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Sample records for ae star hd

  1. The Herbig Ae Star HD 163296 in X-Rays

    Science.gov (United States)

    Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward

    2004-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT approximately 0.5 approximately kev), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least approximately 100 approximately G and perhaps as high as several kG.

  2. The Herbig Ae star HD 163296 in X-rays

    CERN Document Server

    Swartz, D A; Elsner, R F; Ghosh, K K; Grady, C A; Wassell, E; Woodgate, B E; Kimble, R A; Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward; Woodgate, Bruce E.; Kimble, Randy A.

    2005-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT~0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion.

  3. Photometric variability of the Herbig Ae star HD 37806

    CERN Document Server

    Rucinski, S M; Hareter, M; Pojmanski, G; Kuschnig, R; Matthews, J M; Guenther, D B; Moffat, A F J; Sasselov, D; Weiss, W W

    2010-01-01

    The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales ranging between minutes and several years. A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <~0.05 on a time scale of a few years. The resulting variability has properties of stochastic "red" nois...

  4. Active phenomena in the pre-main sequence Herbig Ae star HD 163296

    Science.gov (United States)

    Catala, C.; Praderie, F.; Simon, T.; Talavera, A.; The, P. S.

    1989-01-01

    Observations by IUE of the short-term variability of the Mg II and Ca II resonance lines in the Herbig Ae star HD 163296 are presented. Evidence that these lines show a phenomenon of rotational modulation, similar to the one observed in AB Aur, another Herbig Ae star is found. The variations in the spectrum of HD 163296 are even more conspicuous than in the spectrum of AB Aur. Magnetically structured winds may thus be a widespread phenomenon among the pre-main sequence Herbig Ae/Be stars.

  5. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    DEFF Research Database (Denmark)

    Järvinen, S. P.; Hubrig, S.; Schöller, M.;

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra...... of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability...

  6. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999

    Science.gov (United States)

    Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.

    1993-01-01

    Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10(exp -8) solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.

  7. MOST observations of the Herbig Ae {\\delta}-Scuti star HD 34282

    CERN Document Server

    Casey, M P; Guenther, D B; Weiss, W W; Amado, P J; Díaz-Fraile, D; Rodriguez, E; Kuschnig, R; Matthews, J M; Moffat, A F J; Rowe, J F; Rucinski, S M; Sasselov, D

    2012-01-01

    MOST observations and model analysis of the Herbig Ae star HD 34282 (V1366 Ori) reveal {\\delta}-Scuti pulsations. 22 frequencies are observed, 10 of which confirm those previously identified by Amado et al. (2006), and 12 of which are newly discovered in this work. We show that the weighted-average frequency in each group fits the radial p-mode frequencies of viable models. We argue that the observed pulsation spectrum extends just to the edge to the acoustic cut-off frequency and show that this also is consistent with our best-fitting models.

  8. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    CERN Document Server

    Järvinen, S P; Schöller, M; Ilyin, I; Carroll, T A; Korhonen, H

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magn...

  9. The magnetic field of the pre-main sequence Herbig Ae star HD 190073

    Science.gov (United States)

    Catala, C.; Alecian, E.; Donati, J.-F.; Wade, G. A.; Landstreet, J. D.; Böhm, T.; Bouret, J.-C.; Bagnulo, S.; Folsom, C.; Silvester, J.

    2007-01-01

    Context: The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. Aims: The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. Methods: We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution, high signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Results: Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74± 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. Conclusions: .This magnetic detection contributes an important new observational discovery which will aid our understanding of stellar magnetism at intermediate masses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  10. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    CERN Document Server

    Ellerbroek, L E; Dougados, C; Cabrit, S; Sitko, M L; Sana, H; Kaper, L; de Koter, A; Klaassen, P D; Mulders, G D; Mendigutia, I; Grady, C A; Grankin, K; van Winckel, H; Bacciotti, F; Russell, R W; Lynch, D K; Hammel, H B; Beerman, L C; Day, A N; Huelsman, D M; Werren, C; Henden, A; Grindlay, J

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination...

  11. The circumstellar disc around the Herbig AeBe star HD169142

    CERN Document Server

    Dent, W R F; Osorio, M; Calvet, N; Anglada, G

    2006-01-01

    We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy), unresolved (~1") 7 mm continuum emission, being one of the brightest isolated Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm wavelength range, indicating that the observed flux density at 7mm is most likely dominated by thermal dust emission coming from a circumstellar disc. We use available photometric data from the literature to model the spectral energy distribution (SED) of this object from radio to near-ultraviolet frequencies. The observed SED can be understood in terms of an irradiated accretion disc with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star with an age of ~10 Myr....

  12. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD101412

    CERN Document Server

    Schöller, M; Cahuasqui, J A; Drake, N A; Hubrig, S; Petr-Gotzens, M G; Savanov, I S; Wolff, B; Gonzalez, J F; Mysore, S; Ilyin, I; Jarvinen, S P; Stelzer, B

    2016-01-01

    Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD101412. We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He I lambda 10,830 and Pa gamma lines, formed in the accretion region. We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD101412 can be explained by rotational modulation of line profiles generated by accreting gas with a pe...

  13. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD 101412

    Science.gov (United States)

    Schöller, M.; Pogodin, M. A.; Cahuasquí, J. A.; Drake, N. A.; Hubrig, S.; Petr-Gotzens, M. G.; Savanov, I. S.; Wolff, B.; González, J. F.; Mysore, S.; Ilyin, I.; Järvinen, S. P.; Stelzer, B.

    2016-07-01

    Context. Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. Aims: We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD 101412. Methods: We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD 101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD 101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He iλ10 830 and Paγ lines, formed in the accretion region. Results: We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD 101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d±1.68d. The discovery of this period, about half of the magnetic rotation period Pm = 42.076d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 087.C-0124(A), 088.C-0218(A,B,C,E), 090.C-0331(A), and 092.C-0126(A).

  14. Near-infrared interferometric observation of the Herbig Ae star HD144432 with VLTI/AMBER

    CERN Document Server

    Chen, Lei; Wang, Yang; Weigelt, Gerd; Hofmann, Karl-Heinz; Kraus, Stefan; Schertl, Dieter; Lagarde, Stephane; Natta, Antonella; Petrov, Roman; Robbe-Dubois, Sylvie; Tatulli, Eric

    2012-01-01

    We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the structure of its inner dust disk. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H- and K-band visibilities, the near- and mid-infrared visibilities from the literature, and the SED of HD144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. We derived a K-band ring-fit radius of 0.17 \\pm 0.01 AU and an H-band radius of 0.18 \\pm 0.01 AU (for a distance of 145 pc). This measured K-band radius of \\sim0.17 AU lies in the range between the dust sublimation radius of \\sim0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (\\sim0.27 AU). We found that an additional extended halo component is required in both the geometric and temperature-gradi...

  15. Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD104237

    CERN Document Server

    Tatulli, E; Natta, A; Testi, L

    2006-01-01

    We investigate the origin of the $\\mathrm{Br}\\gamma$ emission of the Herbig Ae star HD104237 on Astronomical Unit (AU) scales. Using AMBER/VLTI at a spectral resolution R=1500 spatially resolve the emission in both the BrGamma line and the adjacent continuum. The visibility does not vary between the continuum and the BrGamma line, even though the line is strongly detected in the spectrum, with a peak intensity 35% above the continuum. This demonstrates that the line and continuum emission have similar size scales. We assume that the K-band continuum excess originates in a ``puffed-up'' inner rim of the circumstellar disk, and discuss the likely origin of BrGamma. We conclude that this emission most likely arises from a compact disk wind, launched from a region 0.2-0.5 AU from the star, with a spatial extent similar to that of the near infrared continuum emission region, i.e, very close to the inner rim location.

  16. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters

    CERN Document Server

    Fumel, Aurelie

    2011-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile. To do this, we worked on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present a mode identification corresponding to the detected dominan...

  17. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    NARCIS (Netherlands)

    L.E. Ellerbroek; L. Podio; C. Dougados; S. Cabrit; M.L. Sitko; H. Sana; L. Kaper; A. de Koter; P.D. Klaassen; G.D. Mulders; I. Mendigutía; C.A. Grady; K. Grankin; H. van Winckel; F. Bacciotti; R.W. Russell; D.K. Lynch; H.B. Hammel; L.C. Beerman; A.N. Day; D.M. Huelsman; C. Werren; A. Henden; J. Grindlay

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the out

  18. The compact H$\\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry

    CERN Document Server

    Mendigutía, I; Mourard, D; Muzerolle, J

    2016-01-01

    This work presents CHARA/VEGA H$\\alpha$ spectro-interferometry (R ~ 6000, and $\\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The observed H$\\alpha$ emission is spatially unresolved, indicating that the size of the H$\\alpha$ emitting region is smaller than ~ 0.21 and 0.12 au for HD 179218 and HD 141529 (~ 15 and 16 R*, respectively). This is smaller than for the two other HAeBes previously observed with the same instrumentation. Two different scenarios have been explored in order to explain the compact line emitting regions. A hot, several thousand K, blackbody disc is consistent with the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is able to reproduce the bulk of the H$\\alpha$ emission shown by HD 179218, confirming previous estimates from MA shock modelling with a mass accretion rate of 10^-8 Msun/yr, and an inclination to the line of sight between 30 and 50 degr. The H$\\al...

  19. Gas and dust mass in the disk around the Herbig Ae star HD169142

    CERN Document Server

    Panić, Olja; Wilner, David; Qi, Chunhua

    2008-01-01

    We investigate the physical structure of the gas component of the disk around the pre-main-sequence star HD169142. The 13CO and C18O J=2-1 line emission is observed from the disk with 1.4'' resolution using the Submillimeter Array. We adopt the disk physical structure derived from a model which fits the spectral energy distribution of HD169142. We obtain the full three-dimensional information on the CO emission with the aid of a molecular excitation and radiative transfer code. This information is used for the analysis of our observations and previous 12CO J=2-1 and 1.3 mm continuum data. The disk is in Keplerian rotation and seen at an inclination close to 13 deg from face-on. We conclude that the regions traced by different CO isotopologues are distinct in terms of their vertical location within the disk, their temperature and their column densities. With the given disk structure, we find that freeze-out is not efficient enough to remove a significant amount of CO from gas phase. Both observed lines match t...

  20. DISCOVERY OF A TWO-ARMED SPIRAL STRUCTURE IN THE GAPPED DISK AROUND HERBIG Ae STAR HD 100453

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Kevin; Apai, Daniel [Department of Astronomy/Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Kasper, Markus [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Robberto, Massimo, E-mail: kwagner@as.arizona.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2015-11-01

    We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (∼42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (∼21–29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ∼850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects.

  1. Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD163296: evidence for refractory dust?

    CERN Document Server

    Benisty, M; Isella, A; Berger, J-P; Massi, F; LeBouquin, J-B; Merand, A; Duvert, G; Kraus, S; Malbet, F; Olofsson, J; Robbe-Dubois, S; Testi, L; Vannier, M; Weigelt, G

    2009-01-01

    We present new long-baseline spectro-interferometric observations of the HerbigAe star HD163296 obtained in the H and K bands with the AMBER instrument at VLTI. The observations cover a range of spatial resolutions between 3 and 12 milli-arcseconds, with a spectral resolution of ~30. With a total of 1481 visibilities and 432 closure phases, they result in the best (u,v) coverage achieved on a young star so far. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model where a dominant contribution to the H and K band emissions arises from an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At the latter distance from the sta...

  2. High-resolution Br-gamma spectro-interferometry of the transitional Herbig Ae/Be star HD 100546: a Keplerian gaseous disc inside the inner rim

    CERN Document Server

    Mendigutía, I; Oudmaijer, R D; Fairlamb, J R; Carciofi, A C; Ilee, J D; Vieira, R G

    2015-01-01

    We present spatially and spectrally resolved Br-gamma emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br-gamma spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2-4 mas and 12000. The Br-gamma visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br-gamma line -displaced 0.6 mas (0.06 au at 100 pc) NE from the star- and that of the K-band continuum emission -displaced 0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br-gamma line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest ...

  3. The Herbig Ae SB2 System HD 104237

    CERN Document Server

    Cowley, Charles R; Hubrig, Swetlana

    2013-01-01

    The double-lined spectroscopic binary HD 104237 (DX Cha) is part of a complex system of some half-dozen nearby young stars. We report a significant change from an orbit for the SB2 system derived from 1999-2000 observations. We obtain abundances from the primary and secondary spectra. The abundance analysis uses both detailed spectral synthesis and determinations based on equivalent widths of weak absorption lines with W(lambda) typically < 25 mA. Abundances are derived for 25 elements in the primary, and 17 elements in the secondary. Apart from lithium and zirconium, abundances do not depart significantly from solar. Lithium may be marginally enhanced with respect to the meteoritic value in the primary. It somewhat depleted in the secondary. The emission-line spectrum is typical of Herbig Ae stars. We compare and contrast the spectra of the HD 104237 primary and two other Herbig Ae stars with low v.sin(i), HD 101412 and HD 190073.

  4. Variability of Disk Emission in Pre-main Sequence and Related Stars. V. Changes in the Innermost Disk Structure of the Herbig AE Star HD 31648 = MWC 480

    Science.gov (United States)

    Fernandes, Rachel; Long, Zachary; Sitko, Michael L.; Grady, C. A.; Kusakabe, Nobuhiko

    2017-01-01

    We present five epochs of near IR observations of the protoplanetary disk around HD 31648 (MWC 480). A mass accretion rate of approximately 1.1×10-7 Msun/year was derived from Brγ and Paβ lines. The spectral energy distribution (SED) reveals a variability of about 30% between 1.5 and 10 microns. We present the theoretical modeling analysis of the disk in HD 31648 using Monte-Carlo Radiation Transfer Code (MRTC). We find that varying the height of the inner rim successfully produces a shift in the NIR flux.

  5. HARPS spectropolarimetry of Herbig Ae/Be stars

    CERN Document Server

    Hubrig, S; Schoeller, M; Curto, G Lo

    2013-01-01

    Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right- and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD58647 and HD98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD104237 by Donati et al. and confirm the previous detection of a...

  6. The Disk Atmospheres of Three Herbig Ae/Be Stars

    CERN Document Server

    Harker, D E; Wooden, D H; Temi, P; Harker, David E.; Woodward, Charles E.; Wooden, Diane H.; Temi, Pasquale

    2004-01-01

    We present infrared (IR) spectrophotometry ($R \\simeq 180$) of three Herbig Ae/Be stars surrounded by possible protoplanetary disks: HD 150193, HD100546 and HD 179218. We construct a mid-IR spectral energy distributions (SED) for each object by using $7.6 - 13.2$ \\micron HIFOGS spectra, 2.4 -- 45 \\micron\\ spectrophotometry from the {\\it ISO} SWS, the 12, 25, 60, and 100 \\micron\\ photometric points from IRAS, and for HD 179218, photometric bolometric data points from the Mt. Lemmon Observing Facility. The SEDs are modeled by using an expanded version of the \\citet{chigol97} two-layer, radiative and hydrostatic equilibrium, passive disk. This expanded version includes the emission from Mg-pure crystalline olivine (forsterite) grains in the disk surface layer. HD 150193 contains no crystals while HD 100546 and HD 179218 respectively show evidence of having crystalline silicates in the surface layers of their disks. We find that the inner region of HD100546 has a 37% higher crystalline-to-amorphous silicate ratio...

  7. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614 . Further evidence for a giant planet inside the disk?

    Science.gov (United States)

    Carmona, A.; Thi, W. F.; Kamp, I.; Baruteau, C.; Matter, A.; van den Ancker, M.; Pinte, C.; Kóspál, A.; Audard, M.; Liebhart, A.; Sicilia-Aguilar, A.; Pinilla, P.; Regály, Zs.; Güdel, M.; Henning, Th.; Cieza, L. A.; Baldovin-Saavedra, C.; Meeus, G.; Eiroa, C.

    2017-02-01

    Context. Quantifying the gas surface density inside the dust cavities and gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the inner disk of HD 139614, an accreting 9 Myr Herbig Ae star with a (pre-)transition disk exhibiting a dust gap from 2.3 ± 0.1 to 5.3 ± 0.3 AU. Methods: We observed HD 139614 with ESO/VLT CRIRES and obtained high-resolution (R 90 000) spectra of CO ro-vibrational emission at 4.7 μm. We derived constraints on the disk's structure by modeling the CO isotopolog line-profiles, the spectroastrometric signal, and the rotational diagrams using grids of flat Keplerian disk models. Results: We detected υ = 1 → 0 12CO, 2→1 12CO, 1→0 13CO, 1→0 C18O, and 1→0 C17O ro-vibrational lines. Lines are consistent with disk emission and thermal excitation. 12CO υ = 1 → 0 lines have an average width of 14 km s-1, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km s-1 narrower than 12CO υ = 1 → 0, and are dominated by emission at R ≥ 6 AU. The 12CO υ = 1 → 0 composite line-profile indicates that if there is a gap devoid of gas it must have a width narrower than 2 AU. We find that a drop in the gas surface density (δgas) at R R R R ≤ 1 AU of 5 × 1015 cm-2 (NH ≤ 5 × 1019 cm-2). Conclusions: The dust gap in the disk of HD 139614 has molecular gas. The distribution and amount of gas at R ≤ 6 AU in HD 139614 is very different from that of a primordial disk. The gas surface density in the disk at R ≤ 1 AU and at 1 R 2 AU) gas gap, suggest the presence of an embedded program 091.C-0671(B).

  8. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?

    CERN Document Server

    Carmona, A; Kamp, I; Baruteau, C; Matter, A; Ancker, M van den; Pinte, C; Kóspál, A; Audard, M; Liebhart, A; Sicilia-Aguilar, A; Pinilla, P; Regály, Zs; Güdel, M; Henning, Th; Cieza, L A; Baldovin-Saavedra, C; Meeus, G; Eiroa, C

    2016-01-01

    Context: Quantifying the gas content inside the dust gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the disk of HD 139614, a Herbig Ae star with a transition disk exhibiting a dust gap from 2.3 to 6 AU. Methods: We have obtained ESO/VLT CRIRES high-resolution spectra of CO ro-vibrational emission. We derive disk structure constraints by modeling the line profiles, the spectroastrometric signal, and the rotational diagrams using flat Keplerian disk models. Results: We detected v=1-0 12CO, 2-1 12CO, 1-0 13CO, 1-0 C18O, and 1-0 C17O ro-vibrational lines. 12CO v=1-0 lines have an average width of 14 km/s, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km/s narrower, and are dominated by emission at R>6 AU. The 12CO v=1-0 line profile indicates that if there is a gap in the gas it must be narrower than 2 AU. We find that a drop in the gas surface density (delta_gas)...

  9. Accretion Rates in Herbig Ae stars

    CERN Document Server

    López, R G; Testi, L; Habart, E

    2006-01-01

    Accretion rates from disks around pre-main sequence stars are of importance for our understanding of planetary formation and disk evolution. We provide in this paper estimates of the mass accretion rates in the disks around a large sample of Herbig Ae stars. We obtained medium resolution 2 micron spectra and used the results to compute values of Macc from the measured luminosity of the Br_gamma emission line, using a well established correlation between L(Br_gamma) and the accretion luminosity Lacc. We find that 80% of the stars, all of which have evidence of an associated circumstellar disk, are accreting matter, with rates 3x10^{-9} 10^{-7} Msun/yr. In most HAe stars the accretion rate is sufficiently low that the gas in the inner disk, inside the dust evaporation radius, is optically thin and does not prevent the formation of a puffed-up rim, where dust is directly exposed to the stellar radiation. When compared to the Macc values found for lower-mass stars in the star forming regions Taurus and Ophiuchus,...

  10. The Herbig Ae SB2 system HD 104237

    Directory of Open Access Journals (Sweden)

    Cowley C. R.

    2014-01-01

    Full Text Available We present here the most recent abundance analysis of this Herbig Ae system based on high-resolution UVES and HARPS spectra and the results of our magnetic field measurements using high-resolution spectra obtained with HARPSpol.

  11. Mid-infrared spectra of PAH emission in Herbig AeBe stars

    CERN Document Server

    Sloan, G C; Forrest, W J; Leibensperger, E; Sargent, B; Li, A; Najita, J; Watson, D M; Brandl, B R; Chen, C H; Green, J D; Markwick-Kemper, F; Herter, T L; D'Alessio, P; Morris, P W; Barry, J; Hall, P; Myers, P C; Houck, J R

    2005-01-01

    We present spectra of four Herbig AeBe stars obtained with the Infrared Spectrograph (IRS). on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 um emission feature shifted to 6.3 um and the strongest C-C skeletal-mode feature occuring at 7.9 um instead of at 7.7 um as is often seen. Remarkably, none of the four stars have silicate emission. The strength of the 7.9 um feature varies with respect to the 11.3 um feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 um. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 um which may be related to the 12.7 um PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 u...

  12. The evolved pulsating CEMP star HD112869

    CERN Document Server

    Začs, L; Grankina, A; Deveikis, V; Kaminskyi, B; Pavlenko, Y; Musaev, F

    2015-01-01

    Radial velocity measurements, $BVR_C$ photometry, and high-resolution spectroscopy in the wavelength region from blue to near infrared are employed in order to clarify the evolutionary status of the carbon-enhanced metal-poor star HD112869 with unique ratio of carbon isotopes in the atmosphere. An LTE abundance analysis was carried out using the method of spectral synthesis and new self consistent 1D atmospheric models. The radial velocity monitoring confirmed semiregular variations with a peak-to-peak amplitude of about 10 km $s^{-1}$ and a dominating period of about 115 days. The light, color and radial velocity variations are typical of the evolved pulsating stars. The atmosphere of HD112869 appears to be less metal-poor than reported before, [Fe/H] = -2.3 $\\pm$0.2 dex. Carbon to oxygen and carbon isotope ratios are found to be extremely high, C/O $\\simeq$ 12.6 and $^{12}C/^{13}C \\gtrsim$ 1500, respectively. The s-process elements yttrium and barium are not enhanced, but neodymium appears to be overabundan...

  13. Investigation of the magnetic field characteristics of Herbig Ae/Be stars: Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp stars

    CERN Document Server

    Wade, G A; Bagnulo, S; Landstreet, J D; Mason, E; Silvester, J; Alecian, E; Böhm, T; Bouret, J C; Catala, C; Donati, J F; Folsom, C; Bale, K

    2006-01-01

    We are investigating the magnetic characteristics of pre-main sequence Herbig Ae/Be stars, with the aim of (1) understanding the origin and evolution of magnetism in intermediate-mass stars, and (2) exploring the influence of magnetic fields on accretion, rotation and mass-loss at the early stages of evolution of A, B and O stars. We have begun by conducting 2 large surveys of Herbig Ae/Be stars, searching for direct evidence of photospheric magnetic fields via the longitudinal Zeeman effect. From observations obtained using FORS1 at the ESO-VLT and ESPaDOnS at the Canada-France-Hawaii Telescope, we report the confirmed detection of magnetic fields in 4 pre-main sequence A- and B-type stars, and the apparent (but as yet unconfirmed) detection of fields in 2 other such stars. We do not confirm the detection of magnetic fields in several stars reported by other authors to be magnetic: HD 139614, HD 144432 or HD 31649. One of the most evolved stars in the detected sample, HD 72106A, shows clear evidence of stron...

  14. Triggered Star Formation Surrounding Wolf-Rayet Star HD 211853

    Science.gov (United States)

    Liu, Tie; Wu, Yuefang; Zhang, Huawei; Qin, Sheng-Li

    2012-05-01

    The environment surrounding Wolf-Rayet (W-R) star HD 211853 is studied in molecular, infrared, as well as radio, and H I emission. The molecular ring consists of well-separated cores, which have a volume density of 103 cm-3 and kinematic temperature ~20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From the spectral energy distribution modeling toward the young stellar objects, the sequential star formation is revealed on a large scale in space spreading from the W-R star to the molecular ring. A small-scale sequential star formation is revealed toward core "A," which harbors a very young star cluster. Triggered star formations are thus suggested. The presence of the photodissociation region, the fragmentation of the molecular ring, the collapse of the cores, and the large-scale sequential star formation indicate that the "collect and collapse" process functions in this region. The star-forming activities in core "A" seem to be affected by the "radiation-driven implosion" process.

  15. Triggered star formation surrounding Wolf-Rayet star HD 211853

    CERN Document Server

    Liu, Tie; Zhang, Huawei; Qin, Sheng-Li

    2012-01-01

    The environment surrounding Wolf-Rayet star HD 211853 is studied in molecular emission, infrared emission, as well as radio and HI emission. The molecular ring consists of well-separated cores, which have a volume density of 10$^{3}$ cm$^{-3}$ and kinematic temperature $\\sim$20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From SED modeling towards the young stellar objects (YSOs), sequential star formation is revealed on a large scale in space spreading from the Wolf-Rayet star to the molecular ring. A small scale sequential star formation is revealed towards core A, which harbors a very young star cluster. Triggered star formations is thus suggested. The presence of PDR, the fragmentation of the molecular ring, the collapse of the cores, the large scale sequential star formation indicate the "Collect and Collapse" process functions in this region. The star forming activities in core A seem to be affected by the "Radiation-Driven Implosion" (...

  16. TRIGGERED STAR FORMATION SURROUNDING WOLF-RAYET STAR HD 211853

    Energy Technology Data Exchange (ETDEWEB)

    Liu Tie; Wu Yuefang; Zhang Huawei [Department of Astronomy, Peking University, 100871 Beijing (China); Qin Shengli, E-mail: liutiepku@gmail.com [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

    2012-05-20

    The environment surrounding Wolf-Rayet (W-R) star HD 211853 is studied in molecular, infrared, as well as radio, and H I emission. The molecular ring consists of well-separated cores, which have a volume density of 10{sup 3} cm{sup -3} and kinematic temperature {approx}20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From the spectral energy distribution modeling toward the young stellar objects, the sequential star formation is revealed on a large scale in space spreading from the W-R star to the molecular ring. A small-scale sequential star formation is revealed toward core 'A', which harbors a very young star cluster. Triggered star formations are thus suggested. The presence of the photodissociation region, the fragmentation of the molecular ring, the collapse of the cores, and the large-scale sequential star formation indicate that the 'collect and collapse' process functions in this region. The star-forming activities in core 'A' seem to be affected by the 'radiation-driven implosion' process.

  17. Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509

    Science.gov (United States)

    Wittrock, Justin M.; Kane, Stephen R.; Horch, Elliott P.; Hirsch, Lea; Howell, Steve B.; Ciardi, David R.; Everett, Mark E.; Teske, Johanna K.

    2016-11-01

    An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important, because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD 2638 and HD 164509. The stellar companion to HD 2638 has been previously detected, but the companion to HD 164509 is a newly discovered companion. The angular separation for HD 2638 is 0.512 ± 0.″002 and for HD 164509 is 0.697+/- 0\\buildrel{\\prime\\prime}\\over{.} 002. This corresponds to a projected separation of 25.6 ± 1.9 au and 36.5 ± 1.9 au, respectively. By employing stellar isochrone models, we estimate the mass of the stellar companions of HD 2638 and HD 164509 to be 0.483 ± 0.007 M ⊙ and 0.416+/- 0.007 {M}⊙ , respectively, and their effective temperatures to be 3570 ± 8 K and 3450 ± 7 K, respectively. These results are consistent with the detected companions being late-type M dwarfs.

  18. Magnetic fields of Herbig Ae/Be stars

    Directory of Open Access Journals (Sweden)

    Hubrig S.

    2014-01-01

    Full Text Available We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. The magnetic field geometries of these stars, investigated with spectropolarimetric time series, can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields have recently been observed with X-shooter in the visible and the near-IR, as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of the accretion flow and the accretion disk gas emission.

  19. The nature of the late B-type stars HD 67044 and HD 42035

    CERN Document Server

    Monier, R; Royer, F

    2016-01-01

    While monitoring a sample of apparently slowly rotating superficially normal bright late B and early A stars in the northern hemisphere, we have discovered that HD 67044 and HD 42035, hitherto classified as normal late B-type stars, are actually respectively a new chemically peculiar star and a new spectroscopic binary containing a very slow rotator HD 42035 S with ultra-sharp lines (vsini = 3.7 km/s) and a fast rotator HD 42035 B with broad lines. The lines of Ti, Cr, Mn, Sr, Y, Zr and Ba are conspicuous features in the high resolution SOPHIE spectrum of HD 67044. The HgII line at 3983.93 A is also present as a weak feature. The composite spectrum of HD 42035 is characterised by very sharp lines formed in HD 42035 S superimposed onto the shallow and broad lines of HD 42035 B. These very sharp lines are mostly due to light elements from C to Ni, the only heavy species definitely present are Sr and Ba. Selected lines of 21 chemical elements from He up to Hg have been synthesized using model atmospheres compute...

  20. Magnetospheres and Disk Accretion in Herbig Ae/Be Stars

    CERN Document Server

    Muzerolle, J; Calvet, N; Hartmann, L

    2004-01-01

    We present evidence of magnetically-mediated disk accretion in Herbig Ae/Be stars. Magnetospheric accretion models of Balmer and sodium profiles calculated with appropriate stellar and rotational parameters are in qualitative agreement with the observed profiles of the Herbig Ae star UX Ori, and yield a mass accretion rate of ~ 10^{-8} Msun/yr. If more recent indications of an extremely large rotation rate for this object are correct, the magnetic field geometry must deviate from that of a standard dipole in order to produce line emission consistent with observed flux levels. Models of the associated accretion shock qualitatively explain the observed distribution of excess fluxes in the Balmer discontinuity for a large ensemble of Herbig Ae/Be stars, and imply typically small mass accretion rates, < 10^{-7} Msun/yr. In order for accretion to proceed onto the star, significant amounts of gas must exist inside the dust destruction radius, which is potentially problematic for recently advocated scenarios of "...

  1. Probing the Structure of the Accretion Region in a Sample of Magnetic Herbig Ae/Be Stars

    CERN Document Server

    Pogodin, M A; Drake, N A; Hubrig, S; Schoeller, M; Petr-Gotzens, M; Franco, G A P; Lopes, D F; Kozlova, O V; Wolff, B; Gonzalez, J F; Carroll, T A; Mysore, S

    2014-01-01

    We present the results of a study of the temporal behaviour of several diagnostic lines formed in the region of the accretion-disk/star interaction in the three magnetic Herbig Ae stars HD101412, HD104237, and HD190073. More than 100 spectra acquired with the ISAAC, X-shooter, and CRIRES spectrographs installed at the VLT-8m telescope (ESO, Chile), as well as at other observatories (OHP, Crimean AO) were analyzed. The spectroscopic data were obtained in the He I lambda10830, Pa gamma and He I lambda5876 lines. We found that the temporal behaviour of the diagnostic lines in the spectra of all program stars can be widely explained by a rotational modulation of the line profiles generated by a local accretion flow. This result is in good agreement with the predictions of the magnetospheric accretion model. For the first time, the rotation period of HD104237 (P_rot = 5.37+-0.03 days), as well as the inclination angle (i = 21+-4deg) were determined. Additional analysis of the HARPSpol spectra of HD104237 and HD190...

  2. The (BETA) Pictoris Phenomenon Among Herbig Ae/Be Stars

    Science.gov (United States)

    Grady, C. A.; Perez, M. R.; Talavera, A.; Bjorkman, K. S.; deWinter, D.; The, P.-S.; Molster, F. J.; vandenAncker, M. E.; Sitko, M. L.; Morrison, N. D.; Beaver, M. L.; McCollum, B.; Castelaz, M. W.

    1996-01-01

    We present a survey of high dispersion UV and optical spectra of Herbig Ae/Be (HAeBe) and related stars. We find accreting, circumstellar gas over the velocity range +100 to +400 km/s, and absorption profiles similar to those seen toward Beta Pic, in 36% of the 33 HAeBe stars with IUE data as well as in 3 non-emission B stars. We also find evidence of accretion in 7 HAeBe stars with optical data only. Line profile variability appears ubiquitous. As a group, the stars with accreting gas signatures have higher v sin i than the stars with outflowing material, and tend to exhibit large amplitude (greater than or equal to 1(sup m)) optical light variations. All of the program stars with polarimetric variations that are anti-correlated with the optical light, previously interpreted as the signature of a dust disk viewed close to equator-on, also show spectral signatures of accreting gas. These data imply that accretion activity in HAeBe stars is preferentially observed when the line of sight transits the circumstellar dust disk. Our data imply that the spectroscopic signatures of accreting circumstellar material seen in Beta Pic are not unique to that object, but instead are consistent with interpretation of Beta Pic as a comparatively young A star with its associated circumstellar disk.

  3. Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509

    CERN Document Server

    Wittrock, Justin M; Horch, Elliott P; Hirsch, Lea; Howell, Steve B; Ciardi, David R; Everett, Mark E; Teske, Johanna K

    2016-01-01

    An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 nm and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD 2638 and HD 164509. The stellar companion to HD 2638 has been previously detected, but the companion to HD 164509 is a newly discovered companion. The angular separation for HD 2638 is $0.512 \\pm 0.002\\arcsec$ and for HD 164509 is $0.697 \\pm 0.002\\arcsec$. This corresponds to a projected separation of $25.6 \\pm 1.9$ AU and $36.5 \\pm 1.9$ AU, respectively. By employing stellar isochrone models, we e...

  4. Disk wind and magnetospheric accretion in emission from the Herbig Ae star MWC 480

    Science.gov (United States)

    Tambovtseva, L. V.; Grinin, V. P.; Potravnov, I. S.; Mkrtichian, D. E.

    2016-09-01

    The young Herbig Ae star MWC 480 (HD 31648) is one of the comprehensively spectroscopically studied stars in the ultraviolet, optical, and infrared spectral ranges. Using non-LTE modeling of its hydrogen spectrum, we have calculated the contribution to the hydrogen emission from such important regions of the circumstellar environment as the disk wind and the magnetosphere. We have used our own observations of the stellar spectrum performed with the 2.4-m telescope at the Thai National Observatory to quantitatively check our theoretical calculations. In addition, all of the visible and infrared spectra available in the literature have been used for a qualitative comparison. The modeling results have revealed a significant role of the magneto-centrifugal disk wind in the formation of atomic hydrogen emission. The cause of the emission line variability in the spectrum ofMWC 480 is discussed.

  5. Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314

    CERN Document Server

    Sato, Bun'ei; Liu, Yujuan; Harakawa, Hiroki; Izumiura, Hideyuki; Kambe, Eiji; Toyota, Eri; Murata, Daisuke; Lee, Byeong-Cheol; Masuda, Seiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro; Ida, Shigeru; Zhao, Gang; Han, Inwoo

    2010-01-01

    We report the detections of two substellar companions orbiting around evolved intermediate-mass stars from precise Doppler measurements at Subaru Telescope and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of 1.9 M_sun and has a planet of minimum mass m_2sini=2.9 M_J orbiting with period of P=176 d and eccentricity of e=0.11. HD 180314 is also a K0 giant with 2.6 M_sun and hosts a substellar companion of m_2sin i=22 M_J, which falls in brown-dwarf mass regime, in an orbit with P=396 d and e=0.26. HD 145457 b is one of the innermost planets and HD 180314 b is the seventh candidate of brown-dwarf-mass companion found around intermediate-mass evolved stars.

  6. Infrared spectroscopy of the Herbig Ae-Be stars

    Science.gov (United States)

    Harvey, P. M.

    1984-01-01

    Infrared spectroscopy from 1.5-2.3 microns is presented for nine Ae and Be stars believed to be pre-main-sequence. Brackett-gamma emission is seen in most or all the spectra, and higher-order Brackett recombination lines are visible in a number of the spectra. The strengths of the emission lines are generally less than or equal to the expected fluxes from H II regions which have been postulated to explain Balmer and Paschen continuum excesses in these stars. The circumstellar H II regions may be optically thick in some of the Brackett lines. No other lines are visible in the spectra, e.g., He or H2. The infrared continua are generally smooth; they confirm the presence of excess emission over that expected from the stellar photospheres. If the excesses are produced by thermal emission from dust, the dust grains must exist up to temperatures of 1300 K-1500 K.

  7. GASPS observations of Herbig Ae/Be stars with PACS/Herschel. The atomic and molecular content of their protoplanetary discs

    CERN Document Server

    Meeus, G; Mendigutia, I; Kamp, I; Thi, W F

    2012-01-01

    We observed a sample of 20 representative Herbig Ae/Be stars and five A-type debris discs with PACS onboard of Herschel. The observations were done in spectroscopic mode, and cover far-IR lines of [OI], [CII], CO, CH+, H2O and OH. We have a [OI]63 micron detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. [OI]145 micron is only detected in 25%, CO J=18-17 in 45% (and less for higher J transitions) of the Herbig Ae/Be stars and for [CII] 157 micron, we often found spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. CH+, first seen in HD 100546, is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and stellar or disc parameters, such as stellar luminosity, UV and X-ray fl...

  8. Search for exoplanet around northern circumpolar stars - Four planets around HD 11755, HD 12648, HD 24064, and 8 Ursae Minoris

    CERN Document Server

    Lee, B -C; Lee, S -M; Jeong, G; Oh, H -I; Han, I; Lee, J W; Lee, C -U; Kim, S -L; Kim, K -M

    2015-01-01

    Aims. This program originated as the north pole region extension of the established exoplanet survey using 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). The aim of our paper is to find exoplanets in northern circumpolar stars with a precise radial velocity (RV) survey. Methods. We have selected about 200 northern circumpolar stars with the following criteria: Dec. > 70 degree, 0.6 < B-V < 1.6, HIPPARCOS_scat < 0.05 magnitude, and 5.0 < mv < 7.0. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used for the RV survey. Chromospheric activities, the HIPPARCOS photometry, and line bisectors were analyzed to exclude other causes for the RV variations. Results. In 2010, we started to monitor the candidates and have completed initial screening for all stars for the last five years. We present the detection of four new exoplanets. Stars HD 11755, HD 12648, HD 24064, and 8 UMi all show evidence for giant planets in Keplerian motion. The companion ...

  9. ISO spectroscopy of disks around Herbig Ae/Be stars

    CERN Document Server

    Van den Ancker, M E

    2004-01-01

    We have investigated the infrared spectra of all 46 Herbig Ae/Be stars for which spectroscopic data is available in the ISO data archive. Our quantitative analysis of these spectra focusses on the emission bands linked to polycyclic aromatic hydrocarbons (PAHs), the amorphous 10 micron silicate band and the crystalline silicate band at 11.3 micron. We have detected PAH emission in 57% of the Herbig stars in our sample. Clear examples of differences in the PAH spectra are present within our sample, indicating differences in PAH size, chemistry and/or ionization. Amorphous silicate emission was detected in the spectra of 52% of the sample stars, amorphous silicate absorption in 13%. We have detected crystalline silicate emission in 11 stars (24% of our sample), of which four (9%) also display strong PAH emission. We have classified the sample sources according to the strength of their mid-IR energy distribution. The systems with stronger mid-infared (20-100 um) excesses relative to their near-infrared (1-5 um) ...

