguing martian 'find.' Strangely, the two dune types have different shapes and a different relative brightness. There are two explanations for the relationship seen here, and neither can be distinguished as 'the answer'--(1) it is possible that the brighter dunes are old and cemented, and represent some ancient wind activity, whereas the dark dunes are modern and are marching across the older, 'fossilized' dune forms, or (2) the bright dunes are composed of grains that are much larger or more dense than those that compose the dark dunes. In the latter scenario, the bright dunes move more slowly and are over-taken by the dark dunes because their grains are harder to transport. An interpretation involving larger or denser grains is consistent with the small size and even-spacing of the bright dunes, as well, but usually on Earth such features occur on the surfaces of larger, finer-grained dunes, not under them. The actual composition of either the bright or dark materials are unknown. This example is located on the floor of an impact crater in western Arabia Terra at 10.7oN, 351.0oW. The picture is illuminated from the right.

  7. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  8. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  9. Source brightness fluctuation correction of solar absorption Fourier Transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-01-01

    Full Text Available Solar absorption Fourier Transform infrared spectrometry is considered a precise and accurate method for the observation of trace gases in the atmosphere. The precision and accuracy of such measurements are dependent on the stability of the light source. Fluctuations in the source brightness reduce the precision and accuracy of the trace gas concentrations, but cannot always be avoided. Thus, a strong effort is made within the community to reduce the impact of source brightness fluctuations by applying a correction on the spectra following the measurements. So far, it could be shown that the precision and accuracy of CO2 total column concentrations could be improved by applying a source brightness fluctuation correction to spectra in the near infrared spectral region.

    The analysis of trace gas concentrations obtained from spectra in the mid infrared spectral region is fundamental. However, spectra below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents a source brightness fluctuation correction.

    Here, we show a method of source brightness fluctuation correction, which can be applied on spectra in the whole infrared spectral region including spectra measured with a MCT detector. We present a solution to remove the unknown offset in MCT interferograms allowing MCT spectra for an application of source brightness fluctuation correction. This gives an improvement in the quality of MCT spectra and we demonstrate an improvement in the retrieval of O3 profiles and total column concentrations.

    For a comparison with previous studies, we apply our source brightness fluctuation correction method on spectra in the near infrared spectral region and show an improvement in the retrieval of CO2 total column concentrations.

  10. Hydrologic applications of Nimbus 5 ESMR data. [observations of low brightness temperatures in aquifers

    Science.gov (United States)

    Schmugge, T. J.; Rango, A.; Allison, L. J.; Wilheit, T. T.

    1974-01-01

    A region of low brightness temperature lying along the Mississippi River from Cairo, Illinois, to Morganza, Louisiana was observed in early Nimbus 5 Electrically Scanning Microwave Radiometer images. This region, which generally corresponds to an outwash aquifer in the Mississippi Valley, had brightness temperatures, at times as much as 40 K below the surrounding (drier) older uplands. Fluctuations of as much as 30 K were observed during the time interval 15 December 1972 to 28 February 1973. Comparison images taken from the Earth Resources Technology Satellite indicate that the study area is aligned with the Mississippi River floodplain, a region of potentially high soil moisture content. The brightness temperature fluctuations were compared with variations in precipitation and other hydrologic parameters in order to delineate the causative factors.

  11. High Brightness Plasmon-Enhanced Nanostructured Gold Photoemitters

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; Kong, Lingmei; El-Khoury, Patrick Z.; Hess, Wayne P.

    2014-12-30

    Plasmonic nanohole arrays are fabricated in gold thin films by focused ion beam (FIB) lithography. Subsequent heat treatment creates sub 100 nm nanometric structures including tips, rods and flakes, all localized in the nanohole array region. The combined nanohole array and nanostructured surface comprise an efficient photoemitter. High brightness photoemission is observed from this construct using photoemission electron microscopy (PEEM), following 780 nm femtosecond (fs) laser irradiation. By comparing our observables to results of finite difference time domain (FDTD) calculations, we demonstrate that photoemission from the sub-100 nm structures is enhanced in the region of propagating surface plasmons launched from the nanohole arrays. Additionally, by tuning hole diameter and separation in the nanohole array, the photoemission intensity of nanostructured photoemitters can be controlled. We observe a photoemission enhancement of over 108, relative to photoemission from the flat region of the gold substrate at laser intensities well below the ablation threshold.

  12. Enrichment of nutritional value of Phyllanthus emblica fruit juice using the probiotic bacterium, Lactobacillus paracasei HII01 mediated fermentation

    Directory of Open Access Journals (Sweden)

    Sartjin PEERAJAN

    2016-01-01

    Full Text Available The fermented herbal juices are capable of curing and preventing diseases and reducing the aging progress. The present study was performed to investigate the fermentation of Phyllanthus emblica fruit by Lactobacillus paracasei HII01 with respect to carbon sources, polyphenols, and antioxidant properties. The physical changes, for instance, color, odor, taste, turbidity and gas formation, throughout the fermentation process was manually monitored. The fermented product was rich in polyphenolic content. The acid content and pH of the product were under the norms of Thai community product standards. Antioxidant properties of the fermented product were proved using ABTS, and FRAP assays. Chelation based study suggested that fermented P. emblica fruit juices are healthy enough to stabilize the oxidized form of the metal ion. The optimum fermentation period was 15 days. All the results supported that studied carbon sources did not interfere with the quality of the product. This report is the prelude study on the use of probiotic starter culture for the production of P. emblica fruit based lactic acid bacteria fermented beverages (LAFB enriched with bioactive compounds. Further research on the impact of different carbon sources and upstream processes on the quality of LAFB is currently in progress.

  13. Wave and Wind Direction Effects on SFMR Brightness Temperatures

    Science.gov (United States)

    Holbach, Heather; Uhlhorn, Eric; Bourassa, Mark

    2015-04-01

    Surface winds in a tropical cyclone are essential for determining its strength. Currently the Stepped-Frequency Microwave Radiometer (SFMR) and Global Positioning System (GPS) dropwindsondes are the main instruments used for obtaining in situ surface wind measurements. The platforms for these instruments are the National Oceanographic and Atmospheric Administration (NOAA) P-3 and Air Force C-130J hurricane hunter aircraft. The SFMR measures sea surface microwave brightness temperatures at six frequencies ranging from 4.7 to 7.2 GHz. Surface wind speed estimates are obtained from these brightness temperatures by using a retrieval algorithm that employs a geophysical model function relating surface emissivity and wind speed. The SFMR is designed to obtain a single nadir track of surface wind speeds directly beneath the aircraft during level flight and not when turning because of the complexity of the wave field and foam distribution when the SFMR views the surface off-nadir or during aircraft rolls. However, the effects of the wave field on the measurements can be investigated using measurements obtained during the 2008 and 2014 Atlantic hurricane seasons. An SFMR module was flown in precipitation-free regions of the tropical cyclones to collect data at specified roll angles of 15°, 30°, 45°, and 60° in some cases. Excess brightness temperatures are then calculated with respect to zero wind speed values and independent of wind direction. An asymmetry is found in the resulting excess brightness temperatures. It is hypothesized that this asymmetry is caused by the direction of wave propagation and the angle at which the wave field is viewed by the SFMR. Wind direction may also play a role in the asymmetry. To analyze the asymmetry further measurement from WindSat will be used. Once the relationship is determined between surface wind speed, brightness temperature, and incidence angle a technique will be developed to obtain a surface wind speed when the aircraft is

  14. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  15. Probable Bright Supernova discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-09-01

    A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  16. Brightness of synchrotron radiation from wigglers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca, E-mail: gianluca.geloni@xfel.eu [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-01-21

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called ‘depth-of-field’ effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  17. Dark matter in low surface brightness galaxies

    NARCIS (Netherlands)

    de Blok, WJG; McGaugh, SS; Persic, M; Salucci, P

    1997-01-01

    Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that LSB

  18. Brightness and darkness as perceptual dimensions.

    Directory of Open Access Journals (Sweden)

    Tony Vladusich

    2007-10-01

    Full Text Available A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D space varying from bright to dark. The results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  19. Alberta Associations for Bright Children Members' Handbook.

    Science.gov (United States)

    Alberta Association for Bright Children, Edmonton.

    This handbook is designed to provide information to parents of gifted children in Alberta, Canada. The handbook outlines the mission and objectives of the Alberta Associations for Bright Children and describes the structure of the non-profit organization. The booklet then addresses: (1) the characteristics of gifted children; (2) the rights of…

  20. Brightness of synchrotron radiation from wigglers

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called 'depth-of-field' effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  1. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  2. Bright Future for Petroleum Development Cooperation

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenqing

    1996-01-01

    @@ China's oil prospects look bright, since reform and opening speed up. The oil production of 1995 is 148 million tons and the confirmed reserves of oil and gas only occupy one-fifth of those possible to be verified, the petroleum exploration will be deepened to locate and confirm the remaining reserves.

  3. Simultaneous brightness contrast of foraging Papilio butterflies.

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-05-22

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast.

  4. Young stellar population and ongoing star formation in the HII complex Sh2-252

    CERN Document Server

    Jose, Jessy; Samal, M R; Ojha, D K; Ogura, K; Kim, J S; Kobayashi, N; Goyal, A; Chauhan, N; Eswaraiah, C

    2013-01-01

    In this paper an extensive survey of the star forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history. This complex is composed of five embedded clusters associated with the sub-regions A, C, E, NGC 2175s and Teu 136. Using 2MASS-NIR and Spitzer-IRAC, MIPS photometry we identified 577 young stellar objects (YSOs), of which, 163 are Class I, 400 are Class II and 14 are transition disk YSOs. Spatial distribution of the candidate YSOs shows that they are mostly clustered around the sub-regions in the western half of the complex, suggesting enhanced star formation activity towards its west. Using the spectral energy distribution and optical colour-magnitude diagram based age analyses, we derived probable evolutionary status of the sub-regions of Sh2-252. Our analysis shows that the region A is the youngest (~ 0.5 Myr), the regions B, C and E are of similar evolutionary stage (~ 1-2 Myr) and the cluster...

  5. Sleeping Giants? - X-ray search for low-luminosity AGN candidates in nearby optically bright galaxies

    CERN Document Server

    Kalcheva, Ivayla E

    2014-01-01

    In this Master's project, the X-ray nuclear properties of a sample of bright nearby galaxies are explored. This is done by matching their comprehensive optical spectroscopic classification to the latest available XMM-Newton catalogue - 3XMM-DR4. The good coverage (approx. 38 per cent) ensures that a statistically representative sample is investigated. All nuclear and morphological subsets found within the original sample of 486 galaxies are encompassed, but early-type galaxies and galaxies with optical features characteristic for active galactic nuclei (AGN) are favoured. The results from the investigation of the properties of our cross-matched sample are overall consistent with the presence of a large fraction of X-ray - detected low-luminosity AGN (LLAGN). The X-ray - detected galaxies within our HII and transition-LINER subsets are of particular interest, as they could harbour LLAGN missed by optical spectroscopic selection. The properties of these nuclei are explored by X-ray spectral fitting of available...

  6. The nature of solar brightness variations

    Science.gov (United States)

    Shapiro, A. I.; Solanki, S. K.; Krivova, N. A.; Cameron, R. H.; Yeo, K. L.; Schmutz, W. K.

    2017-09-01

    Determining the sources of solar brightness variations1,2, often referred to as solar noise3, is important because solar noise limits the detection of solar oscillations3, is one of the drivers of the Earth's climate system4,5 and is a prototype of stellar variability6,7—an important limiting factor for the detection of extrasolar planets. Here, we model the magnetic contribution to solar brightness variability using high-cadence8,9 observations from the Solar Dynamics Observatory (SDO) and the Spectral And Total Irradiance REconstruction (SATIRE)10,11 model. The brightness variations caused by the constantly evolving cellular granulation pattern on the solar surface were computed with the Max Planck Institute for Solar System Research (MPS)/University of Chicago Radiative Magnetohydrodynamics (MURaM)12 code. We found that the surface magnetic field and granulation can together precisely explain solar noise (that is, solar variability excluding oscillations) on timescales from minutes to decades, accounting for all timescales that have so far been resolved or covered by irradiance measurements. We demonstrate that no other sources of variability are required to explain the data. Recent measurements of Sun-like stars by the COnvection ROtation and planetary Transits (CoRoT)13 and Kepler14 missions uncovered brightness variations similar to that of the Sun, but with a much wider variety of patterns15. Our finding that solar brightness variations can be replicated in detail with just two well-known sources will greatly simplify future modelling of existing CoRoT and Kepler as well as anticipated Transiting Exoplanet Survey Satellite16 and PLAnetary Transits and Oscillations of stars (PLATO)17 data.

  7. New low surface brightness dwarf galaxies in the Centaurus group

    CERN Document Server

    Müller, Oliver; Binggeli, Bruno

    2016-01-01

    We conducted an extensive CCD search for faint, unresolved dwarf galaxies of very low surface brightness in the whole Centaurus group region encompassing the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc, respectively. The aim is to significantly increase the sample of known Centaurus group members down to a fainter level of completeness, serving as a basis for future studies of the 3D structure of the group. Following our previous survey of 60 square degrees covering the M 83 subgroup, we extended and completed our survey of the Centaurus group region by imaging another 500 square degrees area in the g and r bands with the wide-field Dark Energy Survey Camera at the 4m Blanco telescope at CTIO. The limiting central surface brightness reached for suspected Centaurus members is $\\mu_r \\approx 29$ mag arcsec$^{-2}$, corresponding to an absolute magnitude $M_r \\approx -9.5$. The images were enhanced using different filtering techniques. We found 41 new dwarf galaxy candidates, which togethe...