  10. Line Identifications and Preliminary Synthesis of High-resolution Infrared Spectra of CP and Herbig Ae Stars

    Science.gov (United States)

    Cowley, Charles R.; Castelli, F.; Hubrig, S.; Wolff, B.; Elkin, V.

    2012-01-01

    We report on surveys of infrared spectra of chemically peculiar and Herbig Ae stars based on CRIRES (Kaufl, et al. SPIE, 5492, 1218 2004). We discuss the magnetic CP stars Gamma Equ and HD 154708, and multiple-phase observations of the Herbig Ae star HD 101412. The Be star HR 4537 and HgMn HR 6620 were also examined. The primary emphasis of the present work is on line identifications primarily in four regions, 1065-1091, 1084-1109,1550-1587, and 2276-2313nm (with order gaps). Observations were reduced with recipes available from the ESO CRIRES data reduction pipeline. Wavelength calibration is determined from daytime ThAr arc lamp exposures. Generally speaking, this is not rich in atomic lines. The strongest features are the Paschen line P6 (1093.81nm), and He I (108.30nm). The latter shows phase variations indicative of a more complex magnetic field than that of a pure dipole. No individual molecular lines were found in these early stars, though CO emission from circumstellar material is likely present in HR 4537 and HD 101412. We used atomic line lists from Kurucz's site (kurucz.harvard.edu) and VALD (http://vald.astro.univie.ac.at/ cf. Kupka et al. 1999, A&AS, 138, 119), supplemented by Outred (J. Phys. Chem. Ref. Data 7, 1, 1978). The following spectra were identified in Gamma Equ: C I, Si I, Ca I, Mg I, II, Cr I, Fe I, Sr II, and Ce III (1584.75nm). The Ap star spectra show broad Zeeman patterns compatible with published models and field strengths. Synthetic calculations used SYNTHE and SYNTHMAG (Piskunov N. E., 1999, in Astrophys. Space Sci. Library Vol. 243, Solar polarization. Kluwer, p 515). The γ Equ model is from Heiter et al. (2002, A&A, 392, 619). and the line list from VALD.

  11. On the nature of the {delta} Scuti star HD 115520

    Energy Technology Data Exchange (ETDEWEB)

    Pena, J H; Cervantes-Sodi, B; Cano, M; Sorcia, M A [Instituto de AstronomIa, Universidad Nacional Autonoma de Mexico, Mexico D.F., Apdo. Postal 70-264 (Mexico); Fox, L; Alvarez, M [Observatorio Astronomico Nacional, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada B.C., Apdo. Postal 877 (Mexico); Pena, R [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico); Munoz, G; Vargas, B [Escuela Superior de Ingenier Mecanica y Electrica, Instituto Politecnico Nacional, Av. IPN s/n, 07738 Mexico, D.F. (Mexico); Sareyan, J P [Observatoire de la Cote d' Azur (France)], E-mail: jhpena@astroscu.unam.mx

    2008-10-15

    Observing Delta Scuti stars is most important as their multi-frequency spectrum of radial pulsations provide strong constraints on the physics of the stars interior; so any new detection and observation of these stars is a valuable contribution to asteroseismology. While performing uvby-beta photoelectric photometry of some RR Lyrae stars acquired in 2005 at the Observatorio Astronomico Nacional, Mexico, we also observed several standard stars, HD115520 among them. After the reduction this star showed indications of variability. In view of this, a new observing run was carried out in 2006 during which we were able to demonstrate its variability and its nature as a Delta Scuti star. New observations in 2007 permitted us to determine its periodic content with more accuracy. This, along with the uvby-beta photoelectric photometry allowed us to deduce its physical characteristics and pulsational modes.

  12. Asteroseismology of the $\\delta$ Scuti star HD 50844

    CERN Document Server

    Chen, X H; Lai, X J; Wu, T

    2016-01-01

    Aims. We aim to probe the internal structure and investigate more detailed information of the $\\delta$ Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the $\\delta$ Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree $l$ and azimuthal number $m$ are unique. The corresponding rotational period of HD 50844 is found to be 2.44$^{+0.13}_{-0.08}$ days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as...

  13. Spectropolarimetry of the H-alpha line in Herbig Ae/Be stars

    CERN Document Server

    Harrington, D M

    2007-01-01

    Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS telescope, we have obtained a large number of high precision spectropolarimetrc observations (284) of Herbig AeBe stars collected over 53 nights totaling more than 300 hours of observing. Our sample of five HAeBe stars: AB Aurigae, MWC480, MWC120, MWC158 and HD58647, all show systematic variations in the linear polarization amplitude and direction as a function of time and wavelength near the H-alpha line. In all our stars, the H-alpha line profiles show evidence of an intervening disk or outflowing wind, evidenced by strong emission with an absorptive component. The linear polarization varies by 0.2% to 1.5% with the change typically centered in the absorptive part of the line profile. These observations are inconsistent with a simple disk-scattering model or a depolarization model which produce polarization changes centered on the emmissive core. We speculate that polarized absorption via optical pumping of the intervening gas may be the c...

  14. CHARACTERIZING THE RIGIDLY ROTATING MAGNETOSPHERE STARS HD 345439 AND HD 23478

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, J. P.; Lomax, J. R. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Chojnowski, S. D. [Department of Astronomy, New Mexico State University, 1780 E University Avenue, Las Cruces, NM 88003 (United States); Davenport, J. R. A. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Bartz, J.; Pepper, J. [Lehigh University, Department of Physics, 413 Deming Lewis Lab, 16 Memorial Drive, East Bethlehem, PA 18015 (United States); Whelan, D. G. [Department of Physics, Austin College, 900 N. Grand Avenue, Sherman, TX 75090 (United States); Eikenberry, S. S. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Majewski, S. R.; Skrutskie, M. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Richardson, N. D., E-mail: wisniewski@ou.edu [Département de Physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada)

    2015-10-01

    The SDSS III APOGEE survey recently identified two new σ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the Kilodegree Extremely Little Telescope, Wide Angle Search for Planets, and ASAS surveys reveals the presence of a ∼0.7701 day period in each data set, suggesting the system is among the faster known σ Ori E analogs. We also see clear evidence that the strength of Hα, H i Brackett series lines, and He i lines also vary on a ∼0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5 m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H i lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H i Br-11 line strength and line profile in multi-epoch observations of HD 23478 from the SDSS-III APOGEE instrument. The observed periodic behavior is consistent with that recently reported by Sikora and collaborators in optical spectra.

  15. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    Science.gov (United States)

    Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Ilyin, I.

    2016-04-01

    Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars. Aims: We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. Methods: We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the help of magnetic Doppler imaging techniques and model atmospheres taking the effects of strong magnetic fields and nonsolar chemical composition into account. Results: We improved the atmospheric parameters of the star, Teff = 9850 ± 250 K and log g = 4.05 ± 0.10. We performed detailed abundance analysis, which confirmed that HD 125248 has abundances typical of other Ap stars, and discovered significant vertical stratification effects for the Fe ii and Cr ii ions. We computed LSD Stokes profiles using several line masks corresponding to Fe-peak and rare earth elements, and studied their behavior with rotational phase. Combining previous longitudinal field measurements with our own observations, we improved the rotational period of the star Prot = 9.29558 ± 0.00006 d. Magnetic Doppler imaging of HD 125248 showed that its magnetic field is mostly poloidal and quasi-dipolar with two large spots of different polarity and field strength. The chemical maps of Fe, Cr, Ce, Nd, Gd, and Ti show abundance contrasts of 0.9-3.5 dex. Among these elements, the Fe abundance map does not show high-contrast features. Cr is overabundant around the negative magnetic pole and has 3.5 dex abundance range. The rare earth elements and Ti are overabundant near the positive magnetic pole. Conclusions: The magnetic field of HD 125248 has strong deviations from the classical oblique dipole field

  16. A spectroscopic analysis of the chemically peculiar star HD207561

    CERN Document Server

    Joshi, S; Martinez, P; Sachkov, M; Joshi, Y C; Seetha, S; Chakradhari, N K; Mary, D L; Girish, V; Ashoka, B N

    2012-01-01

    In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is s...

  17. Chemical Abundances of the magnetic CP star HD 168733

    Science.gov (United States)

    Collado, A.; López-García, Z.

    2009-04-01

    A detailed abundance analysis has been carried out for the magnetic CP star HD 168733 using high-resolution spectra obtained with the EBASIM echelle spectrograph at the 2.1 m CASLEO telescope in Argentina. The spectral coverage is 382-700 nm. It is neither a silicon nor a mercury-manganese star. Compared to the Sun, C and N are slightly overabundant, while Mg and S are deficient, Si is normal and P and Cl are overabundant. The iron peak elements Sc, Ti, Cr and Fe are overabundant. Lines of Ti III and Fe III are also identified. HD 168733 shows a great overabundance of Ga, Sr, Y, Zr, Xe, Pt, Hg and of some rare earths.

  18. Characterizing the Rigidly Rotating Magnetosphere Stars HD 345439 and HD 23478

    CERN Document Server

    Wisniewski, J P; Davenport, J R A; Bartz, J; Pepper, J; Whelan, D G; Eikenberry, S S; Lomax, J R; Majewski, S R; Richardson, N D; Skrutskie, M

    2015-01-01

    The SDSS III APOGEE survey recently identified two new $\\sigma$ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the KELT, SuperWASP, and ASAS surveys reveals the presence of a $\\sim$0.7701 day period in each dataset, suggesting the system is amongst the faster known $\\sigma$ Ori E analogs. We also see clear evidence that the strength of H-alpha, H I Brackett series lines, and He I lines also vary on a $\\sim$0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H I lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H I Br-11 ...

  19. CNO and F abundances in the barium star HD 123396

    CERN Document Server

    Alves-Brito, Alan; Yong, David; Meléndez, Jorge; Vásquez, Sergio

    2011-01-01

    [Abridged] Barium stars are moderately rare chemically peculiar objects which are believed to be the result of the pollution of an otherwise normal star by material from an evolved companion on the asymptotic giant branch (AGB). We aim to derive carbon, nitrogen, oxygen, and fluorine abundances for the first time from infrared spectra of the barium red giant star HD 123396 to quantitatively test AGB nucleosynthesis models for producing barium stars via mass accretion. High-resolution and high S/N infrared spectra were obtained using the Phoenix spectrograph mounted at the Gemini South telescope. The abundances were obtained through spectrum synthesis of individual atomic and molecular lines, using the MOOG stellar line analysis program together with Kurucz's stellar atmosphere models. The analysis was classical, using 1D stellar models and spectral synthesis under the assumption of local thermodynamic equilibrium. We confirm that HD 123396 is a metal-deficient barium star ([Fe/H] = -1.05), with A(C) = 7.88, A...

  20. An Analysis of the Rapidly Rotating Bp star HD 133880

    Science.gov (United States)

    Bailey, J. D.; Grunhut, J.; Shultz, M.; Wade, G.; Landstreet, J. D.; Bohlender, D.; Lim, J.; Wong, K.; Drake, S.; Linsky, J.

    2012-01-01

    HD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (nu sin i approx = 103km/s) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti. Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using ZEEMAN, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P = 0.877 476 +/- 0.000009 d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements; except Mg, are overabundant compared to the Son. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in 0, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Ha and Paschen lines in the optical spectra, we could not

  1. Helium stratification in HD 145792: a new Helium strong star

    CERN Document Server

    Catanzaro, G

    2007-01-01

    In this paper we report on the real nature of the star HD 145792, classified as He weak in {\\it ``The General Catalogue of Ap and Am stars''}. By means of FEROS@ESO1.52m high resolution spectroscopic data, we refined the atmospheric parameters of the star, obtaining: T$_{\\rm eff}$ = 14400 $\\pm$ 400 K, $\\log g$ = 4.06 $\\pm$ 0.08 and $\\xi$ = 0 $^{+0.6}$ km s$^{-1}$. These values resulted always lower than those derived by different authors with pure photometric approaches. Using our values we undertook an abundance analysis with the aim to derive, for the first time, the chemical pattern of the star's atmosphere. For metals a pure LTE synthesis (ATLAS9 and SYNTHE) has been used, while for helium a hybrid approach has been preferred (ATLAS9 and SYNSPEC). The principal result of our study is that HD 145792 belongs to He strong class contrary to the previous classification. Moreover, helium seems to be vertically stratified in the atmosphere, decreasing toward deepest layers. For what that concerns metals abundanc...

  2. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Ilyin, I

    2016-01-01

    Intermediate-mass, chemically peculiar stars with strong magnetic fields give us an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in their atmospheres. We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the magnetic Doppler imaging technique. We improved the atmospheric parameters of the star, T_eff = 9850K +/- 250K and logg = 4.05 +/- 0.10. We performed detailed abundance analysis and discovered vertical stratification effects for the FeII and CrII ions. We computed LSD Stokes profiles and studied their behavior with rotational phase. We improved the rotational period of the star P_rot = 9.29558(6)d. Magnetic Doppler imaging of HD 125248 showed that its magn...

  3. An M-dwarf star in the transition disk of Herbig HD142527; Physical parameters and orbital elements

    CERN Document Server

    Lacour, S; Cheetham, A; Greenbaum, A; Pearce, T; Marino, S; Tuthill, P; Pueyo, L; Mamajek, E E; Girard, J H; Sivaramakrishnan, A; Bonnefoy, M; Baraffe, I; Chauvin, G; Olofsson, J; Juhasz, A; Benisty, M; Pott, J -U; Sicilia-Aguilar, A; Henning, T; Cardwell, A; Goodsell, S; Graham, J R; Hibon, P; Ingraham, P; Konopacky, Q; Macintosh, B; Oppenheimer, R; Perrin, M; Rantakyrö, F; Sadakuni, N; Thomas, S

    2015-01-01

    HD 142527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of $\\approx20$ in mass ratio between the two objects makes this binary system different from any other YSO. The HD142527 system could therefore provides a valuable testbed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and the dust trapping observed by ALMA at longer distances. We have observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present here the SEDS for HD 142527A and B from the $R$ band up to the $M$ band as well as the orbital motion of HD 142527B ov...

  4. Evidence for Magnetic Star-Planet Interactions in HD 189733

    Science.gov (United States)

    Wolk, S. J.; Pillitteri, I.; Kashyap, V.; Cohen, O.; Lisse, C.; Knutson, H. A.

    2011-12-01

    We report on XMM-Newton observations of the planetary host star HD 189733. The system has a close in planet and it can potentially affect the coronal structure via interactions with the magnetosphere. During the 2009 secondary eclipse we observed a softening of the X-ray spectrum significant at level of ˜3σ. Further, we observed the most intense flare recorded at either epochs. This flare occurred 3 ks after the end of the eclipse. The flare decay shows several minor ignitions perhaps linked to the main event and hinting for secondary loops that emit triggered by the main loop. Magneto-Hydro-Dynamical (MHD) simulations show that the magnetic interaction between planet and star enhances the density and the magnetic field in a region comprised between the planet and the star because of their relative orbital/rotation motion.

  5. An Analysis of the Rapidly Rotating Bp Star HD 133880

    CERN Document Server

    Bailey, J D; Shultz, M; Wade, G; Landstreet, J D; Bohlender, D; Lim, J; Wong, K; Drake, S; Linsky, J

    2012-01-01

    HD 133880 is a rapidly rotating Bp star and host to one of the strongest magnetic fields of any Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. Twelve new spectra obtained from the FEROS, ESPaDOnS, and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of various elements. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P = 0.877476 \\pm 0.000009 days. The magnetic field structure was characterised by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. This simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe, Nd...

  6. Chromospherically active stars. X - Spectroscopy and photometry of HD 212280

    Science.gov (United States)

    Fekel, Francis C.; Browning, Jared C.; Henry, Gregory W.; Morton, Mary D.; Hall, Douglas S.

    1993-01-01

    The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of about 0.15 mag and a mean period of 29.46 days. Our V data were divided into 11 sets and in all but one case two spots were required to fit the data. Lifetimes of 650 days and a minimum of 1350 days have been determined for two of the four spots. The differential rotation coefficient of 0.05 is relatively small. The age of the system is about 1.9 X 10 exp 9 yrs. The G subgiant is rotating slower than pseudosynchronously while the F-type star is rotating faster.

  7. The CP Galium Stars in the UV. I. HD 168733

    Science.gov (United States)

    Collado, A.; López García, Z.; Levato, H.; Malaroda, S.

    HD 168733 is a magnetic CP star with an unusual spectrum. It was not possible to assign this star to the Si or HgMn group. Jaschek & Jaschek (A&A, 171, 380, 1987) have included this star in a list of objects having strong UV Gallium lines. In order to get some clues about the real nature of this star, we are performing an elemental abundance analysis of this star using spectrograms obtained with EBASIM spectrograph attached to CASLEO 2.15 m telescope. The reduction of the observational material and the measurements of the equivalent widths were carried out using the appropriate IRAF tasks. The atmospheric parameters Teff and log g were determined using uvbybeta photometry and TemLogG code with the corrections suggested by Adelman & Rayle (A&A 447, 685, 2000) for magnetic CP stars. The adopted values are: Teff = 13274 K, log g = 3.58. The chemical abundances are being calculating using WIDTH9 code.

  8. Effect of Photodesorption on Snow Line at the Surface of Optically Thick Circumstellar Disks around Herbig Ae/Be Stars

    CERN Document Server

    Oka, Akinori; Nakamoto, Taishi; Honda, Mitsuhito

    2012-01-01

    We investigate the effect of photodesorption on the snow line position at the surface of a protoplanetary disk around a Herbig Ae/Be star, motivated by the detection of water ice particles at the surface of the disk around HD142527 by Honda et al. For this aim, we obtain the density and temperature structure in the disk with a 1+1D radiative transfer and determine the distribution of water ice particles in the disk by the balance between condensation, sublimation, and photodesorption. We find that photodesorption induced by the far-ultraviolet radiation from the central star depresses the ice-condensation front toward the mid-plane and pushes the surface snow line outward significantly when the stellar effective temperature exceeds a certain critical value. This critical effective temperature depends on the stellar luminosity and mass, the water abundance in the disk, and the yield of photodesorption. We present an approximate analytic formula for the critical temperature. We separate Herbig Ae/Be stars into ...

  9. Magnetic Doppler Imaging of He-strong star HD 184927

    CERN Document Server

    Yakunin, I; Bohlender, D; Kochukhov, O; Tsymbal, V

    2013-01-01

    We have employed an extensive new timeseries of Stokes I and V spectra obtained with the ESPaDOnS spectropolarimeter at the 3.6-m Canada-France-Hawaii Telescope to investigate the physical parameters, chemical abundance distributions and magnetic field topology of the slowly-rotating He-strong star HD 184927. We infer a rotation period of 9.53071+-0.00120 from H-alpha, H-beta, LSD magnetic measurements and EWs of helium lines. We used an extensive NLTE TLUSTY grid along with the SYNSPEC code to model the observed spectra and find a new value of luminosity. In this poster we present the derived physical parameters of the star and the results of Magnetic Doppler Imaging analysis of the Stokes I and V profiles. Wide wings of helium lines can be described only under the assumption of the presence of a large, very helium-rich spot.

  10. The onset of cluster formation around Herbig Ae/Be stars

    CERN Document Server

    Testi, L; Natta, A

    1999-01-01

    The large body of near infrared observations presented in Testi et al. (1997; 1998) are analysed with the aim of characterizing the young stellar clusters surrounding Herbig Ae/Be stars. The results confirm the tendency of early Be stars to be surrounded by dense clusters of lower mass "companions", while Ae stars are never found to be associated with conspicuous groups. The transition between the different environments appears to occur smoothly from Ae to Be stars without a sharp threshold. No correlation of the richness of the stellar groups detected is found with the galactic position or the age of the central Herbig Ae/Be star. The stellar volume densities estimated for the groups surrounding pre-main-sequence stars of intermediate mass show the transition from the low density aggregates of T Tauri stars and the dense clusters around massive stars. Only the most massive stars (10-20Msun) are found to be associated with dense (10^3 pc^-3) stellar clusters. This is exactly the mass regime at which the conve...

  11. An analysis of the rapidly rotating Bp star HD 133880

    Science.gov (United States)

    Bailey, J. D.; Grunhut, J.; Shultz, M.; Wade, G.; Landstreet, J. D.; Bohlender, D.; Lim, J.; Wong, K.; Drake, S.; Linsky, J.

    2012-06-01

    HD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (v sin i≃ 103 km s-1) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti, Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using ZEEMAN, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P= 0.877 476 ± 0.000 009 d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements, except Mg, are overabundant compared to the Sun. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in O, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Hα and Paschen lines in the optical spectra, we could not unambiguously

  12. Stellar Variability of the Exoplanet Hosting Star HD 63454

    CERN Document Server

    Kane, Stephen R; Ciardi, David R; Lee, Jae-Woo; Curto, Gaspare Lo; Lovis, Christophe; Naef, Dominique; Mahadevan, Suvrath; Pilyavsky, Genady; Udry, Stephane; Wang, Xuesong; Wright, Jason

    2011-01-01

    Of the hundreds of exoplanets discovered using the radial velocity technique, many are orbiting close to their host stars with periods less than 10 days. One of these, HD 63454, is a young active K dwarf which hosts a Jovian planet in a 2.82 day period orbit. The planet has a 14% transit probability and a predicted transit depth of 1.2%. Here we provide a re-analysis of the radial velocity data to produce an accurate transit ephemeris. We further analyse 8 nights of time series data to search for stellar activity both intrinsic to the star and induced by possible interactions of the exoplanet with the stellar magnetospheres. We establish the photometric stability of the star at the 3 millimag level despite strong Ca II emission in the spectrum. Finally, we rule out photometric signatures of both star-planet magnetosphere interactions and planetary transit signatures. From this we are able to place constraints on both the orbital and physical properties of the planet.

  13. Accurate radio and optical positions for the radio star HD 36705 (AB Doradus)

    Science.gov (United States)

    White, Graeme L.; Jauncey, David L.; Batty, Michael J.; Peters, W. L.; Gulkis, S.

    1988-01-01

    Arc-second position measurements of the active star HD 36705 (AB Dor) and of the variable radio source found nearby are presented. These measurements show that the radio source is clearly identified with HD 36705 and not with the nearby red-dwarf star Rst 137B.

  14. Detailed theoretical models for extra-solar planet-host stars: The "red stragglers" HD37124 and HD46375

    CERN Document Server

    Fernandes, Joao

    2004-01-01

    In this paper we analyse and discuss the HR Diagram position of two extra-solar planet-host stars - HD37124 and HD46375 - by means of theoretical stellar evolution models. This work was triggered by the results obtained by Laws et al. (2003) who found that these stars were in contradiction to the expectation based on their high metallicity. Fixing the age of both stars with the value based on their chromospheric activity levels and computing our own evolutionary models using the CESAM code, we are able to reproduce the observed luminosity, effective temperature and metallicity of both stars for a set of stellar parameters that are astrophysically reliable even if it is non-trivial to interpret the absolute values for these parameters. Our results are discussed in the context of the stellar properties of low mass stars.

  15. Characterisation of the magnetic fields of the Herbig Be stars HD 200775 and V380 0ri

    CERN Document Server

    Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J C; Donati, J F; Folsom, C P; Landstreet, J D; Silvester, J

    2006-01-01

    The origin of the magnetic fields of the chemically peculiar main sequence Ap/Bp stars is still matter of intense debate. The recent discoveries of magnetic fields in Herbig Ae/Be stars using high resolution data obtained with the spectropolarimeter ESPaDOnS at CFHT provide a strong argument in favour of the fossil field hypothesis. Using a simple oblique rotator model of a centered dipole, we fit the Stokes V LSD profiles of two of these magnetic HAeBe stars, HD 200775 and V380 Ori, as well as their variations on timescales from days to months. We find that in both cases the dipole hypothesis is acceptable and we determine the rotation period, the angle between rotation and magnetic axes and the intensity of the magnetic field at pole.

  16. Stellar activity of planetary host star HD 189 733

    Science.gov (United States)

    Boisse, I.; Moutou, C.; Vidal-Madjar, A.; Bouchy, F.; Pont, F.; Hébrard, G.; Bonfils, X.; Croll, B.; Delfosse, X.; Desort, M.; Forveille, T.; Lagrange, A.-M.; Loeillet, B.; Lovis, C.; Matthews, J. M.; Mayor, M.; Pepe, F.; Perrier, C.; Queloz, D.; Rowe, J. F.; Santos, N. C.; Ségransan, D.; Udry, S.

    2009-03-01

    Aims: Extra-solar planet search programs require high-precision velocity measurements. They need to determine how to differentiate between radial-velocity variations due to Doppler motion and the noise induced by stellar activity. Methods: We monitored the active K2V star HD 189 733 and its transiting planetary companion, which has a 2.2-day orbital period. We used the high-resolution spectograph SOPHIE mounted on the 1.93-m telescope at the Observatoire de Haute-Provence to obtain 55 spectra of HD 189 733 over nearly two months. We refined the HD 189 733b orbit parameters and placed limits on both the eccentricity and long-term velocity gradient. After subtracting the orbital motion of the planet, we compared the variability in spectroscopic activity indices with the evolution in the radial-velocity residuals and the shape of spectral lines. Results: The radial velocity, the spectral-line profile, and the activity indices measured in He I (5875.62 Å), Hα (6562.81 Å), and both of the Ca II H&K lines (3968.47 Å and 3933.66 Å, respectively) exhibit a periodicity close to the stellar-rotation period and the correlations between them are consistent with a spotted stellar surface in rotation. We used these correlations to correct for the radial-velocity jitter due to stellar activity. This results in achieving high precision in measuring the orbital parameters, with a semi-amplitude K = 200.56 ± 0.88 m s-1 and a derived planet mass of MP = 1.13 ± 0.03 M_Jup. Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (program 07A.PNP.CONS).

  17. X-ray Study of the Intermediate-Mass Young Stars Herbig Ae/Be Stars

    CERN Document Server

    Hamaguchi, K; Koyama, K; Hamaguchi, Kenji; Yamauchi, Shigeo; Koyama, Katsuji

    2004-01-01

    We present the ASCA results of intermediate-mass pre-main-sequence stars (PMSs), or Herbig Ae/Be stars (HAeBes). Among the 35 ASCA pointed-sources, we detect 11 plausible X-ray counterparts. X-ray luminosities of the detected sources in the 0.5-10 keV band are in the range of log LX ~30-32 ergs s-1, which is systematically higher than those of low-mass PMSs. This fact suggests that the contribution of a possible low-mass companion is not large. Most of the bright sources show significant time variation, particularly, two HAeBes - MWC 297 and TY CrA - exhibit flare-like events with long decay timescales (e-folding time ~ 10-60 ksec). These flare shapes are similar to those of low-mass PMSs. The X-ray spectra are successfully reproduced by an absorbed one or two-temperature thin-thermal plasma model. The temperatures are in the range of kT ~1-5 keV, which are significantly higher than those of main-sequence OB stars (kT < 1 keV). These X-ray properties are not explained by wind driven shocks, but are more li...

  18. Warm H2O and OH in the disk around the Herbig star HD 163296

    CERN Document Server

    Fedele, D; van Dishoeck, E F; Herczeg, G J; Evans, N J; Bouwman, J; Henning, Th; Green, J

    2012-01-01

    We present observations of far-infrared (50-200 micron) OH and H2O emission of the disk around the Herbig Ae star HD 163296 obtained with Herschel/PACS in the context of the DIGIT key program. In addition to strong [OI] emission, a number of OH doublets and a few weak highly excited lines of H2O are detected. The presence of warm H2O in this Herbig disk is confirmed by a line stacking analysis, enabled by the full PACS spectral scan, and by lines seen in Spitzer data. The line fluxes are analyzed using an LTE slab model including line opacity. The water column density is 10^14 - 10^15 cm^-2, and the excitation temperature is 200-300 K implying warm gas with a density n > 10^5 cm^-3. For OH we find a column density of 10^14 - 2x10^15 cm^-2 and T_ex ~ 300-500 K. For both species we find an emitting region of r ~ 15-20 AU from the star. We argue that the molecular emission arises from the protoplanetary disk rather than from an outflow. This far-infrared detection of both H2O and OH contrasts with near- and mid-...

  19. B fields in OB stars (BOB): FORS2 spectropolarimetric follow-up of the two rare rigidly rotating magnetosphere stars HD23478 and HD345439

    CERN Document Server

    Hubrig, S; Fossati, L; Morel, T; Castro, N; Oskinova, L M; Przybilla, N; Eikenberry, S S; Nieva, M F; Langer, N

    2015-01-01

    Massive B-type stars with strong magnetic fields and fast rotation are very rare and provide a mystery for theories of both star formation and magnetic field evolution. Only two such stars, called sigma Ori E analogs, were previously known. Recently, a team involved in APOGEE, one of the Sloan Digital Sky Survey III programs, announced the discovery of two additional rigidly rotating magnetosphere stars, HD23478 and HD345439. The presence of magnetic fields in these newly discovered sigma Ori E analogs was not investigated in the past. In the framework of our ESO Large Programme, and one normal ESO programme, we carried out low-resolution FORS2 spectropolarimetric observations of HD23478 and HD345439. From the measurements using hydrogen lines, we discover a rather strong longitudinal magnetic field of the order of up to 1.5kG in HD23478, and up to 1.3kG using the entire spectrum. The analysis of HD345439 using four subsequent spectropolarimetric subexposures does not reveal the presence of a magnetic field a...

  20. Abundances and Orbit of the Rhenium Star HD 65949

    Science.gov (United States)

    Cowley, C. R.; Hubrig, S.; Palmeri, P.; Quinet, P.; Biémont, E.; Wahlgren, G. M.; Schütz, O.; González, J. F.

    2010-01-01

    HD 65949 is a late B star in NGC 2516. Two X-ray sources are within 1". The spectrum arguably falls outside of the usual CP star classifications. It may be most closely related to the HgMn stars, having strong Hg II λ3984, and Pt II. But while ? is exceptionally strong, Mn II is only mildly enhanced. The rarely observed Re II spectrum is extraordinarily well developed. Other uncommon identifications are Kr II, Os II, and Th III. Preliminary quantitative work by Cowley, Hubrig, and Wahlgren (JPhCS, 130, 012005, 2008) is now extended to abundances or upper limits of 58 elements. Calculations of atomic structures by the Mons group, assessed through comparisons with experiment, have provided a large number of oscillator strengths making it possible to derive reliable abundances from rare 5d ions, as well as the 4d spectrum of Ru II. Nb II (4d) is confirmed, and its abundance determined using recent work of Nilsson and Ivarsson (A&A, 492, 609, 2008). Many Re II (5d) lines show broad hyperfine structure, easily resolved on ESO HARPS spectra. We provide new orbital elements for this known SB1. The period is 21.28 days and is slowly increasing, indicating the presence of a third body. Using the spectroscopic Teff=13100 and log(g) = 4.0, as well as the orbital data, we estimate primary and secondary masses near 3.3 and 1.6 M⊙, with a separation of some 0.25 AU. Observations: ESO (UVES Progs. 076.D-0172, 081.D-0498), HARPS, and from Complejo Astronomico El Leoncito. Support from Belgian FRS-FNRS is gratefully acknowledged.

  1. Spectro-astrometric Study of HI emission lines from Herbig Ae/Be Stars

    Science.gov (United States)

    Cade Adams, Steven; Brittain, Sean D.; Dougados, Catherine; Benisty, Myriam; Podio, Linda; Whelan, Emma

    2015-01-01

    We present a spectro-astrometric study of the Pa β and Br γ lines from six Herbig Ae/Be stars using NIFS on Gemini North. The goal of this study is to determine the origin of the HI emission lines. By combining the high angular resolution ( 0.1") and intermediate spectral resolution (R~5000) of GEMINI/NIFS we measured the spectro-astrometric signal of the Pa β and Br γ emission lines at the 0.1 mas level. The HAe stars showed no significant spectro-astrometric signal, while the HBe stars did show significant detections. We compare our results to models and discuss the implications for understanding the origin of the HI lines in Herbig Ae/Be stars and their utility for measuring the accretion rate. We also discuss various artifacts in the data and prospects for more sensitive measurements in the future.

  2. B fields in OB stars (BOB): FORS 2 spectropolarimetric follow-up of the two rare rigidly rotating magnetosphere stars HD 23478 and HD 345439

    Science.gov (United States)

    Hubrig, S.; Schöller, M.; Fossati, L.; Morel, T.; Castro, N.; Oskinova, L. M.; Przybilla, N.; Eikenberry, S. S.; Nieva, M.-F.; Langer, N.

    2015-06-01

    Aims: Massive B-type stars with strong magnetic fields and fast rotation are very rare and pose a mystery for theories of star formation and magnetic field evolution. Only two such stars, called σ Ori E analogues, were known until recently. A team involved in APOGEE, one of the Sloan Digital Sky Survey III programs, announced the discovery of two additional rigidly rotating magnetosphere stars, HD 23478 and HD 345439. The magnetic fields in these newly discovered σ Ori E analogues have not been investigated so far. Methods: In the framework of our ESO Large Programme and one normal ESO programme, we carried out low-resolution FORS 2 spectropolarimetric observations of HD 23478 and HD 345439. Results: In the measurements of hydrogen lines, we discover a rather strong longitudinal magnetic field of up to 1.5 kG in HD 23478 and up to 1.3 kG using the entire spectrum. The analysis of HD 345439 using four subsequent spectropolarimetric subexposures does not reveal a magnetic field at a significance level of 3σ. On the other hand, individual subexposures indicate that HD 345439 may host a strong magnetic field that rapidly varies over 88 min. The fast rotation of HD 345439 is also indicated by the behaviour of several metallic and He i lines in the low-resolution FORS 2 spectra that show profile variations already on this short time-scale. Based on observations obtained in the framework of the ESO Prgs. 191.D-0255(E) and 094.D-0355(B).Appendix A is available in electronic form at http://www.aanda.org

  3. TIME-RESOLVED SPECTROSCOPY OF THE POST-AGB STAR HD-56126

    NARCIS (Netherlands)

    OUDMAIJER, RD; BAKKER, EJ

    1994-01-01

    We have investigated the report of Tamura and Takeuti that the H alpha line of the F-type post-AGB star HD56126 is variable on time-scales of minutes. To this end, HD 56126 was observed on two occasions with the William Herschel Telescope. 17 and 30 spectra (first and second runs, respectively) were

  4. Resolved Inner Disks around Herbig Ae/Be Stars

    CERN Document Server

    Eisner, J A; Hillenbrand, L A; Akeson, R L; Sargent, A I

    2004-01-01

    We have observed 14 Herbig Ae/Be sources with the long-baseline near-IR Palomar Testbed Interferometer, All except two sources are resolved at 2.2 um, with angular sizes generally <5 mas. We determine the size scales and orientations of the 2.2 um emission using various models: uniform disks, Gaussians, uniform rings, flat accretion disks with inner holes, and flared disks with puffed-up inner rims; 7 objects display significantly inclined morphologies, generally compatible with the outer disk geometries inferred from millimeter interferometric observations, implying that HAEBE disks are not significantly warped. Using the derived inner disk sizes and inclinations, we compute the spectral energy distributions for two simple physical disk models, and compare these with observed SEDs compiled from the literature and new near-IR photometry. While geometrically flat accretion disk models are consistent with the data for the earliest spectral types in our sample (MWC 297, V1685 Cyg, and MWC 1080), the later-typ...

  5. Pulsation models for the roAp star HD 134214

    CERN Document Server

    Saio, H; Weiss, W W; Matthews, J M; Ryabchikova, T

    2011-01-01

    Precise time-series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD 134214. We have fitted the observed frequencies with theoretical frequencies of axisymmetric modes in a grid of stellar models with dipole magnetic fields. We find that, among models with a standard composition of $(X,Z) = (0.70,0.02)$ and with suppressed convection, eigenfrequencies of a $1.65\\,{\\rm M}_\\odot$ model with $\\log T_{\\rm eff} = 3.858$ and a polar magnetic field strength of 4.1kG agree best with the observed frequencies. We identify the observed pulsation frequency with the largest amplitude as a deformed dipole ($\\ell = 1$) mode, and the four next-largest-amplitude frequencies as deformed $\\ell = 2$ modes. These modes have a radial quasi-node in the outermost atmospheric layers ($\\tau \\sim 10^{-3}$). Although the model frequencies agree roughly with observed ones, they are all above the acoustic cut-off frequency for the model atmosphere and hen...

  6. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380

    Institute of Scientific and Technical Information of China (English)

    Blesson Mathew; D. P. K. Banerjee; N. M. Ashok; Annapurni Subramaniam; Bhaskaran Bhavya; Vishal Joshi

    2012-01-01

    We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain.This object,which is a member of the young cluster NGC 7380,has been variously proposed to be a Be star,a D-type symbiotic and a Herbig Ae/Be star in separate studies.Here we present optical spectroscopy,near-IR photometry and narrow band Hα imaging of the nebulosity in its environment.Analysis of all these results,including the spectral energy distribution constructed from available data,strongly indicate the source to be a Herbig Ae/Be star.The star is found to be accompanied by a nebulosity with an interesting structure.A bow-shock shaped structure,similar to a cometary nebula,is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e.the star DH Cep).An interesting spectroscopic finding,from the forbidden [SⅡ] 6716,6731 (A) and [OI] 6300 (A) lines,is the detection of a blue-shifted high velocity outflow (200 ±50 km s- 1) from the star.

  7. How non-magnetic are "non-magnetic" Herbig Ae/Be stars?

    CERN Document Server

    Wade, G A; Catala, C; Bagnulo, S; Landstreet, J D; Flood, J; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Silvester, J

    2007-01-01

    Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we have acquired about 125 observations of some 70 stars in which no magnetic fields are detected. Using a Monte Carlo approach, we have performed statistical comparisons of the observed longitudinal fields and LSD Stokes V profiles of these apparently non-magnetic stars with a variety of field models. This has allowed us to derive general upper limits on the presence of dipolar fields in the sample, and to place realistic upper limits on undetected dipole fields which may be present in individual stars. This paper briefly reports the results of the statistical modeling, as well as field upper limits for individual stars of particular interest.

  8. The prevalence of weak magnetic fields in Herbig Ae stars: The case of PDS2

    CERN Document Server

    Hubrig, S; Schöller, M; Ilyin, I

    2015-01-01

    Models of magnetically driven accretion and outflows reproduce many observational properties of T Tauri stars, but the picture is much less clear for the Herbig Ae/Be stars, due to the poor knowledge of their magnetic field strength and topology. The Herbig Ae star PDS2 was previously included in two magnetic studies based on low-resolution spectropolarimetric observations. Only in one of these studies the presence of a weak mean longitudinal magnetic field was reported. In the present study, for the first time, high-resolution HARPS spectropolarimetric observations of PDS2 are used to investigate the presence of a magnetic field. A firm detection of a weak longitudinal magnetic field is achieved using the multi-line singular value decomposition method for Stokes profile reconstruction (=33+-5G). To gain better knowledge of typical magnetic field strengths in late Herbig Be and Herbig Ae stars, we compiled previous magnetic field measurements, revealing that only very few stars have fields stronger than 200G,...