  8. The Physics and Applications of High Brightness Electron Beams

    Science.gov (United States)

    Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

    2007-09-01

    .]. -- Working Group 1. Summary of working group 1 on electron sources / M. Ferrario and G. Gatti. Design and RF measurements of an X-band accelerating structure for the SPARC project / D. Alesini ... [et al.]. Mitigation of RF gun breakdown by removal of tuning rods in high field regions / A.M. Cook... [et al.]. Measurements of quantum efficiency of Mg films produced by pulsed laser ablation deposition for application to bright electron sources / G. Gatti ... [et al.]. The S-band 1.6 cell RF gun correlated energy spread dependence on Pi and 0 mode relative amplitude / F. Schmerge ... [et al.]. RF gun photo-emission model for metal cathodes including time dependent emission / J.F. Schmerge ... [et al.]. Superconducting photocathodes / J. Smedley ... [et al.]. -- Working Group 2. Summary of Working Group 2: diagnostics and beam manipulation / G. Travish. Observation of coherent edge radiation emitted by a 100 Femtosecond compressed electron beam / G. Andonian, M, Dunning, E. Hemsing, J. B. Rosenzweig ... [et al.]. PARMELA simulations for PITZ: first machine studies and interpretation of measurements / M. Boscolo ... [et al.]. The LCLS single-shot relative bunch length monitor system / M.P. Dunning ... [et al.]. Beam shaping and permanent magnet quadrupole focusing with applications to the plasma wakefield accelerator / R.J. England ... [et al.]. Commissioning of the SPARC movable emittance meter and its first operation at PITZ / D. Filippetto... [et al.]. Experimental testing of dynamically optimized photoelectron beams / J.B. Rosenzweig ... [et al.]. Synchronization between the laser and electron beam in a photocathode RF gun / A. Sakumi ... [et al.]. Method of bunch radiation photochronography with 10 Femtosecond and less resolution / A. Tron and I. Merinov -- Working Group 3. New challenges in theory and modeling-summary for working group 3. L. Giannessi. Resonant modes in a 1.6 cells RF gun / M. Ferrario and C. Ronsivalle. Emittance degradation due to wake fields in a high

  9. Subjective comparison of brightness preservation methods for local backlight dimming displays

    DEFF Research Database (Denmark)

    Korhonen, Jari; Mantel, Claire; Forchhammer, Søren

    2015-01-01

    Local backlight dimming is a popular technology in high quality Liquid Crystal Displays (LCDs). In those displays, the backlight is composed of contributions from several individually adjustable backlight segments, set at different backlight luminance levels in different parts of the screen......, according to the luma of the target image displayed on LCD. Typically, transmittance of the liquid crystal cells (pixels) located in the regions with dimmed backlight is increased in order to preserve their relative brightness with respect to the pixels located in the regions with bright backlight...... ordering to compare the relevant methods on a real-life LCD with a local backlight dimming capability. In general, our results show that locally adapted brightness preservation methods produce more preferred visual outcome than global methods, but dependency on the content is also observed. Based...

  10. Observation of Dissipative Bright Soliton and Dark Soliton in an All-Normal Dispersion Fiber Laser

    Directory of Open Access Journals (Sweden)

    Chunyang Ma

    2016-01-01

    Full Text Available This paper proposes a novel way for controlling the generation of the dissipative bright soliton and dark soliton operation of lasers. We observe the generation of dissipative bright and dark soliton in an all-normal dispersion fiber laser by employing the nonlinear polarization rotation (NPR technique. Through adjusting the angle of the polarizer and analyzer, the mode-locked and non-mode-locked regions can be obtained in different polarization directions. Numerical simulation shows that, in an appropriate pump power range, the dissipative bright soliton and dark soliton can be generated simultaneously in the mode-locked and non-mode-locked regions, respectively. If the pump power exceeds the top limit of this range, only dissipative soliton will exist, whereas if it is below the lower bound of this range, only dark soliton will exist.

  11. Emittance measurement of high-brightness microbeams

    Energy Technology Data Exchange (ETDEWEB)

    Ishizuka, Hiroshi; Nakahara, Yuriko (Fukuoka Inst. of Tech. (Japan)); Kawasaki, Sunao; Musyoki, S.; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto

    1994-09-01

    Arrays of microtriodes have recently become available due to the development of microfabricated field-emission electron sources. Computer simulation has shown that the brightness of beams emitted by them is significantly higher than that of the common microbeams, and possible application of the accelerated beam to free electron lasers has been discussed. Experimentation on beam generation has started, but methods for diagnosing the beam have not yet been established. Difficulty is predicted, because of the high brightness, in applying the conventional methods of emittance measurement. In this paper we propose a new method that determines the emittance without using apertures. The cross section of a converging beam is elongated by a quadrupole lens, and parameters of the emittance ellipse are obtained from the beam size on a screen when changing either the strength or the axial position of the quadrupole lens. (author).

  12. Human CD56bright NK Cells

    DEFF Research Database (Denmark)

    Michel, Tatiana; Poli, Aurélie; Cuapio, Angelica

    2016-01-01

    Human NK cells can be subdivided into various subsets based on the relative expression of CD16 and CD56. In particular, CD56(bright)CD16(-/dim) NK cells are the focus of interest. They are considered efficient cytokine producers endowed with immunoregulatory properties, but they can also become...... cytotoxic upon appropriate activation. These cells were shown to play a role in different disease states, such as cancer, autoimmunity, neuroinflammation, and infection. Although their phenotype and functional properties are well known and have been extensively studied, their lineage relationship with other...... NK cell subsets is not fully defined, nor is their precise hematopoietic origin. In this article, we summarize recent studies about CD56(bright) NK cells in health and disease and briefly discuss the current controversies surrounding them....

  13. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  14. Brightness of synchrotron radiation from wigglers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2014-12-15

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called 'depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. In the geometrical optics limit computations can be performed analytically. Within this limit, we restrict ourselves to the case of the beam size-dominated regime, which is typical for synchrotron radiation facilities in the X-ray wavelength range. We give a direct demonstration of the fact that the apparent horizontal source size is broadened in proportion to the beamline opening angle and to the length of the wiggler. While this effect is well-understood, a direct proof appears not to have been given elsewhere. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in literature.

  15. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  16. Extreme Ultraviolet Explorer Bright Source List

    Science.gov (United States)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  17. The Bright SHARC Survey The Cluster Catalog

    CERN Document Server

    Romer, A K; Holden, B P; Ulmer, M P; Pildis, R A; Merrelli, A J; Adami, C; Burke, D J; Collins, C A; Metevier, A J; Kron, Richard G; Commons, K

    1999-01-01

    We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 sq.deg and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified thirty-seven clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696Bright SHARC clusters have not been listed in any previously ...

  18. Brightness illusion in the guppy (Poecilia reticulata).

    Science.gov (United States)

    Agrillo, Christian; Miletto Petrazzini, Maria Elena; Bisazza, Angelo

    2016-02-01

    A long-standing debate surrounds the issue of whether human and nonhuman species share similar perceptual mechanisms. One experimental strategy to compare visual perception of vertebrates consists in assessing how animals react in the presence of visual illusions. To date, this methodological approach has been widely used with mammals and birds, while few studies have been reported in distantly related species, such as fish. In the present study we investigated whether fish perceive the brightness illusion, a well-known illusion occurring when 2 objects, identical in physical features, appear to be different in brightness. Twelve guppies (Poecilia reticulata) were initially trained to discriminate which rectangle was darker or lighter between 2 otherwise identical rectangles. Three different conditions were set up: neutral condition between rectangle and background (same background used for both darker and lighter rectangle); congruent condition (darker rectangle in a darker background and lighter rectangle in a lighter background); and incongruent condition (darker rectangle in a lighter background and lighter rectangle in a darker background). After reaching the learning criterion, guppies were presented with the illusory pattern: 2 identical rectangles inserted in 2 different backgrounds. Guppies previously trained to select the darker rectangle showed a significant choice of the rectangle that appears to be darker by human observers (and vice versa). The human-like performance exhibited in the presence of the illusory pattern suggests the existence of similar perceptual mechanisms between humans and fish to elaborate the brightness of objects.

  19. Synaptic elements for GABAergic feed-forward signaling between HII horizontal cells and blue cone bipolar cells are enriched beneath primate S-cones.

    Directory of Open Access Journals (Sweden)

    Christian Puller

    Full Text Available The functional roles and synaptic features of horizontal cells in the mammalian retina are still controversial. Evidence exists for feedback signaling from horizontal cells to cones and feed-forward signaling from horizontal cells to bipolar cells, but the details of the latter remain elusive. Here, immunohistochemistry and confocal microscopy were used to analyze the expression patterns of the SNARE protein syntaxin-4, the GABA receptor subunits α1 and ρ, and the cation-chloride cotransporters NKCC and KCC2 in the outer plexiform layer of primate retina. In macaque retina, as observed previously in other species, syntaxin-4 was expressed on dendrites and axon terminals of horizontal cells at cone pedicles and rod spherules. At cones, syntaxin-4 appeared densely clustered in two bands, at horizontal cell dendritic tips and at the level of desmosome-like junctions. Interestingly, in the lower band where horizontal cells may synapse directly onto bipolar cells, syntaxin-4 was highly enriched beneath short-wavelength sensitive (S cones and colocalized with calbindin, a marker for HII horizontal cells. The enrichment at S-cones was not observed in either mouse or ground squirrel. Furthermore, high amounts of both GABA receptor and cation-chloride cotransporter subunits were found beneath primate S-cones. Finally, while syntaxin-4 was expressed by both HI and HII horizontal cell types, the intense clustering and colocalization with calbindin at S-cones indicated an enhanced expression in HII cells. Taken together, GABA receptors beneath cone pedicles, chloride transporters, and syntaxin-4 are putative constituents of a synaptic set of proteins which would be required for a GABA-mediated feed-forward pathway via horizontal cells carrying signals directly from cones to bipolar cells.

  20. Bright Solitons in a PT-Symmetric Chain of Dimers

    Directory of Open Access Journals (Sweden)

    Omar B. Kirikchi

    2016-01-01

    Full Text Available We study the existence and stability of fundamental bright discrete solitons in a parity-time- (PT- symmetric coupler composed by a chain of dimers that is modelled by linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anticontinuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, in contrast to the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.

  1. Estimation of the space density of low surface brightness galaxies

    NARCIS (Netherlands)

    Briggs, FH

    1997-01-01

    The space density of low surface brightness and tiny gas-rich dwarf galaxies are estimated for two recent catalogs: the Arecibo Survey of Northern Dwarf and Low Surface Brightness Galaxies and the Catalog of Low Surface Brightness Galaxies, List II. The goals are (1) to evaluate the additions to the

  2. Looking for outflow and infall signatures in high mass star forming regions

    CERN Document Server

    Klaassen, P D; Beuther, H

    2011-01-01

    (Context) Many physical parameters change with time in star forming regions. Here we attempt to correlate changes in infall and outflow motions in high mass star forming regions with evolutionary stage using JCMT observations. (Aims) From a sample of 45 high mass star forming regions in three phases of evolution, we investigate the presence of established infall and outflow tracers to determine whether there are any trends attributable to the age of the source. (Methods) We obtained JCMT observations of HCO+/H13CO+ J=4-3 to trace large scale infall, and SiO J=8-7 to trace recent outflow activity. We compare the infall and outflow detections to the evolutionary stage of the host source (high mass protostellar objects, hypercompact HII regions and ultracompact HII regions). We also note that the integrated intensity of SiO varies with the full width at half maximum of the H13CO+. (Results) We find a surprising lack of SiO detections in the middle stage (Hypercompact HII regions), which may be due to an observat...

  3. The outer disks of early-type galaxies. I. Surface-brightness profiles of barred galaxies

    NARCIS (Netherlands)

    Erwin, Peter; Pohlen, Michael; Beckman, John E.

    2008-01-01

    We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman type I and II profiles, their origins, and their possible relation to disk truncations. This paper discuss

  4. Mesopic models : from brightness matching to visual performance in night-time driving: a review

    NARCIS (Netherlands)

    Eloholma, M.; Liesiö, M.; Halonen, L.; Walkey, H.; Goodman, T.; Alferdinck, J.W.A.M.; Frieding, A.; Schanda, J.; Bodrogi, P.; Várady, G.

    2005-01-01

    At present, suitable methods to evaluate the visual effectiveness of lighting products in the mesopic region are not available. The majority of spectral luminous efficiency functions obtained to date in the mesopic range have been acquired by heterochromatic brightness matching. However, the most re

  5. Release of the AKARI-FIS Bright Source Catalogue β-1

    NARCIS (Netherlands)

    Yamamura, I.; Makiuti, S.; Ikeda, N.; Fukuda, Y.; Yamauchi, C.; Hasegawa, S.; Nakagawa, T.; Narumi, H.; Baba, H.; Takagi, T.; Jeong, W.-S.; Oh, S. H.; Lee, H. M.; Savage, R.; Rahman, N.; Thomson, M.; Oliver, S.; Figueredo, E.; Serjeant, S.; White, G. J.; Pearson, C.; Wang, L.; Rowan-Robinson, M.; Kester, D.; van der Wolk, G.; Barthel, P.; Salama, A.; Alfageme, C.; García-Lario, P.; Stephenson, C.; Cohen, M.; Mueller, T. G.

    2009-01-01

    The AKARI; satellite has made an All-Sky Survey at six bands in the mid- and far-infrared spectral region. One of the primary goals of the AKARI survey is to produce all-sky infrared source catalogues. We report the release of the first version of the AKARI FIS Bright Source Catalogue (β-1) for four

  6. The outer disks of early-type galaxies. I. Surface-brightness profiles of barred galaxies

    NARCIS (Netherlands)

    Erwin, Peter; Pohlen, Michael; Beckman, John E.