  9. X-shooting Herbig Ae/Be stars: Accretion probed by near-infrared He I emission

    NARCIS (Netherlands)

    Oudmaijer, R.D.; Van Den Ancker, M. E.; Baines, D.; Caselli, P.; Drew, J.E.; Hoare, M.G.; Lumsden, S.L.; Montesinos, B.; Sim, S.; Vink, J.S.; Wheelwright, H.E.; de Wit, W.J.M.

    2011-01-01

    The Herbig Ae/Be stars are intermediate mass pre-main sequence stars that bridge the gap between the low mass T Tauri stars and the Massive Young Stellar Objects. In this mass range, the acting star forming mechanism switches from magnetically controlled accretion to an as yet unknown mechanism, but

  10. ALMA detection of the rotating molecular disk wind drom the young star HD 163296

    CERN Document Server

    Klaassen, P D; Mathews, G S; De Gregorio-Monsalvo, J C Mottram I; van Dishoeck, E F; Takahashi, S; Akiyama, E; Chapillon, E; Espada, D; Hales, A; Hogerheijde, M R; Rawlings, M; Schmalzl, M; Testi, L

    2013-01-01

    Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew morphology and extends more than 10" from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet which is moving at much higher velocities. We show that the J=3-2 emission is likely heavily filtered by the interferometer, but the J=2-1 emission suffers less due to the larger beam and measurable angular scales. Excitation analysis suggests temperatures...

  11. Einstein X-ray observations of Herbig Ae/Be stars

    Science.gov (United States)

    Damiani, F.; Micela, G.; Sciortino, S.; Harnden, F. R., Jr.

    1994-01-01

    We have investigated the X-ray emission from Herbig Ae/Be stars, using the full set of Einstein Imaging Proportional Counter (IPC) observations. Of a total of 31 observed Herbig stars, 11 are confidently identified with X-ray sources, with four additonal dubious identifications. We have used maximum likelihood luminosity functions to study the distribution of X-ray luminosity, and we find that Be stars are significantly brighter in X-rays than Ae stars and that their X-ray luminosity is independent of projected rotational velocity v sin i. The X-ray emission is instead correlated with stellar bolometric luminosity and with effective temperature, and also with the kinetic luminosity of the stellar wind. These results seem to exclude a solar-like origin for the X-ray emission, a possibility suggested by the most recent models of Herbig stars' structure, and suggest an analogy with the X-ray emission of O (and early B) stars. We also observe correlations between X-ray luminosity and the emission at 2.2 microns (K band) and 25 microns, which strengthen the case for X-ray emission of Herbig stars originating in their circumstellar envelopes.

  12. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380

    CERN Document Server

    Mathew, Blesson; Ashok, N M; Subramaniam, Annapurni; Bhavya, B; Joshi, Vishal

    2012-01-01

    We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band H-alpha imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e. the star DH Cep). An interesting spectroscopic finding, from the forbidden [SII] 6716, 6731 \\AA and [OI] 6300 \\AA lines, is the detection of a blue-shifted high velocity outflow ...

  13. THE CHEMICAL COMPOSITIONS OF VERY METAL-POOR STARS HD 122563 AND HD 140283: A VIEW FROM THE INFRARED

    Energy Technology Data Exchange (ETDEWEB)

    Afşar, Melike [Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir (Turkey); Sneden, Christopher; Kim, Hwihyun, E-mail: melike.afsar@ege.edu.tr, E-mail: chris@astro.as.utexas.edu, E-mail: dtj@astro.as.utexas.edu, E-mail: hwihyun@astro.as.utexas.edu, E-mail: mace@astro.as.utexas.edu, E-mail: afrebel@mit.edu [Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712 (United States); and others

    2016-03-10

    From high resolution (R ≃ 45,000), high signal-to-noise ratio (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = −3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O i] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.

  14. Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra

    CERN Document Server

    Tanrıverdi, Taner

    2015-01-01

    This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003) were analysed to compute their elemental abundances using ATLAS9 (Kurucz, 1993, 2005; Sbordone et al., 2004). In our analysis we assumed local thermodynamic equilibrium. The atmospheric parameters of HD 80057 used in this study are from Firnstein & Przybilla (2012), and that of HD80404 are derived from spectral energy distribution, ionization equilibria of Cr I/II and Fe I/II, and the fits to the wings of Balmer lines and Paschen lines as Teff = 7700 +/- 150 K and log g=1.60 +/- 0.15 (in cgs). The microturbulent velocities of HD 80057 and HD 80404 have been determined as 4.3 +/- 0.1 and 2.2 +/- 0.7 km s^-1 . The rotational velocities are 15 +/-1 and 7 +/- 2 km s^-1 and their macroturbulence velocities are 24 +/-2 and 2+/-1 km s^-1 . We have given the abundances...

  15. Asteroseismology and forced oscillations of HD 209295, the first member of two classes of pulsating star

    CERN Document Server

    Handler, G; Shobbrook, R R; Koen, C; Bruch, A; Romero-Colmenero, E; Pamyatnykh, A A; Willems, B; Eyer, L; James, D J; Maas, T; Crause, L A

    2001-01-01

    We report the discovery of both intermediate-order gravity mode and low-order pressure mode pulsation in the same star, HD 209295. It is therefore both a gamma Doradus and a delta Scuti star, which makes it the first confirmed member of two classes of pulsating star. This object is located in a close binary system with an unknown, but likely degenerate companion in an eccentric orbit, and some of the gamma Doradus pulsation frequencies are exact integer multiples of the orbital frequency. We suggest that these pulsations are tidally excited. HD 209295 may be the progenitor of an intermediate-mass X-Ray binary.

  16. The Chemical Compositions of Very Metal-Poor Stars HD 122563 and HD 140283; A View From the Infrared

    CERN Document Server

    Afşar, Melike; Frebel, Anna; Kim, Hwihyun; Mace, Gregory N; Kaplan, Kyle F; Lee, Hye-In; Oh, Hee-Young; Oh, Jae Sok; Pak, Soojong; Park, Chan; Pavel, Michael D; Yuk, In-Soo; Jaffe, Daniel T

    2016-01-01

    From high resolution (R = 45,000), high signal-to-noise (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = -3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to...

  17. Evolution of the dust/gas environment around Herbig Ae/Be stars

    CERN Document Server

    Liu, Tie; Wu, Yuefang; Qin, Sheng-Li; Miller, Martin

    2011-01-01

    With the KOSMA 3-m telescope, 54 Herbig Ae/Be stars were surveyed in CO and $^{13}$CO emission lines. The properties of the stars and their circumstellar environments are studied by fitting the SEDs. The mean line width of $^{13}$CO (2-1) lines of this sample is 1.87 km s$^{-1}$. The average column density of H$_{2}$ is found to be $4.9\\times10^{21}$ cm$^{-2}$ for the stars younger than $10^{6}$ yr, while drops to $2.5\\times10^{21}$ cm$^{-2}$ for those older than $10^{6}$ yr. No significant difference is found among the SEDs of Herbig Ae stars and Herbig Be stars at the same age. The infrared excess decreases with age. The envelope masses and the envelope accretion rates decease with age after $10^{5}$ yr. The average disk mass of the sample is $3.3\\times10^{-2} M_{\\sun}$. The disk accretion rate decreases more slowly than the envelope accretion rate. A strong correlation between the CO line intensity and the envelope mass is found.

  18. The complex circumstellar environment of HD 142527

    NARCIS (Netherlands)

    Verhoeff, A. P.; Min, M.; Pantin, E.; Waters, L.B.F.M.; Tielens, A. G. G. M.; Honda, M.; Fujiwara, H.; Bouwman, J.; Van Boekel, R.; Dougherty, S.M.; de Koter, A.; Dominik, C.; Mulders, G. D.

    2011-01-01

    Context. The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of i

  19. The complex circumstellar environment of HD142527

    NARCIS (Netherlands)

    Verhoeff, A. P.; Min, M.; Pantin, E.; Waters, L. B. F. M.; Tielens, A. G. G. M.; Honda, M.; Fujiwara, H.; Bouwman, J.; van Boekel, R.; Dougherty, S. M.; de Koter, A.; Dominik, C.; Mulders, G. D.

    2011-01-01

    Context. The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of i

  20. The classification of frequencies in the {\\gamma} Doradus / {\\delta} Scuti hybrid star HD 49434

    OpenAIRE

    Brunsden, E.; Pollard, K.R.; Cottrell, P. L.; Uytterhoeven, K.; Wright, D J; De Cat, P.

    2014-01-01

    Hybrid stars of the {\\gamma} Doradus and {\\delta} Scuti pulsation types have great potential for asteroseismic analysis to explore their interior structure. To achieve this, mode identi- fications of pulsational frequencies observed in the stars must be made, a task which is far from simple. In this work we begin the analysis by scrutinizing the frequencies found in the CoRoT photometric satellite measurements and ground-based high-resolution spectroscopy of the hybrid star HD 49434. The resu...

  1. STEREO observations of HD90386 (RX Sex): a δ-Scuti or a hybrid star?

    Science.gov (United States)

    Ozuyar, D.; Stevens, I. R.; Whittaker, G.; Sangaralingam, V.

    2016-04-01

    HD90386 is a rarely studied bright A2V type δ Scuti star (V = 6.66 mag). It displays short-term light curve variations which are originated due to either a beating phenomenon or a non-periodic variation. In this paper, we presented high-precision photometric data of HD90386 taken by the STEREO satellite between 2007 and 2011 to shed light on its internal structure and evolution stage. From the frequency analysis of the four-year data, we detected that HD90386 had at least six different frequencies between 1 and 15 c d-1. The most dominant frequencies were found at around 10.25258 c d-1 (A ∼ 1.92 mmag) and 12.40076 c d-1 (A ∼ 0.61 mmag). Based on the ratio between these frequencies, the star was considered as an overtone pulsator. The variation in pulsation period over 35 years was calculated to be dP/Pdt = 5.39(2) x 10-3 yr-1. Other variabilities at around 1.0 c d-1 in the amplitude spectrum of HD90386 were also discussed. In order to explain these variabilities, possible rotational effects and γ Dor type variations were focused. Consequently, depending on the rotation velocity of HD90386, we speculated that these changes might be related to γ Dor type high-order g-modes shifted to the higher frequencies and that HD90386 might be a hybrid star.

  2. Comparison between accretion-related properties of Herbig Ae/Be and T Tauri stars

    CERN Document Server

    Mendigutía, I

    2013-01-01

    This paper summarizes several results concerning the comparison between accretion-related properties of cool (T Tauri; T < 7000 K, M < 1 Msun and hot (Herbig Ae/Be; 7000 < T(K) < 13000; 1 < M(Msun) < 6) pre-main sequence (PMS) stars. This comparison gives insight into the analogies/differences in the physics of the star-disk interaction and in the physical mechanisms driving disk dissipation. Several optical and near-IR line luminosities used for low-mass objects are also valid to estimate typical accretion rates for intermediate-mass stars under similar empirical expressions. In contrast, the Halpha width at 10% of peak intensity is used as an accretion tracer for T Tauris, but is not reliable to estimate accretion rates for Herbig Ae/Bes. This can be explained as a consequence of the different stellar rotation rates that characterize both types of stars. In addition, there are similar trends when the accretion rate is related to the near-IR colours and disk masses, suggesting that viscous ...

  3. Chromospherically active stars. II - HD 82558, a young single BY Draconis variable

    Science.gov (United States)

    Fekel, Francis C.; Bopp, Bernard W.; Africano, John L.; Goodrich, Bret D.; Palmer, Leigh Hunter

    1986-01-01

    It is presently noted that the HD 82558 chromospherically active star is a young and rapidly rotating K2 V single BY Draconis variable with very strong far-UV emission features and an H-alpha line filled to the continuum level by emission. HD 82558 has constant velocity and is not a member of the Hyades Supercluster. Its light curve behavior, which appears to have been stable for several hundred rotation cycles, is reminiscent of that of the young, rapidly rotating, single K V variable H II 1883 in the Pleiades; this stability may be characteristic of young, single, chromospherically active stars.

  4. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii

    DEFF Research Database (Denmark)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.;

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations...... of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(-0.45)(+0.18), 2.29(-0.82)(+0.96), and 9.33(-2.18)(+6.07) keV, or an optically thin thermal plasma...

  5. 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.

  6. Is there a compact companion orbiting the late O-type binary star HD 164816?

    Science.gov (United States)

    Trepl, L.; Hambaryan, V. V.; Pribulla, T.; Tetzlaff, N.; Chini, R.; Neuhäuser, R.; Popov, S. B.; Stahl, O.; Walter, F. M.; Hohle, M. M.

    2012-12-01

    We present a multi-wavelength (X-ray, γ-ray, optical and radio) study of HD 164816, a late O-type X-ray detected spectroscopic binary. X-ray spectra are analysed and the X-ray photon arrival times are checked for pulsation. In addition, newly obtained optical spectroscopic monitoring data on HD 164816 are presented. They are complemented by available radio data from several large-scale surveys as well as the Fermi γ-ray data from its Large Area Telescope. We report the detection of a low energy excess in the X-ray spectrum that can be described by a simple absorbed blackbody model with a temperature of ˜50 eV as well as a 9.78 s pulsation of the X-ray source. The soft X-ray excess, the X-ray pulsation and the kinematical age would all be consistent with a compact object like a neutron star as companion to HD 164816. The size of the soft X-ray excess emitting area is consistent with a circular region with a radius of about 7 km, typical for neutron stars, while the emission measure (EM) of the remaining harder emission is typical for late O-type single or binary stars. If HD 164816 includes a neutron star born in a supernova, this supernova should have been very recent and should have given the system a kick, which is consistent with the observation that the star HD 164816 has a significantly different radial velocity than the cluster mean. In addition we confirm the binarity of HD 164816 itself by obtaining an orbital period of 3.82 d, projected masses m1sin3i = 2.355(69) M⊙, m2sin3i = 2.103(62) M⊙ apparently seen at low inclination angle, determined from high-resolution optical spectra.

  7. The Mid-Infrared Polarization of the Herbig Ae Star WL 16: An Interstellar Origin?

    CERN Document Server

    Zhang, Han; Pantin, Eric; Li, Dan; Wright, Christopher M; Mariñas, Naibí; Barnes, Peter; Li, Aigen; Packham, Christopher

    2016-01-01

    We present high-resolution (0".4) mid-infrared (mid-IR) polarimetric images and spectra of WL 16, a Herbig Ae star at a distance of 125 pc. WL 16 is surrounded by a protoplanetary disk of $\\sim$ 900 AU in diameter, making it one of the most extended Herbig Ae/Be disks as seen in the mid-IR. The star is behind, or embedded in, the $\\rho$ Ophiuchus molecular cloud, and obscured by 28 magnitudes of extinction at optical wavelengths by the foreground cloud. Mid-IR polarization of WL 16, mainly arises from aligned elongated dust grains present along the line of sight, suggesting a uniform morphology of polarization vectors with an orientation of 33\\degr (East from North) and a polarization fraction of $\\sim$ 2.0\\%. This orientation is consistent with previous polarimetric surveys in the optical and near-IR bands to probe large-scale magnetic fields in the Ophiuchus star formation region, indicating that the observed mid-IR polarization toward WL 16 is produced by the dichroic absorption of magnetically aligned for...

  8. CHEMICAL ABUNDANCES OF THE MAGNETIC CP STAR HD 168733

    Directory of Open Access Journals (Sweden)

    Ana Collado

    2009-01-01

    Full Text Available Se ha llevado a cabo un an lisis detallado de las abundancias en la estrella CP magn tica HD 168733 utilizando espectros de alta resoluci n obtenidos con el espectr grafo echelle EBASIM del telescopio de 2.1 m de CASLEO en Argentina. Los espectros cubren la regi n 382{700 nm. La estrella no puede ser clasi cada ni como una peculiar de HgMn ni como perteneciente al grupo CP2 de silicio. Comparada con el Sol, C, N son levementes sobreabundantes mientras que el Mg y S son de cientes, Si es normal y P y Cl son sobreabundantes. Los elementos del pico de hierro: Sc, Ti, Cr y Fe son sobreabundantes. Se han identi cado tambi n l neas de Ti III y Fe III. HD 168733 muestra una gran sobreabundancia de Ga, Sr, Y, Zr, Xe, Pt, Hg y algunas tierras raras.

  9. Non-thermal radio emission from O-type stars. I. HD 168112

    CERN Document Server

    Blomme, R; De Becker, M; Rauw, G; Runacres, M C; Gunawan, D Y A S; Chapman, J M

    2005-01-01

    We present a radio lightcurve of the O5.5 III(f+) star HD 168112, based on archive data from the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). The fluxes show considerable variability and a negative spectral index, thereby confirming that HD 168112 is a non-thermal radio emitter. The non-thermal radio emission is believed to be due to synchrotron radiation from relativistic electrons that have been Fermi accelerated in shocks. For HD 168112, it is not known whether these shocks are due to a wind-wind collision in a binary system or to the intrinsic instability of the stellar wind driving mechanism. Assuming HD 168112 to be a single star, the Van Loo et al. (2005) synchrotron model shows that the velocity jump of the shocks should be very high, or there should be a very large number of shocks in the wind. Neither of these is compatible with time-dependent hydrodynamical calculations of O star winds. If, on the other hand, we assume that HD 168112 is a binary, the high velocity jump i...

  10. Line Identification of the Si Star HD 87240

    Directory of Open Access Journals (Sweden)

    C. Saffe

    2004-01-01

    Full Text Available Se presentan las identificaciones de las líneas de la estrella peculiar tipo Ap Si HD 87240 (_ = - 59_ 51` 00:1`` en el intervalo espectral 3710{5520. Este objeto es miembro del cúmulo abierto meridional NGC 3114. La comparación de este objeto con otras estrellas Ap Si del campo muestra que tienen en común muchas de las anomalías en sus líneas.

  11. PAH Emission from Disks around Intermediate-Mass Stars: The Peculiar Aroma of Hydrocarbons Orbiting Herbig Ae/Be Stars

    Science.gov (United States)

    Keller, L. D.; Sloan, G. C.

    2009-12-01

    Over half of the intermediate-mass young stellar objects in the Galaxy (e.g. Herbig Ae/Be stars or HAeBe) have high-contrast emission in the mid-infrared spectral features of polycyclic aromatic hydrocarbons (PAHs) above the continuum produced by thermal emission from dust in the circumstellar disks. We have examined the PAH emission in detail for 30 HAeBe stars observed with the Spitzer IRS. We have identified some trends that, should they survive in a larger sample of HAeBe stars, will allow us to infer large-scale disk geometry (both inner and outer) and the degree of photo-processing of organic molecular material in HAeBe disks: HAeBe stars apparently have distinctive PAH spectra among the many other astronomical environments that are characterized by strong PAH emission; strong PAH emission is not necessarily an indicator of a particular disk geometry; PAH spectra of HAeBe stars change systematically with stellar effective temperature; PAH in HAeBe disks are ionized. As part of a Spitzer archival project we are applying our spectral analysis methods to an even larger sample of HAeBe stars observed with the IRS and currently available in the Spitzer archive. Here we report preliminary results as we begin the larger study.

  12. HD 101065, the Most Peculiar Star: First Results from Precise Radial Velocity Study

    Indian Academy of Sciences (India)

    D. E. Mkrtichian; A. P. Hatzes

    2005-06-01

    In this paper we discuss the prospects for asteroseismology with spatial resolution and motivate studies of the most chemically peculiar roAp star HD 101065. We present the first results from a high-precision radial velocity (RV) study of HD 101065 based on data spanning four nights that were acquired using the HARPS echelle-spectrometer at the ESO 3.6 m telescope. The analysis of individual nights showed the amplitude and phase modulation of the dominant mode. The analysis of the whole data set showed the presence of multi-periodic oscillations with two groups of equally-spaced modes. We find = 65.2 Hz and = 7.3 Hz for the large and the small spacing, respectively. HD 101065 is the only roAp star to show the existence of two groups of = 0, 2 and = 1, 3 excited modes.

  13. The peculiar abundance pattern of the new Hg-Mn star HD 30085

    CERN Document Server

    Monier, R; Royer, F; Griffin, R E M

    2015-01-01

    Using high-dispersion, high-quality spectra of HD 30085 obtained with the echelle spectrograph SOPHIE at Observatoire de Haute Provence, we show that this star contains strong lines of the s-process elements Sr II, Y II and Zr II. Line syntheses of the lines yield large overabundances of Sr, Y, Zr which are characteristic of HgMn stars. The Sr-Y-Zr triad of abundances is inverted in HD 30085 compared to that in our solar system. The violation of the odd-even rule suggests that physical processes such as radiative diffusion, chemical fractionation and others must be at work in the atmosphere of HD 30085, and that the atmosphere is stable enough to sustain them.

  14. The circumstellar envelope of the C-rich post-AGB star HD 56126

    NARCIS (Netherlands)

    Hony, S; Tielens, AGGM; Waters, LBFM; de Koter, A

    2003-01-01

    We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch "21 mum object" HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model th

  15. Modeling Kepler Observations of Solar-like Oscillations in the Red Giant Star HD 186355

    DEFF Research Database (Denmark)

    Jiang, C.; Jiang, B.W.; Christensen-Dalsgaard, Jørgen;

    2011-01-01

    We have analyzed oscillations of the red giant star HD 186355 observed by the NASA Kepler satellite. The data consist of the first five quarters of science operations of Kepler, which cover about 13 months. The high-precision time-series data allow us to accurately extract the oscillation...

  16. Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha

    CERN Document Server

    Böhm, T; Catala, C; Alecian, E; Pollard, K; Wright, D

    2008-01-01

    In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spect...

  17. The mid-infrared polarization of the Herbig Ae star WL 16: an interstellar origin?

    Science.gov (United States)

    Zhang, Han; Telesco, Charles M.; Pantin, Eric; Li, Dan; Wright, Christopher M.; Mariñas, Naibí; Barnes, Peter; Li, Aigen; Packham, Christopher

    2017-03-01

    We present high-resolution (0.4 arcsec) mid-infrared (mid-IR) polarimetric images and spectra of WL 16, a Herbig Ae star at a distance of 125 pc. WL 16 is surrounded by a protoplanetary disc of ∼ 900 au in diameter, making it one of the most extended Herbig Ae/Be discs as seen in the mid-IR. The star is behind, or embedded in, the ρ Ophiuchus molecular cloud, and obscured by 28 mag of extinction at optical wavelengths by the foreground cloud. Mid-IR polarization of WL 16 mainly arises from aligned elongated dust grains present along the line of sight, suggesting a uniform morphology of polarization vectors with an orientation of 33°(east from north) and a polarization fraction of ∼ 2.0 per cent. This orientation is consistent with previous polarimetric surveys in the optical and near-IR bands to probe large-scale magnetic fields in the Ophiuchus star formation region, indicating that the observed mid-IR polarization towards WL 16 is produced by the dichroic absorption of magnetically aligned foreground dust grains by a uniform magnetic field. Using polarizations of WL 16 and Elias 29, a nearby polarization standard star, we constrain the polarization efficiency, p10.3/A10.3, for the dust grains in the ρ Ophiuchus molecular cloud to be ≃1.0 per cent mag-1. WL 16 has polycyclic aromatic hydrocarbon (PAH) emission features detected at 8.6, 11.2, 12.0, and 12.7 μm by our spectroscopic data, and we find an anticorrelation between the PAH surface brightness and the PAH ionization fraction between the north-west and south-west sides of the disc.

  18. Dust evolution in protoplanetary disks around Herbig Ae/Be stars - The Spitzer view

    CERN Document Server

    Juhasz, A; Henning, Th; Acke, B; Ancker, M E van den; Meeus, G; Dominik, C; Min, M; Tielens, A G G M; Waters, L B F M

    2010-01-01

    In this paper we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validity of standard protoplanetary dust models and studied grain growth and crystal formation. On the basis of the analyzed spectra, the major constituents of protoplanetary dust around Herbig Ae/Be stars are amorphous silicates with olivine and pyroxene stoichiometry, crystalline forsterite and enstatite and silica. No other solid state features, indicating other abundant dust species, are present in the Spitzer spectra. Deviations of the synthetic spectra from the observations are most likely related to grain shape effects and uncertainties in the iron content of the dust grains. Our analysis revealed that larger grains are more abundant in the disk atmosphere of flatter disks than in that of flared disks, indicating t...

  19. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements

    CERN Document Server

    Alecian, E; Catala, C; Grunhut, J H; Landstreet, J D; Bagnulo, S; Böhm, T; Folsom, C P; Marsden, S; Waite, I

    2012-01-01

    This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly-polarised spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterised by a resolving power of about 65,000, and a spectral coverage from about 3700 ang to 1 micron. The peak SNR per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this first paper, we describe the sample selection, ...

  20. A parameter study of self-consistent disk models around Herbig AeBe stars

    CERN Document Server

    Meijer, J; De Koter, A; Dullemond, C P; Van Boekel, R; Waters, L B F M

    2008-01-01

    We present a parameter study of self-consistent models of protoplanetary disks around Herbig AeBe stars. We use the code developed by Dullemond and Dominik, which solves the 2D radiative transfer problem including an iteration for the vertical hydrostatic structure of the disk. This grid of models will be used for several studies on disk emission and mineralogy in followup papers. In this paper we take a first look on the new models, compare them with previous modeling attempts and focus on the effects of various parameters on the overall structure of the SED that leads to the classification of Herbig AeBe stars into two groups, with a flaring (group I) or self-shadowed (group II) SED. We find that the parameter of overriding importance to the SED is the total mass in grains smaller than 25um, confirming the earlier results by Dullemond and Dominik. All other parameters studied have only minor influences, and will alter the SED type only in borderline cases. We find that there is no natural dichotomy between ...

  1. Near-Infrared Interferometric Measurements of Herbig Ae/Be Stars

    CERN Document Server

    Eisner, J A; Akeson, R L; Hillenbrand, L A; Sargent, A I

    2003-01-01

    We have observed the Herbig Ae/Be sources AB Aur, VV Ser, V1685 Cyg (BD+40 4124), AS 442, and MWC 1080 with the Palomar Testbed Interferometer, obtaining the longest baseline near-IR interferometric observations of this class of objects. All of the sources are resolved at 2.2 microns with angular size scales generally <5 mas, consistent with the only previous near-IR interferometric measurements of Herbig Ae/Be stars by Millan-Gabet and collaborators. We determine the angular size scales and orientations predicted by uniform disk, Gaussian, ring, and accretion disk models. Although it is difficult to distinguish different radial distributions, we are able to place firm constraints on the inclinations of these models, and our measurements are the first that show evidence for significantly inclined morphologies. In addition, the derived angular sizes for the early type Herbig Be stars in our sample, V1685 Cyg and MWC 1080, agree reasonably well with those predicted by the face-on accretion disk models used b...

  2. Radio observations of HD 93129A: The earliest O star with the highest mass loss ?

    CERN Document Server

    Benaglia, P; Benaglia, Paula; Koribalski, Baerbel

    2004-01-01

    We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities of S_(3cm) = 2.0 +- 0.2 mJy and S_(6cm) = 4.1 +- 0.4 mJy. The resulting spectral index of alpha = -1.2 +- 0.3 (S_(nu) = k . nu^alpha) indicates predominantly non-thermal emission, suggesting HD 93129A may be a binary system. We propose that the observed 3 cm radio emission is mostly coming from the non-thermal wind collision region of a binary, and, to a lesser extent, from the thermal winds of the primary and secondary stars in HD 93129A. At a stellar distance of 2.8 kpc, we derive a mass-loss rate M_dot = 5.1 x 10^(-5) M_sun/yr, assuming the thermal fraction of the 3 cm emission is about 0.5.

  3. Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

    CERN Document Server

    Costa, J E S; Peña, J; Creevey, O; Li, Z P; Chevreton, M; Belmonte, J A; Alvarez, M; Machado, L Fox; Parrao, L; Hernendez, F Perez; Fernández, A; Fremy, J R; Pau, S; Alonso, R

    2007-01-01

    The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.

  4. Host Star Properties and Transit Exclusion for the HD 38529 Planetary System

    CERN Document Server

    Henry, Gregory W; Wang, Sharon X; Wright, Jason T; Boyajian, Tabetha S; von Braun, Kaspar; Ciardi, David R; Dragomir, Diana; Farrington, Chris; Fischer, Debra A; Hinkel, Natalie R; Howard, Andrew W; Jensen, Eric; Laughlin, Gregory; Mahadevan, Suvrath; Pilyavsky, Genady

    2013-01-01

    The transit signature of exoplanets provides an avenue through which characterization of exoplanetary properties may be undertaken, such as studies of mean density, structure, and atmospheric composition. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) is a program to expand the catalog of transiting planets around bright host stars by refining the orbits of known planets discovered with the radial velocity technique. Here we present results for the HD 38529 system. We determine fundamental properties of the host star through direct interferometric measurements of the radius and through spectroscopic analysis. We provide new radial velocity measurements that are used to improve the Keplerian solution for the two known planets, and we find no evidence for a previously postulated third planet. We also present 12 years of precision robotic photometry of HD 38529 that demonstrate the inner planet does not transit and the host star exhibits cyclic variations in seasonal mean brightness with a timesc...

  5. Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498

    CERN Document Server

    Joshi, S; Kochukhov, O; Sachkov, M; Tiwari, S K; Chakradhari, N K; Piskunov, N

    2009-01-01

    We present the results on the photometric and spectroscopic monitoring of a luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using three-channel fast photometer attached to the 1.04-m optical telescope at ARIES, Nainital. The photometric data of five nights of year 2007 show clear signature of 15-min periodicity. However, the follow-up observations during 2007--2009 could not repeated any such periodicity. To confirm the photometric light variations, the time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the Main Sequence and its atmospheric abundances are similar to two other evolved Ap stars HD133792 and HD204411: large overabundances of Si, Cr,...

  6. The nature of the light variability of magnetic Of?p star HD 191612

    Science.gov (United States)

    Krtička, J.

    2016-10-01

    Context. A small fraction of hot OBA stars host global magnetic fields with field strengths of the order of 0.1-10 kG. This leads to the creation of persistent surface structures (spots) in stars with sufficiently weak winds as a result of the radiative diffusion. These spots become evident in spectroscopic and photometric variability. This type of variability is not expected in stars with strong winds, where the wind inhibits the radiative diffusion. Therefore, a weak photometric variability of the magnetic Of?p star HD 191612 is attributed to the light absorption in the circumstellar clouds. Aims: We study the nature of the photometric variability of HD 191612. We assume that the variability results from variable wind blanketing induced by surface variations of the magnetic field tilt and modulated by stellar rotation. Methods: We used our global kinetic equilibrium (NLTE) wind models with radiative force determined from the radiative transfer equation in the comoving frame (CMF) to predict the stellar emergent flux. Our models describe the stellar atmosphere in a unified manner and account for the influence of the wind on the atmosphere. The models are calculated for different wind mass-loss rates to mimic the effect of magnetic field tilt on the emergent fluxes. We integrate the emergent fluxes over the visible stellar surface for individual rotational phases, and calculate the rotationally modulated light curve of HD 191612. Results: The wind blanketing that varies across surface of HD 191612 is able to explain a part of the observed light variability in this star. The mechanism is able to operate even at relatively low mass-loss rates. The remaining variability is most likely caused by the flux absorption in circumstellar clouds. Conclusions: The variable wind blanketing is an additional source of the light variability in massive stars. The presence of the rotational light variability may serve as a proxy for the magnetic field.

  7. The Near-Star Environment: Spectropolarimetry of Herbig Ae/Be Stars

    CERN Document Server

    Harrington, D M

    2007-01-01

    The near-star environment around young stars is very dynamic with winds, disks, and outflows. These processes are involved in star and planet formation, and influence the formation and habitability of planets around host stars. Even for the closest young stars, this will not be imaged even after the completion of the next generation of telescopes decades from now and other proxies must be used. The polarization of light across individual spectral lines is such a proxy that contains information about the geometry and density of circumstellar material on these small spatial scales. We have recently built a high-resolution spectropolarimeter (R~13000 to 50000) for the HiVIS spectrograph on the 3.67m AEOS telescope. We used this instrument to monitor several young intermediate-mass stars over many nights. These observations show clear spectropolarimetric signatures typically centered on absorptive components of the spectral lines, with some signatures variable in time. The survey also confirms the large spectrosc...

  8. Photometric and Polarimetric Activity of the Herbig Ae Star VX Cas

    Science.gov (United States)

    Shakhovskoi, D. N.; Rostopchina, A. N.; Grinin, V. P.; Minikulov, N. Kh.

    2003-04-01

    We present the results of our simultaneous photometric and polarimetric observations of the Herbig Ae/Be star VX Cas acquired in 1987 2001. The star belongs to the UX Ori subtype of young variable stars and exhibits a rather low level of photometric activity: only six Algol-like minima with amplitudes ΔV>1m were recorded in 15 years of observations. Two of these minima, in 1998 and 2001, were the deepest in the history of the star’s photometric studies, with V amplitudes of about 2m. In each case, the dimming was accompanied by an increase in the linear polarization in agreement with the law expected for variable circumstellar extinction. The highest V polarization was about 5%. Observations of VX Cas in the deep minima revealed a turnover of the color tracks, typical of stars of this type and due to an increased contribution from radiation scattered in the circumstellar disk. We separated the observed polarization of VX Cas into interstellar (P is) and intrinsic (P in) components. Their position angles differ by approximately 60°, with P is dominating in the bright state and P in dominating during the deep minima. The competition of these two polarization components leads to changes in both the degree and position angle of the polarization during the star’s brightness variations. Generally speaking, in terms of the behavior of the brightness, color indices, and linear polarization, VX Cas is similar to other UX Ori stars studied by us earlier. A number of episodes of photometric and polarimetric activity suggest that, in their motion along highly eccentric orbits, circumstellar gas and dust clouds can enter the close vicinity of the star (and be disrupted there).

  9. HD 30187 B and HD 39927 B: Two suspected nearby hot subdwarfs in resolved binaries (based on observations made with the ESA Hipparcos satellite)

    DEFF Research Database (Denmark)

    Makarov, V.V.; Fabricius, C.

    1999-01-01

    Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual......Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual...

  10. Magnetism and binarity of the Herbig Ae star V380 Ori

    CERN Document Server

    Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Landstreet, J D

    2009-01-01

    In this paper we report the results of high-resolution circular spectropolarimetric monitoring of the Herbig Ae star V380 Ori, in which we discovered a magnetic field in 2005. A careful study of the intensity spectrum reveals the presence of a cool spectroscopic companion. By modelling the binary spectrum we infer the effective temperature of both stars: $10500\\pm 500$ K for the primary, and $5500\\pm500$ K for the secondary, and we argue that the high metallicity ($[M/H] = 0.5$), required to fit the lines may imply that the primary is a chemically peculiar star. We observe that the radial velocity of the secondary's lines varies with time, while that of the the primary does not. By fitting these variations we derive the orbital parameters of the system. We find an orbital period of $104\\pm5$ d, and a mass ratio ($M_{\\rm P}/M_{\\rm S}$) larger than 2.9. The intensity spectrum is heavily contaminated with strong, broad and variable emission. A simple analysis of these lines reveals that a disk might surround the...

  11. A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars

    CERN Document Server

    Brittain, Sean D; Carr, John S; Ádámkovics, Máté; Reynolds, Nickalas

    2016-01-01

    We present a study of ro-vibrational OH and CO emission from 21 disks around Herbig Ae/Be stars. We find that the OH and CO luminosities are proportional over a wide range of stellar ultraviolet luminosities. The OH and CO line profiles are also similar, indicating that they arise from roughly the same radial region of the disk. The CO and OH emission are both correlated with the far-ultraviolet luminosity of the stars, while the PAH luminosity is correlated with the longer wavelength ultraviolet luminosity of the stars. Although disk flaring affects the PAH luminosity, it is not a factor in the luminosity of the OH and CO emission. These properties are consistent with models of UV-irradiated disk atmospheres. We also find that the transition disks in our sample, which have large optically thin inner regions, have lower OH and CO luminosities than non-transition disk sources with similar ultraviolet luminosities. This result, while tentative given the small sample size, is consistent with the interpretation t...

  12. High-resolution 25 \\mu m imaging of the disks around Herbig Ae/Be stars

    CERN Document Server

    Honda, M; Okamoto, Y K; Kataza, H; Yamashita, T; Miyata, T; Sako, S; Fujiyoshi, T; Sakon, I; Fujiwara, H; Kamizuka, T; Mulders, G D; Lopez-Rodriguez, E; Packham, C; Onaka, T

    2015-01-01

    We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 \\mu m using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of equal numbers of objects belonging to the two categories defined by Meeus et al. (2001); 11 group I (flaring disk) and II (at disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is hard to be resolved with 8 meter class telescopes in Q-band due to the strong emission from the unresolved innermost region of the disk. It indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 \\mu m, we suggest that many, not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 \\mu m supports that group II disks have continuous at disk geometr...

  13. NuSTAR AND SWIFT Observations of the Fast Rotating Magnetized White Dwarf AE Aquarii

    Science.gov (United States)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; Gotthelf, Eric V.; Hayashi, Takayuki; Kaspi, Victoria M.; Rana, Vikram R.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, Will W.

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P(sub spin) = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (LX (is) approximately 10(exp 31) erg per second). We have analyzed overlapping observations of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(+0.18 / -0.45), 2.29(+0.96 / -0.82), and 9.33 (+6.07 / -2.18) keV, or an optically thin thermal plasma model with two temperatures of 1.00 (+0.34 / -0.23) and 4.64 (+1.58 / -0.84) keV plus a power-law component with photon index of 2.50 (+0.17 / -0.23). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence for a previously reported sharp feature in the pulse profile.

  14. An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional Disk

    CERN Document Server

    Rodriguez, Luis F; Dzib, Sergio A; Ortiz-Leon, Gisela; Loinard, Laurent; Macias, Enrique; Anglada, Guillem

    2014-01-01

    AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated with the inner regions of AB Aur and conclude that the morphology, orientation, spectral index and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that c...

  15. Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

    CERN Document Server

    Briquet, M; Gonzalez, J F; Hubrig, S; Hackman, T

    2010-01-01

    Aims. We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. Methods. Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. Results. For HD 11753, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for HD 53244 and HD 221507 the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P_rot (HD 11753)=9.54 d, P_rot (HD 53244)=6.16 d, and P_rot (HD 221507)=...