    We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman type I and II profiles, their origins, and their possible relation to disk truncations. This paper

  7. Quantitative Measurements of Daytime Near Infrared Sky Brightness at the AEOS 3.6 m Telescope

    Science.gov (United States)

    2014-09-01

    techniques for high-resolution imaging of satellites from the AEOS telescope. 1 MOTIVATION At first glance it would appear that imaging in the near...sensitivity, which includes spectral regions of strong atmospheric extinction . The sky brightness results in this case represent the mean flux that would

  8. Fluorescence intensity and bright spot analyses using a confocal microscope for photodynamic diagnosis of brain tumors.

    Science.gov (United States)

    Yoneyama, Takeshi; Watanabe, Tetsuyo; Kagawa, Hiroyuki; Hayashi, Yutaka; Nakada, Mitsutoshi

    2017-03-01

    In photodynamic diagnosis using 5-aminolevulinic acid (5-ALA), discrimination between the tumor and normal tissue is very important for a precise resection. However, it is difficult to distinguish between infiltrating tumor and normal regions in the boundary area. In this study, fluorescent intensity and bright spot analyses using a confocal microscope is proposed for the precise discrimination between infiltrating tumor and normal regions. From the 5-ALA-resected brain tumor tissue, the red fluorescent and marginal regions were sliced for observation under a confocal microscope. Hematoxylin and eosin (H&E) staining were performed on serial slices of the same tissue. According to the pathological inspection of the H&E slides, the tumor and infiltrating and normal regions on confocal microscopy images were investigated. From the fluorescent intensity of the image pixels, a histogram of pixel number with the same fluorescent intensity was obtained. The fluorescent bright spot sizes and total number were compared between the marginal and normal regions. The fluorescence intensity distribution and average intensity in the tumor were different from those in the normal region. The probability of a difference from the dark enhanced the difference between the tumor and the normal region. The bright spot size and number in the infiltrating tumor were different from those in the normal region. Fluorescence intensity analysis is useful to distinguish a tumor region, and a bright spot analysis is useful to distinguish between infiltrating tumor and normal regions. These methods will be important for the precise resection or photodynamic therapy of brain tumors. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Dynamics of annular bright field imaging in scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Findlay, S.D., E-mail: scott@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Shibata, N. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Sawada, H.; Okunishi, E.; Kondo, Y. [JEOL Ltd., Tokyo 196-8558 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2010-06-15

    We explore the dynamics of image formation in the so-called annular bright field mode in scanning transmission electron microscopy, whereby an annular detector is used with detector collection range lying within the cone of illumination, i.e. the bright field region. We show that this imaging mode allows us to reliably image both light and heavy columns over a range of thickness and defocus values, and we explain the contrast mechanisms involved. The role of probe and detector aperture sizes is considered, as is the sensitivity of the method to intercolumn spacing and local disorder.

  10. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  11. The role of the Fraunhofer lines in solar brightness variability

    CERN Document Server

    Shapiro, A I; Krivova, N A; Tagirov, R V; Schmutz, W K

    2015-01-01

    The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and waveleng...

  12. The dearth of nuclear star clusters in bright galaxies

    Science.gov (United States)

    Arca-Sedda, M.; Capuzzo-Dolcetta, R.; Spera, M.

    2016-03-01

    We investigate the interaction of a massive globular cluster (GC) with a super massive black hole (SMBH), located at the centre of its host galaxy, by means of direct N-body simulations. The results show that tidal distortions induced by the stellar background and the SMBH act on a time shorter than that of dynamical friction decay for a 106 M⊙ GC whenever the SMBH mass exceeds ˜108 M⊙. This implies an almost complete dissolution of the infalling GC before it reaches the inner region (≲5 pc) of the parent galaxy. The generalization of this result to a larger sample of infalling GCs shows that such destructive process may prevent the formation and growth of a bright galactic nucleus. Another interesting, serendipitous, result we obtained is that the close interaction between the SMBH and the GC produces a `wave' of stars that escape from the cluster and, in a fraction, even from the whole galaxy.

  13. Star Formation in Bright Rimmed Clouds. I. Millimeter and Submillimeter Molecular Line Surveys

    CERN Document Server

    De Vries, C H; Snell, R L; Vries, Christopher H. De; Narayanan, Gopal; Snell, Ronald L.

    2002-01-01

    We present the results of the first detailed millimeter and submillimeter molecular line survey of bright rimmed clouds, observed at FCRAO in the CO (J=1-0), C18O (J=1-0), HCO+ (J=1-0), H13CO+ (J=1-0), and N2H+ (J=1-0) transitions, and at the HHT in the CO (J=2-1), HCO+ (J=3-2), HCO+ (J=4-3), H13CO+ (J=3-2), and H13CO+ (J=4-3) molecular line transitions. The source list is composed of a selection of bright rimmed clouds from the catalog of such objects compiled by Sugitani et al. (1991). We also present observations of three Bok globules done for comparison with the bright rimmed clouds. We find that the appearance of the millimeter CO and HCO+ emission is dominated by the morphology of the shock front in the bright rimmed clouds. The HCO+ (J=1-0) emission tends to trace the swept up gas ridge and overdense regions which may be triggered to collapse as a result of sequential star formation. Five of the seven bright rimmed clouds we observe seem to have an outflow, however only one shows the spectral line blue...

  14. Kinematics of magnetic bright features in the solar photosphere

    CERN Document Server

    Jafarzadeh, Shahin; Cameron, R H; Barthol, P; Rodriguez, J Blanco; Iniesta, J C del Toro; Gandorfer, A; Gizon, L; Hirzberger, J; Knoelker, M; Pillet, V Martinez; Suarez, D Orozco; Riethmueller, T L; Schmidt, W; van Noort, M

    2016-01-01

    Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of the turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high-spatial resolution with Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, gamma=1.0), travelers with constant speeds over a supergranule (gamma=1.9-2.0), and decelerating movers in the vicinity of flux-emergence and/or within active regions (gamma=1.4-1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km^2/s, 80-90 km^2/s, and 25-70 km^2/s, respectively. The MBFs in these three types of regions are found to display a distinct ki...

  15. Kinematics of Magnetic Bright Features in the Solar Photosphere

    Science.gov (United States)

    Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Martínez Pillet, V.; Orozco Suárez, D.; Riethmüller, T. L.; Schmidt, W.; van Noort, M.

    2017-03-01

    Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high spatial resolution with Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet-Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, γ =1.0), travelers with constant speeds over a supergranule (γ =1.9{--}2.0), and decelerating movers in the vicinity of flux emergence and/or within active regions (γ =1.4{--}1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km2 s‑1, 80–90 km2 s‑1, and 25–70 km2 s‑1, respectively. The MBFs in these three types of regions are found to display a distinct kinematic behavior at a confidence level in excess of 95%.

  16. Ionization Parameter as a Diagnostic of Radiation and Wind Pressures in H II Regions and Starburst Galaxies

    CERN Document Server

    Yeh, Sherry C C

    2012-01-01

    The ionization parameter U is potentially useful for measuring radiation pressure feedback from massive star clusters, as it reflects the radiation-to-gas-pressure ratio and is readily derived from mid-infrared line ratios. We consider several effects which determine the apparent value of U in HII regions and galaxies. An upper limit is set by the compression of gas by radiation pressure. The pressure from stellar winds and the presence of neutral clumps both reduce U for a given radiation intensity. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, inducing observational bias on galactic scales. We explore these effects analytically and numerically, and use them to interpret previous observational results. We find that radiation confinement sets the upper limit log_10 U = -1 seen in individual regions. Unresolved starbursts display a maximum value of ~ -2.3. While lower, this is also consistent with a large portion of their HII regions being radiati...

  17. Coronal bright points associated with minifilament eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Yang, Bo; Yang, Dan, E-mail: hjcsolar@ynao.ac.cn [Also at Graduate School of Chinese Academy of Sciences, Beijing, China. (China)

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  18. Spectral evolution of bright NS LMXBs

    CERN Document Server

    Paizis, A; Mainardi, L I; Titarchuk, L

    2010-01-01

    Theoretical and observational support suggests that the spectral evolution of neutron-star LMXBs, including transient hard X-ray tails, may be explained by the interplay between thermal and bulk motion Comptonization. In this framework, we developed a new model for the X-ray spectral fitting XSPEC package which takes into account the effects of both thermal and dynamical (i.e. bulk) Comptonization, CompTB. Using data from the INTEGRAL satellite, we tested our model on broad band spectra of a sample of persistently low magnetic field bright neutron star Low Mass X-ray Binaries, covering different spectral states. The case of the bright source GX 5-1 is presented here. Particular attention is given to the transient powerlaw-like hard X-ray (above 30 keV) tail that we interpret in the framework of the bulk motion Comptonization process, qualitatively describing the physical conditions of the environment in the innermost part of the system.

  19. Sublimation in bright spots on (1) Ceres.

    Science.gov (United States)

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.

  20. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  1. The molecular gas associated with the Orion bright bar

    Science.gov (United States)

    Omodaka, Toshihiro; Hayashi, Masahiko; Hasegawa, Telsuo; Hayashi, Saeko S.

    1994-07-01

    Detailed studies of the shocked region associated with the Orion bright bar are presented. The millimeter wave spectral lines of (12)CO (J = 1-0), (13)CO (J = 1-0), CS (J = 2-1), HCO(+) (J = 1-0), and H51 alpha have been observed across the bright bar. The intensity of all the molecular species shows a rapid increase close to the ionization front and a significant falloff at a distance of approximately 50 sec farther out from it. This suggests the existence of a layer of dense molecular gas just outside the ionization front. This layer has a velocity redshifted by 1-2 km s-1 relative to the ambient molecular cloud, which can be due to acceleration by thermal and kinetic pressure from the H II region or due to a passage of a shock. The high-density molecular layer associated with the bar is probably a shock-compressed layer driven by the ionization front of M42. A multitransitional anaylsis of the CS emission shows that the H2 volume density of the molecular gas is larger than that of the ambient gas by a factor of 3. The apparent density enhancement of a factor of 3 in the shocked gas is too small for a radiative shock in a homogeneous medium; density inhomgeneities or clumpiness in the pre- and postshocked layer may account for this apparently small compression ratio. This layer is exposed to intense UV radiation from the Trapezium stars and a photodissocited region is formed between neutral layer and the ionization front. The similarity in distribution of the thermally excited H2 emissions arising from shock fronts and or dense phtotodissociation regions and the millimeter-wave molecular line emissions originating from cooled shock-compressed regions also supports the idea of homogeneity or clumpiness is the shocked cloud. The gas temperature of this shocked layer is about 100 K and is very high compared with other molecular clouds without an embedded heat source. Both shock heating and radiative heating may contribute to maintain this high temperature.

  2. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  3. Graphical Methods for Quantifying Macromolecules through Bright Field Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hang; DeFilippis, Rosa Anna; Tlsty, Thea D.; Parvin, Bahram

    2008-08-14

    Bright ?eld imaging of biological samples stained with antibodies and/or special stains provides a rapid protocol for visualizing various macromolecules. However, this method of sample staining and imaging is rarely employed for direct quantitative analysis due to variations in sample fixations, ambiguities introduced by color composition, and the limited dynamic range of imaging instruments. We demonstrate that, through the decomposition of color signals, staining can be scored on a cell-by-cell basis. We have applied our method to Flbroblasts grown from histologically normal breast tissue biopsies obtained from two distinct populations. Initially, nuclear regions are segmented through conversion of color images into gray scale, and detection of dark elliptic features. Subsequently, the strength of staining is quanti?ed by a color decomposition model that is optimized by a graph cut algorithm. In rare cases where nuclear signal is significantly altered as a result of samplepreparation, nuclear segmentation can be validated and corrected. Finally, segmented stained patterns are associated with each nuclear region following region-based tessellation. Compared to classical non-negative matrix factorization, proposed method (i) improves color decomposition, (ii) has a better noise immunity, (iii) is more invariant to initial conditions, and (iv) has a superior computing performance

  4. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  5. Dark Skies, Bright Kids Year 8

    Science.gov (United States)

    Bittle, Lauren E.; Wenger, Trey; Johnson, Kelsey E.; Angell, Dylan; Burkhardt, Andrew; Davis, Blair; Firebaugh, Ariel; Hancock, Danielle; Richardson, Whitney; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; McNair, Shunlante; Prager, Brian; Pryal, Matthew; Troup, Nicholas William

    2017-01-01

    We present activities from the eighth year of Dark Skies Bright Kids (DSBK), an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Over the past seven years, our primary focus has been hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools, and over the past several years, we have partnered with local businesses to host our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows. This past summer we expanded our reach through a new initiative to bring week-long summer day camps to south and southwest Virginia, home to some of the most underserved communities in the commonwealth.

  6. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  7. Coupling Bright and Dark Plasmonic Lattice Resonances

    CERN Document Server

    Rodriguez, S R K; Maes, B; Janssen, O T A; Vecchi, G; Rivas, J Gomez

    2011-01-01

    We demonstrate the coupling of bright and dark Surface Lattice Resonances (SLRs), which are collective Fano resonances in 2D plasmonic crystals. As a result of this coupling, a frequency stop-gap in the dispersion relation of SLRs is observed. The different field symmetries of the low and high frequency SLR bands lead to pronounced differences in their coupling to free space radiation. Standing waves of very narrow spectral width compared to localized surface plasmon resonances are formed at the high frequency band edge, while subradiant damping onsets at the low frequency band edge leading the resonance into darkness. We introduce a coupled oscillator analog to the plasmonic crystal, which serves to elucidate the physics of the coupled plasmonic resonances and to estimate very high quality factors (Q>700) for SLRs, which are the highest known for any 2D plasmonic crystal.