  16. Lithium and magnetic fields in giants. HD 232862 : a magnetic and lithium-rich giant star

    CERN Document Server

    Lèbre, A; Nascimento, J D do; Konstantinova-Antova, R; Kolev, D; Aurière, M; De Laverny, P; De Medeiros, J R

    2009-01-01

    We report the detection of an unusually high lithium content in HD 232862, a field giant classified as a G8II star, and hosting a magnetic field. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232862, KU Peg and HD 21018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also analysed Stokes V signatures, looking for a magnetic field on these giants. HD 232862, presents a very high abundance of lithium (ALi = 2.45 +/- 0.25 dex), far in excess of the theoretically value expected at this spectral type and for this luminosity class (i.e, G8II). The evolutionary stage of HD 232862 has been precised, and it suggests a mass in the lower part of the [1.0 Msun ; 3.5 Msun ] mass interval, likely 1.5 to 2.0 solar mass, at the bottom of the Red Giant Branch. Besides, a time variable Stokes V signature has...

  17. Stellar Diameters and Temperatures VI. High angular resolution measurements of the transiting exoplanet host stars HD 189733 and HD 209458 and implications for models of cool dwarfs

    CERN Document Server

    Boyajian, Tabetha; Feiden, Gregory A; Huber, Daniel; Basu, Sarbani; Demarque, Pierre; Fischer, Debra A; Schaefer, Gail; Mann, Andrew W; White, Timothy R; Maestro, Vicente; Brewer, John; Lamell, C Brooke; Spada, Federico; López-Morales, Mercedes; Ireland, Michael; Farrington, Chris; van Belle, Gerard T; Kane, Stephen R; Jones, Jeremy; Brummelaar, Theo A ten; Ciardi, David R; McAlister, Harold A; Ridgway, Stephen; Goldfinger, P J; Turner, Nils H; Sturmann, Laszlo

    2014-01-01

    We present direct radii measurements of the well-known transiting exoplanet host stars HD 189733 and HD 209458 using the CHARA Array interferometer. We find the limb-darkened angular diameters to be theta_LD = 0.3848 +/- 0.0055 and 0.2254 +/- 0.0072 milliarcsec for HD 189733 and HD 209458, respectively. HD 189733 and HD 209458 are currently the only two transiting exoplanet systems where detection of the respective planetary companion's orbital motion from high resolution spectroscopy has revealed absolute masses for both star and planet. We use our new measurements together with the orbital information from radial velocity and photometric time series data, Hipparcos distances, and newly measured bolometric fluxes to determine the stellar effective temperatures (T_eff = 4875 +/- 43, 6093 +/- 103 K), stellar linear radii (R_* = 0.805 +/- 0.016, 1.203 +/- 0.061 R_sun), mean stellar densities (rho_* = 1.62 +/- 0.11, 0.58 +/- 0.14 rho_sun), planetary radii (R_p = 1.216 +/- 0.024, 1.451 +/- 0.074 R_Jup), and mean ...

  18. Spectroscopic Pulsational Frequency Identification and Mode Determination of {\\gamma} Doradus Star HD 12901

    OpenAIRE

    Brunsden, E.; Pollard, K.R.; Cottrell, P. L.; Wright, D J; De Cat, P.

    2012-01-01

    Using multi-site spectroscopic data collected from three sites, the frequencies and pulsational modes of the {\\gamma} Doradus star HD 12901 were identified. A total of six frequencies in the range 1-2 c/d were observed, their identifications supported by multiple line-profile measurement techniques and previously-published photometry. Five frequencies were of sufficient signal-to-noise for mode identification and all five displayed similar three-bump standard deviation profiles which were fit...

  19. HD 98800: An Opportunity to Measure True Masses for Low-Mass PMS Stars

    Science.gov (United States)

    Soderblom, David

    1999-07-01

    HD 98800 became interesting when IRAS found it to have a large infrared excess, indicating a substantial dust disk. But ``HD 98800'' is, in fact, a quadruple system consisting of four K and M stars, and its Hipparcos parallax has now shown that this is a pre-main sequence system. The four stars are in two visible objects, each of which is a spectroscopic binary with a period of about one year. In particular, the Ba-Bb pair is an SB2 with an estimated semi-major axis of about 20 milliarcsec. In TRANS mode, FGS1R can cleanly resolve the Ba-Bb pair and can determine the relative orbit and luminosities for the two components. POS mode observations lead to an absolute orbit and a more precise parallax than is currently available. In this program we propose to follow the HD 98800 Ba-Bb pair over the course of a full orbit during Cycle 8. The combination of FGS1R-TRANS and FGS1R-POS observations will provide gravitational masses for two low-mass PMS stars. In addition, the co nstraints of coevality and knowled ge of the astrophysical properties of the components {temperatures, luminosities, composition} make these observations a crucial test of our models of pre-main sequence evolution. These may be the first true masses determined for low-mass PMS objects, and so can provide a fundamental test of PMS evolutionary tracks.

  20. Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049

    CERN Document Server

    Kochukhov, O; Valenti, J A; Stempels, H C; Snik, F; Rodenhuis, M; Piskunov, N; Makaganiuk, V; Keller, C U; Johns-Krull, C M

    2014-01-01

    Intermediate-mass, magnetic chemically peculiar (Ap) stars provide a unique opportunity to study the topology of stellar magnetic fields in detail and to investigate magnetically driven processes of spot formation. Here we aim to derive the surface magnetic field geometry and chemical abundance distributions for the extraordinary Ap star HD 75049. This object hosts a surface field of ~30 kG, one of the strongest known for any non-degenerate star. We used time-series of high-resolution HARPS intensity and circular polarisation observations. These data were interpreted with the help of magnetic Doppler imaging and model atmospheres incorporating effects of a non-solar chemical composition and a strong magnetic field. We refined the rotational period of HD 75049 to Prot=4.048267+/-0.000036 d. We also derived basic stellar parameters, Teff=10250+/-250 K and logg=4.3+/-0.1. Magnetic Doppler imaging revealed that the field topology of HD 75049 is poloidal and dominated by a dipolar contribution with a peak surface ...

  1. Elemental abundance studies of the Ultraviolet Gallium CP star HD 168733

    Science.gov (United States)

    Collado, A. E.; López-García, Z.; Levato, H.; Malaroda, S.

    2009-05-01

    We report elemental abundance studies of the ultraviolet gallium CP star HD 168733. It is neither a silicon, nor a mercury-manganese star and a longitudinal magnetic field of the order of -594 gauss has been detected in it. The high resolution spectra were obtained with the EBASIM spectrograph attached to the 2.10 m telescope at CASLEO Observatory. The abundances results obtained show that Si es normal, Ti Cr and Fe are rich, PII, SII, GaII, SrII, YII, ZrII are present and its abundances are being determined. The presence of RE will be also investigated.

  2. Spectroscopic Pulsational Frequency and Mode Determination of the $\\gamma$ Doradus Star HD 189631

    OpenAIRE

    Davie, Matthew W.; Pollard, Karen R.; Cottrell, Peter L.; Brunsden, Emily; Wright, Duncan J.; De Cat, Peter

    2014-01-01

    We present improvement and confirmation of identified frequencies and pulsation modes for the $\\gamma$ Doradus star HD 189631. This work improves upon previous studies by incorporating a significant number of additional spectra and precise determination of frequencies. Four frequencies were identified for this star: $1.6774 \\pm 0.0002$ d$^{-1}$, $1.4174 \\pm 0.0002$ d$^{-1}$, $0.0714 \\pm 0.0002$ d$^{-1}$, and $1.8228 \\pm 0.0002$ d$^{-1}$ which were identified with the modes ($l$,$m$) = ($1,+1$...

  3. Few Skewed Disks Found in First Closure-Phase Survey of Herbig Ae/Be stars

    CERN Document Server

    Monnier, J D; Millan-Gabet, R; Traub, W; Schloerb, F P; Pedretti, E; Benisty, M; Carleton, N P; Haguenauer, P; Kern, P; Labeye, P; Lacasse, M G; Malbet, F; Perraut, K; Pearlman, M; Zhao, M

    2006-01-01

    Using the 3-telescope IOTA interferometer on Mt. Hopkins, we report results from the first near-infrared (lambda=1.65 mu) closure-phase survey of Young Stellar Objects (YSOs). These closure phases allow us to unambiguously detect departures from centrosymmetry (i.e., skew) in the emission pattern from YSO disks on the scale of ~4 milliarcseconds, expected from generic ``flared disk'' models. Six of fourteen targets showed small, yet statistically-significant, non-zero closure phases, with largest values from the young binary system MWC 361-A and the (pre-main sequence?) Be star HD 45677. Our observations are quite sensitive to the vertical structure of the inner disk and we confront the predictions of the ``puffed-up inner wall'' models of Dullemond, Dominik, and Natta (DDN). Our data support disks models with curved inner rims because the expected emission appear symmetrically-distributed around the star over a wide range of inclination angles. In contrast, our results are incompatible with the models posses...

  4. HD314884: A Slowly Pulsating B star in a Close Binary

    CERN Document Server

    Johnson, Christopher B; Maccarone, T; Britt, C T; Davis, H; Jonker, P G; Torres, M A P; Steeghs, D; Greiss, S; Nelemans, G

    2014-01-01

    We present the results of a spectroscopic and photometric analysis of HD314884, a slowly pulsating B star (SPB) in a binary system with detected soft X-ray emission. We spectrally classify the B star as a B5V-B6V star with T$_{eff}$ = 15,490 $\\pm$ 310 K, log $g$ = 3.75 $\\pm$ 0.25 dex, and a photometric period of P$_{0}$ = 0.889521(12) days. A spectroscopic period search reveals an orbital period for the system of P$_{orb}$ = 1.3654(11) days. The discrepancy in the two periods and the identification of a second and third distinct frequency in the photometric fourier transform at P$_1$ = 3.1347(56) and P$_2$ = 1.517(28) days provides evidence that HD314884 is a slowly pulsating B star (SPB) with at least three oscillation frequencies. These frequencies appear to originate from higher-order, non-linear tidal pulsations. Using the dynamical parameters obtained from the radial velocity curve, we find the most probable companion mass to be M$_1$ = $\\sim$0.8 M$_{\\odot}$ assuming a typical mass for the B star and mos...

  5. The challenge of measuring magnetic fields in strongly pulsating stars: the case of HD 96446

    CERN Document Server

    Järvinen, S P; Ilyin, I; Schöller, M; Briquet, M

    2016-01-01

    Among the early B-type stars, He-rich Bp stars exhibit the strongest large-scale organized magnetic fields with a predominant dipole contribution. The presence of $\\beta$ Cep-like pulsations in the typical magnetic early Bp-type star HD 96446 was announced a few years ago, but the analysis of the magnetic field geometry was hampered by the absence of a reliable rotation period and a sophisticated procedure for accounting for the impact of pulsations on the magnetic field measurements. Using new spectropolarimetric observations and a recently determined rotation period based on an extensive spectroscopic time series, we investigate the magnetic field model parameters of this star under more detailed considerations of the pulsation behaviour of the line profiles.

  6. HD15082b, a short-period planet orbiting an A-star

    Directory of Open Access Journals (Sweden)

    Lodieu N.

    2011-02-01

    Full Text Available Most of the known transiting extrasolar planets orbit slowly rotating F, G or K stars. In here we report on the detection of a transiting planet orbiting the bright, rapidly rotating A5 star HD15082, recently made by SuperWASP. Time resolved spectroscopic observations taken during transit show a hump caused by the planet crossing the line profile. From the analysis of the spectra, we derive the radius of the planet and find that it is orbiting retrograde in respect to the spin of the star. Because of its small distance from an A5 star, this planet must be one of the hottest planets known, which makes it relatively easy to detect it in the IR. We thus tried to detect it using the TNG but did not succeed. Using direct imaging, we search for possible companions, and found one candidate.

  7. The peculiar O6f star HD 148937 and the symmetrically surrounding nebulae

    Science.gov (United States)

    Johnson, H. M.

    1972-01-01

    The ultraviolet continuum of the star is observed and, after standard reddening corrections are applied, it is found to be hotter than a model 05 V star. The Of star and its two companions are photometered around wavelength 4640, 4686, and 4861 A. The results confirm Westerlund's (1960) absolute visual magnitude of about -6 for the Of star and confirm his rejection of NGC 6164-5 as a planetary nebula. Peculiarities of the system of nebular shells around HD 148937, of which NGC 6164-5 are the innermost, are discussed with reference to radiofrequency data. A standard extrapolation from the optical flux density of NGC 6164-5 predicts a detectable radio source but it does not appear in the relevant surveys.

  8. AN IONIZED OUTFLOW FROM AB AUR, A HERBIG AE STAR WITH A TRANSITIONAL DISK

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Luis F.; Zapata, Luis A.; Ortiz-León, Gisela N.; Loinard, Laurent [Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Dzib, Sergio A. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Macías, Enrique; Anglada, Guillem, E-mail: l.rodriguez@crya.unam.mx [Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada (Spain)

    2014-09-20

    AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated with the inner regions of AB Aur and conclude that the morphology, orientation, spectral index, and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that centimeter continuum emission is present in association with stars with transitional disks, but at levels than are becoming detectable only with the upgraded radio arrays. On the other hand, assuming that the jet velocity is 300 km s{sup –1}, we find that the ratio of mass loss rate to accretion rate in AB Aur is ∼0.1, similar to that found for less evolved systems.

  9. First discovery of a magnetic field in a main sequence delta Scuti star: the Kepler star HD188774

    CERN Document Server

    Neiner, Coralie

    2015-01-01

    The Kepler space mission provided a wealth of {\\delta} Sct-{\\gamma} Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related surface inhomogeneities. In particular, the Kepler {\\delta} Sct-{\\gamma} Dor hybrid candidate HD 188774 shows a few low frequencies in its light and radial velocity curves, whose origin is unclear. In this work, we check for the presence of a magnetic field in HD 188774. We obtained two spectropolarimetric measurements with ESPaDOnS at CFHT. The data were analysed with the least squares deconvolution method. We detected a clear magnetic signature in the Stokes V LSD profiles. The origin of the low frequencies detected in HD 188774 is therefore most probably the rotational modulation of surface spots possibly related to the presence of a magnetic field. Consequently, HD 188774 is not a genuine hybrid {\\delta} Sct-{\\gamma} Dor star, but the first known magne...

  10. Temperaments of young stars: Rapid mass-accretion rate changes in T Tauri and Herbig Ae stars

    CERN Document Server

    Costigan, Gráinne; Scholz, Aleks; Ray, Tom; Testi, Leonardo

    2014-01-01

    Variability in emission lines is a characteristic feature in young stars and can be used as a tool to study the physics of the accretion process. Here we present a study of H{\\alpha} variability in 15 T Tauri and Herbig Ae stars (K7-B2) over a wide range of time windows, from minutes, to hours, to days, and years. We assess the variability using linewidth measurements and the time series of line profiles. All objects show gradual, slow profile changes on time-scales of days. In addition, in three cases there is evidence for rapid variations in H{\\alpha} with typical time-scales of 10 min, which occurs in 10% of the total covered observing time. The mean accretion-rate changes, inferred from the line fluxes,are 0.01-0.07 dex for time-scales of < 1 hour, 0.04-0.4 dex for time-scales of days, and 0.13-0.52 dex for time-scales of years. In Costigan et al. 2012 we derived an upper limit finding that the intermediate (days) variability dominated over longer (years) variability. Here our new results, based on muc...

  11. HD 140283: A STAR IN THE SOLAR NEIGHBORHOOD THAT FORMED SHORTLY AFTER THE BIG BANG

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Howard E.; Nelan, Edmund P. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); VandenBerg, Don A. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada); Schaefer, Gail H. [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Harmer, Dianne, E-mail: bond@stsci.edu, E-mail: nelan@stsci.edu, E-mail: vandenbe@uvic.ca, E-mail: schaefer@chara-array.org, E-mail: diharmer@noao.edu [National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85726 (United States)

    2013-03-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 {+-} 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 {+-} 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about {+-}0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 {+-} 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang.

  12. Pulsations in the atmosphere of the roAp star HD 24712 II. Theoretical models

    CERN Document Server

    Saio, Hideyuki; Sachkov, Mikhail

    2009-01-01

    We discuss pulsations of the rapidly oscillating Ap (roAp) star HD 24712 (HR 1217) based on nonadiabatic analyses taking into account the effect of dipole magnetic fields. We have found that all the pulsation modes appropriate for HD 24712 are damped; i.e., the kappa-mechanism excitation in the hydrogen ionization layers is not strong enough to excite high-order p-modes with periods consistent with observed ones, all of which are found to be above the acoustic cut-off frequencies of our models. The main (2.721 mHz) and the highest (2.806 mHz) frequencies are matched with modified $l=2$ and $l=3$ modes, respectively. The large frequency separation ($\\approx 68 \\mu$Hz) is reproduced by models which lay within the error box of HD 24712 on the HR diagram. The nearly equally spaced frequencies of HD 24712 indicate the small frequency separation to be as small as $\\approx 0.5\\mu$Hz. However, the small separation derived from theoretical $l=1$ and 2 modes are found to be larger than $\\sim 3\\mu$Hz. The problem of equ...

  13. The nature of the light variability of magnetic Of?p star HD 191612

    CERN Document Server

    Krticka, J

    2016-01-01

    A small fraction of hot OBA stars host global magnetic fields with field strengths of the order of 0.1-10 kG. This leads to the creation of persistent surface structures (spots) in stars with sufficiently weak winds as a result of the radiative diffusion. These spots become evident in spectroscopic and photometric variability. This type of variability is not expected in stars with strong winds, where the wind inhibits the radiative diffusion. Therefore, a weak photometric variability of the magnetic Of?p star HD 191612 is attributed to the light absorption in the circumstellar clouds. We study the nature of the photometric variability of HD 191612. We assume that the variability results from variable wind blanketing induced by surface variations of the magnetic field tilt and modulated by stellar rotation. We used our global kinetic equilibrium (NLTE) wind models with radiative force determined from the radiative transfer equation in the comoving frame (CMF) to predict the stellar emergent flux. Our models de...

  14. MOST discovers a multimode delta Scuti star in a triple system: HD 61199

    CERN Document Server

    Hareter, M; Lehmann, H; Tsymbal, V; Hüber, D; Lenz, P; Weiss, W W; Matthews, J M; Rucinski, S; Rowe, J F; Kuschnig, R; Günther, D B; Moffat, A F J; Sasselov, D; Walker, G A H; Scholtz, A

    2008-01-01

    A field star, HD 61199 (V ~ 8), simultaneously observed with Procyon by the MOST (Microvariability & Oscillations of STars) satellite in continuous runs of 34, 17, and 34 days in 2004, 2005, and 2007, was found to pulsate in 11 frequencies in the delta Scuti range with amplitudes from 1.7 down to 0.09 mmag. The photometry also showed variations with a period of about four days. To investigate the nature of the longer period, 45 days of time-resolved spectroscopy was obtained at the Thueringer Landessternwarte Tautenburg in 2004. The radial velocity measurements indicate that HD 61199 is a triple system. A delta Scuti pulsator with a rich eigenspectrum in a multiple system is promising for asteroseismology. Our objectives were to identify which of the stars in the system is the delta Scuti variable and to obtain the orbital elements of the system and the fundamental parameters of the individual components, which are constrained by the pulsation frequencies of the delta Scuti star. Classical Fourier techniq...

  15. Spectroscopic Pulsational Frequency Identification and Mode Determination of Gamma Doradus Star HD135825

    CERN Document Server

    Brunsden, E; Cottrell, P L; Wright, D J; De Cat, P; Kilmartin, P M

    2012-01-01

    We present the mode identification of frequencies found in spectroscopic observations of the Gamma Doradus star HD135825. Four frequencies were successfully identified: 1.3150 +/- 0.0003 1/d; 0.2902 +/- 0.0004 1/d; 1.4045 +/- 0.0005 1/d; and 1.8829 +/- 0.0005 1/d. These correspond to (l, m) modes of (1,1), (2,-2), (4,0) and (1,1) respectively. Additional frequencies were found but they were below the signal-to-noise limit of the Fourier spectrum and not suitable for mode identification. The rotational axis inclination and vsini of the star were determined to be 87 degrees (nearly edge-on) and 39.7 km/s (moderate for Gamma Doradus stars) respectively. A simultaneous fit of these four modes to the line profile variations in the data gives a reduced chi square of 12.7. We confirm, based on the frequencies found, that HD135825 is a bona fide Gamma Doradus star.

  16. Discovery of a Low-Mass Companion to the F7V star HD 984

    CERN Document Server

    Meshkat, T; Mamajek, E E; Quanz, S P; Chauvin, G; Kenworthy, M A; Rameau, J; Meyer, M R; Lagrange, A -M; Lannier, J; Delorme, P

    2015-01-01

    We report the discovery of a low-mass companion to the nearby (d = 47 pc) F7V star HD 984. The companion is detected 0.19" away from its host star in the L' band with the Apodizing Phase Plate on NaCo/VLT and was recovered by L'-band non-coronagraphic imaging data taken a few days later. We confirm the companion is co-moving with the star with SINFONI integral field spectrograph H+K data. We present the first published data obtained with SINFONI in pupil-tracking mode. HD 984 has been argued to be a kinematic member of the 30 Myr-old Columba group, and its HR diagram position is not altogether inconsistent with being a ZAMS star of this age. By consolidating different age indicators, including isochronal age, coronal X-ray emission, and stellar rotation, we independently estimate a main sequence age of 115$\\pm$85 Myr (95% CL) which does not rely on this kinematic association. The mass of directly imaged companions are usually inferred from theoretical evolutionary tracks, which are highly dependent on the age...

  17. HD 65949: The Highest Known Mercury Excess Of Any CP Star?

    CERN Document Server

    Cowley, C R; Gonzalez, G F; Núñez, N S; Cowley, Charles R.

    2006-01-01

    ESO spectra of HD 65949 show it to be unlike any of the well-known types within its temperature range $\\approx$ 13600K. It is neither a silicon, nor a mercury-manganese star, though it has a huge Hg II line at $\\lambda$3984. We estimate $\\log({\\rm Hg/H}) + 12.0 \\approx 7.4$. This is higher than any published stellar mercury abundance. HD 65949 is a member of a nearby open cluster, NGC 2516, which is only slightly older than the Pleiades, and has been of recent interest because of its numerous X-ray emission stars, including HD 65949 itself, or a close companion. A longitudinal magnetic field of the order of -290 Gauss at the 4.7~$\\sigma$ level was very recently diagnosed from accurate circular spectropolarimetric observations with FORS 1 at the VLT. The spectral lines are sharp, allowing a thorough identification study. Second spectra of Ti, Cr, and Fe are rich. Mn II is well identified but not unusually strong. Numerous lines of S II and P II are found, but not Ga II. The resonance lines of Sr II are strong....

  18. Testing stellar evolution models with the retired A star HD 185351

    Science.gov (United States)

    Hjørringgaard, J. G.; Silva Aguirre, V.; White, T. R.; Huber, D.; Pope, B. J. S.; Casagrande, L.; Justesen, A. B.; Christensen-Dalsgaard, J.

    2016-10-01

    The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. (2014) using interferometry, spectroscopy and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of 1.5M⊙. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from ˜1.6 - 1.9M⊙ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as considering the additional constraint of the observed g-mode period spacing. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the overshooting efficiency using low-luminosity red giant stars. A theoretical model with metallicity [Fe/H] = 0.16dex, mixing-length parameter αMLT = 2.00, and convective overshooting efficiency parameter f = 0.030 is found to be in complete agreement with all observational constraints for a stellar mass of M ≃ 1.60M⊙.

  19. Testing stellar evolution models with the retired A star HD 185351

    Science.gov (United States)

    Hjørringgaard, J. G.; Silva Aguirre, V.; White, T. R.; Huber, D.; Pope, B. J. S.; Casagrande, L.; Justesen, A. B.; Christensen-Dalsgaard, J.

    2017-01-01

    The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. using interferometry, spectroscopy, and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of 1.5 M⊙. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from ˜1.6 to 1.9 M⊙ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here, we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as the additional constraint of the observed g-mode period spacing is considered. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the overshooting efficiency using low-luminosity red giant stars. A theoretical model with metallicity [Fe/H] = 0.16 dex, mixing-length parameter αMLT = 2.00, and convective overshooting efficiency parameter f = 0.030 is found to be in complete agreement with all observational constraints for a stellar mass of M ≃ 1.60 M⊙.

  20. Is there a compact companion orbiting the late O-type binary star HD 164816?

    CERN Document Server

    Trepl, L; Pribulla, T; Tetzlaff, N; Chini, R; Neuhäuser, R; Popov, S B; Stahl, O; Walter, F M; Hohle, M M

    2012-01-01

    We present a multi-wavelength (X-ray, $\\gamma$-ray, optical and radio) study of HD 194816, a late O-type X-ray detected spectroscopic binary. X-ray spectra are analyzed and the X-ray photon arrival times are checked for pulsation. In addition, newly obtained optical spectroscopic monitoring data on HD 164816 are presented. They are complemented by available radio data from several large scale surveys as well as the \\emph{FERMI} $\\gamma$-ray data from its \\emph{Large Area Telescope}. We report the detection of a low energy excess in the X-ray spectrum that can be described by a simple absorbed blackbody model with a temperature of $\\sim$ 50 eV as well as a 9.78 s pulsation of the X-ray source. The soft X-ray excess, the X-ray pulsation, and the kinematical age would all be consistent with a compact object like a neutron star as companion to HD 164816. The size of the soft X-ray excess emitting area is consistent with a circular region with a radius of about 7 km, typical for neutron stars, while the emission m...

  1. HD 179821 (V1427 Aql, IRAS 19114+0002) - a massive post-red supergiant star?

    Science.gov (United States)

    Şahin, T.; Lambert, David L.; Klochkova, Valentina G.; Panchuk, Vladimir E.

    2016-10-01

    We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe] = 1.0 ± 0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H] = 0.4 dex places it among the most metal-rich stars yet analysed. The abundance analysis of this luminous star is based on high-resolution and high-quality (S/N ≈ 120-420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over 21 epochs. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters over all epochs: Teff = 7350 ± 200 K, log g= +0.6 ± 0.3, and a microturbulent velocity ξ = 6.6 ± 1.6 km s-1 and [Fe/H] = 0.4 ± 0.2, and a carbon abundance [C/Fe] = -0.19 ± 0.30. We find oxygen abundance [O/Fe] = -0.25 ± 0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 ± 2.0 km s-1 is determined from both strong and weak Fe I and Fe II lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] ≈ 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for H α line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.

  2. HD 41641: a classical $\\delta$ Sct-type pulsator with chemical signatures of an Ap star

    CERN Document Server

    Escorza, A; Tkachenko, A; Van Reeth, T; Ryabchikova, T; Neiner, C; Poretti, E; Rainer, M; Michel, E; Baglin, A; Aerts, C

    2016-01-01

    Among the known groups of pulsating stars, $\\delta$ Sct stars are one of the least understood. The theoretical models do not predict the oscillation frequencies that observations reveal. Complete asteroseismic studies are necessary to improve these models and better understand the internal structure of these targets. In this paper, we study the $\\delta$ Sct star HD 41641 with the ultimate goal of understanding its oscillation pattern. The target has been simultaneously observed by the CoRoT space telescope and the HARPS high-resolution spectrograph. The photometric data set was analyzed with the software package PERIOD04, while FAMIAS was used to analyze the line profile variations. The method of spectrum synthesis was used for spectroscopically determining the fundamental atmospheric parameters and the individual chemical abundances. A total of 90 different frequencies was identified and analyzed. An unambiguous identification of the azimuthal order of the surface geometry could be provided for the dominant ...

  3. Spectroscopic Pulsational Frequency Identification and Mode Determination of {\\gamma} Doradus Star HD 12901

    CERN Document Server

    Brunsden, E; Cottrell, P L; Wright, D J; De Cat, P

    2012-01-01

    Using multi-site spectroscopic data collected from three sites, the frequencies and pulsational modes of the {\\gamma} Doradus star HD 12901 were identified. A total of six frequencies in the range 1-2 c/d were observed, their identifications supported by multiple line-profile measurement techniques and previously-published photometry. Five frequencies were of sufficient signal-to-noise for mode identification and all five displayed similar three-bump standard deviation profiles which were fitted well with (l,m)=(1,1) modes. These fits had reduced chi-squared values of less than 18. We propose that this star is an excellent candidate to test models of non-radially pulsating {\\gamma} Doradus stars as a result of the presence of multiple (1,1) modes.

  4. Spectroscopic Pulsational Frequency and Mode Determination of the $\\gamma$ Doradus Star HD 189631

    CERN Document Server

    Davie, Matthew W; Cottrell, Peter L; Brunsden, Emily; Wright, Duncan J; De Cat, Peter

    2014-01-01

    We present improvement and confirmation of identified frequencies and pulsation modes for the $\\gamma$ Doradus star HD 189631. This work improves upon previous studies by incorporating a significant number of additional spectra and precise determination of frequencies. Four frequencies were identified for this star: $1.6774 \\pm 0.0002$ d$^{-1}$, $1.4174 \\pm 0.0002$ d$^{-1}$, $0.0714 \\pm 0.0002$ d$^{-1}$, and $1.8228 \\pm 0.0002$ d$^{-1}$ which were identified with the modes ($l$,$m$) = ($1,+1$), ($1,+1$), ($2,-2$), and ($1,+1$) respectively. These findings are in agreement with the most recent literature. The prevalence of ($l$,$m$) = ($1,+1$) modes in $\\gamma$ Doradus stars is starting to become apparent and we discuss this result.

  5. The classification of frequencies in the {\\gamma} Doradus / {\\delta} Scuti hybrid star HD 49434

    CERN Document Server

    Brunsden, E; Cottrell, P L; Uytterhoeven, K; Wright, D J; De Cat, P

    2014-01-01

    Hybrid stars of the {\\gamma} Doradus and {\\delta} Scuti pulsation types have great potential for asteroseismic analysis to explore their interior structure. To achieve this, mode identi- fications of pulsational frequencies observed in the stars must be made, a task which is far from simple. In this work we begin the analysis by scrutinizing the frequencies found in the CoRoT photometric satellite measurements and ground-based high-resolution spectroscopy of the hybrid star HD 49434. The results show almost no consistency between the frequencies found using the two techniques and no characteristic period spacings or couplings were identified in either dataset. The spectroscopic data additionally show no evidence for any long term (5 year) variation in the dominant frequency. The 31 spectroscopic frequencies identified have standard deviation profiles suggesting multiple modes sharing (l, m) in the {\\delta} Scuti frequency region and several skewed modes sharing the same (l, m) in the {\\gamma} Doradus frequenc...

  6. X-Ray Spectroscopy of the O2 If* Star HD 93129A

    Science.gov (United States)

    Cohen, D. H.

    2012-12-01

    The O2 If* star, HD 93129A, is among the earliest in the Galaxy and has one of the strongest winds of any O star. In this paper, we show that its hard and strong X-ray emission can be understood in terms of the standard embedded wind shock paradigm for effectively single, hot, massive stars. Wind attenuation of the intrinsically soft X-ray emission is an important effect, which explains the hardness of the observed X-rays. We measure the degree of wind absorption in two different ways in order to derive a mass-loss rate of roughly 6 × 10-6 Msun; yr-1. This value is consistent with the observed Hα line if a clumping factor of fcl = 12 is assumed.

  7. A Comprehensive Analysis of the Magnetic Standard Star HD 94660: Host of a Massive Compact Companion?

    CERN Document Server

    Bailey, J D; Landstreet, J D

    2015-01-01

    Detailed information about the magnetic geometry, atmospheric abundances and radial velocity variations has been obtained for the magnetic standard star HD 94660 based on high-dispersion spectroscopic and spectropolarimetric observations from the UVES, HARPSpol and ESPaDOnS instruments. We perform a detailed chemical abundance analysis using the spectrum synthesis code zeeman for a total of 17 elements. Using both line-of-sight and surface magnetic field measurements, we derive a simple magnetic field model that consists of dipole, quadrupole and octupole components. The observed magnetic field variations of HD 94660 are complex and suggest an inhomogeneous distribution of chemical elements over the stellar surface. This inhomogeneity is not reflected in the abundance analysis, from which all available spectra are modelled, but only a mean abundance is reported for each element. The derived abundances are mostly non-solar, with striking overabundances of Fe-peak and rare-earth elements. Of note are the clear ...

  8. VizieR Online Data Catalog: HST photometry of stars in HD 97950 (Pang+, 2016)

    Science.gov (United States)

    Pang, X.; Pasquali, A.; Grebel, E. K.

    2016-07-01

    The HD97950 cluster and its immediate surroundings in the giant HII region NGC3603 were observed with the Hubble Space Telescope (HST). The ultraviolet (UV) data were taken with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in 2005 (GO 10602, PI: Jesus Maiz Apellaniz) through the F220W, F250W, F330W, and F435W filters. The HRC is characterized by a spatial resolution of 0.03"/pixel and a field of view of 29''*25''. The optical observations were carried out with the Wide Field and Planetary Camera 2 (WFPC2) in two epochs: 1997 (GO 6763, PI: Laurent Drissen) and 2007 (GO 11193, PI: Wolfgang Brandner) through the F555W, F675W, and F814W filters. The Planetary Camera (PC) chip was centered on the cluster (0.045"/pixel, 40''*40'') for both programs. Pang et al. 2013 (cat. J/ApJ/764/73) reduced the two-epoch WFPC2 data and identified more than 400 member stars on the PC chip via relative proper motions. Of these member stars, 142 are in common between the HRC and PC images and thus have UV and optical photometry available (see Table1). Among the HD97950 cluster member stars determined from relative proper motions (Pang et al. 2013, cat. J/ApJ/764/73, Table2), there are five main-sequence (MS) stars located in the cluster with projected distances of r<0.7pc from the center, for which there are also spectral types available from Table3 of Melena et al. (2008AJ....135..878M). The photometry of these five MS stars is presented in Table2. The individual color excesses and extinctions of the member main sequence stars are listed in Table3. (3 data files).

  9. A 12-year Activity Cycle for the Nearby Planet Host Star HD 219134

    Science.gov (United States)

    Johnson, Marshall C.; Endl, Michael; Cochran, William D.; Meschiari, Stefano; Robertson, Paul; MacQueen, Phillip J.; Brugamyer, Erik J.; Caldwell, Caroline; Hatzes, Artie P.; Ramírez, Ivan; Wittenmyer, Robert A.

    2016-04-01

    The nearby (6.5 pc) star HD 219134 was recently shown by Motalebi et al. and Vogt et al. to host several planets, the innermost of which is transiting. We present 27 years of radial velocity (RV) observations of this star from the McDonald Observatory Planet Search program, and 19 years of stellar activity data. We detect a long-period activity cycle measured in the Ca ii SHK index, with a period of 4230 ± 100 days (11.7 years), very similar to the 11 year solar activity cycle. Although the period of the Saturn-mass planet HD 219134 h is close to half that of the activity cycle, we argue that it is not an artifact due to stellar activity. We also find a significant periodicity in the SHK data due to stellar rotation with a period of 22.8 days. This is identical to the period of planet f identified by Vogt et al., suggesting that this RV signal might be caused by rotational modulation of stellar activity rather than a planet. Analysis of our RVs allows us to detect the long-period planet HD 219134 h and the transiting super-Earth HD 219134 b. Finally, we use our long time baseline to constrain the presence of longer period planets in the system, excluding to 1σ objects with M{sin}i\\gt 0.36{M}J at 12 years (corresponding to the orbital period of Jupiter) and M{sin}i\\gt 0.72{M}J at a period of 16.4 years (assuming a circular orbit for an outer companion).

  10. Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

    Science.gov (United States)

    Seok, Ji Yeon; Li, Aigen

    2017-02-01

    A distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm, is often detected in protoplanetary disks (PPDs). These features are commonly attributed to polycyclic aromatic hydrocarbons (PAHs). We model these emission features in the infrared spectra of 69 PPDs around 14 T Tauri and 55 Herbig Ae/Be stars in terms of astronomical PAHs. For each PPD, we derive the size distribution and the charge state of the PAHs. We then examine the correlations of the PAH properties (i.e., sizes and ionization fractions) with the stellar properties (e.g., stellar effective temperature, luminosity, and mass). We find that the characteristic size of the PAHs tends to correlate with the stellar effective temperature ({T}{eff}) and interpret this as the preferential photodissociation of small PAHs in systems with higher {T}{eff} of which the stellar photons are more energetic. In addition, the PAH size shows a moderate correlation with the red-ward wavelength shift of the 7.7 μm PAH feature that is commonly observed in disks around cool stars. The ionization fraction of PAHs does not seem to correlate with any stellar parameters. This is because the charging of PAHs depends on not only the stellar properties (e.g., {T}{eff}, luminosity) but also their spatial distribution in the disks. The marginally negative correlation between PAH size and stellar age suggests that continuous replenishment of PAHs via the outgassing of cometary bodies and/or the collisional grinding of planetesimals and asteroids is required to maintain the abundance of small PAHs against complete destruction by photodissociation.

  11. Flaring vs. self-shadowed disks: the SEDs of Herbig Ae/Be stars

    CERN Document Server

    Dullemond, C P

    2004-01-01

    Isolated Herbig Ae stars can be divided into two groups (Meeus et al. 2001): those with an almost flat spectral energy distribution in the mid-infrared (`group I'), and those with a strong decline towards the far-infrared (`group II'). In this paper we show that the group I vs. II distinction can be understood as arising from flaring vs. self-shadowed disks. We show that these two types of disks are natural solutions of the 2-D radiation-hydrostatic structure equations. Disks with high optical depth turn out to be flaring and have a strong far-IR emission, while disks with an optical depth below a certain threshold drop into the shadow of their own puffed-up inner rim and are weak in the far-IR. In spite of not having a directly irradiated surface layer, self-shadowed disks still display dust features in emission, in agreement with observations of group II sources. We propose an evolutionary scenario in which a disk starts out with a flaring shape (group I source), and then goes through the process of grain g...

  12. Spectroscopic Evidence of Sporadic Gas Accretion onto the Herbig AE Stars with Non-Periodic Algol-Type Minima

    Science.gov (United States)

    Kozlova, O. V.; Grinin, V. P.; Rostopchina, A. N.

    We present the results of simultaneous spectroscopic and photometric observations for six isolated Herbig Ae stars with non-periodic Algol-like minima: UX Ori, BF Ori, CQ Tau, SV Cep, VX Gas, and WW Vul. In all cases the Ha line has the profile typical for axially symmetric accretion. In the spectra of five stars (CQ Tau is the exception) the strong He I 5876 Å line has been observed in absorption which is not typical of normal A stars. In three cases: UX Ori, VX Cas, and WW Vul, variability of this line is found. We did not observe any correlation between the strength of this line and the brightness of the stars. These observational facts are considered as evidence for gas accretion, which is probably an important property of young stars with non-periodic Algol-type minima.