  8. Substructure of Quiet Sun Bright Points

    CERN Document Server

    Andic, Aleksandra; Goode, Phillip R

    2010-01-01

    Since photospheric bright points (BPs) were first observed, there has been a question as to how are they structured. Are they just single flux tubes or a bundle of the flux-tubes? Surface photometry of the quiet Sun (QS) has achieved resolution close to 0.1" with the New Solar Telescope at Big Bear Solar Observatory. This resolution allowed us to detect a richer spectrum of BPs in the QS. The smallest BPs we observed with TiO 705.68 nm were 0.13", and we were able to resolve individual components in some of the BPs clusters and ribbons observed in the QS, showing that they are composed of the individual BPs. Average size of observed BPs was 0.22".

  9. Brightness temperature for 166 radio sources

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong Huang; Yu-Hai Yuan; Jiang-He Yang; Yi Liu; Jun Tao; Ying Gao; Tong-Xu Hua; Rui-Guang Lin; Jiang-Shui Zhang; Jing-Yi Zhang; Yi-Ping Qin

    2009-01-01

    Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8, 8 and 14.5 GHz), we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528-250) with an average timescale of △tobs=17.1±16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06 K. In addition, we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.

  10. Quantum Assisted Electrometry using Bright Atomic Resonances

    CERN Document Server

    Sedlacek, J; Kübler, H; Löw, R; Pfau, T; Shaffer, J P

    2012-01-01

    We demonstrate a new method for measuring radio frequency (RF) electric fields based on quantum interference in an atom. Using a bright resonance prepared within an electromagnetically induced transparency window we are able to achieve a sensitivity of ~ 30 {\\mu}V cm^-1 sqrt(Hz)^-1. For this work, we demonstrated detection of RF electric fields as small as ~ 8 {\\mu}V cm^-1. The sensitivity is currently limited by the spectral bandwidth of the lasers used in the experiment and can be significantly improved in the future. The method can serve as a new quantum based standard for RF electrometry. The reproducibility, accuracy and stability of using a quantum system for measuring RF electric fields promises to advance electrometry to the current levels of magnetometry.

  11. Source brightness fluctuation correction of solar absorption fourier transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-06-01

    Full Text Available The precision and accuracy of trace gas observations using solar absorption Fourier Transform infrared spectrometry depend on the stability of the light source. Fluctuations in the source brightness, however, cannot always be avoided. Current correction schemes, which calculate a corrected interferogram as the ratio of the raw DC interferogram and a smoothed DC interferogram, are applicable only to near infrared measurements. Spectra in the mid infrared spectral region below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents the established source brightness fluctuation correction. This problem can be overcome by a determination of the offset using the modulation efficiency of the instrument. With known modulation efficiency the offset can be calculated, and the source brightness correction can be performed on the basis of offset-corrected interferograms. We present a source brightness fluctuation correction method which performs the smoothing of the raw DC interferogram in the interferogram domain by an application of a running mean instead of high-pass filtering the corresponding spectrum after Fourier transformation of the raw DC interferogram. This smoothing can be performed with the onboard software of commercial instruments. The improvement of MCT spectra and subsequent ozone profile and total column retrievals is demonstrated. Application to InSb interferograms in the near infrared spectral region proves the equivalence with the established correction scheme.

  12. Automatic Method for Identifying Photospheric Bright Points and Granules Observed by Sunrise

    CERN Document Server

    Javaherian, Mohsen; Amiri, Ali; Ziaei, Shervin

    2014-01-01

    In this study, we propose methods for the automatic detection of photospheric features (bright points and granules) from ultra-violet (UV) radiation, using a feature-based classifier. The methods use quiet-Sun observations at 214 nm and 525 nm images taken by Sunrise on 9 June 2009. The function of region growing and mean shift procedure are applied to segment the bright points (BPs) and granules, respectively. Zernike moments of each region are computed. The Zernike moments of BPs, granules, and other features are distinctive enough to be separated using a support vector machine (SVM) classifier. The size distribution of BPs can be fitted with a power-law slope -1.5. The peak value of granule sizes is found to be about 0.5 arcsec^2. The mean value of the filling factor of BPs is 0.01, and for granules it is 0.51. There is a critical scale for granules so that small granules with sizes smaller than 2.5 arcsec^2 cover a wide range of brightness, while the brightness of large granules approaches unity. The mean...

  13. Skylab experiment SO73: Gegenschein/zodiacal light. [electrophotometry of surface brightness and polarization

    Science.gov (United States)

    Weinberg, J. L.

    1976-01-01

    A 10 color photoelectric polarimeter was used to measure the surface brightness and polarization associated with zodiacal light, background starlight, and spacecraft corona during each of the Skylab missions. Fixed position and sky scanning observations were obtained during Skylab missions SL-2 and SL-3 at 10 wavelenghts between 4000A and 8200A. Initial results from the fixed-position data are presented on the spacecraft corona and on the polarized brightness of the zodiacal light. Included among the fixed position regions that were observed are the north celestial pole, south ecliptic pole, two regions near the north galactic pole, and 90 deg from the sun in the ecliptic. The polarized brightness of the zodiacal light was found to have the color of the sun at each of these positions. Because previous observations found the total brightness to have the color of the sun from the near ultraviolet out to 2.4 micrometers, the degree of polarization of the zodiacal light is independent of wavelength from 4000A to 8200A.

  14. HIRS channel 12 brightness temperature dataset and its correlations with major climate indices

    Directory of Open Access Journals (Sweden)

    L. Shi

    2013-07-01

    Full Text Available A new version of the High-Resolution Infrared Radiation Sounder (HIRS upper tropospheric water vapor channel (channel 12 brightness temperature dataset is developed using intersatellite calibrated data. In this dataset, only those pixels affected by upper tropospheric clouds are discarded. Compared to the previous version that was based on column-clear-sky data, the new version has much better daily spatial coverage. The HIRS observation patterns are compared to microwave sounder measurements. The differences between the two types of sounders vary with respect to brightness temperature with larger differences for higher (dry values. Correlations between the HIRS upper tropospheric water vapor channel brightness temperatures and several major climate indices show strong signals during cold seasons. The selected climate indices track climate variation signals covering regions from the tropics to the poles. Qualitatively, moist signals are correlated with troughs and ascending branches of the circulation, while dry signals occur with ridges and descent. These correlations show the potential of using the upper tropospheric water vapor channel brightness temperature dataset together with a suite of many atmospheric variables to monitor regional climate changes and locate global teleconnection patterns.

  15. The dark side of solar photospheric G-band bright points

    Science.gov (United States)

    Riethmüller, T. L.; Solanki, S. K.

    2017-02-01

    Bright, small-scale magnetic elements found mainly in intergranular lanes at the solar surface are named bright points (BPs). They show high contrasts in Fraunhofer G-band observations and are described by nearly vertical slender flux tubes or sheets. A recent comparison between BP observations in the ultraviolet (UV) and visible spectral range recorded with the balloon-borne observatory Sunrise and state-of-the-art magnetohydrodynamical (MHD) simulations revealed a kilogauss magnetic field for 98% of the synthetic BPs. Here we address the opposite question, namely which fraction of pixels hosting kilogauss fields coincides with an enhanced G-band brightness. We carried out 3D radiation MHD simulations for three magnetic activity levels (corresponding to the quiet Sun, weak and strong plage) and performed a full spectral line synthesis in the G-band. Only 7% of the kilogauss pixels in our quiet-Sun simulation coincide with a brightness lower than the mean quiet-Sun intensity, while 23% of the pixels in the weak-plage simulation and even 49% in the strong-plage simulation are associated with a local darkening. Dark strong-field regions are preferentially found in the cores of larger flux patches that are rare in the quiet Sun, but more common in plage regions, often in the vertices of granulation cells. The significant brightness shortfall in the core of larger flux patches coincides with a slight magnetic field weakening. Kilogauss elements in the quiet Sun are, on average, brighter than similar features in plage regions. Almost all strong-field pixels display a more or less vertical magnetic field orientation. Hence, in the quiet Sun, G-band BPs correspond almost one-to-one with kilogauss elements. In weak plage, the correspondence is still very good, but not perfect.

  16. Discovery of Very High Energy Gamma-Ray Emission in the W 28 (G6.4-0.1) Region and Multiwavelength Comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Rowell, G.; /Adelaide U.; Brion, E.; /DAPNIA, Saclay; Reimer, O.; /Stanford U., HEPL /KIPAC, Menlo Park; Moriguchi, Y.; Fukui, Yasuo; /Nagoya U.; Djannati-Atai, A.; /APC, Paris; Funk, S.; /Stanford U., HEPL /KIPAC, Menlo Park

    2007-10-29

    H.E.S.S. observations of the old-age (>10{sup 4} yr; {approx} 0.5 degree diameter) composite supernova remnant (SNR)W28 reveal very high energy (VHE) {gamma}-ray emission situated at its northeastern and southern boundaries. The northeastern VHE source (HESS J1801-233) is in an area where W 28 is interacting with a dense molecular cloud, containing OH masers, local radio and X-ray peaks. The southern VHE sources (HESS J1800-240 with components labeled A, B and C) are found in a region occupied by several HII regions, including the ultracompact HII region W 28A2. Our analysis of NANTEN CO data reveals a dense molecular cloud enveloping this southern region, and our reanalysis of EGRET data reveals MeV/GeV emission centered on HESS J1801-233 and the northeastern interaction region.

  17. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  18. Stability of Bright Solitons in Bose-Einstein Condensates

    Institute of Scientific and Technical Information of China (English)

    YU Hui-You; YAN Jia-Ren; XIE Qiong-Tao

    2004-01-01

    We investigate the stability of bright solitons in Bose-Einstein condensates by including a feeding term and a loss one in the Gross-Pitaevskii equation. Based on the direct approach of perturbation theory for the nonlinear Schrodinger equation, we give the explicit dependence of the height and other related quantities of bright solitons on the feeding and loss term. It is found that the three-body recombination loss plays a crucial role in stabilizing bright solitons.

  19. Study of Three-Dimensional Image Brightness Loss in Stereoscopy

    Directory of Open Access Journals (Sweden)

    Hsing-Cheng Yu

    2015-10-01

    Full Text Available When viewing three-dimensional (3D images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval

  20. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars

    CERN Document Server

    Bastien, Fabienne A; Pepper, Joshua

    2014-01-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50%...

  1. High Brightness Neutron Source for Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  2. Sparkling EUV bright dots observed with Hi-C

    CERN Document Server

    Regnier, S; Walsh, R W; Winebarger, A R; Cirtain, J; Golub, L; Korreck, K E; Mitchell, N; Platt, S; Weber, M; De Pontieu, B; Title, A; Kobayashi, K; Kuzin, S; DeForest, C E

    2014-01-01

    Observing the Sun at high time and spatial scales is a step towards understanding the finest and fundamental scales of heating events in the solar corona. The Hi-C instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 11 July 2012, which exhibits several interesting features in the EUV line at 193\\AA: one of them is the existence of short, small brightenings ``sparkling" at the edge of the active region; we call these EUV Bright Dots (EBDs). Individual EBDs have a characteristic duration of 25s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength, however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA suggesting a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different...

  3. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    Energy Technology Data Exchange (ETDEWEB)

    Chesny, D. L.; Oluseyi, H. M. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Orange, N. B. [OrangeWave Innovative Science, LLC, Moncks Corner, SC 29461 (United States); Champey, P. R. [Department of Optical Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  4. Quiet-Sun Network Bright Point Phenomena with Sigmoidal Signatures

    Science.gov (United States)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  5. QUASI-PERIODIC OSCILLATION OF A CORONAL BRIGHT POINT

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Tanmoy; Banerjee, Dipankar [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Tian, Hui, E-mail: tsamanta@iiap.res.in, E-mail: hui.tian@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-06-20

    Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Imager magnetogram on board the Solar Dynamics Observatory, and spectroscopic data from the newly launched Interface Region Imaging Spectrograph (IRIS). The detailed analysis shows that the BP evolves throughout our observing period along with changes in underlying photospheric magnetic flux and shows periodic brightenings in different EUV and far-UV images. With the highest possible spectral and spatial resolution of IRIS, we attempted to identify the sources of these oscillations. IRIS sit-and-stare observation provided a unique opportunity to study the time evolution of one footpoint of the BP as the slit position crossed it. We noticed enhanced line profile asymmetry, enhanced line width, intensity enhancements, and large deviation from the average Doppler shift in the line profiles at specific instances, which indicate the presence of sudden flows along the line-of-sight direction. We propose that transition region explosive events originating from small-scale reconnections and the reconnection outflows are affecting the line profiles. The correlation between all these parameters is consistent with the repetitive reconnection scenario and could explain the quasi-periodic nature of the brightening.

  6. Relationships between brightness of nighttime lights and population density

    Science.gov (United States)

    Naizhuo, Z.

    2012-12-01

    lit area, relatively large under-estimations would emerge in the urban core regions. Previous studies have shown that GDP, carbon dioxide emission, and electric power consumption strongly correlate to urban population (Ghosh et al., 2010; Sutton et al., 2007; Zhao et al., 2012). Thus, although this study only examined the relationships between brightness of nighttime lights and population density, the results can provide insight for the spatial disaggregations of socioeconomic data (e.g. GDP, carbon dioxide emission, and electric power consumption) using the satellite nighttime light image data. Simply distributing the socioeconomic data to each pixel in proportion to the DN value of the nighttime light images may generate relatively large errors. References Bharit N, Tatem AJ, Ferrari MJ, Grais RF, Djibo A, Grenfell BT, 2011. Science, 334:1424-1427. Ghosh T, Elvidge CD, Sutton PC, Baugh KE, Ziskin D, Tuttle BT, 2010. Energies, 3:1895-1913. Oda T, Maksyutov S, 2011. Atmospheric Chemistry and Physics, 11:543-556. Sutton PC, Elvidge CD, Ghosh T, 2007. International Journal of Ecological Economics and Statistics, 8:5-21. Zhao N, Ghosh T, Samson EL, 2012. International Journal of Remote sensing, 33:6304-6320.

  7. Lamp spectrum and spatial brightness at photopic levels

    DEFF Research Database (Denmark)

    Fotios, Steve; Atli, Deniz; Cheal, Chris

    2015-01-01

    Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but a...

  8. Brightness limitations of cold field emitters caused by Coulomb interactions

    NARCIS (Netherlands)

    Cook, B.J.; Verduin, T.; Hagen, C.W.; Kruit, P.

    2010-01-01

    Emission theory predicts that high brightness cold field emitters can enhance imaging in the electron microscope. This (neglecting chromatic aberration) is because of the large (coherent) probe current available from a high brightness source and is based on theoretically determined values of reduced

  9. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    Science.gov (United States)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Hazmin Sabri, Nor; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  10. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    Science.gov (United States)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Sabri, Nor Hazmin; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  11. Edge integration and the perception of brightness and darkness

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2006-01-01

    How do induced brightness and darkness signals from local and remote surfaces interact to determine the final achromatic color percept of a target surface? An emerging theory of achromatic color perception posits that brightness and darkness percepts are computed by weighting and summing the

  12. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    Energy Technology Data Exchange (ETDEWEB)

    Nangle, John [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simon, Joseph [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  13. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.; Butterfield, Karla [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  14. GOMOS bright limb ozone data set

    Directory of Open Access Journals (Sweden)

    S. Tukiainen

    2015-01-01

    Full Text Available We have created a daytime ozone profile data set from the measurements of the Global Ozone Monitoring by Occultation of Stars (GOMOS instrument on board the Envisat satellite. This so-called GOMOS bright limb (GBL data set contains ~ 358 000 stratospheric daytime ozone profiles measured by GOMOS in 2002–2012. The GBL data set complements the widely used GOMOS night-time data based on stellar occultation measurements. The GBL data set is based on the GOMOS daytime occultations but instead of the transmitted star light, we use limb scattered solar light. The ozone profiles retrieved from these radiance spectra cover 18–60 km tangent height range and have approximately 2–3 km vertical resolution. We show that these profiles are generally in better than 10% agreement with the NDACC (Network for the Detection of Atmospheric Composition Change ozone sounding profiles and with the GOMOS night-time, MLS (Microwave Limb Sounder, and OSIRIS (Optical Spectrograph, and InfraRed Imaging System satellite measurements. However, there is a 10–13% negative bias at 40 km tangent height and a 10–50% positive bias at 50 km when the solar zenith angle > 75°. These biases are most likely caused by stray light which is difficult to characterize and remove entirely from the measured spectra. Nevertheless, the GBL data set approximately doubles the amount of useful GOMOS ozone profiles and improves coverage of the summer pole.

  15. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  16. The Los Alamos high-brightness photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, P.G.

    1991-01-01

    For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

  17. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new mechanical electrodeposition technology was proposed, and nanocrystalline nickel deposit with bright and smooth surface was prepared in the bath without any additive agents. Unlike traditional methods, the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing. Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits, pinholes and nodules. Furthermore, comparing with the deposit prepared by traditional methods, the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm. Every diffraction peak’s intensity of the deposit was reduced, the preferential orientation degree of (200) decreased and those of (111) and (220) increased. The microhardness notably increased. The magnetic properties were also changed with decreased saturation magnetization and increased coercive force. It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.

  18. MODIS BRIGHTNESS TEMPERATURE DATA ASSIMILATION UNDER CLOUDY CONDITIONS: METHODS AND IDEAL TESTS

    Institute of Scientific and Technical Information of China (English)

    DING Wei-yu; WAN Qi-lin; ZHANG Chen-zhong; CHEN Zi-tong; HUANG Yan-yan

    2010-01-01

    Clouds have important effects on the infrared radiances transmission in that the inclusion of cloud effects in data assimilation can not only improve the quality of the assimilated atmospheric parameters greatly, but also minimize the initial error of cloud parameters by adjusting part of the infrared radiances data. On the basis of the Grapes-3D-var (Global and Regional Assimilation and Prediction Enhanced System), cloud liquid water, cloud ice water and cloud cover are added as the governing variables in the assimilation. Under the conditions of clear sky, partly cloudy cover and totally cloudy cover, the brightness temperature of 16 MODIS channels are assimilated respectively in ideal tests. Results show that when the simulated background brightness temperatures are lower than the observation, the analyzed field will increase the simulated brightness temperature by increasing its temperature and reducing its moisture, cloud liquid water, cloud ice water, and cloud cover. The simulated brightness temperature can be reduced if adjustment is made in the contrary direction. The adjustment of the temperature and specific humidity under the clear sky conditions conforms well to the design of MODIS channels, but it is weakened for levels under cloud layers. The ideal tests demonstrate that by simultaneously adding both cloud parameters and atmospheric parameters as governing variables during the assimilation of infrared radiances, both the cloud parameters and atmospheric parameters can be adjusted using the observed infrared radiances and conventional meteorological elements to make full use of the infrared observations.

  19. Reverberation in the UV-Optical Continuum Brightness Fluctuations of MACHO Quasar 13.5962.237

    CERN Document Server

    Schild, Rudolph E; Protopapas, Pavlos

    2009-01-01

    We examine the nature of brightness fluctuations in the UV-Optical spectral region of an ordinary quasar with 881 optical brightness measurements made during the epoch 1993 - 1999. We find evidence for systematic trends having the character of a pattern of reverberations following an initial disturbance. The initial pulses have brightness increases of order 20% and pulse widths of 50 days, and the reverberations have typical amplitudes of 12% with longer mean pulse widths of order 80 days and pulse separations of order 90 days. The repeat pattern occurs over the same time scales whether the initial disturbance is a brightening or fading. The lags of the pulse trains are comparable to the lags seen previously in reverberation of the broad blue-shifted emission lines following brightness disturbances in Seyfert galaxies, when allowance is made for the mass of the central object. In addition to the burst pulse trains, we find evidence for a semi-periodicity with a time scale of 2 years. These strong patterns of ...

  20. Hi-C Observations of Penumbral Bright Dots

    Science.gov (United States)

    Alpert, S. E.; Tiwari, S. K.; Moore, R. L.; Savage, S. L.; Winebarger, A. R.

    2014-01-01

    We use high-quality data obtained by the High Resolution Coronal Imager (Hi-C) to examine bright dots (BDs) in a sunspot's penumbra. The sizes of these BDs are on the order of 1 arcsecond (1") and are therefore hard to identify using the Atmospheric Imaging Assembly's (AIA) 0.6" pixel(exp -1) resolution. These BD become readily apparent with Hi-C's 0.1" pixel(exp -1) resolution. Tian et al. (2014) found penumbral BDs in the transition region (TR) by using the Interface Region Imaging Spectrograph (IRIS). However, only a few of their dots could be associated with any enhanced brightness in AIA channels. In this work, we examine the characteristics of the penumbral BDs observed by Hi-C in a sunspot penumbra, including their sizes, lifetimes, speeds, and intensity. We also attempt to find any association of these BDs to the IRIS BDs. There are fewer Hi-C BDs in the penumbra than seen by IRIS, though different sunspots were studied. We use 193 Angstroms Hi-C data from July 11, 2012 which observed from approximately 18:52:00 UT- 18:56:00 UT and supplement it with data from AIA's 193 Angstrom passband to see the complete lifetime of the dots that were born before and/or lasted longer than Hi- C's 5-minute observation period. We use additional AIA passbands and compare the light curves of the BDs at different temperatures to test whether the Hi-C BDs are TR BDs. We find that most Hi-C BDs show clear movement, and of those that do, they move in a radial direction, toward or away from the sunspot umbra. Single BDs interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to move less. Many of the properties of our BDs are similar to the extreme values of the IRIS BDs, e.g., they move slower on average and their sizes and lifetimes are on the higher end of the IRIS BDs. We infer that our penumbral BDs are the large-scale end of the distribution of BDs observed by IRIS.

  1. Compositional differences among Bright Spots on the Ceres surface

    Science.gov (United States)

    Palomba, Ernesto; Longobardo, Andrea; De Sanctis, Maria Cristina; Stein, Nathaniel; Ehlmann, Bethany; Ammannito, Eleonora; Giacomo Carrozzo, Filippo; Raponi, Andrea; Ciarniello, Mauro; Frigeri, Alessandro; Capria, Maria Teresa; Tosi, Federico; Zambon, Francesca; Fonte, Sergio; Giardino, Marco; Capaccioni, Fabrizio; Raymond, Carol; Russell, Christopher T.; VIR-Dawn Team

    2016-10-01

    The Dawn mission detected areas of a relatively higher albedo defined as "bright spots" (BS) on the Ceres surface. The most important member of this family is represented by the Occator crater and more precisely by the two very high albedo areas located on the crater floor.In this work we identified BS on Ceres by using the hyperspectral data produced by the VIR instrument [1]. We used an approach similar to the one used for Vesta [2], identifying 38 BS. More than 80% of BS's are related to features generated by impacts. The remaining cases concern diffused material, spots, a scarp and the Ahuna Mons.The absolute value of the albedo at 1.2 um of BS is approximately 40% larger than the average Ceres albedo, with the two Occator bright areas being by far the brightest on the entire surface.The general spectral behavior with respect to surroundings includes increased band depths at 2.7, 3.4 and 4.0 um. This is clear especially for the Occator region [3], but is a common behavior also for other BS. This strongly supports that carbonates, producing the 3.4 and 4.0 um absorption band, are the main brightening agent in these regions [3]. Another common trend is the shallowing of the 3.05 um band [4], related to ammonia.Increase of the two carbonate band depths is always evident in BS; this is not always true for the 2.7 um band. Six BS show a 2.7 um band depth decrease with respect to the surroundings. These six BS correspond to impact features; therefore, a possible interpretation is a dehydration due to the impact.Four other BS show instead a 3.05 um band deepening, contrarily to the common BS behavior. The interpretation of this observation is in progress.AcknowledgementsVIR was funded and coordinated by ASI, and built by SELEX ES, with the scientific leadership of IAPS-INAF, Rome, Italy, and is operated by IAPS-INAF, Rome, Italy. Support of the Dawn Teams is gratefully acknowledged.References[1] De Sanctis, M.C. et al., 2011, SSR, 163, 329[2] Palomba, E., et al. 2014

  2. Testing sky brightness models against radial dependency: A dense two dimensional survey around the city of Madrid, Spain

    Science.gov (United States)

    Zamorano, J.; Sánchez de Miguel, A.; Ocaña, F.; Pila-Díez, B.; Gómez Castaño, J.; Pascual, S.; Tapia, C.; Gallego, J.; Fernández, A.; Nievas, M.

    2016-09-01

    We present a study of the night sky brightness around the extended metropolitan area of Madrid using Sky Quality Meter (SQM) photometers. The map is the first to cover the spatial distribution of the sky brightness in the centre of the Iberian peninsula. These surveys are necessary to test the light pollution models that predict night sky brightness as a function of the location and brightness of the sources of light pollution and the scattering of light in the atmosphere. We describe the data-retrieval methodology, which includes an automated procedure to measure from a moving vehicle in order to speed up the data collection, providing a denser and wider survey than previous works with similar time frames. We compare the night sky brightness map to the nocturnal radiance measured from space by the DMSP satellite. We find that (i) a single source model is not enough to explain the radial evolution of the night sky brightness, despite the predominance of Madrid in size and population and (ii) that the orography of the region should be taken into account when deriving geo-specific models from general first-principles models. We show the tight relationship between these two luminance measures. This finding sets up an alternative roadmap to extended studies over the globe that will not require the local deployment of photometers or trained personnel.

  3. Irradiated shocks in the W28 A2 massive star-forming region: a site for cosmic rays acceleration?

    CERN Document Server

    Gusdorf, A; Gerin, M; Guesten, R

    2015-01-01

    The formation of massive stars play a crucial role in galaxies from numerous points of view. The protostar generates a strong ultraviolet radiation field that ionizes its surroundings, and it drives powerful shock waves in the neighbouring medium in the form of jets and bipolar outflows, whose structure can be partially organized by local, strong magnetic field. Such an ejection activity locally modifies the interstellar chemistry, contributing to the cycle of matter. It also significantly participates to the energetic balance of galaxies. In the latter stages of massive star formation, the protostar is surrounded by an ultra-compact HII region, and irradiates its bipolar outflows, where an intrinsically strong magnetic field structure is associated to the generally high densities. In the HII region, or in the bipolar outflows, the question of in situ cosmic rays acceleration can then be raised by the simultaneous presence of strong magnetic fields, significant ionization of the matter, and mechanical energy ...

  4. Laser-synthesized oxide-passivated bright Si quantum dots for bioimaging

    OpenAIRE

    2016-01-01

    Crystalline silicon (Si) nanoparticles present an extremely promising object for bioimaging based on photoluminescence (PL) in the visible and near-infrared spectral regions, but their efficient PL emission in aqueous suspension is typically observed after wet chemistry procedures leading to residual toxicity issues. Here, we introduce ultrapure laser-synthesized Si-based quantum dots (QDs), which are water-dispersible and exhibit bright exciton PL in the window of relative tissue transparenc...