  13. Iron-Group Abundances in the Metal-Poor Main Sequence Turnoff Star HD~84937

    CERN Document Server

    Sneden, Christopher; Kobayashi, Chiaki; Pignatari, Marco; Lawler, James E; Hartog, Elizabeth A Den; Wood, Michael P

    2015-01-01

    We have derived new very accurate abundances of the Fe-group elements Sc through Zn (Z = 21-30) in the bright main-sequence turnoff star HD 84937, based on high-resolution spectra covering the visible and ultraviolet spectral regions. New or recent laboratory transition data for 14 species of seven elements have been used. Abundances from more than 600 lines of non-Fe species have been combined with about 550 Fe lines in HD 84937 to yield abundance ratios of high precision. The abundances have been determined from both neutral and ionized transitions, which generally are in agreement with each other. We find no substantial departures from standard LTE Saha ionization balance in this [Fe/H] = -2.32 star. Noteworthy among the abundances are: [Co/Fe] = 0.14 and [Cu/Fe] = -0.83, in agreement with past studies abundance trends in this and other low metallicity stars; and = 0.31, which has not been noted previously. A detailed examination of scandium, titanium, and vanadium abundances in large-sample spectroscopic...

  14. Searching for Star-Planet interactions within the magnetosphere of HD 189733

    CERN Document Server

    Fares, R; Moutou, C; Jardine, M M; Griessmeier, J -M; Zarka, P; Shkolnik, E L; Bohlender, D; Catala, C; Cameron, A C

    2010-01-01

    HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (June 2007 and July 2008). HD 189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40 G. The star is differentially rotating, with latitudinal angular velocity shear of domega = 0.146 +- 0.049 rad/d, corresponding to equatorial and polar periods of 11.94 +- 0.16 d and 16.53 +- 2.43 d respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric int...

  15. Multi-element Doppler imaging of the CP2 star HD 3980

    CERN Document Server

    Nesvacil, N; Shulyak, D; Obbrugger, M; Weiss, W; Drake, N A; Hubrig, S; Ryabchikova, T; Kochukhov, O; Piskunov, N; Polosukhina, N

    2013-01-01

    In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980. Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions. Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Exce...

  16. Diamonds in HD 97048

    CERN Document Server

    Habart, E; Natta, A; Carbillet, M

    2004-01-01

    We present adaptive optics high angular resolution ($\\sim0\\farcs$1) spectroscopic observations in the 3 $\\mu$m region of the Herbig Ae/Be star HD 97048. For the first time, we spatially resolve the emission in the diamond features at 3.43 and 3.53 $\\mu$m and in the adjacent continuum. Using both the intensity profiles along the slit and reconstructed two-dimensional images of the object, we derive full-width at half-maximum sizes consistent with the predictions for a circumstellar disk seen pole-on. The diamond emission originates in the inner region ($R \\lesssim 15$ AU) of the disk.

  17. A Resolved Debris Disk Around the Candidate Planet-hosting Star HD 95086

    Science.gov (United States)

    Moor, A.; Abraham, P.; Kospal, A.; Szabo, Gy. M.; Apai, D.; Balog, Z.; Csengeri, T.; Grady, C.; Henning, Th.; Juhasz, J.; Kiss, Cs.; Pasucci, I.; Szulagyi, J.; Vavrek, R.

    2013-01-01

    Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD 95086. The strong infrared excess of the system indicates that, similar to HR8799, Beta Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD 95086 disk, and to investigate its possible interaction with the newly discovered planet, here we present new optical, infrared, and millimeter observations. We detected no CO emission, excluding the possibility of an evolved gaseous primordial disk. Simple blackbody modeling of the spectral energy distribution suggests the presence of two spatially separate dust belts at radial distances of 6 and 64 AU. Our resolved images obtained with the Herschel Space Observatory reveal a characteristic disk size of approx. 6.0 × 5.4 (540 × 490 AU) and disk inclination of approx 25 deg. Assuming the same inclination for the planet candidate's orbit, its reprojected radial distance from the star is 62 AU, very close to the blackbody radius of the outer cold dust ring. The structure of the planetary system at HD 95086 resembles the one around HR8799. Both systems harbor a warm inner dust belt and a broad colder outer disk and giant planet(s) between the two dusty regions. Modeling implies that the candidate planet can dynamically excite the motion of planetesimals even out to 270 AU via their secular perturbation if its orbital eccentricity is larger than about 0.4. Our analysis adds a new example to the three known systems where directly imaged planet(s) and debris disks coexist.

  18. Low-frequency GMRT observations of the magnetic Bp star HR Lup (HD 133880)

    Science.gov (United States)

    George, Samuel J.; Stevens, Ian R.

    2012-06-01

    We present radio observations of the magnetic chemically peculiar Bp star HR Lup (HD 133880) at 647 and 277 MHz with the GMRT. At both frequencies the source is not detected but we are able to determine upper limits to the emission. The 647 MHz limits are particularly useful, with a 5σ value of 0.45 mJy. Also, no large enhancements of the emission were seen. The non-detections, along with previously published higher frequency detections, provide evidence that an optically thick gyrosynchrotron model is the correct mechanism for the radio emission of HR Lup.

  19. Low-frequency GMRT observations of the magnetic Bp star HR Lup (HD 133880)

    CERN Document Server

    George, Samuel J

    2012-01-01

    We present radio observations of the magnetic chemically peculiar Bp star HR Lup (HD 133880) at 647 and 277 MHz with the GMRT. At both frequencies the source is not detected but we are able to determine upper limits to the emission. The 647 MHz limits are particularly useful, with a 5\\sigma\\ value of 0.45 mJy. Also, no large enhancements of the emission were seen. The non-detections, along with previously published higher frequency detections, provide evidence that an optically thick gyrosynchrotron model is the correct mechanism for the radio emission of HR Lup.

  20. Spectroscopic Pulsational Frequency Identification and Mode Determination of Gamma Doradus Star HD135825

    OpenAIRE

    Brunsden, E.; Pollard, K.R.; Cottrell, P. L.; Wright, D J; De Cat, P.; Kilmartin, P.M.

    2012-01-01

    We present the mode identification of frequencies found in spectroscopic observations of the Gamma Doradus star HD135825. Four frequencies were successfully identified: 1.3150 +/- 0.0003 1/d; 0.2902 +/- 0.0004 1/d; 1.4045 +/- 0.0005 1/d; and 1.8829 +/- 0.0005 1/d. These correspond to (l, m) modes of (1,1), (2,-2), (4,0) and (1,1) respectively. Additional frequencies were found but they were below the signal-to-noise limit of the Fourier spectrum and not suitable for mode identification. The r...

  1. Testing stellar evolution models with the retired A star HD 185351

    CERN Document Server

    Hjørringgaard, Jakob G; White, Tim R; Huber, Daniel; Pope, Benjamin J S; Casagrande, Luca; Justesen, Anders B; Christensen-Dalsgaard, Jørgen

    2016-01-01

    The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. (2014) using interferometry, spectroscopy and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of $1.5\\mathrm{M}_{\\odot}$. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from $\\sim 1.6-1.9\\mathrm{M}_{\\odot}$ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as considering the additional constraint of the observed g-mode period spacing. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the...

  2. Multiwavelength study of the magnetically active T Tauri star HD 283447

    Science.gov (United States)

    Feigelson, Eric D.; Welty, Alan D.; Imhoff, Catherine; Hall, Jeffrey C.; Etzel, Paul B.; Phillips, Robert B.; Lonsdale, Colin J.

    1994-01-01

    We observed the luminous T Tauri star HD 283447 = V773 Tauri simultaneously at X-ray, ultraviolet, optical photometric and spectroscopic, and radio wavelengths for several hours on UT 1992 September 11. ROSAT, IUE, Very Large Array (VLA) and an intercontinental Very Long Baseline Interferometry (VLBI) network, and three optical observatories participated in the campaign. The star is known for its unusually high and variable nonthermal radio continuum emission. High levels of soft X-ray and Mg II line emission are discovered, with luminosity L(sub x) = 5.5 x 10(exp 30) ergs/s (0.2 - 2 keV) and L(sub Mg II) = 1 x 10(exp 29) ergs/s, respectively. Optically, the spectrum exhibits rather weak characteristics of `classical' T Tauri stars. A faint, broad emission line component, probably due to a collimated wind or infall, is present. During the campaign, the radio luminosity decreased by a factor of 4, while optical/UV lines and X-ray emission remained strong but constant. The large gyrosynchrotron-emitting regions are therefore decoupled from the chromospheric and coronal emission. Five models for the magnetic geometry around the star are discussed; solar-type activity, dipole magnetosphere, star-disk magnetic coupling, disk magnetic fields, and close binary interaction. The data suggest that two magnetic geometries are simultaneously present: complex multipolar fields like those on the Sun, and a large-scale field possibly associated with the circumstellar disk.

  3. The Cool Giant HD 77361 - A Super Li-Rich Star

    CERN Document Server

    Lyubimkov, L S; Metlov, V G; Pavlenko, Ya V; Poklad, D B; Rachkovskaya, T M

    2016-01-01

    Super Li-rich stars form a very small and enigmatic group whose existence cannot be explained in terms of the standard stellar evolution theory. The goal of our study is to check the reality of this group of cool giants based on an independent technique. We have carried out such a check using the K giant HD 77361 (HR 3597), which has previously been assigned to this rare type, as an example. We have redetermined the effective temperature Teff and surface gravity log g for this star. We have applied two different methods, photometric and spectroscopic, to estimate Teff (the accuracy of the Li-abundance determination depends significantly on this parameter). The value of log g has been found from the highly accurate parallax of this nearby star. To apply the photometric method of determining Teff, we have performed UBV observations of the star, which yielded V = 6.18 +/- 0.03, B - V = 1.13 +/- 0.01, and U - B = 1.18+/-0.05. The following parameters of the star have been found: effective temperature Teff = 4370+...

  4. Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682

    CERN Document Server

    Grunhut, J H; Sundqvist, J O; ud-Doula, A; Neiner, C; Ignace, R; Marcolino, W L F; Rivinius, Th; Fullerton, A; Kaper, L; Mauclaire, B; Buil, C; Garrel, T; Ribeiro, J; Ubaud, S

    2012-01-01

    The O9IV star HD 57682, discovered to be magnetic within the context of the MiMeS survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, the MiMeS Collaboration has continued to obtain spectroscopic and magnetic observations in order to refine our knowledge of its magnetic field strength and geometry, rotational period, and spectral properties and variability. In this paper we report new ESPaDOnS spectropolarimetric observations of HD 57682, which are combined with previously published ESPaDOnS data and archival H{\\alpha} spectroscopy. This dataset is used to determine the rotational period (63.5708 \\pm 0.0057 d), refine the longitudinal magnetic field variation and magnetic geometry (dipole surface field strength of 880\\pm50 G and magnetic obliquity of 79\\pm4\\circ as measured from the magnetic longitudinal field variations, assuming an inclination of 60\\circ), and examine the p...

  5. Coordinated X-ray and Optical observations of Star-Planet Interaction in HD 17156

    CERN Document Server

    Maggio, A; Scandariato, G; Lanza, A F; Sciortino, S; Borsa, F; Bonomo, A S; Claudi, R; Covino, E; Desidera, S; Gratton, R; Micela, G; Pagano, I; Piotto, G; Sozzetti, A; Cosentino, R; Maldonado, J

    2015-01-01

    The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focused our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. Here we present results of the XMM-Newton observations and of a five month coordinated optical campaign with the HARPS-N spectrograph. We observed HD 17156 with XMM-Newton when the planet was approaching the apoastron and then at the following periastron passage, quasi simultaneously with HARPS-N. We obtained a clear ($\\approx 5.5\\sigma$) X-ray detection only at the periastron visit, accompanied by a significant increase of the $R'_{\\rm HK}$ chromospheric index. We discuss two possible scenarios for the activity enhancement: magnetic reconnection and flaring or accretion onto the star of material tidally stripped from the planet. In any case, this is possibly the first evidence of a magnetic SPI effect caught in action.

  6. High-resolution X-ray spectroscopy of the magnetic Of?p star HD148937

    CERN Document Server

    Naze, Y; Walborn, N R

    2011-01-01

    High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800km/s), i.e. narrower than the O line recorded by RGS, which possibly indicates that the hot plasma is multi-thermal and has several origins. These data further indicate a main plasma temperature of about 0.6keV and a formation of the X-ray emission at about one stellar radius above the photosphere. From the spectral fits and the H-to-He line ratios, the presence of very hot plasma is however confirmed, though with a smaller relative strength than for the prototype magnetic oblique rotator $\\theta^1$\\,Ori\\,C. Both stars thus share many similarities, but HD148937 appears less extreme than $\\theta^1$\\,Ori\\,C despite having also a large magnetic confinement parameter.

  7. The spectral variability and magnetic field characteristics of the Of?p star HD 148937

    CERN Document Server

    Wade, G A; Graefener, G; Howarth, I D; Martins, F; Petit, V; Vink, J S; Bagnulo, S; Folsom, C P; Nazé, Y; Walborn, N R; Townsend, R H D; Evans, C J

    2011-01-01

    We reportmagnetic and spectroscopic observations and modeling of the Of?p star HD 148937 within the context of theMagnetism in Massive Stars (MiMeS) Large Program at the Canada-France-Hawaii Telescope. Thirty-two high signal-to-noise ratio circularly polarised (Stokes V) spectra and 13 unpolarised (Stokes I) spectra of HD 148937 were acquired in 2009 and 2010. A definite detection of a Stokes V Zeeman signature is obtained in the grand mean of all observations (in both Least-Squares Deconvolved (LSD) mean profiles and individual spectral lines). The longitudinalmagnetic field inferred from the Stokes V LSD profiles is consistently negative, in contrast to the essentially zero field strength measured from the diagnostic null profiles. A period search of new and archival equivalent width measurements confirms the previously-reported 7.03 d variability period. The variation of equivalent widths is not strictly periodic: we present evidence for evolution of the amount or distribution of circumstellar plasma. Inte...

  8. Gas and dust spectra of the D' type symbiotic star HD330036

    CERN Document Server

    Angeloni, R; Ciroi, S; Rafanelli, P

    2007-01-01

    We present a comprehensive and self-consistent modelling of the D' type symbiotic star (SS) HD330036 from radio to UV. Within a colliding-wind scenario, we analyse the continuum, line and dust spectra by means of SUMA, a code that simulates the physical conditions of an emitting gaseous cloud under the coupled effect of ionization from an external radiation source and shocks. We find that the UV lines are emitted from high density gas between the stars downstream of the reverse shock, while the optical lines are emitted downstream of the shock propagating outwards the system. As regards with the continuum SED, three shells are identified in the IR, at 850K, 320 K and 200 K with radii r = 2.8 10^13 cm, 4 10^14$ cm, and 10^15 cm, respectively, adopting a distance to Earth d=2.3 kpc: interestingly, all these shells appear to be circumbinary. The analysis of the unexploited ISO-SWS spectrum reveals that both PAHs and crystalline silicates coexist in HD330036, with PAHs associated to the internal shell at 850 K, a...

  9. The first magnetic maps of a pre-main sequence binary star system - HD 155555

    CERN Document Server

    Dunstone, N J; Cameron, A Collier; Marsden, S C; Jardine, M; Stempels, H C; Vlex, J C Ramirez; Donati, J -F

    2008-01-01

    We present the first maps of the surface magnetic fields of a pre-main sequence binary system. Spectropolarimetric observations of the young, 18 Myr, HD 155555 (V824 Ara, G5IV + K0IV) system were obtained at the Anglo-Australian Telescope in 2004 and 2007. Both datasets are analysed using a new binary Zeeman Doppler imaging (ZDI) code. This allows us to simultaneously model the contribution of each component to the observed circularly polarised spectra. Stellar brightness maps are also produced for HD 155555 and compared to previous Doppler images. Our radial magnetic maps reveal a complex surface magnetic topology with mixed polarities at all latitudes. We find rings of azimuthal field on both stars, most of which are found to be non-axisymmetric with the stellar rotational axis. We also examine the field strength and the relative fraction of magnetic energy stored in the radial and azimuthal field components at both epochs. A marked weakening of the field strength of the secondary star is observed between t...

  10. Abundances of neutron-capture elements in the Hot Extreme-Helium Stars V1920 Cygni and HD 124448

    CERN Document Server

    Pandey, G; Rao, N K; Jeffery, C S; Pandey, Gajendra; Lambert, David L.

    2004-01-01

    Analysis of HST STIS ultraviolet spectra of two hot extreme helium stars (EHes): V1920 Cyg and HD 124448 provide the first measurements of abundances of neutron-capture elements for EHes. Although the two stars have similar abundances for elements up through the iron-group, they differ strikingly in their abundances of heavier elements: V1920 Cyg is enriched by a factor of 30 in light neutron-capture elements (Y/Fe, Zr/Fe) relative to HD 124448. These differences in abundances of neutron-capture elements among EHes mirrors that exhibited by the RCrB stars, and is evidence supporting the view that there is an evolutionary connection between these two groups of hydrogen-deficient stars. Also, the abundances of Y and Zr in V1920 Cyg provide evidence that at least one EHe star went through a s-process synthesis episode in its earlier evolution.

  11. HD 18078: A very slowly rotating Ap star with an unusual magnetic field structure

    Science.gov (United States)

    Mathys, G.; Romanyuk, I. I.; Kudryavtsev, D. O.; Landstreet, J. D.; Pyper, D. M.; Adelman, S. J.

    2016-02-01

    Context. The existence of a significant population of Ap stars with very long rotation periods (up to several hundred years) has progressively emerged over the past two decades. However, only lower limits of the periods are known for most of them because their variations have not yet been observed over a sufficient timebase. Aims: We determine the rotation period of the slowly rotating Ap star HD 18078 and we derive constraints on the geometrical structure of its magnetic field. Methods: We combine measurements of the mean magnetic field modulus obtained from 1990 to 1997 with determinations of the mean longitudinal magnetic field spanning the 1999-2007 time interval to derive an unambiguous value of the rotation period. We show that this value is consistent with photometric variations recorded in the Strömgren uvby photometric system between 1995 and 2004. We fit the variations of the two above-mentioned field moments with a simple model to constrain the magnetic structure. Results: The rotation period of HD 18078 is (1358 ± 12) d. The geometrical structure of its magnetic field is consistent to first order with a colinear multipole model whose axis is offset from the centre of the star. Conclusions: HD 18078 is only the fifth Ap star with a rotation period longer than 1000 d for which the exact value of that period (as opposed to a lower limit) could be determined. The strong anharmonicity of the variations of its mean longitudinal magnetic field and the shift between their extrema and those of the mean magnetic field modulus are exceptional and indicative of a very unusual magnetic structure. Based in part on observations made at Observatoire de Haute Provence (CNRS), France; at Kitt Peak National Observatory, National Optical Astronomy Observatory (NOAO Prop. ID: KP2442; PI: T. Lanz), which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation; at the Canada

  12. Surface structure of the CoRoT CP2 target star HD 50773

    CERN Document Server

    Lüftinger, T; Weiss, W; Petit, P; Aurière, M; Nesvacil, N; Gruberbauer, M; Shulyak, D; Alecian, E; Baglin, A; Baudin, F; Catala, C; Donati, J -F; Kochukhov, O; Michel, E; Piskunov, N; Roudier, T; Samadi, R

    2009-01-01

    We compare surface maps of the chemically peculiar star HD 50773 produced with a Bayesian technique and based on high quality CoRoT photometry with those derived from rotation phase resolved spectropolarimetry. The goal is to investigate the correlation of surface brightness with surface chemical abundance distribution and the stellar magnetic field. The rotational period of the star was determined from a nearly 60 day long continuous light curve obtained during the initial run of CoRoT. Using a Bayesian approach to star-spot modelling, which in this work is applied for the first time for the photometric mapping of a CP star, we derived longitudes, latitudes and radii of four different spot areas. Additional parameters like stellar inclination and the spot's intensities were also determined. The CoRoT observations triggered an extensive ground-based spectroscopic and spectropolarimetric observing campaign and enabled us to obtain 19 different high resolution spectra in Stokes parameters I and V with NARVAL, E...

  13. Precise Modeling of the Exoplanet Host Star and CoRoT Main Target HD 52265

    CERN Document Server

    Escobar, M E; Ballot, J; Charpinet, S; Dolez, N; Hui-Bon-Hoa, A; Vauclair, G; Gizon, L; Mathur, S; Quirion, P O; Stahn, T

    2012-01-01

    This paper presents a detailed and precise study of the characteristics of the Exoplanet Host Star and CoRoT main target HD 52265, as derived from asteroseismic studies. The results are compared with previous estimates, with a comprehensive summary and discussion. The basic method is similar to that previously used by the Toulouse group for solar-type stars. Models are computed with various initial chemical compositions and the computed p-mode frequencies are compared with the observed ones. All models include atomic diffusion and the importance of radiative accelerations is discussed. Several tests are used, including the usual frequency combinations and the fits of the \\'echelle diagrams. The possible surface effects are introduced and discussed. Automatic codes are also used to find the best model for this star (SEEK, AMP) and their results are compared with that obtained with the detailed method. We find precise results for the mass, radius and age of this star, as well as its effective temperature and lu...

  14. Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light

    CERN Document Server

    Garufi, Antonio; Schmid, Hans Martin; Avenhaus, Henning; Buenzli, Esther; Wolf, Sebastian

    2014-01-01

    The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric fac...

  15. Stellar parameters and accretion rate of the transition disk star HD 142527 from X-shooter

    Energy Technology Data Exchange (ETDEWEB)

    Mendigutía, I.; Fairlamb, J.; Oudmaijer, R. D. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Montesinos, B. [Centro de Astrobiología, Departamento de Astrofísica (CSIC-INTA), ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Najita, J. R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Brittain, S. D. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States); Van den Ancker, M. E., E-mail: I.Mendigutia@leeds.ac.uk [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München (Germany)

    2014-07-20

    HD 142527 is a young pre-main-sequence star with properties indicative of the presence of a giant planet and/or a low-mass stellar companion. We have analyzed an X-Shooter/Very Large Telescope spectrum to provide accurate stellar parameters and accretion rate. The analysis of the spectrum, together with constraints provided by the spectral energy distribution fitting, the distance to the star (140 ± 20 pc), and the use of evolutionary tracks and isochrones, led to the following set of parameters: T{sub eff} = 6550 ± 100 K, log g = 3.75 ± 0.10, L{sub *}/L{sub ☉} = 16.3 ± 4.5, M{sub *}/M{sub ☉} = 2.0 ± 0.3, and an age of 5.0 ± 1.5 Myr. This stellar age provides further constraints to the mass of the possible companion estimated by Biller et al., being between 0.20 and 0.35 M{sub ☉}. Stellar accretion rates obtained from UV Balmer excess modeling and optical photospheric line veiling, and from the correlations with several emission lines spanning from the UV to the near-IR, are consistent with each other. The mean value from all previous tracers is 2 (±1) × 10{sup –7} M{sub ☉} yr{sup –1}, which is within the upper limit gas flow rate from the outer to the inner disk recently provided by Cassasus et al.. This suggests that almost all gas transferred between both components of the disk is not trapped by the possible planet(s) in between but fall onto the central star, although it is discussed how the gap flow rate could be larger than previously suggested. In addition, we provide evidence showing that the stellar accretion rate of HD 142527 has increased by a factor ∼7 on a timescale of 2 to 5 yr.

  16. Stellar Parameters and Accretion Rate of the Transition Disk Star HD 142527 from X-Shooter

    Science.gov (United States)

    Mendigutía, I.; Fairlamb, J.; Montesinos, B.; Oudmaijer, R. D.; Najita, J. R.; Brittain, S. D.; van den Ancker, M. E.

    2014-07-01

    HD 142527 is a young pre-main-sequence star with properties indicative of the presence of a giant planet and/or a low-mass stellar companion. We have analyzed an X-Shooter/Very Large Telescope spectrum to provide accurate stellar parameters and accretion rate. The analysis of the spectrum, together with constraints provided by the spectral energy distribution fitting, the distance to the star (140 ± 20 pc), and the use of evolutionary tracks and isochrones, led to the following set of parameters: T eff = 6550 ± 100 K, log g = 3.75 ± 0.10, L */L ⊙ = 16.3 ± 4.5, M */M ⊙ = 2.0 ± 0.3, and an age of 5.0 ± 1.5 Myr. This stellar age provides further constraints to the mass of the possible companion estimated by Biller et al., being between 0.20 and 0.35 M ⊙. Stellar accretion rates obtained from UV Balmer excess modeling and optical photospheric line veiling, and from the correlations with several emission lines spanning from the UV to the near-IR, are consistent with each other. The mean value from all previous tracers is 2 (±1) × 10-7 M ⊙ yr-1, which is within the upper limit gas flow rate from the outer to the inner disk recently provided by Cassasus et al.. This suggests that almost all gas transferred between both components of the disk is not trapped by the possible planet(s) in between but fall onto the central star, although it is discussed how the gap flow rate could be larger than previously suggested. In addition, we provide evidence showing that the stellar accretion rate of HD 142527 has increased by a factor ~7 on a timescale of 2 to 5 yr.

  17. Multi-element Doppler imaging of the CP2 star HD 3980

    Science.gov (United States)

    Nesvacil, N.; Lüftinger, T.; Shulyak, D.; Obbrugger, M.; Weiss, W.; Drake, N. A.; Hubrig, S.; Ryabchikova, T.; Kochukhov, O.; Piskunov, N.; Polosukhina, N.

    2012-01-01

    Context. In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. Aims: The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980. Methods: Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions. Results: Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Except for La, which is clearly depleted in the area of the magnetic poles, no obvious correlation with the magnetic field has been found for these elements otherwise. Ca, Cr, and Fe appear enhanced along the rotational equator and the area around the magnetic poles. The intersection between the magnetic and the rotational equator constitutes an exception, especially for Ca and Cr, which are depleted in that region. Conclusions: No obvious correlation between the theoretically predicted abundance patterns and those determined in this study could be found. This can be attributed to a lack of up-to-date theoretical models, especially for rare earth elements. Table 1 is available in electronic form at http://www.aanda.org

  18. Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star

    Energy Technology Data Exchange (ETDEWEB)

    Van Grootel, V.; Gillon, M.; Scuflaire, R. [Institut d' Astrophysique et de Géophysique, Université de Liège, 17 Allée du 6 Août, B-4000 Liège (Belgium); Valencia, D. [Department of Physical and Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4 (Canada); Madhusudhan, N.; Demory, B.-O.; Queloz, D. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Dragomir, D. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr. Suite 102, Goleta, CA 93117 (United States); Howe, A. R.; Burrows, A. S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Deming, D. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ehrenreich, D.; Lovis, C.; Mayor, M.; Pepe, F.; Segransan, D.; Udry, S. [Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, CH-1290 Sauverny (Switzerland); Seager, S., E-mail: valerie.vangrootel@ulg.ac.be [Department of Earth, Atmospheric and Planetary Sciences, Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2014-05-01

    Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass (M {sub *} = 0.77 ± 0.05 M {sub ☉}) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-High Resolution Echelle Spectrometer (Keck-HIRES) radial velocities and Microvariability and Oscillations of STars (MOST) and Spitzer photometry. HD 97658 b is a massive (M{sub P}=7.55{sub −0.79}{sup +0.83} M{sub ⊕}) and large (R{sub P}=2.247{sub −0.095}{sup +0.098}R{sub ⊕} at 4.5 μm) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, of at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the knowledge of the HD 97658 system, in particular by constraining its age. Orbiting a bright host star, HD 97658 b will be a key target for upcoming space missions such as the Transiting Exoplanet Survey Satellite (TESS), the Characterizing Exoplanet Satellite (CHEOPS), the Planetary Transits and Oscillations of stars (PLATO), and the James Webb Space Telescope to characterize thoroughly its structure and atmosphere.

  19. HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode

    CERN Document Server

    Holdsworth, Daniel L; Smalley, Barry; Saio, Hideyuki; Handler, Gerald; Murphy, Simon J; Lehmann, Holger

    2016-01-01

    We present an analysis of the first Kepler K2 mission observations of a rapidly oscillating Ap (roAp) star, HD 24355 ($V=9.65$). The star was discovered in SuperWASP broadband photometry with a frequency of 224.31 d$^{-1}$, (2596.18 $\\mu$Hz; $P = 6.4$ min) and an amplitude of 1.51 mmag, with later spectroscopic analysis of low-resolution spectra showing HD 24355 to be an A5 Vp SrEu star. The high precision K2 data allow us to identify 13 rotationally split sidelobes to the main pulsation frequency of HD 24355. This number of sidelobes combined with an unusual rotational phase variation show this star to be the most distorted quadrupole roAp pulsator yet observed. In modelling this star, we are able to reproduce well the amplitude modulation of the pulsation, and find a close match to the unusual phase variations. We show this star to have a pulsation frequency higher than the critical cut-off frequency. This is currently the only roAp star observed with the Kepler spacecraft in Short Cadence mode that has a p...

  20. Chandra Characterization of X-ray Emission in the Young F-Star Binary System HD 113766

    CERN Document Server

    Lisse, C M; Wolk, S J; Günther, H M; Chen, C H; Grady, C A

    2016-01-01

    Using Chandra we have obtained imaging X-ray spectroscopy of the 10 to 16 Myr old F-star binary HD 113766. We individually resolve the binary components for the first time in the X-ray and find a total 0.3 to 2.0 keV luminosity of 2.2e29 erg/sec, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only 10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or sub-stellar member of HD113766 with Lx > 6e25 erg s-1 within 2 arcmin of the binary pair. The ratio of the two stars Xray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. (2012). The emission is soft for both stars, kTApec = 0.30 to 0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks which we rule out. A possible 2.8 +/- 0.15 (2{\\sigma}) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and...

  1. Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star

    Science.gov (United States)

    Mugrauer, M.; Dinçel, B.

    2016-07-01

    We report on our follow-up spectroscopy of HD 1071478 B, a recently detected faint co-moving companion of the exoplanet host star HD 107148 A. The companion is separated from its primary star by about 35 arcsec (or 1790 AU of projected separation) and its optical and near infrared photometry is consistent with a white dwarf, located at the distance of HD 107148 A. In order to confirm the white dwarf nature of the co-moving companion, we obtained follow-up spectroscopic observations of HD 107148 B with CAFOS at the CAHA 2.2 m telescope. According to our CAFOS spectroscopy HD 107148 B is a DA white dwarf with an effective temperature in the range between 5900 and 6400 K. The properties of HD 107148 B can further be constrained with the derived effective temperature and the known visual and infrared photometry of the companion, using evolutionary models of DA white dwarfs. We obtain for HD 107148 B a mass of 0.56±0.05 M_⊙, a luminosity of (2.0±0.2)×10-4 L_⊙, log g [cm s-2])=7.95±0.09, and a cooling age of 2100±270 Myr. With its white dwarf companion the exoplanet host star HD 107148 A forms an evolved stellar system, which hosts at least one exoplanet. So far, only few of these evolved systems are known, which represent only about 5 % of all known exoplanet host multiple stellar systems. HD 107148 B is the second confirmed white dwarf companion of an exoplanet host star with a projected separation to its primary star of more than 1000 AU. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  2. KNOW THE STAR, KNOW THE PLANET. V. CHARACTERIZATION OF THE STELLAR COMPANION TO THE EXOPLANET HOST STAR HD 177830

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Lewis C. Jr.; Beichman, Charles; Burruss, Rick; Cady, Eric; Lockhart, Thomas G. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA 91109 (United States); Oppenheimer, Rebecca; Brenner, Douglas; Luszcz-Cook, Statia; Nilsson, Ricky [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Crepp, Justin R. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Baranec, Christoph [Institute for Astronomy, University of Hawai‘i at Mānoa, Hilo, HI 96720-2700 (United States); Dekany, Richard; Hillenbrand, Lynne [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Hinkley, Sasha [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); King, David; Parry, Ian R. [Institute of Astronomy, University of Cambridge, Madingley Road., Cambridge, CB3 OHA (United Kingdom); Pueyo, Laurent [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Sivaramakrishnan, Anand; Soummer, Rémi [Department of Astronomy, Stockholm University, AlbaNova University Center, Roslagstullsbacken 21, SE-10691 Stockholm (Sweden); Rice, Emily L., E-mail: lewis.c.roberts@jpl.nasa.gov [Department of Engineering Science and Physics, College of Staten Island, City University of New York, Staten Island, NY 10314 (United States); and others

    2015-10-15

    HD 177830 is an evolved K0IV star with two known exoplanets. In addition to the planetary companions it has a late-type stellar companion discovered with adaptive optics imagery. We observed the binary star system with the PHARO near-IR camera and the Project 1640 coronagraph. Using the Project 1640 coronagraph and integral field spectrograph we extracted a spectrum of the stellar companion. This allowed us to determine that the spectral type of the stellar companion is a M4 ± 1 V. We used both instruments to measure the astrometry of the binary system. Combining these data with published data, we determined that the binary star has a likely period of approximately 800 years with a semimajor axis of 100–200 AU. This implies that the stellar companion has had little or no impact on the dynamics of the exoplanets. The astrometry of the system should continue to be monitored, but due to the slow nature of the system, observations can be made once every 5–10 years.

  3. Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740

    CERN Document Server

    Krticka, J; Markova, H; Mikulasek, Z; Zverko, J; Prvak, M; Skarka, M

    2013-01-01

    The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2m MPG/ESO telescope. We are able to reproduce the observed visual ligh...

  4. HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star?

    CERN Document Server

    Sahin, Timur; Klochkova, Valentina G; Panchuk, Vladimir E

    2016-01-01

    We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0$\\pm$0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich stars yet analyzed. The abundance analysis of this luminous star is based on high resolution and high quality (S/N$\\approx$120--420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over twenty-one epochs. Standard 1D {\\sc LTE} analysis provides a fresh determination of the atmospheric parameters over all epochs: \\Teff = 7350$\\pm$200 \\kelvin, \\logg = +0.6$\\pm$0.3, and a microturbulent velocity $\\xi =$ 6.6$\\pm$1.6 km s$^{\\rm -1}$ and [Fe/H] = 0.4$\\pm$0.2, and a carbon abundance [C/Fe]= $-$0.19$\\pm$0.30. We find oxygen abundance [O/Fe]= $-$0.25$\\pm$0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 $\\pm$ 2.0 km s$^{\\rm -1}$ is determined from both strong and we...

  5. Magnetic fields on young, moderately rotating Sun-like stars II. EK Draconis (HD 129333)

    CERN Document Server

    Waite, Ian; Carter, Brad; Petit, Pascal; Jeffers, Sandra; Morin, Julien; Vidotto, Aline; Donati, Jean-Francois

    2016-01-01

    The magnetic fields, activity and dynamos of young solar-type stars can be empirically studied using time-series of spectropolarimetric observations and tomographic imaging techniques such as Doppler imaging and Zeeman Doppler imaging. In this paper we use these techniques to study the young Sun-like star EK Draconis (Sp-Type: G1.5V, HD 129333) using ESPaDOnS at the Canada-France-Hawaii Telescope and NARVAL at the T\\`elescope Bernard Lyot. This multi-epoch study runs from late 2006 until early 2012. We measure high levels of chromospheric activity indicating an active, and varying, chromosphere. Surface brightness features were constructed for all available epochs. The 2006/7 and 2008 data show large spot features appearing at intermediate-latitudes. However, the 2012 data indicate a distinctive polar spot. We observe a strong, almost unipolar, azimuthal field during all epochs that is similar to that observed on other Sun-like stars. Using magnetic features, we determined an average equatorial rotational vel...

  6. HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang

    CERN Document Server

    Bond, Howard E; VandenBerg, Don A; Schaefer, Gail H; Harmer, Dianne; 10.1088/2041-8205/765/1/L12

    2013-01-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the HR diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 +/- 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 +/- 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especia...

  7. Non-radial pulsations in the γ Doradus star HD 195068

    Science.gov (United States)

    Jankov, S.; Mathias, P.; Chapellier, E.; Le Contel, J.-M.; Sareyan, J.-P.

    2006-07-01

    We present high resolution spectroscopic observations of the γ Doradus star HD 195068. About 230 spectra were collected over 2 years. Time series analysis performed on radial velocity data shows a main peak at 1.61 d-1 , a frequency not yet detected in photometry. The Hipparcos photometric 1.25 d-1 frequency is easily recovered as is 1.30 d-1 while the third photometric frequency, 0.97 d-1 , is only marginally present. The good quality of our data, which includes 196 spectra collected over seven consecutive nights, shows that both the 1.61 d-1 and intermediate 1.27 d-1 (mixture of 1.25 and 1.30 d-1 ) frequencies are present in the line profile variations. Using the Fourier-Doppler Imaging (FDI) method, the variability associated with 1.61 d-1 can be successfully modeled by a non-radial pulsation mode ℓ=5± 1, |m|=4± 1. For the intermediate frequency 1.27 d-1 we deduce ℓ=4± 1, |m|=3± 1. Evidence that the star is not pulsating in the radial mode (ℓ=0) rules out a previous classification as an RR Lyrae type star. We investigate the time variability of FDI power spectra concluding that the observed temporal variability of modes can be explained by a beating phenomenon between closely spaced frequencies of two non-radial modes. The distribution of the oscillation power within the line profile indicates that there is a significant tangential velocity component of oscillations characteristic of high radial order gravity modes which are predicted to be observed in γ Doradus type stars.

  8. Nanodiamonds around HD 97048 and Elias 1

    NARCIS (Netherlands)

    Van Kerckhoven, C; Tielens, AGGM; Waelkens, C

    2002-01-01

    We present an analysis of ISO-SWS observations of the Herbig Ae/Be stars HD 97048 and Elias 1. Besides the well-known family of IR emission bands at 3.3, 6.2, "7.7", 8.6 and 11.2 mum these objects show strong, peculiar emission features at 3.43 and 3.53 mum. The latter two features show pronounced s

  9. The unstable fate of the planet orbiting the A-star in the HD 131399 triple stellar system

    CERN Document Server

    Veras, Dimitri; Gaensicke, Boris T

    2016-01-01

    Validated planet candidates need not lie on long-term stable orbits, and instability triggered by post-main-sequence stellar evolution can generate architectures which transport rocky material to white dwarfs, polluting them. The giant planet HD 131399Ab orbits its parent A star at a projected separation of about 50-100 au. The host star, HD 131399A, is part of a hierarchical triple with HD 131399BC being a close binary separated by a few hundred au from the A star. Here, we determine the fate of this system, and find that (i) stability along the main sequence is achieved only for a favourable choice of parameters within the errors, and (ii) even for this choice, in almost every instance the planet is ejected during the transition between the giant branch and white dwarf phases of HD 131399A. This result provides an example of both how the free-floating planet population may be enhanced by similar systems, and how instability can manifest in the polluted white dwarf progenitor population.

  10. The unstable fate of the planet orbiting the A star in the HD 131399 triple stellar system

    Science.gov (United States)

    Veras, Dimitri; Mustill, Alexander J.; Gänsicke, Boris T.