  5. Architectural Trend of the Epoch: Architect Chernyshev as a bright representative of the Siberian Modern

    OpenAIRE

    Olga Uspenskaya

    2016-01-01

    The article is about a bright representative of the Siberian Modern, Leonid Alexandrovich Chernyshev, who made a great contribution to the development of Krasnoyarsk city architecture. On the initiative of the Board of the Krasnoyarsk regional organization of the Union of Architects of Russia the year 2015 in Krasnoyarsk was announced the Year of the Architect Chernyshev to commemorate his 140th anniversary. During the anniversary year several important events will be held to demonstrate the ...

  6. Dark Skies, Bright Kids: Year 2

    Science.gov (United States)

    Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

    2011-01-01

    The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

  7. MAGNETIC FLUX SUPPLEMENT TO CORONAL BRIGHT POINTS

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China); Madjarska, Maria S., E-mail: z.huang@sdu.edu.cn [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

    2016-02-10

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the magnetic fluxes. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While magnetic cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak magnetic features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the magnetic activities responsible for the BP heating may involve small weak fields.

  8. Bright Times for an Ancient Star

    Science.gov (United States)

    Fuhrmann, K.; Chini, R.

    2017-01-01

    Field stars of Population II are among the oldest sources in the Galaxy. Most of their solar-type dwarfs are non-single and, given their extreme age, a significant fraction is accompanied by stellar remnants. Here we report the discovery of the bright F7V star 49 Lib as a massive and very metal-rich Population II field blue straggler, along with evidence for a white dwarf as its dark and unseen companion. 49 Lib is known as a relatively fast-rotating, single-lined spectroscopic binary in a 3 year orbit and with an apparent age of about τ ≃ 2.3 Gyr. Its chemistry and kinematics, however, both consistently imply that 49 Lib must be an ancient Population II star at τ ≃ 12 Gyr. With reference to the inclination from the astrometric orbit, leading to a {M}{WD}={0.50}-0.04+0.03 M⊙ low-mass white dwarf, and in view of the {M}{BS}={1.55}-0.13+0.07 M⊙ massive, evolved F-type blue straggler star, we demonstrate that 49 Lib must have been the subject of a mostly conservative mass transfer with a near-equal-mass M ≃ 1.06 + 1.00 M⊙ G-type binary at birth. For its future evolution, we point to the possibility as a progenitor system toward a type Ia supernova. Most importantly, however, we note that the remarkable metal enrichment of 49 Lib at [Mg/H] = +0.23 and [Fe/H] = ‑0.11 has principally very relevant implications for the early epoch when the Milky Way came into being.

  9. Dark Skies, Bright Kids! Year 4

    Science.gov (United States)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  10. Dark Skies, Bright Kids! Year 3

    Science.gov (United States)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  11. Sequential Star Formation in RCW 34: A Spectroscopic Census of the Stellar Content of High-mass Star-forming Regions

    CERN Document Server

    Bik, A; Waters, L B F M; Horrobin, M; Henning, Th; Vasyunina, T; Beuther, H; Linz, H; Kaper, L; Ancker, M van den; Lenorzer, A; Churchwell, E; Kurtz, S; Kouwenhoven, M B N; Stolte, A; de Koter, A; Thi, W- F; Comeron, F; Waelkens, Ch

    2010-01-01

    We present VLT/SINFONI integral field spectroscopy of RCW 34 along with Spitzer/IRAC photometry of the surroundings. RCW 34 consists of three different regions. A large bubble has been detected on the IRAC images in which a cluster of intermediate- and low-mass class II objects is found. At the northern edge of this bubble, an HII region is located, ionized by 3 OB stars. Intermediate mass stars (2 - 3 Msun) are detected of G- and K- spectral type. These stars are still in the pre-main sequence (PMS) phase. North of the HII region, a photon-dominated region is present, marking the edge of a dense molecular cloud traced by H2 emission. Several class 0/I objects are associated with this cloud, indicating that star formation is still taking place. The distance to RCW 34 is revised to 2.5 +- 0.2 kpc and an age estimate of 2 - 1 Myrs is derived from the properties of the PMS stars inside the HII region. The most likely scenario for the formation of the three regions is that star formation propagates from South to ...

  12. Brightness of synchrotron radiation from undulators and bending magnets

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2014-07-15

    We consider the maximum of the Wigner distribution (WD) of synchrotron radiation (SR) fields as a possible definition of SR source brightness. Such figure of merit was originally introduced in the SR community by Kim. The brightness defined in this way is always positive and, in the geometrical optics limit, can be interpreted as maximum density of photon flux in phase space. For undulator and bending magnet radiation from a single electron, the WD function can be explicitly calculated. In the case of an electron beam with a finite emittance the brightness is given by the maximum of the convolution of a single electron WD function and the probability distribution of the electrons in phase space. In the particular case when both electron beam size and electron beam divergence dominate over the diffraction size and the diffraction angle, one can use a geometrical optics approach. However, there are intermediate regimes when only the electron beam size or the electron beam divergence dominate. In this asymptotic cases the geometrical optics approach is still applicable, and the brightness definition used here yields back once more the maximum photon flux density in phase space. In these intermediate regimes we find a significant numerical disagreement between exact calculations and the approximation for undulator brightness currently used in literature. We extend the WD formalism to a satisfactory theory for the brightness of a bending magnet. We find that in the intermediate regimes the usually accepted approximation for bending magnet brightness turns out to be inconsistent even parametrically.

  13. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Science.gov (United States)

    Hur, Kwang-Ho; Mueller, Joachim D

    2015-01-01

    The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  14. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  15. The dearth of nuclear star clusters in bright galaxies

    CERN Document Server

    Arca-Sedda, Manuel; Spera, Mario

    2015-01-01

    We investigate the interaction of a massive globular cluster (GC) with a super massive black hole (SMBH), located at the centre of its host galaxy, by means of direct $N$-body simulations. The results show that tidal distortions induced by the stellar background and the SMBH act on a time shorter than that of dynamical friction decay for a $10^6$ M$_\\odot$ GC whenever the SMBH mass exceeds $\\sim 10^8$ M$_\\odot$. This implies an almost complete dissolution of the infalling GC before it reaches the inner region ($\\lesssim 5$ pc) of the parent galaxy. The generalization of this result to a larger sample of infalling GCs shows that such destructive process may prevent the formation and growth of a bright galactic nucleus. Another interesting, serendipitous, result we obtained is that the close interaction between the SMBH and the GC produces a ``wave'' of stars that escape from the cluster and, in a fraction, even from the whole galaxy.

  16. Hi-C Observations of Sunspot Penumbral Bright Dots

    CERN Document Server

    Alpert, Shane E; Moore, Ronald L; Winebarger, Amy R; Savage, Sabrina L

    2016-01-01

    We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 \\AA\\ and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1\\arcsec\\ and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 \\AA\\ images, which have 1.2\\arcsec\\ spatial resolution, but become readily apparent with Hi-C's five times better spatial resolution. We supplement Hi-C data with data from AIA's 193 \\AA\\ passband to see the complete lifetime of the BDs that appeared before and/or lasted longer than Hi-C's 3-minute observation period. Most Hi-C BDs show clear lateral movement along penumbral striations, toward or away from the sunspot umbra. Single BDs often interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to have smaller displacements. These BDs are about as numerous but move slower on average than Interface Region Imaging Spectrograph (IRIS) BDs, rec...

  17. Suzaku observations of the low surface brightness cluster A76

    CERN Document Server

    Ota, N; Ibaraki, Y; Boehringer, H; Chon, G

    2013-01-01

    Context: We present results of Suzaku observations of a nearby galaxy cluster A76 at z=0.0395. This cluster is characterized by extremely low X-ray surface brightness and is hereafter referred to as the LSB cluster. Aims: To understand the nature and thermodynamic evolution of the LSB cluster by studying the physical properties of the hot intracluster medium in A76. Methods: We conducted two-pointed Suzaku observations of A76 and examined the global gas properties of the cluster by XIS spectral analysis. We also performed deprojection analysis of annular spectra and derived radial profiles of gas temperature, density and entropy out to approximately 850 kpc (~ 0.6 r_200) and 560 kpc (~0.4 r_200) in A76 East and A76 West, respectively. Results: The measured global temperature and metal abundance are approximately 3.3 keV and 0.24 solar, respectively. From the deprojection analysis, the entropy profile is found to be flat with respect to radius. The entropy within the central region (r < 0.2r_200) is excepti...

  18. Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile

    Science.gov (United States)

    Gilbert, Karoline M.; Guhathakurta, Puragra; Beaton, Rachael L.; Bullock, James; Geha, Marla C.; Kalirai, Jason S.; Kirby, Evan N.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J.; Tollerud, Erik J.; Tanaka, Mikito; Chiba, Masashi

    2012-11-01

    We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 ± 0.2 and extends to a projected distance of at least ~175 kpc (~2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California

  19. ECR Ion Source for a High-Brightness Cyclotron

    Science.gov (United States)

    Comeaux, Justin; McIntyre, Peter; Assadi, Saeed

    2011-10-01

    New technology is being developed for high-brightness, high-current cyclotrons with performance benefits for accelerator-driven subcritical fission power, medical isotope production, and proton beam cancer therapy. This paper describes the design for a 65 kV electron cyclotron resonance (ECR) ion source that will provide high-brightness beam for injection into the cyclotron. The ion source is modeled closely upon the one that is used at the Paul Scherrer Institute. Modifications are being made to provide enhanced brightness and compatibility for higher-current operation.

  20. Low dimensional neutron moderators for enhanced source brightness

    DEFF Research Database (Denmark)

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan;

    2014-01-01

    In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...

  1. Variations in the Bivariate Brightness Distribution with different galaxy types

    CERN Document Server

    Cross, N; Lemon, D; Liske, J; Cross, Nicholas; Driver, Simon; Lemon, David; Liske, Jochen

    2002-01-01

    We present Bivariate Brightness Distributions (BBDs) for four spectral types discriminated by the 2dFGRS. We discuss the photometry and completeness of the 2dFGRS using a deep, wide-field CCD imaging survey. We find that there is a strong luminosity-surface brightness correlation amongst galaxies with medium to strong emission features, with gradient $\\beta_{\\mu}=0.25\\pm0.05$ and width $\\sigma_{\\mu}=0.56\\pm0.01$. Strong absorption line galaxies, show a bimodal distribution, with no correlation between luminosity and surface brightness.

  2. The Oriented Difference of Gaussians (ODOG) model of brightness perception: Overview and executable Mathematica notebooks.

    Science.gov (United States)

    Blakeslee, Barbara; Cope, Davis; McCourt, Mark E

    2016-03-01

    The Oriented Difference of Gaussians (ODOG) model of brightness (perceived intensity) by Blakeslee and McCourt (Vision Research 39:4361-4377, 1999), which is based on linear spatial filtering by oriented receptive fields followed by contrast normalization, has proven highly successful in parsimoniously predicting the perceived intensity (brightness) of regions in complex visual stimuli such as White's effect, which had been believed to defy filter-based explanations. Unlike competing explanations such as anchoring theory, filling-in, edge-integration, or layer decomposition, the spatial filtering approach embodied by the ODOG model readily accounts for the often overlooked but ubiquitous gradient structure of induction which, while most striking in grating induction, also occurs within the test fields of classical simultaneous brightness contrast and the White stimulus. Also, because the ODOG model does not require defined regions of interest, it is generalizable to any stimulus, including natural images. The ODOG model has motivated other researchers to develop modified versions (LODOG and FLODOG), and has served as an important counterweight and proof of concept to constrain high-level theories which rely on less well understood or justified mechanisms such as unconscious inference, transparency, perceptual grouping, and layer decomposition. Here we provide a brief but comprehensive description of the ODOG model as it has been implemented since 1999, as well as working Mathematica (Wolfram, Inc.) notebooks which users can employ to generate ODOG model predictions for their own stimuli.

  3. Global Snow Mass Measurements and the Effect of Stratigraphic Detail on Inversion of Microwave Brightness Temperatures

    Science.gov (United States)

    Richardson, Mark; Davenport, Ian; Gurney, Robert

    2014-05-01

    Snow provides large seasonal storage of freshwater, and information about the distribution of snow mass as snow water equivalent (SWE) is important for hydrological planning and detecting climate change impacts. Large regional disagreements remain between estimates from reanalyses, remote sensing and modelling. Assimilating passive microwave information improves SWE estimates in many regions, but the assimilation must account for how microwave scattering depends on snow stratigraphy. Physical snow models can estimate snow stratigraphy, but users must consider the computational expense of model complexity versus acceptable errors. Using data from the National Aeronautics and Space Administration Cold Land Processes Experiment and the Helsinki University of Technology microwave emission model of layered snowpacks, it is shown that simulations of the brightness temperature difference between 19 and 37 GHz vertically polarised microwaves are consistent with advanced microwave scanning radiometer-earth observing system and special sensor microwave imager retrievals once known stratigraphic information is used. Simulated brightness temperature differences for an individual snow profile depend on the provided stratigraphic detail. Relative to a profile defined at the 10-cm resolution of density and temperature measurements, the error introduced by simplification to a single layer of average properties increases approximately linearly with snow mass. If this brightness temperature error is converted into SWE using a traditional retrieval method, then it is equivalent to ±13 mm SWE (7 % of total) at a depth of 100 cm. This error is reduced to ±5.6 mm SWE (3 % of total) for a two-layer model.