    2017-02-01

    Validated planet candidates need not lie on long-term stable orbits, and instability triggered by post-main-sequence stellar evolution can generate architectures which transport rocky material to white dwarfs, hence polluting them. The giant planet HD 131399Ab orbits its parent A star at a projected separation of about 50-100 au. The host star, HD 131399A, is part of a hierarchical triple with HD 131399BC being a close binary separated by a few hundred au from the A star. Here, we determine the fate of this system, and find the following: (i) Stability along the main sequence is achieved only for a favourable choice of parameters within the errors. (ii) Even for this choice, in almost every instance, the planet is ejected during the transition between the giant branch and white dwarf phases of HD 131399A. This result provides an example of both how the free-floating planet population may be enhanced by similar systems and how instability can manifest in the polluted white dwarf progenitor population.

  11. The Lick-Carnegie Survey: A New Two-Planet System Around the Star HD 207832

    CERN Document Server

    Haghighipour, Nader; Rivera, Eugenio J; Henry, Gregory W; Vogt, Steven S

    2012-01-01

    Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of 0.56 and 0.73 Jupiter-masses with orbital periods of ~162 and ~1156 days, and eccentricities of 0.13 and 0.27, respectively. Stromgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have migrated from the region of giant planet formation to closer orbits. In order to examine the possibility of the existence of additional (small) planets in the system, we studied the orbital stability of hypothetical terrestrial-sized objects in the region between the two planets and interior to the orbit of the inner body. Results indicated that stable orbits exist only in a small region interior to planet b...

  12. Stellar parameters and accretion rate of the transition disk star HD 142527 from X-Shooter

    CERN Document Server

    Mendigutía, I; Montesinos, B; Oudmaijer, R D; Najita, J R; Brittain, S D; Ancker, M E van den

    2014-01-01

    HD 142527 is a young pre-main sequence star with properties indicative of the presence of a giant planet or/and a low-mass stellar companion. We have analyzed an X-Shooter/Very Large Telescope spectrum to provide accurate stellar parameters and accretion rate. The analysis of the spectrum, together with constraints provided by the SED fitting, the distance to the star (140 +- 20 pc) and the use of evolutionary tracks and isochrones, lead to the following set of parameters T_eff = 6550 +- 100 K, log g = 3.75 +- 0.10, L_*/L_sun = 16.3 +- 4.5, M_*/M_sun = 2.0 +- 0.3 and an age of 5.0 +- 1.5 Myr. This stellar age provides further constrains to the mass of the possible companion estimated by Biller et al. (2012), being in-between 0.20 and 0.35 M_sun. Stellar accretion rates obtained from UV Balmer excess modelling, optical photospheric line veiling, and from the correlations with several emission lines spanning from the UV to the near-IR, are consistent to each other. The mean value from all previous tracers is 2 ...

  13. Activity and Magnetic Field Structure of the Sun-Like Planet Hosting Star HD 1237

    CERN Document Server

    Alvarado-Gómez, J D; Grunhut, J; Fares, R; Donati, J -F; Alecian, E; Kochukhov, O; Oksala, M; Morin, J; Redfield, S; Cohen, O; Drake, J J; Jardine, M; Matt, S; Petit, P; Walter, F M

    2015-01-01

    We analyse the magnetic activity characteristics of the planet hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field measurements consistent with our ZDI analysis, with a period of 7 days. We investigate the effect of customising the LSD mask to the line depths of the observed spectrum and find that it has a minimal effect on shape of the extracted Stokes V profile but does result in a small increase in the S/N ($\\sim$ 7%). We find that using a Milne-Eddington solution to describe the local line profile provides a better fit to the LSD profiles in this slowly rotating star, which also impacts the recovered ZDI field distribution. We also introduce a fit-stopping criterion based on the information content (entropy) of the ZDI maps solution set. The recovered magnetic field maps show a strong (+90 G) ring-like azimuthal field distribution and a complex radial field dominating at mid latitudes ($\\sim$45 degr...

  14. THE LICK-CARNEGIE SURVEY: A NEW TWO-PLANET SYSTEM AROUND THE STAR HD 207832

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institute of Washington, Washington, DC 20015 (United States); Rivera, Eugenio J.; Vogt, Steven S. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, Nashville, TN 37209 (United States)

    2012-09-01

    Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of Msin i = 0.56 M{sub Jup} and 0.73 M{sub Jup}, with orbital periods of {approx}162 and {approx}1156 days, and eccentricities of 0.13 and 0.27, respectively. Stroemgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have migrated from the region of giant planet formation to closer orbits. In order to examine the possibility of the existence of additional (small) planets in the system, we studied the orbital stability of hypothetical terrestrial-sized objects in the region between the two planets and interior to the orbit of the inner body. Results indicated that stable orbits exist only in a small region interior to planet b. However, the current observational data offer no evidence for the existence of additional objects in this system.

  15. The circumstellar envelope of the C-rich post-AGB star HD 56126

    CERN Document Server

    Hony, S; Waters, L B F M; De Koter, A

    2003-01-01

    We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch ``21 micron object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use amorphous carbon, hydrogenated amorphous carbon, magnesium sulfide and titanium carbide. We present a detailed parametrisation of the optical properties of hydrogenated amorphous carbon as a function of H/C content. The mid-infrared imaging and spectroscopy is best reproduced by a single dust shell from 1.2 to 2.6 arcsec radius around the central star. This shell originates from a short period during which the mass-loss rate exceeded 10^(-4) M_sun/yr. We find that the strength of the ``21'' micron feature poses a problem for the TiC identification. The low abundance of Ti requires very high absorption cross-sections in the ultraviolet and visible wavelength range to explain the st...

  16. Magnetic Doppler imaging of the roAp star HD 24712

    CERN Document Server

    Lüftinger, T; Ryabchikova, T; Piskunov, N; Weiss, W W; Ilyin, I

    2009-01-01

    We present the first magnetic Doppler images of a rapidly oscillating Ap (roAp) star. We deduce information about magnetic field geometry and abundance distributions of a number of chemical elements on the surface of the hitherto best studied roAp star, HD 24712, using the magnetic Doppler imaging (MDI) code, INVERS10, which allows us to reconstruct simultaneously and consistently the magnetic field geometry and elemental abundance distributions on a stellar surface. For this purpose we analyse time series spectra obtained in Stokes I and V parameters with the SOFIN polarimeter at the Nordic Optical Telescope and recover surface abundance structures of sixteen different chemical elements, respectively ions, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. For the rare earth elements (REE) Pr and Nd separate maps were obtained using lines of the first and the second ionization stage. We find and confirm a clear dipolar structure of the surface magnetic field and an unexpected correl...

  17. PAH emission from Herbig AeBe stars: Do hydrocarbons in proto-planetary disks have a unique aroma?

    Science.gov (United States)

    Keller, Luke; Sloan, Greg

    2008-03-01

    Over half of the intermediate-mass young stellar objects in the Galaxy (e.g. Herbig AeBe stars or HAeBe) have high-contrast emission in the mid-infrared spectral features of polycyclic aromatic hydrocarbons (PAHs) above the continuum produced by thermal emission from dust in the circumstellar disks. We have examined the PAH emission in detail for a sample of 19 HAeBe stars observed with the Spitzer IRS as part of the IRS Disks GTO program. Even with this relatively small sample, we have identified some trends that, should they survive in a larger sample of HAeBe stars, will allow us to infer large-scale disk geometry (both inner and outer) and the degree of photo-processing of organic molecular material in HAeBe disks. The bottom line of our work thus far is that HAeBe apparently have distinctive PAH spectra among the many other astronomical environments that are characterized by strong PAH emission. We therefore propose to apply our spectral analysis methods to an additional 57 HAeBe observed with the IRS and currently (or soon to be) available in the Spitzer archive. Our total sample of 76 HAeBe stars will allow closer scrutiny of the trends that we have identified in our empirical study and will also be the subject of a detailed disk modeling effort that will include the PAH emission.

  18. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370

    Science.gov (United States)

    Hrudková, M.; Hatzes, A.; Karjalainen, R.; Lehmann, H.; Hekker, S.; Hartmann, M.; Tkachenko, A.; Prins, S.; Van Winckel, H.; De Nutte, R.; Dumortier, L.; Frémat, Y.; Hensberge, H.; Jorissen, A.; Lampens, P.; Laverick, M.; Lombaert, R.; Pápics, P. I.; Raskin, G.; Sódor, Á.; Thoul, A.; Van Eck, S.; Waelkens, C.

    2017-01-01

    We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 ± 1.0 MJupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our programme to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coudé echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph High Efficiency and Resolution Mercator Echelle Spectrograph of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 ± 4.5 d) variation with a semi-amplitude K = 133 ± 25 m s- 1, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ˜88 yr in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-amplitude radial velocity variations and only future continued monitoring of this system may answer this uncertainty. From Kepler photometry, we find that HD 175370 is most likely a low-mass red giant branch or asymptotic giant branch star.

  19. Chandra Characterization of X-Ray Emission in the Young F-Star Binary System HD 113766

    Science.gov (United States)

    Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Günther, H. M.; Chen, C. H.; Grady, C. A.

    2017-02-01

    Using Chandra, we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 1029 erg s‑1, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with Lx > 6 × 1025 erg s‑1 within 2‧ of the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kTApec = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2σ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to Lx ∼ 2 × 1029 erg s‑1 argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 106 years. At 1028–1029 erg s‑1 X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.

  20. Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star

    CERN Document Server

    Van Grootel, V; Valencia, D; Madhusudhan, N; Dragomir, D; Howe, A R; Burrows, A S; Demory, B -O; Deming, D; Ehrenreich, D; Lovis, C; Mayor, M; Pepe, F; Queloz, D; Scuflaire, R; Seager, S; Segransan, D; Udry, S

    2014-01-01

    Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass ($M_*=0.77\\pm0.05\\,M_{\\odot}$) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-HIRES radial velocities, and MOST and Spitzer photometry. HD 97658 b is a massive ($M_P=7.55^{+0.83}_{-0.79} M_{\\oplus}$) and large ($R_{P} = 2.247^{+0.098}_{-0.095} R_{\\oplus}$ at 4.5 $\\mu$m) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, by at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the kno...

  1. An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star

    CERN Document Server

    Santos, N C; Faria, J P; Rey, J; Correia, A C M; Laskar, J; Udry, S; Adibekyan, V; Bouchy, F; Delgado-Mena, E; Melo, C; Dumusque, X; Hébrard, G; Lovis, C; Mayor, M; Montalto, M; Mortier, A; Pepe, F; Figueira, P; Sahlmann, J; Ségransan, D; Sousa, S G

    2016-01-01

    With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1years) massive (msini=15.1MJup) companion (HD219828c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD219828b, with a minimum mass of 21 MEarth and a period of 3.83days. The dynamical analysis shows that the system is stable. The HD219828 system is extreme and unique in several aspects. First, among all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like H...

  2. Imaging an 80 au Radius Dust Ring around the F5V Star HD 157587

    Science.gov (United States)

    Millar-Blanchaer, Maxwell A.; Wang, Jason J.; Kalas, Paul; Graham, James R.; Duchêne, Gaspard; Nielsen, Eric L.; Perrin, Marshall; Moon, Dae-Sik; Padgett, Deborah; Metchev, Stanimir; Ammons, S. Mark; Bailey, Vanessa P.; Barman, Travis; Bruzzone, Sebastian; Bulger, Joanna; Chen, Christine H.; Chilcote, Jeffrey; Cotten, Tara; De Rosa, Robert J.; Doyon, Rene; Draper, Zachary H.; Esposito, Thomas M.; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Johnson-Groh, Mara; Konopacky, Quinn; Larkin, James E.; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Matthews, Brenda C.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

    2016-11-01

    We present H-band near-infrared polarimetric imaging observations of the F5V star HD 157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of ∼80–100 au. The new GPI data complement recent Hubble Space Telescope/STIS observations that show the disk extending out to over 500 au. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry, we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of ∼70° and a 1.5 ± 0.6 au stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the form of the scattering phase function and remains poorly constrained. The disk is not recovered in total intensity due in part to strong adaptive optics residuals, but we recover three point sources. Considering the system’s proximity to the galactic plane and the point sources’ positions relative to the disk, we consider it likely that they are background objects and unrelated to the disk’s offset from the star.

  3. Velocity Curve Analysis of Spectroscopic Binary Stars AI Phe, GM Dra, HD 93917 and V502 Oph by Nonlinear Regression

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We introduce a new method to derive the orbital parameters of spectroscopic binary stars by nonlinear least squares of (o - c). Using the measured radial velocity data of the four double lined spectroscopic binary systems,AI Phe,GM Dra,HD 93917 and V502 Oph,we derived both the orbital and combined spectroscopic elements of these systems.Our numerical results are in good agreement with the those obtained using the method of Lehmann-Filhés.

  4. Imaging an 80 AU Radius Dust Ring Around the F5V Star HD 157587

    CERN Document Server

    Millar-Blanchaer, Maxwell A; Kalas, Paul; Graham, James R; Duchene, Gaspard; Nielsen, Eric L; Perrin, Marshall; Moon, Dae-Sik; Padgett, Deborah; Metchev, Stanimir; Ammons, S Mark; Bailey, Vanessa P; Barman, Travis; Bruzzone, Sebastian; Bulger, Joanna; Chen, Christine H; Chilcote, Jeffrey; Cotten, Tara; De Rosa, Robert J; Doyon, Rene; Draper, Zachary H; Esposito, Thomas M; Fitzgerald, Michael P; Follette, Katherine B; Gerard, Benjamin L; Greenbaum, Alexandra Z; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Johnson-Groh, Mara; Konopacky, Quinn; Larkin, James E; Macintosh, Bruce; Maire, Jerome; Marchis, Franck; Marley, Mark S; Marois, Christian; Matthews, Brenda C; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rajan, Abhijith; Rameau, Julien; Rantakyro, Fredrik T; Savransky, Dmitry; Schneider, Adam C; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

    2016-01-01

    We present $H$-band near-infrared polarimetric imaging observations of the F5V star HD~157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of $\\sim$80$-$100~AU. The new GPI data complement recent HST/STIS observations that show the disk extending out to over 500~AU. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of $\\sim 70\\degr$ and a $1.5\\pm0.6$ AU stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the for...

  5. Towards an understanding of the Of?p star HD 191612: optical spectroscopy

    CERN Document Server

    Howarth, Ian D; Lennon, Danny J; Puls, Joachim; Naze, Yael; Annuk, K; Antokhin, I; Bohlender, D A; Bond, H; Donati, J -F; Georgiev, L; Gies, D; Harmer, D; Herrero, A; Kolka, I; McDavid, D; Morel, T; Negueruela, I; Rauw, G; Reig, P

    2007-01-01

    We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe-O8fp). The Balmer and HeI lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. Metal lines and HeII absorptions (including many selective emission lines but excluding He II 4686A emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with P(orb) = 1542d, e=0.45. We conduct a model-atmosphere analysis of the primary, and find that the system is consistent with a O8: giant with a B1: main-sequence secondary. Since the periodic 538-d changes are unrelated to orbital motion, rotational modulation of a magnetically constrained plasma is strongly favoured as the most likely underlying `clock'. An upper limit on the equatorial rotation is consistent with this hypothesis, but is too weak to provide a strong constraint.

  6. An icy Kuiper-Belt around the young solar-type star HD 181327

    CERN Document Server

    Lebreton, J; Thi, W -F; Roberge, A; Donaldson, J; Schneider, G; Maddison, S T; Ménard, F; Riviere-Marichalar, P; Mathews, G S; Kamp, I; Pinte, C; Dent, W R F; Barrado, D; Duchêne, G; Gonzalez, J -F; Grady, C A; Meeus, G; Pantin, E; Williams, J P; Woitke, P

    2011-01-01

    HD 181327 is a young F5/F6V star belonging to the Beta Pictoris moving group (12 Myr). It harbors an optically thin belt of circumstellar material at 90 AU. We aim to study the dust properties in the belt in details, and to constrain the gas-to-dust ratio. We obtained far-IR observations with the Herschel/PACS instrument, and 3.2 mm observations with the ATCA array. The geometry of the belt is constrained with newly reduced HST/NICMOS images that break the degeneracy between the disk geometry and the dust properties. We use the radiative transfer code GRaTer to compute a large grid of models, and we identify the grain models that best reproduce the Spectral Energy Distribution through a Bayesian analysis. We attempt to detect the [OI] and [CII] lines with PACS spectroscopy, providing observables to our photochemical code ProDiMo. The HST observations confirm that the dust is confined in a narrow belt. The continuum is detected in the far-IR with PACS and the disk is resolved with both PACS and ATCA. A medium ...

  7. A spectroscopic survey of Herbig Ae/Be stars with X-Shooter II: Accretion diagnostic lines

    CERN Document Server

    Fairlamb, John R; Mendigutia, Ignacio; Ilee, John D; Ancker, Mario E van den

    2016-01-01

    The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of Pre-Main Sequence(PMS) stars above the low-mass range ($8{\\rm\\thinspace M_{\\odot}}$). This paper is the second in a series exploring accretion in 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning the UV to NIR, in order to obtain their line luminosities. The line luminosities were compared to accretion luminosities, which were determined directly from measurements of an UV-excess. When detected, emission lines always demonstrate a correlation with the accretion luminosity, regardless of detection frequency. The average relationship between accretion luminosity and line luminosity is found to be ${\\thinspace L_{\\rm acc}}\\propto{\\thinspace L_{\\rm line}}^{1.16 \\pm 0.15}$. This is in agreement with the findings in Classical T Tauri stars, although the HAeBe relationship is generally steeper, particularly towards the Herbig Be mass range. Since all observed li...

  8. A spectroscopic survey of Herbig Ae/Be stars with X-Shooter - II. Accretion diagnostic lines

    Science.gov (United States)

    Fairlamb, J. R.; Oudmaijer, R. D.; Mendigutia, I.; Ilee, J. D.; van den Ancker, M. E.

    2017-02-01

    The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of pre-main-sequence(PMS) stars above the low-mass range (8 M_{⊙}). This paper is the second in a series exploring accretion in 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning the UV (ultraviolet) to NIR (near infrared), in order to obtain their line luminosities. The line luminosities were compared to accretion luminosities that were determined directly from measurements of a UV excess. When detected, emission lines always demonstrate a correlation with the accretion luminosity, regardless of detection frequency. The average relationship between accretion luminosity and line luminosity is found to be L_acc ∝ L_line1.16 ± 0.15. This is in agreement with the findings in Classical T Tauri stars, although the HAeBe relationship is generally steeper, particularly towards the Herbig Be mass range. Since all observed lines display a correlation with the accretion luminosity, all of them can be used as accretion tracers. This has increased the number of accretion diagnostic lines in HAeBes 10-fold. However, questions still remain on the physical origin of each line, which may not be due to accretion.

  9. Brackett γ radiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars

    Science.gov (United States)

    Tambovtseva, L. V.; Grinin, V. P.; Weigelt, G.

    2016-05-01

    Various disk and outflow components such as the magnetosphere, the disk wind, the gaseous accretion disk, and other regions may contribute to the hydrogen line emission of young Herbig AeBe stars. Non-LTE modeling was performed to show the influence of the model parameters of each emitting region on the intensity and shape of the Brγ line profile, to present the spatial brightness distribution of each component, and to compare the contribution of each component to the total line emission. The modeling shows that the disk wind is the dominant contributor to the Brγ line rather than the magnetosphere and inner gaseous accretion disk. The contribution of the disk wind region to the Hα line is also considered.

  10. Evolutionary status of the Of?p star HD148937 and of its surrounding nebula NGC6164/5

    CERN Document Server

    Mahy, L; Nazé, Y; Royer, P; Lebouteiller, V; Waelkens, C

    2016-01-01

    Aims. The magnetic star HD148937 is the only Galactic Of?p star surrounded by a nebula. The structure of this nebula is particularly complex and is composed, from the center out outwards, of a close bipolar ejecta nebula (NGC6164/5), an ellipsoidal wind-blown shell, and a spherically symmetric Stromgren sphere. The exact formation process of this nebula and its precise relation to the star's evolution remain unknown. Methods. We analyzed infrared Spitzer IRS and far-infrared Herschel/PACS observations of the NGC6164/5 nebula. The Herschel imaging allowed us to constrain the global morphology of the nebula. We also combined the infrared spectra with optical spectra of the central star to constrain its evolutionary status. We used these data to derive the abundances in the ejected material. To relate this information to the evolutionary status of the star, we also determined the fundamental parameters of HD148937 using the CMFGEN atmosphere code. Results. The H$\\alpha$ image displays a bipolar or "8"-shaped ion...

  11. Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150, and HD 46966

    Science.gov (United States)

    Blomme, R.; Mahy, L.; Catala, C.; Cuypers, J.; Gosset, E.; Godart, M.; Montalban, J.; Ventura, P.; Rauw, G.; Morel, T.; Degroote, P.; Aerts, C.; Noels, A.; Michel, E.; Baudin, F.; Baglin, A.; Auvergne, M.; Samadi, R.

    2011-09-01

    Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. Aims: We analyse the CoRoT data corresponding to three hot O-type stars, describing the properties of their light curves and search for pulsational frequencies, which we then compare to theoretical model predictions. Methods: We determine the amplitude spectrum of the data, using the Lomb-Scargle and a multifrequency HMM-like technique. Frequencies are extracted by prewhitening, and their significance is evaluated under the assumption that the light curve is dominated by red noise. We search for harmonics, linear combinations, and regular spacings among these frequencies. We use simulations with the same time sampling as the data as a powerful tool to judge the significance of our results. From the theoretical point of view, we use the MAD non-adiabatic pulsation code to determine the expected frequencies of excited modes. Results: A substantial number of frequencies is listed, but none can be convincingly identified as being connected to pulsations. The amplitude spectrum is dominated by red noise. Theoretical modelling shows that all three O-type stars can have excited modes, but the relation between the theoretical frequencies and the observed spectrum is not obvious. Conclusions: The dominant red noise component in the hot O-type stars studied here clearly points to a different origin than the pulsations seen in cooler O stars. The physical cause of this red noise is unclear, but we speculate on the possibility of sub-surface convection, granulation, or stellar wind inhomogeneities being responsible. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany and Spain

  12. ALMA Observations of the Molecular Gas in the Debris Disk of the 30 Myr Old Star HD 21997

    Science.gov (United States)

    Kospal, A.; Moor, A.; Juhasz, A.; Abraham, P.; Apai, D.; Csengeri, T.; Grady, C. A.; Henning, Th.; Hughes, A. M.; Kiss, Cs.; Pascucci, I.; Schmalzl, M.

    2013-01-01

    The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here, we report on the detection of (12)CO and (13)CO in the J = 2-1 and J = 3-2 transitions and C(18)O in the J = 2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r(sub in) ALMA continuum observations by Moor et al., we conclude that comparable amounts of CO gas and dust are present in the disk. Interestingly, the gas and dust in the HD 21997 system are not colocated, indicating a dust-free inner gas disk within 55 AU of the star. We explore two possible scenarios for the origin of the gas. A secondary origin, which involves gas production from colliding or active planetesimals, would require unreasonably high gas production rates and would not explain why the gas and dust are not colocated. We propose that HD 21997 is a hybrid system where secondary debris dust and primordial gas coexist. HD 21997, whose age exceeds both the model predictions for disk clearing and the ages of the oldest T Tauri-like or transitional gas disks in the literature, may be a key object linking the primordial and the debris phases of disk evolution.

  13. Magnetic fields and differential rotation on the pre-main sequence III: The early-G star HD 106506

    CERN Document Server

    Waite, I A; Carter, B D; Hart, R; Donati, J -F; Vélez, J C Ramírez; Semel, M; Dunstone, N

    2011-01-01

    We present photometry and spectropolarimetry of the pre-main sequence star HD 106506. A photometric rotational period of ~1.416 +/- 0.133 days has been derived using observations at Mount Kent Observatory (MKO). Spectropolarimetric data taken at the 3.9-m Anglo-Australian Telescope (AAT) were used to derive spot occupancy and magnetic maps of the star through the technique of Zeeman Doppler imaging (ZDI). The resulting brightness maps indicate that HD 106506 displays photospheric spots at all latitudes including a predominant polar spot. Azimuthal and radial magnetic images of this star have been derived, and a significant azimuthal magnetic field is indicated, in line with other active young stars. A solar-like differential rotation law was incorporated into the imaging process. Using Stokes I information the equatorial rotation rate, $\\Omega_{eq}$, was found to be 4.54 +/- 0.01 rad/d, with a photospheric shear $\\delta\\Omega$ of $0.21_{-0.03}^{+0.02}$ rad/d. This equates to an equatorial rotation period of ~...

  14. Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars

    CERN Document Server

    Ababakr, K M; Vink, J S

    2016-01-01

    We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560 {\\AA} to 9480 {\\AA}, published to date. A change in linear polarisation across the H{\\alpha} line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small disks around these accreting objects. Thanks to the large wavelength coverage, we can report that H{\\alpha} is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarisation in such cases. Few other spectral lines display changes in polarisation across the line. In addition, H{\\alpha} is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and de...

  15. New Mn II energy levels from STIS-HST spectrum of the HgMn star HD 175640

    CERN Document Server

    Castelli, F; Cowley, C R

    2015-01-01

    The NIST database lists several Mn II lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700 A interval. We aimed to assign energy levels and log gf values to these lines. Semi-empirical line data for Mn II computed by Kurucz were used to synthesize the ultraviolet spectrum of the slow-rotating, HgMn star HD 175640. The spectrum was compared with the high-resolution spectrum observed with the HST-STIS equipment. A UVES spectrum covering the 3050-10000 A region was also examined. We determined a total of 73 new energy levels, 58 from the STIS spectrum of HD 175640 and another 15 from the UVES spectrum. The new energy levels give rise to numerous new computed lines. We have identified more than 50% of the unclassified lines listed in the NIST database and have changed the assignement of another 24 lines. An abundance analysis of the star HD 175640, based on the comparison o...

  16. HIGH-RESOLUTION 25 μM IMAGING OF THE DISKS AROUND HERBIG AE/BE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Mathematics and Physics, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Maaskant, K. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Okamoto, Y. K. [Institute of Astrophysics and Planetary Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Kataza, H. [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Yamashita, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Miyata, T.; Sako, S.; Kamizuka, T. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Fujiyoshi, T.; Fujiwara, H. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States); Sakon, I.; Onaka, T. [Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Mulders, G. D. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Lopez-Rodriguez, E.; Packham, C. [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States)

    2015-05-10

    We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 μm using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of an equal number of objects from each of the two categories defined by Meeus et al.; 11 group I (flaring disk) and II (flat disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is difficult to resolve with 8 m class telescopes in the Q band due to the strong emission from the unresolved innermost region of the disk. This indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 μm, we suggest that many, but not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 μm supports the idea that group II disks have a continuous flat disk geometry. It has been inferred that group I disks may evolve into group II through the settling of dust grains into the mid-plane of the protoplanetary disk. However, considering the growing evidence for the presence of a hole or gap in the disk of group I sources, such an evolutionary scenario is unlikely. The difference between groups I and II may reflect different evolutionary pathways of protoplanetary disks.

  17. Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris

    CERN Document Server

    Mendigutía, I; Montesinos, B; Eiroa, C; Meeus, G; Merín, B; Oudmaijer, R D

    2012-01-01

    We look for trends relating the mass accretion rate (Macc) and the stellar ages (t), spectral energy distributions (SEDs), and disk masses (Mdisk) for a sample of 38 HAeBe stars, comparing them to analogous correlations found for classical T Tauri stars. Our goal is to shed light on the timescale and physical processes that drive evolution of intermediate-mass pre-main sequence objects. Macc shows a dissipation timescale \\tau = 1.3^{+1.0}_{-0.5} Myr from an exponential law fit, while a power law yields Macc(t) \\propto t^{-\\eta}, with \\eta = 1.8^{+1.4}_{-0.7}. This result is based on our whole HAeBe sample (1-6 Msun), but the accretion rate decline most probably depends on smaller stellar mass bins. The near-IR excess is higher and starts at shorter wavelengths (J and H bands) for the strongest accretors. Active and passive disks are roughly divided by 2 x 10^{-7} Msun/yr. The mid-IR excess and the SED shape from the Meeus et al. classification are not correlated with Macc. We find Macc \\propto Mdisk^{1.1 +- 0...

  18. Herbig Ae/Be candidate stars in the innermost Galactic disk: Quartet cluster

    CERN Document Server

    Yasui, Chikako; Hamano, Satoshi; Kondo, Sohei; Izumi, Natsuko; Saito, Masao; Tokunaga, Alan T

    2016-01-01

    In order to investigate the Galactic-scale environmental effects on the evolution of protoplanetary disks, we explored the near-infrared (NIR) disk fraction of the Quartet cluster, which is a young cluster in the innermost Galactic disk at the Galactocentric radius Rg ~ 4 kpc. Because this cluster has a typical cluster mass of ~10^3 M_sun as opposed to very massive clusters, which have been observed in previous studies (>10^4 M_sun), we can avoid intra-cluster effects such as strong UV field from OB stars. Although the age of the Quartet is previously estimated to be 3-8 Myr old, we find that it is most likely ~3-4.5 Myr old. In moderately deep JHK images from the UKIDSS survey, we found eight HAeBe candidates in the cluster, and performed K-band medium-resolution ($R \\equiv \\Delta \\lambda / \\lambda ~ 800$) spectroscopy for three of them with the Subaru 8.2 m telescope. These are found to have both Br\\gamma absorption lines as well as CO bandhead emission, suggesting that they are HAeBe stars with protoplanet...

  19. The nature of the high Galactic latitude O-star HD93521: new results from X-ray and optical spectroscopy

    CERN Document Server

    Rauw, Gregor; Palate, Matthieu

    2012-01-01

    Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5Vp object HD93521 is still uncertain. We have collected X-ray and optical observations to characterize the star and its surroundings. X-ray images and spectra are analyzed to search for traces of a recent star formation event around HD93521 and to search for the signature of a possible compact companion. Optical echelle spectra are analysed with plane-parallel model atmosphere codes, assuming either a spherical star or a gravity darkened rotationally flattened star, to infer the effective temperature and surface gravity, and to derive the He, C, N and O abundances of HD93521. The X-ray images reveal no traces of a population of young low-mass stars coeval with HD93521. The X-ray spectrum of HD93521 is consistent with a normal late O-type star although with subsolar metallicity. No trace of a compact companion is found in the X-ray data. In the optical spectrum, He and N are found to be overabundant, in line with the ...

  20. The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets

    CERN Document Server

    Feng, Y Katherina; Nelson, Benjamin; Wang, Sharon X; Ford, Eric B; Marcy, Geoffrey W; Isaacson, Howard; Howard, Andrew W

    2015-01-01

    We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative on an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a $1 M_{\\rm Jup}$ planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a $2 M_{\\rm Jup}$ planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet...

  1. Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration

    NARCIS (Netherlands)

    Grunhut, J.H.; Wade, G.A.; Marcolino, W.L.F.; Petit, V.; Henrichs, H.F.; Cohen, D.H.; Alecian, E.; Bohlender, D.; Bouret, J.C.; Kochukhov, O.; Neiner, C.; St-Louis, N.; Townsend, R.H.D.

    2009-01-01

    We report the detection of a strong, organized magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Programme. From the fitting of our spe

  2. Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5

    Science.gov (United States)

    Mahy, L.; Hutsemékers, D.; Nazé, Y.; Royer, P.; Lebouteiller, V.; Waelkens, C.

    2017-03-01

    Aims: The magnetic star HD 148937 is the only Galactic Of?p star surrounded by a nebula. The structure of this nebula is particularly complex and is composed, from the center out outwards, of a close bipolar ejecta nebula (NGC 6164/5), an ellipsoidal wind-blown shell, and a spherically symmetric Strömgren sphere. The exact formation process of this nebula and its precise relation to the star's evolution remain unknown. Methods: We analyzed infrared Spitzer IRS and far-infrared Herschel/PACS observations of the NGC 6164/5 nebula. The Herschel imaging allowed us to constrain the global morphology of the nebula. We also combined the infrared spectra with optical spectra of the central star to constrain its evolutionary status. We used these data to derive the abundances in the ejected material. To relate this information to the evolutionary status of the star, we also determined the fundamental parameters of HD 148937 using the CMFGEN atmosphere code. Results: The Hα image displays a bipolar or "8"-shaped ionized nebula, whilst the infrared images show dust to be more concentrated around the central object. We determine nebular abundance ratios of N/O = 1.06 close to the star, and N/O = 1.54 in the bright lobe constituting NGC 6164. Interestingly, the parts of the nebula located further from HD 148937 appear more enriched in stellar material than the part located closer to the star. Evolutionary tracks suggest that these ejecta have occured 1.2-1.3 and 0.6 Myr ago, respectively. In addition, we derive abundances of argon for the nebula compatible with the solar values and we find a depletion of neon and sulfur. The combined analyses of the known kinematics and of the new abundances of the nebula suggest either a helical morphology for the nebula, possibly linked to the magnetic geometry, or the occurrence of a binary merger. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important

  3. Candidate Water Vapor Lines to Locate the H2O Snowline through High-dispersion Spectroscopic Observations. II. The Case of a Herbig Ae Star

    Science.gov (United States)

    Notsu, Shota; Nomura, Hideko; Ishimoto, Daiki; Walsh, Catherine; Honda, Mitsuhiko; Hirota, Tomoya; Millar, T. J.

    2017-02-01

    Observationally measuring the location of the {{{H}}}2{{O}} snowline is crucial for understanding planetesimal and planet formation processes, and the origin of water on Earth. In disks around Herbig Ae stars (T * ∼ 10,000 K, M * ≳ 2.5M ⊙), the position of the {{{H}}}2{{O}} snowline is farther from the central star compared with that around cooler and less massive T Tauri stars. Thus, the {{{H}}}2{{O}} emission line fluxes from the region within the {{{H}}}2{{O}} snowline are expected to be stronger. In this paper, we calculate the chemical composition of a Herbig Ae disk using chemical kinetics. Next, we calculate the {{{H}}}2{{O}} emission line profiles and investigate the properties of candidate water lines across a wide range of wavelengths (from mid-infrared to submillimeter) that can locate the position of the {{{H}}}2{{O}} snowline. Those lines identified have small Einstein A coefficients (∼ {10}-6{--}{10}-3 s‑1) and relatively high upper-state energies (∼1000 K). The total fluxes tend to increase with decreasing wavelengths. We investigate the possibility of future observations (e.g., ALMA, SPICA/SMI-HRS) locating the position of the {{{H}}}2{{O}} snowline. Since the fluxes of those identified lines from Herbig Ae disks are stronger than those from T Tauri disks, the possibility of a successful detection is expected to increase for a Herbig Ae disk.

  4. ALMA OBSERVATIONS OF THE MOLECULAR GAS IN THE DEBRIS DISK OF THE 30 Myr OLD STAR HD 21997

    Energy Technology Data Exchange (ETDEWEB)

    Kóspál, Á. [European Space Agency (ESA-ESTEC, SRE-SA), P.O. Box 299, 2200AG, Noordwijk (Netherlands); Moór, A.; Ábrahám, P.; Kiss, Cs. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Juhász, A.; Schmalzl, M. [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Apai, D. [Department of Astronomy and Department of Planetary Sciences, The University of Arizona, Tucson, AZ 85721 (United States); Csengeri, T. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Grady, C. A. [NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States); Henning, Th. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Hughes, A. M. [Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States); Pascucci, I., E-mail: akospal@rssd.esa.int [Lunar and Planetary Laboratory, Department of Planetary Sciences, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721 (United States)

    2013-10-20

    The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here, we report on the detection of {sup 12}CO and {sup 13}CO in the J = 2-1 and J = 3-2 transitions and C{sup 18}O in the J = 2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r{sub in} < 26 AU, r{sub out} = 138 ± 20 AU, M{sub *}=1.8{sup +0.5}{sub -0.2} M{sub ☉}, and i = 32.°6 ± 3.°1. The total CO mass, as calculated from the optically thin C{sup 18}O line, is about (4-8) × 10{sup –2} M{sub ⊕}, while the CO line ratios suggest a radiation temperature on the order of 6-9 K. Comparing our results with those obtained for the dust component of the HD 21997 disk from ALMA continuum observations by Moór et al., we conclude that comparable amounts of CO gas and dust are present in the disk. Interestingly, the gas and dust in the HD 21997 system are not colocated, indicating a dust-free inner gas disk within 55 AU of the star. We explore two possible scenarios for the origin of the gas. A secondary origin, which involves gas production from colliding or active planetesimals, would require unreasonably high gas production rates and would not explain why the gas and dust are not colocated. We propose that HD 21997 is a hybrid system where secondary debris dust and primordial gas coexist. HD 21997, whose age exceeds both the model predictions for disk clearing and the ages of the oldest T Tauri-like or transitional gas disks in the literature, may be a key object linking the primordial and the debris phases of disk evolution.

  5. Detection of Elements at All Three r-process Peaks in the Metal-Poor Star HD 160617

    CERN Document Server

    Roederer, Ian U; 10.1088/0004-637X/750/1/76

    2012-01-01

    We report the first detection of elements at all three r-process peaks in the metal-poor halo star HD 160617. These elements include arsenic and selenium, which have not been detected previously in halo stars, and the elements tellurium, osmium, iridium, and platinum, which have been detected previously. Absorption lines of these elements are found in archive observations made with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. We present up-to-date absolute atomic transition probabilities and complete line component patterns for these elements. Additional archival spectra of this star from several ground-based instruments allow us to derive abundances or upper limits of 45 elements in HD 160617, including 27 elements produced by neutron-capture reactions. The average abundances of the elements at the three r-process peaks are similar to the predicted solar system r-process residuals when scaled to the abundances in the rare earth element domain. This result for arsenic and selen...

  6. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370

    CERN Document Server

    Hrudková, M; Karjalainen, R; Lehmann, H; Hekker, S; Hartmann, M; Tkachenko, A; Prins, S; van Winckel, H; de Nutte, R; Dumortier, L; Frémat, Y; Hensberge, H; Jorissen, A; Lampens, P; Laverick, M; Lombaert, R; Pápics, P I; Raskin, G; Sódor, Á; Thoul, A; van Eck, S; Waelkens, C

    2016-01-01

    We report on the discovery of a planetary companion candidate with a minimum mass Msini = 4.6 M_J orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our program to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coude echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph HERMES of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 days) variation with a semi-amplitude K = 133 m/s, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ~88 years in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-...

  7. On the interplay between flaring and shadowing in disks around Herbig Ae/Be stars

    CERN Document Server

    Acke, B; Ancker, M van den; Bouwman, J; Ochsendorf, B; Juhasz, A; Waters, R

    2009-01-01

    Based on the SED, Herbig stars have been categorized into two observational groups, reflecting their overall disk structure: group I members have disks with a higher degree of flaring than their group II counterparts. We investigate the 5-35 um Spitzer IRS spectra of a sample of 13 group I sources and 20 group II sources. We focus on the continuum emission to study the underlying disk geometry. We have determined the [30/13.5] and [13.5/7] continuum flux ratios. The 7-um flux excess with respect to the stellar photosphere is measured, as a marker for the strength of the near-IR emission produced by the inner disk. We have compared our data to self-consistent passive-disk model spectra, for which the same quantities were derived. We confirm the literature result that the difference in continuum emission between group I and II sources can largely be explained by a different amount of small dust grains. However, we report a strong correlation between the [30/13.5] and [13.5/7] flux ratios for Meeus group II sour...

  8. A HOT URANUS ORBITING THE SUPER METAL-RICH STAR HD 77338 AND THE METALLICITY-MASS CONNECTION

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, J. S.; Hoyer, S.; Jones, M. I.; Rojo, P.; Day-Jones, A. C.; Ruiz, M. T. [Departamento de Astronomia, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Casilla 36-D (Chile); Jones, H. R. A.; Tuomi, M.; Barnes, J. R.; Pavlenko, Y. V.; Pinfield, D. J. [Center for Astrophysics, University of Hertfordshire, College Lane Campus, Hatfield, Hertfordshire, AL10 9AB (United Kingdom); Murgas, F. [Instituto de Astrofisica de Canarias, Via Lactea, E-38205 La Laguna, Tenerife (Spain); Ivanyuk, O. [Main Astronomical Observatory of National Academy of Sciences of Ukraine, 27 Zabolotnoho, Kyiv 127, 03680 (Ukraine); Jordan, A., E-mail: jjenkins@das.uchile.cl [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, 7820436 Macul, Santiago (Chile)

    2013-04-01

    We announce the discovery of a low-mass planet orbiting the super metal-rich K0V star HD 77338 as part of our ongoing Calan-Hertfordshire Extrasolar Planet Search. The best-fit planet solution has an orbital period of 5.7361 {+-} 0.0015 days and with a radial velocity semi-amplitude of only 5.96 {+-} 1.74 ms{sup -1}, we find a minimum mass of 15.9{sup +4.7}{sub -5.3} M{sub Circled-Plus }. The best-fit eccentricity from this solution is 0.09{sup +0.25}{sub -0.09}, and we find agreement for this data set using a Bayesian analysis and a periodogram analysis. We measure a metallicity for the star of +0.35 {+-} 0.06 dex, whereas another recent work finds +0.47 {+-} 0.05 dex. Thus HD 77338b is one of the most metal-rich planet-host stars known and the most metal-rich star hosting a sub-Neptune-mass planet. We searched for a transit signature of HD 77338b but none was detected. We also highlight an emerging trend where metallicity and mass seem to correlate at very low masses, a discovery that would be in agreement with the core accretion model of planet formation. The trend appears to show that for Neptune-mass planets and below, higher masses are preferred when the host star is more metal-rich. Also a lower boundary is apparent in the super metal-rich regime where there are no very low mass planets yet discovered in comparison to the sub-solar metallicity regime. A Monte Carlo analysis shows that this low-mass planet desert is statistically significant with the current sample of 36 planets at the {approx}4.5{sigma} level. In addition, results from Kepler strengthen the claim for this paucity of the lowest-mass planets in super metal-rich systems. Finally, this discovery adds to the growing population of low-mass planets around low-mass and metal-rich stars and shows that very low mass planets can now be discovered with a relatively small number of data points using stable instrumentation.

  9. Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon. III. HD 50138

    Science.gov (United States)

    Jeřábková, T.; Korčáková, D.; Miroshnichenko, A.; Danford, S.; Zharikov, S. V.; Kříček, R.; Zasche, P.; Votruba, V.; Šlechta, M.; Škoda, P.; Janík, J.

    2016-02-01

    Context. B[e] stars are anomalous objects around which extended circumstellar matter is present. The observed properties of the central star are significantly affected by the surrounding material. Therefore, the use of standard synthetic spectra is disputable in this case and our capability to study these objects is limited. One of the possibilities is to analyse variations of the spectral features. Long-term spectroscopic observations are required for this, but are not found in the literature. For our study we choose the B[e] star HD 50138 of the FS CMa type because of the indication that this star is a post-main-sequence star, although still not highly evolved. Therefore, it can be a good object for testing evolutionary models. Currently, HD 50138 is the most extensively observed FS CMa star which makes it an ideal object for modelling. Our observations fill the gap in the available data. Aims: To describe the variability of HD 50138 we have monitored this star spectroscopically over the last twenty years. To search for the periodicity on short-term scales, series of night-to-night observations were also obtained. We were able to obtain 130 spectra from four different telescopes - 1.06 m at Ritter Observatory (échelle, R ~ 26 000, 32 spectra, 1994-2003), the Perek 2 m telescope at Ondřejov Observatory (slit, R ~ 12 500, 56 spectra, 2004-2013), the 2.12 m telescope at Observatorio Astronomico Nacional San Pedro Martir (échelle, R ~ 18 000, 16 spectra, 2005-2013), and the 0.81 m telescope at Three College Observatory (échelle, R ~ 12 000, 26 spectra, 2013-2014). Methods: We describe and analyse variations of the chosen lines. The measurements of the equivalent widths and radial velocities of the Hα, Hβ, and [O i] λλ 6300, 6364 Å lines are presented. The set of obtained spectra allows us to describe the changes on timescales from days to years. Results: The long-term quasi-periodic trend was found in the variations of the Hα equivalent width and confirmed

  10. Abundance analysis, spectral variability, and search for the presence of a magnetic field in the typical PGa star HD19400

    CERN Document Server

    Hubrig, S; Gonzalez, J F; Carroll, T A; Ilyin, I; Schöller, M; Drake, N A; Korhonen, H; Briquet, M

    2014-01-01

    The aim of this study is to carry out an abundance determination, to search for spectral variability and for the presence of a weak magnetic field in the typical PGa star HD19400. High-resolution, high signal-to-noise HARPS spectropolarimetric observations of HD19400 were obtained at three different epochs in 2011 and 2013. For the first time, we present abundances of various elements determined using an ATLAS12 model, including the abundances of a number of elements not analysed by previous studies, such as Ne I, Ga II, and Xe II. Several lines of As II are also present in the spectra of HD19400. To study the variability, we compared the behaviour of the line profiles of various elements. We report on the first detection of anomalous shapes of line profiles belonging to Mn and Hg, and the variability of the line profiles belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the variability of the line profiles of these elements is caused by their non-uniform surface distribution, similar to the pr...

  11. Discovery of multiple pulsations in the new δ Scuti star HD 92277: Asteroseismology from Dome A, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Weikai; Fu, Jian-Ning; Niu, Jia-Shu; Zhu, Zonghong [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Charpinet, S.; Vauclair, G. [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Cui, Xiangqun; Gong, Xuefei [Nanjing Institute of Astronomical Optics and Technology, Nanjing 210042 (China); Feng, Longlong; Wang, Lifan; Yuan, Xiangyan; Zhu, Zhenxi [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Liu, Qiang; Wang, Lingzhi; Zhou, Xu [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Pennypacker, Carl R. [Center for Astrophysics, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); York, Donald G., E-mail: jnfu@bnu.edu.cn [Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

    2015-02-01

    We report the discovery of low-amplitude oscillations in the star HD 92277 from long, continuous observations in the r and g bands using the CSTAR telescopes in Antarctica. A total of more than 1950 hours of high-quality light curves were used to categorize HD 92277 as a new member of the δ Scuti class. We have detected 21 (20 frequencies are independent and one is the linear combination) and 14 (13 frequencies are independent and one is the linear combination) pulsation frequencies in the r and g bands, respectively, indicating a multi-periodic pulsation behavior. The primary frequency f{sub 1} = 10.810 days{sup −1} corresponds to a period of 0.0925 days and is an l = 1 mode. We estimate a B − V index of 0.39 and derive an effective temperature of 6800 K for HD 92277. We conclude that long, continuous and uninterrupted time-series photometry can be performed from Dome A, Antarctica, and that this is especially valuable for asteroseismology where multi-color observations (often not available from space-based telescopes) assist with mode identification.

  12. Precise radial velocities of giant stars IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a ~13.6 au eccentric binary system

    CERN Document Server

    Ortiz, Mauricio; Trifonov, Trifon; Quirrenbach, Andreas; Mitchell, David; Nowak, Grzegorz; Buenzli, Esther; Zimmerman, Neil; Bonnefoy, Mickael; Skemer, Andy; Defrère, Denis; Lee, Man Hoi; Fischer, Debra; Hinz, Philip

    2016-01-01

    Context: For over 12 years, we have carried out a precise radial velocity survey of a sample of 373 G and K giant stars using the Hamilton \\'Echelle Spectrograph at Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims: We aim at detecting and characterizing substellar+stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods: We obtained high precision radial velocity (RV) measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. In order to discriminate between RV variations due to non-radial pulsation or stellar spots we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to further characterize the system, we obtain high-resolution images with LMIRCam at the Large Binocular Telescope. Results: We report the likely discovery of a giant plane...

  13. The Lick-Carnegie Exoplanet Survey: HD32963 -- A New Jupiter Analog Orbiting a Sun-like Star

    CERN Document Server

    Rowan, Dominick; Laughlin, Gregory; Vogt, Steven S; Butler, R Paul; Burt, Jennifer; Wang, Songhu; Holden, Brad; Hanson, Russell; Arriagada, Pamela; Keiser, Sandy; Teske, Johanna; Diaz, Matias

    2015-01-01

    We present a set of 109 new, high-precision Keck/HIRES radial velocity (RV) observations for the solar-type star HD 32963. Our dataset reveals a candidate planetary signal with a period of 6.49 $\\pm$ 0.07 years and a corresponding minimum mass of 0.7 $\\pm$ 0.03 Jupiter masses. Given Jupiter's crucial role in shaping the evolution of the early Solar System, we emphasize the importance of long-term radial velocity surveys. Finally, using our complete set of Keck radial velocities and correcting for the relative detectability of synthetic planetary candidates orbiting each of the 1,122 stars in our sample, we estimate the frequency of Jupiter analogs across our survey at approximately 3%.

  14. HD 100453: A Link Between Gas-Rich Protoplanetary Disks and Gas-Poor Debris Disks

    CERN Document Server

    Collins, K A; Hamaguchi, K; Wisniewski, J P; Brittain, S; Sitko, M; Carpenter, W J; Williams, J P; Mathews, G S; Williger, G M; Van Boekel, R; Carmona, A; Henning, T; Ancker, M E van den; Meeus, G; Chen, X P; Petre, R; Woodgate, B E

    2009-01-01

    HD 100453 has an IR spectral energy distribution (SED) which can be fit with a power-law plus a blackbody. Previous analysis of the SED suggests that the system is a young Herbig Ae star with a gas-rich, flared disk. We reexamine the evolutionary state of the HD 100453 system by refining its age (based on a candidate low-mass companion) and by examining limits on the disk extent, mass accretion rate, and gas content of the disk environment. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with a spectral type of M4.0V - M4.5V, and derive an age of 10 +/- 2 Myr. We find no evidence of mass accretion onto the star. Chandra ACIS-S imagery shows that the Herbig Ae star has L_X/L_Bol and an X-ray spectrum similar to non-accreting Beta Pic Moving Group early F stars. Moreover, the disk lacks the conspicuous Fe II emission and excess FUV continuum seen in spectra of actively accreting Herbig Ae stars, and from the FUV continuum, we find the accretion rate is < 1.4x10^-9 M_Sun yr^-1. A...

  15. Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt

    CERN Document Server

    Tanner, Angelle; von Braun, Kaspar; Kane, Stephen; Brewer, John M; Farrington, Chris; van Belle, Gerard T; Beichman, Charles A; Fischer, Debra; Brummelaar, Theo A ten; McAlister, Harold A; Schaefer, Gail

    2014-01-01

    We used the CHARA Array to directly measure the angular diameter of HD 69830, home to three Neptune mass planets and an asteroid belt. Our measurement of 0.674+/-0.014 milli-arcseconds for the limb-darkened angular diameter of this star leads to a physical radius of R$_*$ = 0.9058$\\pm$0.0190 R\\sun and luminosity of L* = 0.622+/-0.014 Lsun when combined with a fit to the spectral energy distribution of the star. Placing these observed values on an Hertzsprung-Russel (HR) diagram along with stellar evolution isochrones produces an age of 10.6+/-4 Gyr and mass of 0.863$\\pm$0.043 M\\sun. We use archival optical echelle spectra of HD 69830 along with an iterative spectral fitting technique to measure the iron abundance ([Fe/H]=-0.04+/-0.03), effective temperature (5385+/-44 K) and surface gravity (log g = 4.49+/-0.06). We use these new values for the temperature and luminosity to calculate a more precise age of 7.5+/-Gyr. Applying the values of stellar luminosity and radius to recent models on the optimistic locati...

  16. Precise radial velocities of giant stars. IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a 13.6 au eccentric binary system

    Science.gov (United States)

    Ortiz, Mauricio; Reffert, Sabine; Trifonov, Trifon; Quirrenbach, Andreas; Mitchell, David S.; Nowak, Grzegorz; Buenzli, Esther; Zimmerman, Neil; Bonnefoy, Mickaël; Skemer, Andy; Defrère, Denis; Lee, Man Hoi; Fischer, Debra A.; Hinz, Philip M.

    2016-10-01

    Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G- and K-giant stars using the Hamilton Échelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims: We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods: We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results: We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M⊙ orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions: The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet. Based on observations collected at the Lick Observatory, University of California.Based on observations collected at the

  17. KEPLER-21b: A 1.6 R{sub Earth} PLANET TRANSITING THE BRIGHT OSCILLATING F SUBGIANT STAR HD 179070

    Energy Technology Data Exchange (ETDEWEB)

    Howell, Steve B. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Rowe, Jason F.; Bryson, Stephen T. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Quinn, Samuel N. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Marcy, Geoffrey W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Ciardi, David R. [NASA Exoplanet Science Institute/Caltech, Pasadena, CA 91125 (United States); Chaplin, William J.; Elsworth, Yvonne [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Metcalfe, Travis S. [High Altitude Observatory and Scientific Computing Division, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Monteiro, Mario J. P. F. G. [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Appourchaux, Thierry [Institut d' Astrophysique Spatiale, Universite Paris XI-CNRS (UMR8617), Batiment 121, 91405 Orsay Cedex (France); Basu, Sarbani [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Creevey, Orlagh L. [Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Gilliland, Ronald L. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Quirion, Pierre-Olivier [Canadian Space Agency, 6767 Boulevard de l' Aeroport, Saint-Hubert, QC, J3Y 8Y9 (Canada); Stello, Denis [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Kjeldsen, Hans; Christensen-Dalsgaard, Joergen [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Garcia, Rafael A. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot-IRFU/SAp, 91191 Gif-sur-Yvette Cedex (France); and others

    2012-02-20

    We present Kepler observations of the bright (V = 8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R{sub Earth} object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34 {+-} 0.06 M{sub Sun} and 1.86 {+-} 0.04 R{sub Sun }, respectively, as well as yielding an age of 2.84 {+-} 0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3{sigma}) that the transit event is caused by a 1.64 {+-} 0.04 R{sub Earth} exoplanet in a 2.785755 {+-} 0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of {approx}10 M{sub Earth} (2{sigma}). HD 179070 is the brightest exoplanet host star yet discovered by Kepler.

  18. HD 85567: A Herbig B[e] star or an interacting B[e] binary

    CERN Document Server

    Wheelwright, H E; Garatti, A Caratti o; Lopez, R Garcia

    2013-01-01

    Context. HD 85567 is an enigmatic object exhibiting the B[e] phenomenon, i.e. an infrared excess and forbidden emission lines in the optical. The object's evolutionary status is uncertain and there are conflicting claims that it is either a young stellar object or an evolved, interacting binary. Aims. To elucidate the reason for the B[e] behaviour of HD 85567, we have observed it with the VLTI and AMBER. Methods. Our observations were conducted in the K-band with moderate spectral resolution (R~1500, i.e. 200 km/s). The spectrum of HD 85567 exhibits Br gamma and CO overtone bandhead emission. The interferometric data obtained consist of spectrally dispersed visibilities, closure phases and differential phases across these spectral features and the K-band continuum. Results. The closure phase observations do not reveal evidence of asymmetry. The apparent size of HD 85567 in the K-band was determined by fitting the visibilities with a ring model. The best fitting radius, 0.8 +/- 0.3 AU, is relatively small maki...

  19. Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682

    NARCIS (Netherlands)

    J.H. Grunhut; G.A. Wade; J.O. Sundqvist; A. ud-Doula; C. Neiner; R. Ignace; W.L.F. Marcolino; T. Rivinius; A. Fullerton; L. Kaper; B. Mauclaire; C. Buil; T. Garrel; J. Ribeiro; S. Ubaud

    2012-01-01

    The O9IV star HD 57682, discovered to be magnetic within the context of the Magnetism in Massive Stars (MiMeS) survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, t

  20. Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD 167042

    CERN Document Server

    Sato, Bun'ei; Omiya, Masashi; Izumiura, Hideyuki; Kambe, Eiji; Masuda, Seiji; Takeda, Yoichi; Itoh, Yoichi; Ando, Hiroyasu; Yoshida, Michitoshi; Kokubo, Eiichiro; Ida, Shigeru

    2008-01-01

    We report on the detection of four extrasolar planets orbiting evolved intermediate-mass stars from a precise Doppler survey of G and K giants at Okayama Astrophysical Observatory. All of the host stars are considered to be formerly early F-type or A-type dwarfs when they were on the main sequence. 14 And (K0 III) is a clump giant with a mass of 2.2 M_solar and has a planet of minimum mass m_2sin i=4.8 M_Jup in a nearly circular orbit with a 186 day period. This is one of the innermost planets around evolved intermediate-mass stars and such planets have only been discovered in clump giants. 81 Cet (G5 III) is a clump giant with 2.4 M_solar hosting a planet of m_2sin i=5.3 M_Jup in a 953 day orbit with an eccentricity of e=0.21. 6 Lyn (K0 IV) is a less evolved subgiant with 1.7 M_solar and has a planet of m_2sin i=2.4 M_Jup in a 899 day orbit with e=0.13. HD 167042 (K1 IV) is also a less evolved star with 1.5 M_solar hosting a planet of m_2sin i=1.6 M_Jup in a 418 day orbit with e=0.10. This planet was indepen...

  1. B fields in OB stars (BOB): Detection of a strong magnetic field in the O9.7 V star HD54879

    CERN Document Server

    Castro, N; Hubrig, S; Simón-Díaz, S; Schöller, M; Ilyin, I; Carrol, T A; Langer, N; Morel, T; Schneider, F R N; Przybilla, N; Herrero, A; de Koter, A; Oskinova, L M; Reisenegger, A; Sana, H

    2015-01-01

    The number of magnetic stars detected among massive stars is small; nevertheless, the role played by the magnetic field in stellar evolution cannot be disregarded. Links between line profile variability, enhancements/depletions of surface chemical abundances, and magnetic fields have been identified for low-mass B-stars, but for the O-type domain this is almost unexplored. Based on FORS2 and HARPS spectropolarimetric data, we present the first detection of a magnetic field in HD54879, a single slowly rotating O9.7 V star. Using two independent and different techniques we obtained the firm detection of a surface average longitudinal magnetic field with a maximum amplitude of about 600 G, in modulus. A quantitative spectroscopic analysis of the star with the stellar atmosphere code FASTWIND results in an effective temperature and a surface gravity of 33000$\\pm1000$ K and 4.0$\\pm0.1$ dex. The abundances of carbon, nitrogen, oxygen, silicon, and magnesium are found to be slightly lower than solar, but compatible ...

  2. B fields in OB stars (BOB): The magnetic triple stellar system HD 164492C in the Trifid nebula

    Science.gov (United States)

    González, J. F.; Hubrig, S.; Przybilla, N.; Carroll, T.; Nieva, M.-F.; Ilyin, I.; Järvinen, S.; Morel, T.; Schöller, M.; Castro, N.; Barbá, R.; de Koter, A.; Schneider, F. R. N.; Kholtygin, A.; Butler, K.; Veramendi, M. E.; Langer, N.; BOB Collaboration

    2017-01-01

    HD 164492C is a spectroscopic triple stellar system that has been recently detected to possess a strong magnetic field. We have obtained high-resolution spectroscopic and spectropolarimetric observations over a timespan of two years and derived physical, chemical, and magnetic properties for this object. The system is formed by an eccentric close spectroscopic binary (Ca1-Ca2) with a period of 12.5 days, and a massive tertiary Cb. We calculated the orbital parameters of the close pair, reconstructed the spectra of the three components, and determined atmospheric parameters and chemical abundances by spectral synthesis. From spectropolarimetric observations, multi-epoch measurements of the longitudinal magnetic fields were obtained. The magnetic field is strongly variable on timescales of a few days, with a most probable period in the range of 1.4-1.6 days. Star Cb with Teff ˜ 25 000 K is the apparently fastest rotator and the most massive star of this triple system and has anomalous chemical abundances with a marked overabundance of helium, 0.35±0.04 by number. We identified this star as being responsible for the observed magnetic field, although the presence of magnetic fields in the components of the Ca pair cannot be excluded. Star Ca1 with a temperature of about 24 000 K presents a normal chemical pattern, while the least massive star Ca2 is a mid-B type star (Teff ˜ 15 000 K) with an overabundance of silicon. The obtained stellar parameters of the system components suggest a distance of 1.5 kpc and an age of 10-15 Myr.

  3. Chemical analysis of 24 dusty (pre-)main-sequence stars

    CERN Document Server

    Acke, B; Acke, Bram; Waelkens, Christoffel

    2004-01-01

    We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and Vega-type stars in search for the lambda Bootis phenomenon. We present the results of the elemental abundances of the sample stars. Some of the stars were never before studied spectroscopically at optical wavelengths. We have determined the projected rotational velocities of our sample stars. Furthermore, we discuss stars that depict a (selective) depletion pattern in detail. HD 4881 and HD 139614 seem to display an overall deficiency. AB Aur and possibly HD 126367 have subsolar values for the iron abundance, but are almost solar in silicon. HD 100546 is the only clear lambda Bootis star in our sample.

  4. The circumstellar shell of the post-AGB star HD 56126 the $^{12}CN\\/^{13}CN$ isotope ratio and fractionation

    CERN Document Server

    Bakker, E J; Bakker, Eric J.; Lambert, David L.

    1997-01-01

    We have detected circumstellar absorption lines of the $^{12}$CN and $^{13}$CN Violet and Red System in the spectrum of the post-AGB star HD~56126. From a synthetic spectrum analysis, we derive a Doppler broadening parameter of $b=0.51\\pm0.04$ km~s$^{-1}$, $^{12}$CN/$^{13}$CN$=38\\pm2$, and a lower limit of $2000$ on $^{12}$CN/$^{14}$CN and $^{12}$C$^{14}$N/$^{12}$C$^{15}$N. A simple chemical model has been computed of the circumstellar shell surrounding HD~56126 that takes into account the gas-phase ion-molecule reaction between CN and C$^{+}$. From this we infer that this reaction leads to isotopic fractionation of CN. Taking into account the isotopic exchange reaction and the observed $^{12}$CN/$^{13}$CN we find $^{12}$C/$^{13}$C$\\sim 67$ (for $T_{\\rm kin}=25$ K). Our analysis suggests that $^{12}$CN has a somewhat higher rotational temperature than $^{13}$CN: $T_{\\rm rot}=11.5\\pm0.6$ and $8.0\\pm0.6$ K respectively. We identify possible causes for this difference in excitation temperature, among which the $...

  5. Non-thermal radio emission from O-type stars. II. HD 167971

    CERN Document Server

    Blomme, R; Runacres, M C; Van Loo, S; Gunawan, D Y A S

    2006-01-01

    HD 167971 is a triple system consisting of a 3.3-day eclipsing binary (O5-8 V + O5-8 V) and an O8 supergiant. It is also a well known non-thermal radio emitter. We observed the radio emission of HD 167971 with the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). By combining these data with VLA archive observations we constructed a radio lightcurve covering a 20-yr time-range. We searched for, but failed to find, the 3.3-day spectroscopic period of the binary in the radio data. This could be due to the absence of intrinsic synchrotron radiation at the colliding-wind region between the two components of the eclipsing binary, or due to the large amount of free-free absorption that blocks the synchrotron radiation. We are able to explain many of the observed characteristics of the radio data if the non-thermal emission is produced in a colliding-wind region between the supergiant and the combined winds of the binary. Furthermore, if the system is gravitationally bound, the orbital motion ...

  6. AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Santiago, J.; Pereira, V.; De Castro, E. [Dpto. de Astrofisica y CC. de la Atmosfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Miceli, M.; Bonito, R. [Dipartimento di Fisica, Universita di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Del Valle, M. V.; Romero, G. E. [Instituto Argentino de Radioastronomia (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina); Albacete-Colombo, J. F. [Centro Universitario Regional Zona Atlantica (CURZA), Universidad Nacional del COMAHUE, Monsenor Esandi y Ayacucho, 8500 Viedma, Rio Negro (Argentina); Damiani, F. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)

    2012-09-20

    Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace due to the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30'' northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.

  7. Multi-Epoch Detections of Water Ice Absorption in Edge-on Disks around Herbig Ae Stars: PDS 144N and PDS 453

    CERN Document Server

    Terada, Hiroshi

    2016-01-01

    We report the multi-epoch detections of the water ice in 2.8-4.2 micron spectra of two Herbig Ae stars, PDS 144N (A2 IVe) and PDS 453 (F2 Ve), which have an edge-on circumstellar disk. The detected water ice absorption is found to originate from their protoplanetary disks. The spectra show a relatively shallow absorption of water ice around 3.1 micron for both objects. The optical depths of the water ice absorption are ~0.1 and ~0.2 for PDS 144N and PDS 453, respectively. Compared to the water ice previously detected in low-mass young stellar objects with an edge-on disk with a similar inclination angle, these optical depths are significantly lower. It suggests that stronger UV radiation from the central stars effectively decreases the water ice abundance around the Herbig Ae stars through photodesorption. The water ice absorption in PDS 453 shows a possible variation of the feature among the six observing epochs. This variation could be due to a change of absorption materials passing through our line-of-sigh...

  8. HD 164492C: a rapidly-rotating, H$\\alpha$-bright, magnetic early B star associated with a 12.5d spectroscopic binary

    CERN Document Server

    Wade, G A; Sikora, J; Bernier, M -É; Rivinius, Th; Alecian, E; Petit, V; Grunhut, J H

    2016-01-01

    We employ high resolution spectroscopy and spectropolarimetry to derive the physical properties and magnetic characteristics of the multiple system HD 164492C, located in the young open cluster M20. The spectrum reveals evidence of 3 components: a broad-lined early B star (HD 164492C1), a narrow-lined early B star (HD 164492C2), and a late B star (HD 164492C3). Components C2 and C3 exhibit significant ($>100$ km/s) bulk radial velocity variations with a period of $12.5351(7)$ d that we attribute to eccentric binary motion around a common centre-of-mass. Component C1 exhibits no detectable radial velocity variations. Using constraints derived from modeling the orbit of the C2+C3 binary and from synthesis of the combined spectrum, we determine the approximate physical characteristics of the components. We conclude that a coherent evolutionary solution consistent with the published age of M20 implies a distance to the system of $0.9\\pm 0.2$ kpc, corresponding to the smallest published values. We confirm the dete...

  9. Probing the wind launching regions of the Herbig Be star HD 58647 with high spectral resolution interferometry

    CERN Document Server

    Kurosawa, Ryuichi; Weigelt, G; Natta, A; Benisty, M; Isella, Andrea; Tatulli, Eric; Massi, F; Testi, Leonardo; Kraus, Stefan; Duvert, G; Petrov, Romain G; Stee, Ph

    2016-01-01

    We present a study of the wind launching region of the Herbig Be star HD 58647 using high angular (lambda/2B=0.003") and high spectral (R=12000) resolution interferometric VLTI-AMBER observations of the near-infrared hydrogen emission line, Br-gamma. The star displays double peaks in both Br-gamma line profile and wavelength-dependent visibilities. The wavelength-dependent differential phases show S-shaped variations around the line centre. The visibility level increases in the line (by ~0.1) at the longest projected baseline (88 m), indicating that the size of the line emission region is smaller than the size of the K-band continuum-emitting region, which is expected to arise near the dust sublimation radius of the accretion disc. The data have been analysed using radiative transfer models to probe the geometry, size and physical properties of the wind that is emitting Br-gamma. We find that a model with a small magnetosphere and a disc wind with its inner radius located just outside of the magnetosphere can...

  10. Spectroscopic study of the HgMn star HD 49606: the quest for binarity, abundance stratifications and magnetic field

    Science.gov (United States)

    Catanzaro, G.; Giarrusso, M.; Leone, F.; Munari, M.; Scalia, C.; Sparacello, E.; Scuderi, S.

    2016-08-01

    In this paper, we present a multi-instrument analysis of the mercury-manganese star HD 49606. New spectroscopic observations have been obtained by us with Catania Astrophysical Observatory Spectropolarimeter (CAOS@OAC) and High Accuracy Radial Velocity Planet Searcher-North@Telescopio Nazionale Galileo (HARPS-N@TNG). Combining these observations with archive data coming from other instruments, we performed a comprehensive analysis of this star. We highlight the motion around the centre of mass of a binary system of SB1 type, and we calculate the fundamental parameters characterizing its orbit. We also speculate on the nature of the unseen component. From the fit of H β and H γ, we determined the effective temperature and gravity, while from a number of metal lines, we derive the rotational and microturbulent velocities. Regarding chemical composition, we found underabundances of helium, oxygen, magnesium, sulfur and nickel, solar composition for carbon and overabundances for all the other elements. In particular, mercury abundance is derived taking into account an isotopic mixture different from the terrestrial one. As to magnesium, silicon and phosphorus, we found a non-constant abundance with the optical depth, a result currently considered an evidence of stratification. Spectropolarimetric observations have been performed in the attempt to highlight the presence of a magnetic field, but no detection has been found.

  11. ALMA observations of the molecular gas in the debris disk of the 30 Myr old star HD 21997

    CERN Document Server

    Kóspál, Á; Juhász, A; Ábrahám, P; Apai, D; Csengeri, T; Grady, C A; Henning, Th; Hughes, A M; Kiss, Cs; Pascucci, I; Schmalzl, M

    2013-01-01

    The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here we report on the detection of 12CO and 13CO in the J=2-1 and J=3-2 transitions and C18O in the J=2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r_in < 26 AU, r_out = 138 +/- 20 AU, M_*=1.8 +0.5 -0.2 M_Sun, and i = 32.6 +/- 3.1 degrees. The total CO mass, as calculated from the optically thin C18O line, is about (4-8) x 10^-2 M_Earth, while the CO line ratios suggest a radiation temperature on the order of 6-9 K. Comparing our results with those obtained for the dust component of th...

  12. An interferometric-spectroscopic orbit for the binary HD 195987 Testing models of stellar evolution for metal-poor stars

    CERN Document Server

    Torres, G; Latham, D W; Pan, M; Stefanik, R P; Torres, Guillermo; Boden, Andrew F.; Latham, David W.; Pan, Margaret; Stefanik, Robert P.

    2002-01-01

    We report spectroscopic and interferometric observations of the moderately metal-poor double-lined binary system HD 195987, with an orbital period of 57.3 days. By combining our radial-velocity and visibility measurements we determine the orbital elements and derive absolute masses for the components of M(A) = 0.844 +/- 0.018 Msun and M(B) = 0.6650 +/- 0.0079 Msun, with relative errors of 2% and 1%, respectively. We also determine the orbital parallax, pi(orb) = 46.08 +/- 0.27 mas, corresponding to a distance of 21.70 +/- 0.13 pc. The parallax and the measured brightness difference between the stars in V, H, and K yield the component absolute magnitudes in those bands. We also estimate the effective temperatures of the stars as Teff(A) = 5200 +/- 100 K and Teff(B) = 4200 +/- 200 K. Together with detailed chemical abundance analyses from the literature giving [Fe/H] approximately -0.5 (corrected for binarity) and [alpha/Fe] = +0.36, we use these physical properties to test current models of stellar evolution f...

  13. Non-LTE analysis of subluminous O-star. V - The binary system HD 128220

    Science.gov (United States)

    Gruschinske, J.; Hamann, W. R.; Kudritzki, R. P.; Simon, K. P.; Kaufmann, J. P.

    1983-05-01

    Spectra of the binary system HD 128220 were taken in the UV and in the visual. The hot component - an O subdwarf - is analysed by means of non-LTE calculations. The cool companion has an effective temperature about 5500 ± 500K (Type G). The discussion of the stellar parameters arrives at results which agree with those derived from the mass function (Wallerstein and Wolff, 1966): if both components have about the same mass, these masses lie above 3 M_sun;. An O subdwarf of such a high mass has not yet been found and may be a supernova candidate. However, within the error margin of the orbital data also a mass ratio of MO/MG = 0.5 cannot be excluded, which would lead to stellar parameters which are more common for sdO's.

  14. AE 941.

    Science.gov (United States)

    2004-01-01

    AE 941 [Arthrovas, Neoretna, Psovascar] is shark cartilage extract that inhibits angiogenesis. AE 941 acts by blocking the two main pathways that contribute to the process of angiogenesis, matrix metalloproteases and the vascular endothelial growth factor signalling pathway. When initial development of AE 941 was being conducted, AEterna assigned the various indications different trademarks. Neovastat was used for oncology, Psovascar was used for dermatology, Neoretna was used for ophthalmology and Arthrovas was used for rheumatology. However, it is unclear if these trademarks will be used in the future and AEterna appears to only be using the Neovastat trademark in its current publications regardless of the indication. AEterna Laboratories signed commercialisation agreements with Grupo Ferrer Internacional SA of Spain and Medac GmbH of Germany in February 2001. Under the terms of the agreement, AEterna has granted exclusive commercialisation and distribution rights to AE 941 in oncology to Grupo Ferrer Internacional for the Southern European countries of France, Belgium, Spain, Greece, Portugal and Italy. It also has rights in Central and South America. Medac GmbH will have marketing rights in Germany, the UK, Scandinavia, Switzerland, Austria, Ireland, the Netherlands and Eastern Europe. In October 2002, AEterna Laboratories announced that it had signed an agreement with Australian healthcare products and services company Mayne Group for marketing AE 941 (as Neovastat) in Australia, New Zealand, Canada and Mexico. In March 2003, AEterna Laboratories announced it has signed an agreement with Korean based LG Life Sciences Ltd for marketing AE 941 (as Neovastat) in South Korea. The agreement provides AEterna with upfront and milestone payments, as well as a return on manufacturing and sales of AE 941. AEterna Laboratories had granted Alcon Laboratories an exclusive worldwide licence for AE 941 for ophthalmic products. However, this licence has been terminated. In

  15. The Case of the Tail Wagging the Dog: HD 189733 - Evidence of Hot Jupiter Exoplanets Spinning-up Their Host Stars

    Science.gov (United States)

    Guinan, E. F.

    2013-06-01

    (Abstract only) HD 189733A is an eighth mag K1.5V star that has attracted much attention because it hosts a short period, transiting, hot-Jupiter planet. This planet, HD 189733b, has one of the shortest known orbital periods (P = 2.22 days) and is only 0.031 AU from its host star. Because the system undergoes eclipses and is bright, HD 189733 has been extensively studied. The planet's atmosphere has been found to contain water vapor, methane, CO2, and sodium and possible haze. Spitzer IR observations indicate planet temperature, varying ~970 K to ~1,200 K over its surface (Tinetti (2007). Based on measurements of the K-star's P(rot) from starspot modulations of ~11.95 d, strong coronal X-ray emission and chromospheric Ca II-HK emission indicate a young age of ~0.7 Gyr. But this apparent young age is discrepant with a much older age (> 4 Gyr) inferred from the star's very low Lithium abundance. However, the age of the HD 189733 system can be independently determined by the presence of a faint dM4 companion (HD 189733B) some 12" away. Our Age-Activity relations for this star (no detectable coronal X-ray emission and no H-alpha emission) indicate an age > 4 Gyr (and < 8 Gyr from kinematics and metallicity). This age should apply to its K star companion and its planet. The fast rotation and resultant high activity levels of the K star can best be explained from the increase in its (rotation) angular momentum (AM) from the orbital AM of the planet. This AM transfer occurs from tidal and magnetic interactions of the K star with its planet. Determining the possible decrease in the planet's orbital period is possible from studying the planet eclipse times (which can be done by AAVSO members with CCD photometry). We also discuss the properties of other related short-period exoplanet systems found by the Kepler Mission that show similar behavior - in that close-in hot Jupiter size planets appear to be physically interacting with their host stars. This work is supported by

  16. Discovery of a close substellar companion to the hot subdwarf star HD 149382 - The decisive influence of substellar objects on late stellar evolution

    CERN Document Server

    Geier, S; Heber, U; Morales-Rueda, L

    2009-01-01

    Substellar objects, like planets and brown dwarfs orbiting stars, are by-products of the star formation process. The evolution of their host stars may have an enourmous impact on these small companions. Vice versa a planet might also influence stellar evolution as has recently been argued. Here we report the discovery of a 8-23 Jupiter-mass substellar object orbiting the hot subdwarf HD 149382 in 2.391 days at a distance of only about five solar radii. Obviously the companion must have survived engulfment in the red-giant envelope. Moreover, the substellar companion has triggered envelope ejection and enabled the sdB star to form. Hot subdwarf stars have been identified as the sources of the unexpected ultravoilet emission in elliptical galaxies, but the formation of these stars is not fully understood. Being the brightest star of its class, HD 149382 offers the best conditions to detect the substellar companion. Hence, undisclosed substellar companions offer a natural solution for the long-standing formation...

  17. Non-radial oscillations of the rapidly rotating Be star HD 163868

    NARCIS (Netherlands)

    Savonije, G.J.

    2007-01-01

    Context: Oscillations in rotating stars with frequency barsigma of the same order or smaller than the rotation rate Omega cannot be described by a single spherical harmonic due to the effect of the Coriolis force. This is a serious complication which is usually treated by writing the eigenfunctions

  18. A Survey for a Coeval, Comoving Group Associated with HD 141569

    CERN Document Server

    Aarnio, Alicia N; Stassun, Keivan G; Mamajek, Eric E; James, David J

    2008-01-01

    We present results of a search for a young stellar moving group associated with the star HD 141569, a nearby, isolated Herbig AeBe primary member of a 5+/-3 Myr-old triple star system on the outskirts of the Sco-Cen complex. Our spectroscopic survey identified a population of 21 Li-rich, <30 Myr-old stars within 30 degrees of HD 141569 which possess similar proper motions with the star. The spatial distribution of these Li-rich stars, however, is not suggestive of a moving group associated with the HD 141569 triplet, but rather this sample appears cospatial with Upper Scorpius and Upper Centaurus Lupus. We apply a modified moving cluster parallax method to compare the kinematics of these youthful stars with Upper Scorpius and Upper Centaurus Lupus. Eight new potential members of Upper Scorpius and five new potential members of Upper Centaurus Lupus are identified. A substantial moving group with an identifiable nucleus within 15 degrees (~30 pc) of HD 141569 is not found in this sample. Evidently, the HD 1...