  4. Mapping the low-surface brightness Universe in the UV band with Lyα emission from IGM filaments

    NARCIS (Netherlands)

    Silva, Marta B.; Kooistra, Robin; Zaroubi, Saleem

    2016-01-01

    A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium (IGM). However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in the circum-galactic medium. Here we simulate the

  5. High Resolution CO Observations of Massive Star Forming Regions

    CERN Document Server

    Klaassen, P D; Keto, E R; Zhang, Q; Galván-Madrid, R; Liu, H-Y B

    2011-01-01

    Context. To further understand the processes involved in the formation of massive stars, we have undertaken a study of the gas dynamics surrounding three massive star forming regions. By observing the large scale structures at high resolution, we are able to determine properties such as driving source, and spatially resolve the bulk dynamical properties of the gas such as infall and outflow. Aims. With high resolution observations, we are able to determine which of the cores in a cluster forming massive stars is responsible for the large scale structures. Methods. We present CO observations of three massive star forming regions with known HII regions and show how the CO traces both infall and outflow. By combining data taken in two SMA configurations with JCMT observations, we are able to see large scale structures at high resolution. Results. We find large (0.26-0.40 pc), massive (2-3 M_sun) and energetic (13-17 \\times 10^44 erg) outflows emanating from the edges of two HII regions suggesting they are being ...

  6. The Detection of an Extremely Bright Fast Radio Burst in a Phased Array Feed Survey

    Science.gov (United States)

    Bannister, K. W.; Shannon, R. M.; Macquart, J.-P.; Flynn, C.; Edwards, P. G.; O'Neill, M.; Osłowski, S.; Bailes, M.; Zackay, B.; Clarke, N.; D'Addario, L. R.; Dodson, R.; Hall, P. J.; Jameson, A.; Jones, D.; Navarro, R.; Trinh, J. T.; Allison, J.; Anderson, C. S.; Bell, M.; Chippendale, A. P.; Collier, J. D.; Heald, G.; Heywood, I.; Hotan, A. W.; Lee-Waddell, K.; Madrid, J. P.; Marvil, J.; McConnell, D.; Popping, A.; Voronkov, M. A.; Whiting, M. T.; Allen, G. R.; Bock, D. C.-J.; Brodrick, D. P.; Cooray, F.; DeBoer, D. R.; Diamond, P. J.; Ekers, R.; Gough, R. G.; Hampson, G. A.; Harvey-Smith, L.; Hay, S. G.; Hayman, D. B.; Jackson, C. A.; Johnston, S.; Koribalski, B. S.; McClure-Griffiths, N. M.; Mirtschin, P.; Ng, A.; Norris, R. P.; Pearce, S. E.; Phillips, C. J.; Roxby, D. N.; Troup, E. R.; Westmeier, T.

    2017-05-01

    We report the detection of an ultra-bright fast radio burst (FRB) from a modest, 3.4-day pilot survey with the Australian Square Kilometre Array Pathfinder. The survey was conducted in a wide-field fly’s-eye configuration using the phased-array-feed technology deployed on the array to instantaneously observe an effective area of 160 deg2, and achieve an exposure totaling 13200 deg2 hr . We constrain the position of FRB 170107 to a region 8\\prime × 8\\prime in size (90% containment) and its fluence to be 58 ± 6 Jy ms. The spectrum of the burst shows a sharp cutoff above 1400 MHz, which could be due to either scintillation or an intrinsic feature of the burst. This confirms the existence of an ultra-bright (> 20 Jy ms) population of FRBs.

  7. On the formation of Ganymede's surface brightness asymmetries: Kinetic simulations of Ganymede's magnetosphere

    Science.gov (United States)

    Fatemi, S.; Poppe, A. R.; Khurana, K. K.; Holmström, M.; Delory, G. T.

    2016-05-01

    Ganymede possesses strong surface brightness asymmetries both between its polar cap and equatorial regions and between its leading and trailing hemispheres. Here we test the hypothesis that these asymmetries are due to differential Jovian plasma and energetic particle precipitation to the surface with the combination of a hybrid plasma model (kinetic ions and fluid electrons) and a particle tracing model. We describe the hybrid model, the first of its kind applied to Ganymede, and compare the results to both Galileo observations and previous MHD and MHD-EPIC models of Ganymede. We calculate spatially resolved precipitating Jovian ion fluxes to the surface of Ganymede for energies 1 particle fluxes are the primary driver for altering the surface brightness of Ganymede.

  8. SMEX03 SSM/I Brightness Temperature Data, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  9. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  10. Ultra High Brightness/Low Cost Fiber Coupled Packaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of the proposed effort is maximizing the brightness of fiber coupled laser diode pump sources at a minimum cost. The specific innovation proposed is to...

  11. Bright Prospect for the Polyester Industrial Filament Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Some large companies from Americaand Europe have constructed plantsin China or established long-termstable cooperation relationship withChinese enterprises. A bright devel-opment prospect has therefore beenbrought to the polyester industrial fila-ment sector in China.

  12. SMEX03 SSM/I Brightness Temperature Data, Georgia

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  13. Visible Color and Photometry of Bright Materials on Vesta

    Science.gov (United States)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  14. An observational correlation between stellar brightness variations and surface gravity

    CERN Document Server

    Bastien, Fabienne A; Basri, Gibor; Pepper, Joshua

    2013-01-01

    Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures gravity with an uncertainty of about two per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for >150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity; if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and the root-mean-square brightness variations on timescales of less than eight hours for stars with temperatures ...

  15. Supercontinuum generation with bright and dark solitons in optical fibers

    CERN Document Server

    Milián, Carles; Kudlinski, Alexandre; Skryabin, Dmitry V

    2016-01-01

    We study numerically and experimentally supercontinuum generation in optical fibers with dark and bright solitons simultaneously contributing into the spectral broadening and dispersive wave generation. We report a novel type of weak trapped radiation arising due to interaction of bright solitons with the dark soliton background. This radiation expresses itself as two pulses with the continuously shifting spectra constituting the short and long wavelength limits of the continuum. Our theoretical and experimental results are in good agreement.

  16. Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

    Institute of Scientific and Technical Information of China (English)

    LIU Jinsong

    2001-01-01

    A numerical analysis of the dynamical evolution of bright screening-photovoltaic (SP) spatial solitons in biased photovoltaic-photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low-intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high-intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

  17. A new radial system of dark globules in Monoceros

    CERN Document Server

    Carrasco-Gonz'alez, C; Gyulbudaghian, A; Anglada, G; Lee, C W

    2005-01-01

    Aims. We analyze the LBN 978 HII region in order to study the HII/molecular cloud interaction. Methods. We used the IAC-80 telescope to image the region with narrow-band filters and the Very Large Array to obtain a radio continuum map at 3.6 cm. We also used the DSS2 red images and the NRAO VLA Sky Survey at 20 cm. Results. We have discovered a new radial system of dark globules associated with the LBN 978 HII region, containing a group of at least eight cometary bright-rimmed globules with the same morphological type. The brightest source is also detected in the radio continuum. Analysis of optical and radio emission suggest that this object is photoionized by HD 47432, the central star of the LBN 978 HII region.

  18. Coronal structure and brightness profile of the total solar eclipse on August 1,2008

    Institute of Scientific and Technical Information of China (English)

    ZHAO HaiBin; LIN QiSheng; CHEN YiPing; JIN Sheng; GUAN ZhenBiao; HU Zhongwei

    2009-01-01

    Solar corona is the outermost part of the solar atmosphere.Coronal activities influence space environment between the Sun and the Earth,space weather and the Earth itself.The total solar eclipse (TSE) is the best opportunity to observe the solar corona on ground.During the TSE 2008,a series of images of the corona and partial eclipse of solar disk were obtained using telescope and CCD camera.After image processing,preliminary results of coronal structure are given,and radial brightness profiles of the corona in directions of pole and equator of the Sun are measured.Though in solar activity minimum,the shape and structure of the corona are not symmetry.The equatorial regions are more extent than the polar one,and there are also larger differences between the east and west equatorial regions and between the south and north polar regions.Coronal streamers on east side of the equator,particularly the largest one in east-south direction,are very obvious.The coronal plume in south polar region consists of more polar rays than that in north polar region.These structures are also shown in other observations and data of SOHO.The radial brightness profiles in directions of pole and equator are similar to those of the Van de Hulst model in solar minimum,but there are a few differences due to coronal activity,which is shown in the isophote map of the corona.

  19. HeI in the central Giant HII Region of NGC 5253. A 2D observational approach to collisional and radiative transfer effects

    CERN Document Server

    Monreal-Ibero, Ana; Westmoquette, Mark S; Vilchez, Jose M

    2013-01-01

    ABRIDGED: NGC5253 is an ideal laboratory for detailed studies of starburst galaxies. We present for the first in a starburst galaxy a 2D study of the spatial behavior of collisional and radiative transfer effects in He^+. The HeI lines are analysed based on data obtained with FLAMES and GMOS. Collisional effects are negligible (i.e. 0.1-0.6%) for transitions in the singlet cascade while relatively important for those in the triplet cascade. In particular, they can contribute up to 20% of the flux in the HeIl7065 line. Radiative transfer effects are important over an extended and circular area of 30pc in diameter centered at the Super Star Clusters. HeI abundance, y^+, has been mapped using extinction corrected fluxes of six HeI lines, realistic assumptions for T_e, n_e, and the stellar absorption equivalent width as well as the most recent emissivities. We found a mean of 10^3 y^+ ~81.6 over the mapped area. The relation between the excitation and the total helium abundance, y_tot, is consistent with no abund...

  20. Comparison of the Halpha equivalent width of HII regions in a flocculent and a grand design galaxy: possible evidences for IMF variations

    CERN Document Server

    Cedres, B; Tomita, A; Cedres, Bernabe; Cepa, Jordi; Tomita, Akihiko

    2005-01-01

    We present here a study of the Halpha equivalent widths of the flocculent galaxy NGC 4395 and the grand design galaxy NGC 5457. A difference between the mean values of the Halpha equivalent widths for the two galaxies has been found. Several hypotheses are presented in order to explain this difference: differences in age, metallicity, star formation rate, photon leakage and initial mass function. Various tests and Monte Carlo models are used to find out the most probable cause of this difference. The resultsshow that the possible cause for the difference could be a variation in the initial mass function. This difference is such that it seems to favor a fraction of more massive stars in the grand design galaxy when compared with the flocculent galaxy. This could be due to a change of the environmental conditions due to a density wave.

  1. The FMOS-COSMOS survey of star-forming galaxies at z~1.6. IV: Excitation state and chemical enrichment of HII regions

    CERN Document Server

    Kashino, D; Sanders, D; Kartaltepe, J S; Daddi, E; Renzini, A; Valentino, F; Rodighiero, G; Juneau, S; Kewley, L J; Zahid, H J; Arimoto, N; Nagao, T; Chu, J; Sugiyama, N; Civano, F; Ilbert, O; Kajisawa, M; Fevre, O Le; Maier, C; Onodera, M; Puglisi, A; Taniguchi, Y; COSMOS,

    2016-01-01

    We present results on the physical conditions of the interstellar medium of star-forming galaxies at 1.410^11Msun being well sampled. The excitation state and chemical enrichment of the ionized gas are investigated using diagnostic diagrams based on the ratios of emission line strengths, including Alpha, [NII]6584, [SII]6717,6731, Hbeta, and [OIII]5007. Our data confirm an offset of the star-forming sequence on the BPT diagram ([OIII]/Hbeta vs. [NII]/Halpha), primarily towards higher [OIII]/Hbeta, compared with local star-forming galaxies. Based on the [SII] ratio, we measure an electron density (n_e=222^{+172}_{-128} cm^-3), higher than that of local galaxies. Overall, these changes in emission-line properties are due to a higher ionization parameter in high redshift galaxies as demonstrated by a lower than expected [SII]/Halpha ratio and a comparison to theoretical models. These results likely rule out an offset in the BPT diagram caused by a harder radiation field or AGN as assessed with Chandra. Finally, ...

  2. Anhui Acrobatics Troupe—A Bright Pearl

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    THE Anhui Provincial Acrobatic Troupe was founded in 1956 by members of the former Beijing Youth Acrobatic Troupe and the China Acrobatic Troupe.The first president was the famous acrobat Cao Pengfei,also known as Fei Fei Fei.In the 40 years since its founding the troupe has developed tremendously.It has performed all over China and in nearly 30 countries and regions in the

  3. H-alpha macrospicules - Identification with EUV macrospicules and with flares in X-ray bright points

    Science.gov (United States)

    Moore, R. L.; Tang, F.; Bohlin, J. D.; Golub, L.

    1977-01-01

    The paper presents observational evidence that two newly observed transient solar phenomena, EUV macrospicules and X-ray bright-point flares, are closely related. Time-lapse H-alpha filtergram observations of the limb in quiet regions show small surgelike eruptions called H-alpha macrospicules. From the similarity of H-alpha macrospicules and EUV macrospicules, and from comparison of simultaneous H-alpha and He II 304 A observations, we conclude that H-alpha macrospicules are EUV macrospicules viewed in H-alpha, although most EUV macrospicules are too faint in H-alpha to appear on H-alpha filtergrams of normal exposure. From comparison of simultaneous X-ray and H-alpha observations of flares in X-ray bright points situated on the limb, we show that flares in X-ray bright points often produce H-alpha macrospicules.