  19. Searching for Gas Giant Planets on Solar System Scales: VLT NACO/APP Observations of the Debris Disk Host Stars HD172555 and HD115892

    CERN Document Server

    Quanz, Sascha P; Meyer, Michael R; Girard, Julien H V; Kasper, Markus

    2011-01-01

    Using the APP coronagraph of VLT/NACO we searched for planetary mass companions around HD115892 and HD172555 in the thermal infrared at 4 micron. Both objects harbor unusually luminous debris disks for their age and it has been suggested that small dust grains were produced recently in transient events (e.g., a collision) in these systems. Such a collision of planetesimals or protoplanets could have been dynamically triggered by yet unseen companions. We did not detect any companions in our images but derived the following detection limits: For both objects we would have detected companions with apparent magnitudes between ~13.2-14.1 mag at angular separations between 0.4- 1.0" at the 5-sigma level. For HD115892 we were sensitive to companions with 12.1 mag even at 0.3". Using theoretical models these magnitudes are converted into mass limits. For HD115892 we would have detected objects with 10-15 M_Jup at angular separations between 0.4-1.0" (7-18 AU). At 0.3" (~5.5 AU) the detection limit was ~25 M_Jup. For...

  20. HD 164492C: a rapidly rotating, Hα-bright, magnetic early B star associated with a 12.5 d spectroscopic binary

    Science.gov (United States)

    Wade, G. A.; Shultz, M.; Sikora, J.; Bernier, M.-É.; Rivinius, Th.; Alecian, E.; Petit, V.; Grunhut, J. H.; BinaMIcS Collaboration

    2017-03-01

    We employ high-resolution spectroscopy and spectropolarimetry to derive the physical properties and magnetic characteristics of the multiple system HD 164492C, located in the young open cluster M20. The spectrum reveals evidence of three components: a broad-lined early B star (HD 164492C1), a narrow-lined early B star (HD 164492C2) and a late B star (HD 164492C3). Components C2 and C3 exhibit significant (>100 km s-1) bulk radial velocity variations with a period of 12.5351(7) d that we attribute to eccentric binary motion around a common centre-of-mass. Component C1 exhibits no detectable radial velocity variations. Using constraints derived from modelling the orbit of the C2+C3 binary and from synthesis of the combined spectrum, we determine the approximate physical characteristics of the components. We conclude that a coherent evolutionary solution consistent with the published age of M20 implies a distance to M20 of 0.9 ± 0.2 kpc, corresponding to the smallest published values. We confirm the detection of a strong magnetic field in the combined spectrum. The field is clearly associated with the broad-lined C1 component of the system. Repeated measurement of the longitudinal magnetic field allows the derivation of the rotation period of the magnetic star, Prot = 1.369 86(6) d. We derive the star's magnetic geometry, finding i=63± 6°, β =33± 6° and a dipole polar strength B_d=7.9^{+1.2}_{-1.0} kG. Strong emission - varying according to the magnetic period - is detected in the Hα profile. This is consistent with the presence of a centrifugal magnetosphere surrounding the rapidly rotating magnetic C1 component.

  1. Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R CrA

    CERN Document Server

    Kraus, S; Malbet, F; Meilland, A; Natta, A; Schertl, D; Stee, P; Weigelt, G

    2009-01-01

    Models predict that in the innermost AU of the disk around Herbig Ae/Be star, the dust disk forms a "puffed-up" inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination. Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H- and K-band) spectro-interferometric observations on the Herbig Ae star R CrA. In the derived visibility function, we detect the signatures of an extended (25 mas) and a compact component (5.8 mas), with the compact component contributing about 2/3 of the total flux. The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to 40 deg) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. Our curved puffed-up rim model can reasonably we...

  2. The origin of the excess transit absorption in the HD 189733 system: planet or star?

    CERN Document Server

    Barnes, J R; Staab, D; Anglada-Escudé, G

    2016-01-01

    We have detected excess absorption in the emission cores of Ca II H & K during transits of HD 189733b for the first time. Using observations of three transits we investigate the origin of the absorption, which is also seen in H{\\alpha} and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of {\\Delta}{\\lambda} = 0.4 & 0.6 $\\AA$ yields excess absorption of t$_d$ = 0.0074 $\\pm$ 0.0044 (1.7{\\sigma}; Transit 1) and 0.0214 +/- 0.0022 (9.8{\\sigma}; Transit 2). Similarly, we detect excess H{\\alpha} absorption in a passband of width {\\Delta}{\\lambda} = 0.7 $\\AA$, with t$_d$ = 0.0084 $\\pm$ 0.0016 (5.2{\\sigma}) and 0.0121 $\\pm$ 0.0012 (9.9{\\sigma}). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of t$_d$ = 0.0041 $\\pm$ 0.0006 (6.5{\\sigma}). By considering the time series observations of each line, we find that the excess apparent absorptio...

  3. Conditions for HD Cooling in the First Galaxies Revisited: Interplay between Far-Ultraviolet and Cosmic Ray Feedback in Population III Star Formation

    CERN Document Server

    Nakauchi, Daisuke; Omukai, Kazuyuki

    2014-01-01

    HD dominates the cooling of primordial clouds with enhanced ionization, e.g. shock-heated clouds in structure formation or supernova remnants, relic HII regions of Pop III stars, and clouds with cosmic-ray (CR) irradiation. There, the temperature decreases to several 10 K and the characteristic stellar mass decreases to $\\sim 10\\ {\\rm M}_{\\odot}$, in contrast with first stars formed from undisturbed pristine clouds ($\\sim 100\\ {\\rm M}_{\\odot}$). However, without CR irradiation, even weak far ultra-violet (FUV) irradiation suppresses HD formation/cooling. Here, we examine conditions for HD cooling in primordial clouds including both FUV and CR feedback. At the beginning of collapse, the shock-compressed gas cools with its density increasing, while the relic HII region gas cools at a constant density. Moreover, shocks tend to occur in denser environments than HII regions. Owing to the higher column density and the more effective shielding, the critical FUV intensity for HD cooling in a shock-compressed gas beco...

  4. The origin of the excess transit absorption in the HD 189733 system: planet or star?

    Science.gov (United States)

    Barnes, J. R.; Haswell, C. A.; Staab, D.; Anglada-Escudé, G.

    2016-10-01

    We have detected excess absorption in the emission cores of Ca II H&K during transits of HD 189733b for the first time. Using observations of three transits, we investigate the origin of the absorption, which is also seen in Hα and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of Δλ = 0.4 and 0.6 Å yields excess absorption of td = 0.0074 ± 0.0044 (1.7σ; Transit 1) and 0.0214 ± 0.0022 (9.8σ; Transit 2). Similarly, we detect excess Hα absorption in a passband of width Δλ = 0.7 Å, with td = 0.0084 ± 0.0016 (5.2σ) and 0.0121 ± 0.0012 (9.9σ). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of td = 0.0041 ± 0.0006 (6.5σ). By considering the time series observations of each line, we find that the excess apparent absorption is best recovered in the stellar reference frame. These findings lead us to postulate that the main contribution to the excess transit absorption in the differential light curves arises because the normalizing continuum bands form in the photosphere, whereas the line cores contain a chromospheric component. We cannot rule out that part of the excess absorption signature arises from the planetary atmosphere, but we present evidence which casts doubt on recent claims to have detected wind motions in the planet's atmosphere in these data.

  5. Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies

    CERN Document Server

    Marsden, S C; Vélez, J C Ramírez; Alecian, E; Brown, C J; Carter, B D; Donati, J F; Dunstone, N; Hart, R; Semel, M; Waite, I A

    2011-01-01

    Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced betwee...

  6. The fundamental parameters of the roAp star HD 24712. A rapidly oscillator at the red edge of the instability strip

    Science.gov (United States)

    Perraut, K.; Brandão, I.; Cunha, M.; Shulyak, D.; Mourard, D.; Nardetto, N.; ten Brummelaar, T. A.

    2016-05-01

    Context. There is still a debate about the nature of the mechanism that causes the pulsation excitation of the rapidly oscillating Ap stars that oscillate above the highest theoretically acoustic frequency. HD 24712 is a good test case for such a study because it is bright, its parallax accurately determined, and its frequency spectrum is well known. Aims: Visible long-baseline interferometry is a unique technique for measuring accurate angular diameters of targets as small as the brightest roAp stars, and thus estimating accurate radii by a method as independent as possible of atmosphere models. Methods: We used the visible spectrograph VEGA at the CHARA long-baseline optical array to observe HD 24712, and we derived its limb-darkened diameter. We also estimated its bolometric flux from spectroscopic data in the literature and determined its radius, luminosity, and effective temperature. Results: We determined a limb-darkened angular diameter of 0.335 ± 0.009 mas for HD 24712 and derived a radius of R = 1.772 ± 0.057 R⊙, a luminosity of L = 7.2 ± 1.8 L⊙, and an effective temperature of Teff = 7235 ± 280 K, which is in very close agreement with the values provided by the self-consistent stratified model developed for this star. We used these fundamental parameters to set HD 24712 in the Hertzsprung-Russell diagram. Its position is marginally consistent with the region where high radial order modes are predicted to be excited by the κ-mechanism. Conclusions: We conclude that oscillations in this star are most likely not driven by the κ-mechanism. Based on observations made with the VEGA/CHARA spectro-interferometer.

  7. Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon III. HD 50138

    CERN Document Server

    Jeřábková, T; Miroshnichenko, A; Danford, S; Zharikov, S V; Kříček, R; Zasche, P; Votruba, V; Šlechta, M; Škoda, P; Janík, J

    2015-01-01

    We analyse spectroscopic observations of the B[e] star HD 50138 (MWC 158, V743 Mon, or IRAS 06491-0654), a member of the FS CMa group, obtained over the last twenty years. Four different epochs are identified in the observational data, where the variability of the spectral features is substantially different. Additionally, two long periods of (3 000 +/- 500) and (5 000 +/- 1000) days are found in the variations of the equivalent widths of the H alpha and [OI] 6300 A lines and radial velocities of the H alpha line violet peak. Modest signatures of a regular period of ~34 days in the radial velocities of the H alpha red peak and H beta central depression are found in the season 2013/2014. The H alpha V/R changes indicate a periodicity of ~50 days. The correlations between individual spectral features significantly restricts the model of the object and suggest that it is most likely a binary system with a highly distorted disc with spiral arms around the primary component. At the same time, no obvious signs of t...

  8. Characterization of the X-ray light curve of the gamma Cas-like B1e star HD110432

    CERN Document Server

    Smith, Myron A; Motch, Christian

    2012-01-01

    HD 110432 (BZ Cru; B1Ve) is the brightest member of a small group of "gamma Cas analogs" that emit copious hard X-ray flux, punctuated by ubiquitous "flares." To characterize the X-ray time history of this star, we made a series of six RXTE multi-visit observations in 2010 and an extended observation with the XMM-Newton in 2007. We analyzed these new light curves along with three older XMM-Newton observations from 2002--2003. Distributed over five months, the RXTE observations were designed to search for long X-ray modulations over a few months. These observations indeed suggest the presence of a long cycle with P = 226 days and an amplitude of a factor of two. We also used X-ray light curves constructed from XMM-Newton observations to characterize the lifetimes, strengths, and interflare intervals of 1615 flare-like events in the light curves. After accounting for false positive events, we infer the presence of 955 (2002-2003) and 386 (2007) events we identified as flares. Similarly, as a control we measured...

  9. Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD206893

    CERN Document Server

    Milli, Julien; Christiaens, Valentin; Choquet, Elodie; Bonnefoy, Mickael; Kennedy, Grant M; Wyatt, Mark C; Absil, Olivier; Gonzalez, Carlos A Gomez; del Burgo, Carlos; Matra, Luca; Augereau, Jean-Charles; Boccaletti, Anthony; Delacroix, Christian; Ertel, Steve; Dent, William R F; Forsberg, Pontus; Fusco, Thierry; Girard, Julien H; Habraken, Serge; Huby, Elsa; Karlsson, Mikael; Lagrange, Anne-Marie; Mawet, Dimitri; Mouillet, David; Perrin, Marshall; Pinte, Christophe; Pueyo, Laurent; Reyes, Claudia; Soummer, Remi; Surdej, Jean; Tarricq, Yoann; Wahhaj, Zahed

    2016-01-01

    Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition, and interaction with the circumstellar environment. We aim at discovering and studying new such systems, to further expand our knowledge of how low-mass companions form and evolve. We obtained high-contrast H-band images of the circumstellar environment of the F5V star HD206893, known to host a debris disc never detected in scattered light. These observations are part of the SPHERE High Angular Resolution Debris Disc Survey (SHARDDS) using the InfraRed Dual-band Imager and Spectrograph (IRDIS) installed on VLT/SPHERE. We report the detection of a source with a contrast of 3.6x10^{-5} in the H-band, orbiting at a projected separation of 270 milliarcsecond or 10 au, corresponding to a mass in the range 24 to 73 Mjup for an age of the system in the range 0.2 to 2 Gyr. The detection was confirmed ten months later with VLT/NaCo...

  10. X-ray emission from the double-binary OB-star system QZ Car (HD 93206)

    CERN Document Server

    Parkin, E R; Townsley, L K; Pittard, J M; Moffat, A F J; Naze, Y; Rauw, G; Oskinova, L M

    2011-01-01

    X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The orbit of systems A (O9.7 I+b2 v, PA = 21 d) and B (O8 III+o9 v, PB = 6 d) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three temperature thermal plasma model, characterised by cool, moderate, and hot plasma components at kT ~ 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of ~ 0.2 x 10^22 cm-2. Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of ~ 7 x 10^-13 erg s-1 cm-2, do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. ...

  11. Herschel-PACS observation of gas lines from the disc around HD141569A

    NARCIS (Netherlands)

    Thi, Wing-Fai; Pinte, Christophe; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Ménard, Francois; Martin-Zaidi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, William; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean

    2013-01-01

    At the distance of ˜ 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disc, probably in transition between a massive primordial disc and a debris disc. We observed the fine-structure lines of O I at 63 and 145 μm , and the C II line at 157 μm with the PACS in

  12. A HST study of the environment of the Herbig Ae/Be star LkHa 233 and its bipolar jet

    CERN Document Server

    Melnikov, Stanislav Yu; Eislöffel, Jochen; Bacciotti, Francesca; Locatelli, Ugo; Ray, Thomas P

    2008-01-01

    We present the results of HST/STIS and WFPC2 observations of LkHa 233 and its environment. LkHa233 is a Herbig Ae/Be star with a collimated bipolar jet. We investigate optical forbidden lines along the LkHa 233 jet to determine physical parameters of this jet (electron density n_e, hydrogen ionisation fraction x_e, electron temperature T_e, and mass density n_H). The knowledge of these parameters allows us a direct comparison of a jet from a Herbig star with those from T Tauri stars. The WFPC2 images in broad-band filters clearly show a dark lane caused either by a circumstellar disk or a dust torus. In the blueshifted lobe, n_e is close to or above the critical density for [SII] lines (2.5x10^4 cm^-3) in the first arcsecond and decreases with distance from the source. The ionisation x_e~0.2-0.6 gently rises for the first 500 AU of the flow and shows two re-ionisation events further away from the origin. The T_e varies along the flow between 10^4 K and 3x10^4 K. The (radial) outflow velocities are ~ 80-160 km...

  13. VizieR Online Data Catalog: Solar-type stars from SDSS-III MARVELS. VI. HD 87646 (Ma+, 2016)

    Science.gov (United States)

    Ma, B.; Ge, J.; Wolszczan, A.; Muterspaugh, M. W.; Lee, B.; Henry, G. W.; Schneider, D. P.; Martin, E. L.; Niedzielski, A.; Xie, J.; Fleming, S. W.; Thomas, N.; Williamson, M.; Zhu, Z.; Agol, E.; Bizyaev, D.; da Costa, L. N.; Jiang, P.; Fiorenzano, A. F. M.; Hernandez, J. I. G.; Guo, P.; Grieves, N.; Li, R.; Liu, J.; Mahadevan, S.; Mazeh, T.; Nguyen, D. C.; Paegert, M.; Sithajan, S.; Stassun, K.; Thirupathi, S.; van Eyken, J. C.; Wan, X.; Wang, J.; Wisniewski, J. P.; Zhao, B.; Zucker, S.

    2016-11-01

    We have obtained a total of 16 observations of HD87646 using the W.M. Keck Exoplanet Tracker (KeckET) from 2006 December to 2007 June. The radial velocities obtained are listed in Table1. The KeckET instrument was constructed in 2005 August-2006 February with support from the Keck Foundation. It was coupled with a wide field Sloan Digital Sky Survey telescope (SDSS) and used for the pilot Multi-Object APO RV Exoplanet Large-Area Survey (MARVELS). This is the sixth paper in this series, examining the low-mass companions around solar-type stars from the SDSS-III MARVELS survey (Wisniewski et al. 2012, Cat. J/AJ/143/107; Fleming et al. 2012AJ....144...72F; Ma et al. 2013AJ....145...20M; Jiang et al. 2013AJ....146...65J; De Lee et al. 2013AJ....145..155D). The KeckET instrument consists of eight subsystems-a multi-object fiber feed, an iodine cell, a fixed-delay interferometer system, a slit, a collimator, a grating, a camera, and a 4k*4k CCD detector. In addition, it contains four auxiliary subsystems: the interferometer control, an instrument calibration system, a photon flux monitoring system, and a thermal probe and control system. The instrument is fed with 60 fibers with 200μm core diameters, which are coupled to 180μm core diameter short fibers from the SDSS telescope, corresponding to 3arcsec on the sky at f/5. The resolving power for the spectrograph is R=5100, and the wavelength coverage is ~900Å, centered at 5400Å. KeckET has one spectrograph and one 4k*4k CCD camera that captures one of the two interferometer outputs, and has a 5.5% detection efficiency from the telescope to the detector without the iodine cell under the typical APO seeing conditions (~1.5arcsec seeing). The CCD camera records fringing spectra from 59 objects in a single exposure. Subsequent observations were performed using the Exoplanet Tracker (ET) instrument at Kitt Peak National Observatory (KPNO). Initial follow-up was performed in 2007 November. Additional data points were

  14. Dynamics of the circumstellar gas in the Herbig Ae stars BF Orionis, SV Cephei, WW Vulpeculae and XY Persei

    CERN Document Server

    Mora, A; Natta, A; Grady, C A; De Winter, D; Davies, J K; Ferlet, R; Harris, A W; Miranda, L F; Montesinos, B; Oudmaijer, R D; Palacios, J; Quirrenbach, Andreas G; Rauer, H; Alberdi, A; Cameron, A; Deeg, H J; Garzón, F; Horne, K; Merin, B; Penny, A; Schneider, J; Solano, E; Tsapras, Y; Wesselius, P R

    2004-01-01

    We present high resolution (lambda / Delta_lambda = 49000) echelle spectra of the intermediate mass, pre-main sequence stars BF Ori, SV Cep, WW Wul and XY Per. The spectra cover the range 3800-5900 angstroms and monitor the stars on time scales of months and days. All spectra show a large number of Balmer and metallic lines with variable blueshifted and redshifted absorption features superimposed to the photospheric stellar spectra. Synthetic Kurucz models are used to estimate rotational velocities, effective temperatures and gravities of the stars. The best photospheric models are subtracted from each observed spectrum to determine the variable absorption features due to the circumstellar gas; those features are characterized in terms of their velocity, v, dispersion velocity, Delta v, and residual absorption, R_max. The absorption components detected in each spectrum can be grouped by their similar radial velocities and are interpreted as the signature of the dynamical evolution of gaseous clumps with, in m...

  15. The galactic unclassified B[e] star HD 50138 III. The short-term line profile variability of its photospheric lines

    CERN Document Server

    Fernandes, Marcelo Borges; Nickeler, Dieter H; De Cat, Peter; Lampens, Patricia; Pereira, Claudio Bastos; Oksala, Mary E

    2012-01-01

    HD 50138 presents the B[e] phenomenon, but its nature is not clear yet. This star is known to present spectral variations, which have been associated with outbursts and shell phases. We analyze the line profile variability of HD 50138 and its possible origin, which provide possible hints to its evolutionary stage, so far said to be close to the end of (or slightly beyond) the main sequence. New high-resolution spectra of HD 50138 obtained with the HERMES spectrograph over several nights (five of them consecutively) were analyzed, allowing us to confirm short-term line profile variability. Our new data show short-term variations in the photospheric lines. On the other hand, purely circumstellar lines (such as [O I] lines) do not show such rapid variability. The rotational velocity of HD 50138, V_rot = 90.3 +- 4.3 km/s, and the rotation period, P = 3.64 +- 1.16 d, were derived from the He II 4026A photospheric line. Based on the moment method, we confirm that the origin of this short-term line profile variabili...

  16. Retired A Stars and Their Companions VI. A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD200964

    CERN Document Server

    Johnson, John Asher; Howard, Andrew W; Clubb, Kelsey I; Ford, Eric B; Bowler, Brendan P; Henry, Gregory W; Fischer, Debra A; Marcy, Geoffrey W; Brewer, John M; Schwab, Christian; Reffert, Sabine; Lowe, Thomas B

    2010-01-01

    We report radial velocity measurements of the G-type subgiants 24 Sextanis (=HD90043) and HD200964. Both are massive, evolved stars that exhibit periodic variations due to the presence of a pair of Jovian planets. Photometric monitoring with the T12 0.80m APT at Fairborn Observatory demonstrates both stars to be constant in brightness to <= 0.002 mag, thus strengthening the planetary interpretation of the radial velocity variations. 24 Sex b,c have orbital periods of 453.8 days and 883~days, corresponding to semimajor axes 1.333 AU and 2.08 AU, and minimum masses (Msini) 1.99 Mjup and 0.86 Mjup, assuming a stellar mass 1.54 Msun. HD200964 b,c have orbital periods of 613.8 days and 825 days, corresponding to semimajor axes 1.601 AU and 1.95 AU, and minimum masses 1.85 Mjup and 0.90 Mjup, assuming M* = 1.44 Msun. We also carry out dynamical simulations to properly account for gravitational interactions between the planets. Most, if not all, of the dynamically stable solutions include crossing orbits, suggest...

  17. Regular frequency patterns in the young delta Scuti star HD 261711 observed by the CoRoT and MOST satellites

    CERN Document Server

    Zwintz, K; Guenther, D B; Ryabchikova, T; Baglin, A; Themessl, N; Barnes, T G; Matthews, J M; Auvergne, M; Bohlender, D; Chaintreuil, S; Kuschnig, R; Moffat, A F J; Rowe, J F; Rucinski, S M; Sasselov, D; Weiss, W W

    2013-01-01

    We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in 4 separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group are related to l=0 and l=1 p-mod...

  18. MagAO Imaging of Long-period Objects (MILO). II. A Puzzling White Dwarf around the Sun-like Star HD 11112

    CERN Document Server

    Rodigas, Timothy J; Simon, Amelie; Arriagada, Pamela; Faherty, Jackie; Anglada-Escude, Guillem; Mamajek, Eric E; Weinberger, Alycia; Butler, R Paul; Males, Jared R; Morzinski, Katie; Close, Laird M; Hinz, Philip M; Bailey, Jeremy; Carter, Brad; Jenkins, James S; Jones, Hugh; O'Toole, Simon; Tinney, C G; Wittenmyer, Rob; Debes, John

    2016-01-01

    HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect the object (HD 11112B) at a separation of 2\\fasec 2 (100 AU) at multiple wavelengths spanning 0.6-4 \\microns ~and show that it is most likely a gravitationally-bound cool white dwarf. Modeling its spectral energy distribution (SED) suggests that its mass is 0.9-1.1 \\msun, which corresponds to very high-eccentricity, near edge-on orbits from Markov chain Monte Carlo analysis of the RV and imaging data together. The total age of the white dwarf is $>2\\sigma$ discrepant with that of the primary star under most assumptions. The problem can be resolved if the white dwarf progenitor was initially a double white dwarf binary that then merged into the observed high-mass white dwarf. HD 11112B is a unique and intriguing benchmark object that can be used to calibrate ...

  19. Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307

    CERN Document Server

    Tuomi, Mikko; Gerlach, Enrico; Jones, Hugh R R; Reiners, Ansgar; Rivera, Eugenio J; Vogt, Steven S; Butler, R Paul

    2012-01-01

    The K2.5 dwarf HD 40307 has been reported to host three super-Earths. The system lacks massive planets and is therefore a potential candidate for having additional low-mass planetary companions. We re-derive Doppler measurements from public HARPS spectra of HD 40307 to confirm the significance of the reported signals using independent data analysis methods. We also investigate these measurements for additional low-amplitude signals. We used Bayesian analysis of our radial velocities to estimate the probability densities of different model parameters. We also estimated the relative probabilities of models with differing numbers of Keplerian signals and verified their significance using periodogram analyses. We investigated the relation of the detected signals with the chromospheric emission of the star. As previously reported for other objects, we found that radial velocity signals correlated with the S-index are strongly wavelength dependent. We identify two additional clear signals with periods of 34 and 51 ...

  20. XMM-Newton Observations of HD189733 During Planetary Transits. X-rays Interaction Between Hot Jupiters and the Host Star.

    Science.gov (United States)

    Pillitteri, Ignazio; Wolk, S. J.; Cohen, O.; Kashyap, V.; Knutson, H.; Lisse, C. M.

    2010-03-01

    The irradiation of X-rays from host stars on their nearby gas-giant planets can cause excess heating of the planet which can induce mass loss. Further, it has been argued that the magnetic fields of the two bodies can interact. We present XMM-Newton observations of HD 189733 during the eclipse and planetary transit of its hot jupiter planet HD 189733b in order to investigate any effects of the interaction between the host star and the planet in X-rays. We observe a softening of X-ray spectrum at level of 2 sigmas during the 2009 secondary eclipse. It is followed at 3 ks by an enhancement of the X-ray flux likely due to a flare. No remarkable effects are seen in 2007 transit. Magneto-Hydro-Dynamical (MHD) simulations show that the plasma spectrum could get softer during the eclipse. Further, a region of high plasma density on the stellar corona, and displaced from the planet-star line, should form due to the interaction of magnetic fields of star and planet. The magnetic activity in this region is enhanced and should cause frequent transients. The X-ray observations suggest that these model predictions are globally correct. Despite the simple model adopted and the lack of precise parameters, effects of the interaction of stars and their nearby planets appear to observable in X-rays. X-ray observations allow to probe the structuring and the strength of the complex magnetosphere of the star+planet system.

  1. The TRENDS High-Contrast Imaging Survey. V. Discovery of an Old and Cold Benchmark T-dwarf Orbiting the Nearby G-star HD 19467

    CERN Document Server

    Crepp, Justin R; Howard, Andrew W; Marcy, Geoffrey W; Brewer, John; Fischer, Debra A; Wright, Jason T; Isaacson, Howard

    2013-01-01

    The nearby Sun-like star HD 19467 shows a subtle radial velocity (RV) acceleration of -1.37+/-0.09 m/s/yr over an 16.9 year time baseline (an RV trend), hinting at the existence of a distant orbiting companion. We have obtained high-contrast adaptive optics images of the star using NIRC2 at Keck Observatory and report the direct detection of the body that causes the acceleration. The companion, HD 19467 B, is dK=12.57+/-0.09 mag fainter than its parent star (contrast ratio of 9.4e-6), has blue colors J-K_s=-0.36+/-0.14 (J-H=-0.29+/-0.15), and is separated by 1.653+/-0.004" (51.1+/-1.0 AU). Follow-up astrometric measurements obtained over an 1.1 year time baseline demonstrate physical association through common parallactic and proper motion. We calculate a firm lower-limit of m>51.9^{+3.6}_{-4.3}Mjup for the companion mass from orbital dynamics using a combination of Doppler observations and imaging. We estimate a model-dependent mass of m=56.7^{+4.6}_{-7.2}Mjup from a gyrochronological age of 4.3^{+1.0}_{-1.2...

  2. The Diverse Origins of Neutron-Capture Elements in the Metal-Poor Star HD 94028: Possible Detection of Products of i-process Nucleosynthesis

    CERN Document Server

    Roederer, Ian U; Pignatari, Marco; Herwig, Falk

    2016-01-01

    We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s-process; e.g., [Pb/Fe]=+0.79+/-0.32) and rapid neutron-capture process (r-process; e.g., [Eu/Fe]=+0.22+/-0.12), including unusually large molybdenum ([Mo/Fe]=+0.97+/-0.16) and ruthenium ([Ru/Fe]=+0.69+/-0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe]=-0.06+/-0.19). We analyze an archival near-ultraviolet spectrum of HD94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process pa...

  3. The HARPS search southern extra-solar planets. VII. A very hot jupiter orbiti HD 212301

    DEFF Research Database (Denmark)

    Lo Curto, G.; Mayor, M.; Clausen, J.V.;

    2006-01-01

    Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs......Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs...

  4. Application of the Baade-Wesselink method to a pulsating cluster Herbig Ae star: H254 in IC348

    CERN Document Server

    Ripepi, V; Marconi, M; Catanzaro, G; Claudi, R; Daszyńska-Daszkiewicz, J; Palla, F; Leccia, S; Bernabei, S

    2013-01-01

    In this paper we present new photometric and radial velocity data for the PMS $\\delta$ Sct star H254, member of the young cluster IC 348. Photometric V,R$_C$,I$_C$ light curves were obtained at the Loiano and Asiago telescopes. The radial velocity data was acquired by means of the SARG@TNG spectrograph. High-resolution spectroscopy allowed us to derive precise stellar parameters and the chemical composition of the star, obtaining: T$_{\\rm eff}$\\,=\\,6750\\,$\\pm$\\,150 K; $\\log g$\\,=\\,4.1\\,$\\pm$\\,0.4 dex; [Fe/H]=-0.07$\\pm$0.12 dex. Photometric and spectroscopic data were used to estimate the total absorption in the $V$ band A$_{\\rm V}$=2.06$\\pm$0.05 mag, in agreement with previous estimates. We adopted the technique of the difference in phase and amplitude between different photometric bands and radial velocities to verify that H254 is (definitely) pulsating in a radial mode. This occurrence allowed us to apply the CORS realization of the Baade--Wesselink method to obtain a value for the linear radius of H254 equ...

  5. The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission

    CERN Document Server

    van der Plas, G; Waters, L B F M; Dominik, C

    2014-01-01

    We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main-sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to v$_u$ = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between ~250-2000...

  6. A 30 AU radius CO gas hole in the disk around the Herbig Ae star Oph IRS 48

    CERN Document Server

    Brown, Joanna M; Pontoppidan, Klaus M; van Dishoeck, Ewine F

    2011-01-01

    The physical processes leading to the disappearance of disks around young stars are not well understood. A subclass of transitional disks, the so-called cold disks with large inner dust holes, provide a crucial laboratory for studying disk dissipation processes. IRS 48 has a 30 AU radius hole previously measured from dust continuum imaging at 18.7 micron. Using new optical spectra, we determine that IRS 48 is a pre-main sequence A0 star. In order to characterize this disk's gas distribution, we obtained AO-assisted VLT CRIRES high resolution (R ~100,000) spectra of the CO fundamental rovibrational band at 4.7 micron. All CO emission, including that from isotopologues and vibrationally excited molecules, is off-source and peaks at 30 AU. The gas is thermally excited to a rotational temperature of 260 K and is also strongly UV pumped, showing a vibrational excitation temperature of ~5000 K. We model the kinematics and excitation of the gas and posit that the CO emission arises from the dust hole wall. Prior ima...

  7. Velocity Curve Analysis of the Spectroscopic Binary Stars PV Pup, HD 141929, EE Cet and V921 Her by Nonlinear Regression

    Indian Academy of Sciences (India)

    K. Karami; R. Mohebi

    2007-12-01

    We use the method introduced by Karami & Mohebi (2007), and Karami & Teimoorinia (2007) which enable us to derive the orbital parameters of the spectroscopic binary stars by the nonlinear least squares of observed . curve fitting (o–c). Using the measured experimental data for radial velocities of the four double-lined spectroscopic binary systems PV Pup, HD 141929, EE Cet and V921 Her, we find both the orbital and the combined spectroscopic elements of these systems. Our numerical results are in good agreement with those obtained using the method of Lehmann-Filhés.

  8. MagAO Imaging of Long-period Objects (MILO). I. A Benchmark M Dwarf Companion Exciting a Massive Planet around the Sun-like Star HD 7449

    CERN Document Server

    Rodigas, Timothy J; Faherty, Jackie; Anglada-Escude, Guillem; Kaib, Nathan; Butler, R Paul; Shectman, Stephen; Weinberger, Alycia; Males, Jared R; Morzinski, Katie M; Close, Laird M; Hinz, Philip M; Crane, Jeffrey D; Thompson, Ian; Teske, Johanna; Diaz, Matias; Minniti, Dante; Lopez-Morales, Mercedes; Adams, Fred C; Boss, Alan P

    2015-01-01

    We present high-contrast Magellan adaptive optics (MagAO) images of HD 7449, a Sun-like star with one planet and a long-term radial velocity (RV) trend. We unambiguously detect the source of the long-term trend from 0.6-2.15 \\microns ~at a separation of \\about 0\\fasec 54. We use the object's colors and spectral energy distribution to show that it is most likely an M4-M5 dwarf (mass \\about 0.1-0.2 \\msun) at the same distance as the primary and is therefore likely bound. We also present new RVs measured with the Magellan/MIKE and PFS spectrometers and compile these with archival data from CORALIE and HARPS. We use a new Markov chain Monte Carlo procedure to constrain both the mass ($> 0.17$ \\msun ~at 99$\\%$ confidence) and semimajor axis (\\about 18 AU) of the M dwarf companion (HD 7449B). We also refine the parameters of the known massive planet (HD 7449Ab), finding that its minimum mass is $7.8^{+3.7}_{-1.35}$ \\mj, its semimajor axis is $2.33^{+0.01}_{-0.02}$ AU, and its eccentricity is $0.8^{+0.08}_{-0.06}$. ...

  9. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 I. Spectropolarimetric observations in all four Stokes parameters

    CERN Document Server

    Rusomarov, N; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Makaganiuk, V; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2013-01-01

    High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. Here we present analysis of a unique full Stokes vector spectropolarimetric data set, acquired for the cool magnetic Ap star HD 24712. The goal of our work is to examine circular and linear polarization signatures inside spectral lines and to study variation of the stellar spectrum and magnetic observables as a function of rotational phase. HD 24712 was observed with the HARPSpol instrument at the 3.6-m ESO telescope over a period of 2010-2011. The resulting spectra have S/N ratio of 300-600 and resolving power exceeding 100000. The multiline technique of least-squares deconvolution (LSD) was applied to combine information from the spectral lines of Fe-peak and rare-earth elements. We used the HARPSPol spectra of HD 24712 to study the morphology of the Stokes profile shapes in individual spectral lines and in LSD Stokes profiles cor...

  10. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 II. Two-dimensional Magnetic Doppler Imaging in all four Stokes parameters

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Piskunov, N

    2014-01-01

    Aims: We present a magnetic Doppler imaging study from all Stokes parameters of the cool, chemically peculiar star HD 24712. This is the very first such analysis performed at a resolving power exceeding 10^5. Methods: The analysis is performed on the basis of phase-resolved observations of line profiles in all four Stokes parameters obtained with the HARPSpol instrument attached at the 3.6-m ESO telescope. We use the magnetic Doppler imaging code, INVERS10, which allows us to derive the magnetic field geometry and surface chemical abundance distributions simultaneously. Results: We report magnetic maps of HD 24712 recovered from a selection of FeI, FeII, NdIII, and NaI lines with strong polarization signals in all Stokes parameters. Our magnetic maps successfully reproduce most of the details available from our observation data. We used these magnetic field maps to produce abundance distribution map of Ca. This new analysis shows that the surface magnetic field of HD 24712 has a dominant dipolar component wit...

  11. Improved Ti II log(gf) Values and Abundance Determinations in the Photospheres of the Metal-Poor Star HD 84937

    CERN Document Server

    Wood, M P; Sneden, C; Cowan, J J

    2013-01-01

    Atomic transition probability measurements for 364 lines of Ti II in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrometer are combined with published radiative lifetimes to determine these transition probabilities. The new results are in generally good agreement with previously reported FTS measurements. Use of the new echelle spectrometer, independent radiometric calibration methods, and independent data analysis routines enables a reduction of systematic errors and overall improvement in transition probability accuracy over previous measurements. The new Ti II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ti abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. The Ti abundances derived using Ti II for these two stars match those derived using Ti I and support the relative Ti/...

  12. IMPROVED Co i log(gf) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J. E. [Department of Physics, University of Wisconsin-Madison, 1150 University Ave., Madison, WI 53706 (United States); Sneden, C. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Cowan, J. J., E-mail: jelawler@wisc.edu, E-mail: chris@verdi.as.utexas.edu, E-mail: jjcowan1@ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2015-09-15

    New emission branching fraction measurements for 898 lines of the first spectrum of cobalt (Co i) are determined from hollow cathode lamp spectra recorded with the National Solar Observatory 1 m Fourier transform spectrometer on Kitt Peak, AZ and a high-resolution echelle spectrometer. Published radiative lifetimes from laser induced fluorescence measurements are combined with the branching fractions to determine accurate absolute atomic transition probabilities for the 898 lines. Hyperfine structure (hfs) constants for levels of neutral Co in the literature are surveyed and selected values are used to generate complete hfs component patterns for 195 transitions of Co i. These new laboratory data are applied to determine the Co abundance in the Sun and metal-poor star HD 84937, yielding log ϵ(Co) = 4.955 ± 0.007 (σ = 0.059) based on 82 Co i lines and log ϵ(Co) = 2.785 ± 0.008 (σ = 0.065) based on 66 Co i lines, respectively. A Saha or ionization balance test on the photosphere of HD 84937 is performed using 16 UV lines of Co ii, and good agreement is found with the Co i result in this metal-poor ([Fe i/H] = −2.32, [Fe ii/H] = −2.32) dwarf star. The resulting value of [Co/Fe] = +0.14 supports a rise of Co/Fe at low metallicity that has been suggested in other studies.

  13. Two New Spotted Variables-HD 191262 and HD 191011

    Science.gov (United States)

    Hall, Douglas S.; Henry, Gregory W.

    1992-11-01

    New 1988-1990 photometry in V and B with a 16 inch automatic telescope shows that both HD 191262, a previously known chromospherically active binary, and its comparison star HD 191011 are variable, with starspots judged to be the mechanism in both. In HD 191262 and 191011, respectively, spot rotation periods of 5d.4 coefficients of k=0.054 and 0.28 were estimated. HD 191011, shown to be a KS giant about 475 parsecs away, had eight different spots present during the 2.5 years of observation.

  14. The