  4. OH (1720 MHz) Masers: A Multiwavelength Study of the Interaction between the W51C Supernova Remnant and the W51B Star Forming Region

    CERN Document Server

    Brogan, C L; Hunter, T R; Richards, A M S; Chandler, C J; Lazendic, J S; Koo, B -C; Hoffman, I M; Claussen, M J

    2013-01-01

    We present a comprehensive view of the W51B HII region complex and the W51C supernova remnant (SNR) using new radio observations from the VLA, VLBA, MERLIN, JCMT, and CSO along with archival data from Spitzer, ROSAT, ASCA, and Chandra. Our VLA data include the first 400 cm (74 MHz) continuum image of W51 at high resolution (88 arcsec). The 400 cm image shows non-thermal emission surrounding the G49.2-0.3 HII region, and a compact source of non-thermal emission (W51B_NT) coincident with the previously-identified OH (1720 MHz) maser spots, non-thermal 21 and 90 cm emission, and a hard X-ray source. W51B_NT falls within the region of high likelihood for the position of TeV gamma-ray emission. Using the VLBA three OH (1720 MHz) maser spots are detected in the vicinity of W51B_NT with sizes of 60 to 300 AU and Zeeman effect magnetic field strengths of 1.5 to 2.2 mG. The multiwavelength data demonstrate that the northern end of the W51B HII region complex has been partly enveloped by the advancing W51C SNR and this...

  5. Vegetation, land surface brightness, and temperature dynamics after aspen forest die-off

    Science.gov (United States)

    Huang, Cho-ying; Anderegg, William R. L.

    2014-07-01

    Forest dynamics following drought-induced tree mortality can affect regional climate through biophysical surface properties. These dynamics have not been well quantified, particularly at the regional scale, and are a large uncertainty in ecosystem-climate feedback. We investigated regional biophysical characteristics through time (1995-2011) in drought-impacted (2001-2003), trembling aspen (Populus tremuloides Michx.) forests by utilizing Landsat time series green and brown vegetation cover, surface brightness (total shortwave albedo), and daytime land surface temperature. We quantified the temporal dynamics and postdrought recovery of these characteristics for aspen forests experiencing severe drought-induced mortality in the San Juan National Forest in southwestern Colorado, USA. We partitioned forests into three categories from healthy to severe mortality (Healthy, Intermediate, and Die-off) by referring to field observations of aspen canopy mortality and live aboveground biomass losses. The vegetation cover of die-off areas in 2011 (26.9% of the aspen forest) was significantly different compared to predrought conditions (decrease of 7.4% of the green vegetation cover and increase of 12.1% of the brown vegetation cover compared to 1999). The surface brightness of the study region 9 years after drought however was comparable to predrought estimates (12.7-13.7%). Postdrought brightness was potentially influenced by understory shrubs, since they became the top layer green canopies in disturbed sites from a satellite's point of view. Satellite evidence also showed that the differences of land surface temperature among the three groups increased substantially (≥45%) after drought, possibly due to the reduction of plant evapotranspiration in the Intermediate and Die-off sites. Our results suggest that the mortality-affected systems have not recovered in terms of the surface biophysical properties. We also find that the temporal dynamics of vegetation cover holds

  6. Brightness of synchrotron radiation from undulators and bending magnets.

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2015-03-01

    The maximum of the Wigner distribution (WD) of synchrotron radiation (SR) fields is considered as a possible definition of SR source brightness. Such a figure of merit was originally introduced in the SR community by Kim [(1986), Nucl. Instrum. Methods Phys. Res. A, 246, 71-76]. The brightness defined in this way is always positive and, in the geometrical optics limit, can be interpreted as the maximum density of photon flux in phase space. For undulator and bending magnet radiation from a single electron, the WD function can be explicitly calculated. In the case of an electron beam with a finite emittance the brightness is given by the maximum of the convolution of a single electron WD function and the probability distribution of the electrons in phase space. In the particular case when both electron beam size and electron beam divergence dominate over the diffraction size and the diffraction angle, one can use a geometrical optics approach. However, there are intermediate regimes when only the electron beam size or the electron beam divergence dominate. In these asymptotic cases the geometrical optics approach is still applicable, and the brightness definition used here yields back once more to the maximum photon flux density in phase space. In these intermediate regimes a significant numerical disagreement is found between exact calculations and the approximation for undulator brightness currently used in the literature. The WD formalism is extended to a satisfactory theory for the brightness of a bending magnet. It is found that in the intermediate regimes the usually accepted approximation for bending magnet brightness turns out to be inconsistent even parametrically.

  7. Search for bright nearby M dwarfs with virtual observatory tools

    Energy Technology Data Exchange (ETDEWEB)

    Aberasturi, M.; Caballero, J. A.; Montesinos, B.; Gálvez-Ortiz, M. C.; Solano, E.; Martín, E. L. [Centro de Astrobiología (CSIC-INTA), Departamento de Astrofísica, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain)

    2014-08-01

    Using Virtual Observatory tools, we cross-matched the Carlsberg Meridian 14 and the 2MASS Point Source catalogs to select candidate nearby bright M dwarfs distributed over ∼25,000 deg{sup 2}. Here, we present reconnaissance low-resolution optical spectra for 27 candidates that were observed with the Intermediate Dispersion Spectrograph at the 2.5 m Isaac Newton Telescope (R≈ 1600). We derived spectral types from a new spectral index, R, which measures the ratio of fluxes at 7485-7015 Å and 7120-7150 Å. We also used VOSA, a Virtual Observatory tool for spectral energy distribution fitting, to derive effective temperatures and surface gravities for each candidate. The resulting 27 targets were M dwarfs brighter than J = 10.5 mag, 16 of which were completely new in the Northern hemisphere and 7 of which were located at less than 15 pc. For all of them, we also measured Hα and Na I pseudo-equivalent widths, determined photometric distances, and identified the most active stars. The targets with the weakest sodium absorption, namely, J0422+2439 (with X-ray and strong Hα emissions), J0435+2523, and J0439+2333, are new members in the young Taurus-Auriga star-forming region based on proper motion, spatial distribution, and location in the color-magnitude diagram, which reopens the discussion on the deficit of M2-4 Taurus stars. Finally, based on proper motion diagrams, we report on a new wide M dwarf binary system in the field, LSPM J0326+3929EW.

  8. VELOCITY BUNCHING OF HIGH-BRIGHTNESS ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Musumeci, P; Rosenzweig, J B; Brown, W J; England, R J; Ferrario, M; Jacob, J S; Thompson, M C; Travish, G; Tremaine, A M; Yoder, R

    2004-10-15

    Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments

  9. Velocity bunching of high-brightness electron beams

    Directory of Open Access Journals (Sweden)

    S. G. Anderson

    2005-01-01

    Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

  10. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

  11. Transition undulator radiation as bright infrared sources

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.J. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.

  12. Bright points and ejections observed on the sun by the KORONAS-FOTON instrument TESIS

    Science.gov (United States)

    Ulyanov, A. S.; Bogachev, S. A.; Kuzin, S. V.

    2010-10-01

    Five-second observations of the solar corona carried out in the FeIX 171 Å line by the KORONAS-FOTON instrument TESIS are used to study the dynamics of small-scale coronal structures emitting in and around coronal bright points. The small-scale structures of the lower corona display complex dynamics similar to those of magnetic loops located at higher levels of the solar corona. Numerous detected oscillating structures with sizes below 10 000 km display oscillation periods from 50 to 350 s. The period distributions of these structures are different for P 150 s, which implies that different oscillation modes are excited at different periods. The small-scale structures generate numerous flare-like events with energies 1024-1026 erg (nanoflares) and with a spatial density of one event per arcsecond or more observed over an area of 4 × 1011 km2. Nanoflares are not associated with coronal bright points, and almost uniformly cover the solar disk in the observation region. The ejections of solar material from the coronal bright points demonstrate velocities of 80-110 km/s.

  13. Simulating a slow bar in the low surface brightness galaxy UGC 628

    Science.gov (United States)

    Chequers, Matthew H.; Spekkens, Kristine; Widrow, Lawrence M.; Gilhuly, Colleen

    2016-12-01

    We present a disc-halo N-body model of the low surface brightness galaxy UGC 628, one of the few systems that harbours a `slow' bar with a ratio of corotation radius to bar length of R ≡ R_c/a_b ˜ 2. We select our initial conditions using SDSS DR10 photometry, a physically motivated radially variable mass-to-light ratio profile, and rotation curve data from the literature. A global bar instability grows in our submaximal disc model, and the disc morphology and dynamics agree broadly with the photometry and kinematics of UGC 628 at times between peak bar strength and the onset of buckling. Prior to bar formation, the disc and halo contribute roughly equally to the potential in the galaxy's inner region, giving the disc enough self-gravity for bar modes to grow. After bar formation, there is significant mass redistribution, creating a baryon-dominated inner and dark matter-dominated outer disc. This implies that, unlike most other low surface brightness galaxies, UGC 628 is not dark matter dominated everywhere. Our model nonetheless implies that UGC 628 falls on the same relationship between dark matter fraction and rotation velocity found for high surface brightness galaxies, and lends credence to the argument that the disc mass fraction measured at the location where its contribution to the potential peaks is not a reliable indicator of its dynamical importance at all radii.

  14. The Distribution of Star Formation and Metals in the Low Surface Brightness Galaxy UGC 628

    CERN Document Server

    Young, J E; Wang, Sharon X

    2015-01-01

    We introduce the MUSCEL Program (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies), a project aimed at determining the star-formation histories of low surface brightness galaxies. MUSCEL utilizes ground-based optical spectra and space-based UV and IR photometry to fully constrain the star-formation histories of our targets with the aim of shedding light on the processes that led low surface brightness galaxies down a different evolutionary path from that followed by high surface brightness galaxies, such as our Milky Way. Here we present the spatially-resolved optical spectra of UGC 628, observed with the VIRUS-P IFU at the 2.7-m Harlen J. Smith Telescope at the McDonald Observatory, and utilize emission-line diagnostics to determine the rate and distribution of star formation as well as the gas-phase metallicity and metallicity gradient. We find highly clustered star formation throughout UGC 628, excluding the core regions, and a log(O/H) metallicity around -4.2, with mo...

  15. Towards an Understanding of the Mid-Infrared Surface Brightness of Normal Galaxies

    CERN Document Server

    Dale, D A; Silbermann, N A; Contursi, A; Malhotra, S; Rubin, R H; Dale, Daniel A.; Helou, George; Silbermann, Nancy A.; Contursi, Alessandra; Malhotra, Sangeeta; Rubin, Robert H.

    1999-01-01

    We report a mid-infrared color and surface brightness analysis of IC 10, NGC 1313, and NGC 6946, three of the nearby galaxies studied under the Infrared Space Observatory Key Project on Normal Galaxies. Images with < 9 arcsecond (170 pc) resolution of these nearly face-on, late-type galaxies were obtained using the LW2 (6.75 mu) and LW3 (15 mu) ISOCAM filters. Though their global I_nu(6.75 mu)/I_nu(15 mu) flux ratios are similar and typical of normal galaxies, they show distinct trends of this color ratio with mid-infrared surface brightness. We find that I_nu(6.75 mu)/I_nu(15 mu) ~< 1 only occurs for regions of intense heating activity where the continuum rises at 15 micron and where PAH destruction can play an important role. The shape of the color-surface brightness trend also appears to depend, to the second-order, on the hardness of the ionizing radiation. We discuss these findings in the context of a two-component model for the phases of the interstellar medium and suggest that star formation inte...

  16. A novel high-brightness broadband light-source technology from the VUV to the IR

    Science.gov (United States)

    Horne, Stephen; Smith, Don; Besen, Matthew; Partlow, Matthew; Stolyarov, Daniil; Zhu, Huiling; Holber, William

    2010-04-01

    A novel technology has been developed which enables high-brightness, broadband light output from the VUV to the IR spectral regions. A focused laser is used to sustain a high-pressure xenon discharge inside a bulb, creating a smaller, hotter discharge than can be obtained by using an electrically-driven discharge. This allows for continuous output down to 120 nm wavelength and into the infrared. Application areas include hyperspectral imaging, standoff detection, surveillance, bioanalytical instrumentation, microscopy, and materials studies. Laser-driven optical discharges were first investigated over 30 years ago, providing the initial technical understanding of such discharges. However it took the convergence of two separate elements - the availability of low-cost, high-efficiency CW diode lasers; and a market need for high-brightness, broadband light source - to provide the impetus for further development in this area. Using near-IR CW diode lasers at power levels from 15 W to over 2000 W, we have generated high-pressure xenon discharges having temperatures as high as 10,000 C. The optical brightness of these discharges can be over an order of magnitude higher than those obtainable from the brightest xenon arc lamps, and can be several orders of magnitude brighter than deuterium lamps. Results from modeling of these discharges as well as experimental measurements will be presented.

  17. Life-threatening motor vehicle crashes in bright sunlight.

    Science.gov (United States)

    Redelmeier, Donald A; Raza, Sheharyar

    2017-01-01

    Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight.This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later.The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9-24, P vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash.

  18. Night Sky Brightness at San Pedro Martir Observatory

    Science.gov (United States)

    Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

    2017-03-01

    We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec‑2 since early 2014 due to the present solar cycle.

  19. Sky brightness and twilight measurements at Jogyakarta city, Indonesia

    Science.gov (United States)

    Herdiwijaya, Dhani

    2016-11-01

    The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer.

  20. Dark-bright soliton interactions beyond the integrable limit

    Science.gov (United States)

    Katsimiga, G. C.; Stockhofe, J.; Kevrekidis, P. G.; Schmelcher, P.

    2017-01-01

    In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions, motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. In particular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interaction between two dark-bright solitons in a homogeneous environment beyond the integrable regime, by considering general inter- and intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case where the bright solitons are out of phase. As the intercomponent interaction is increased, we also identify an exponential instability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter gives rise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of the bound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations and monitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis.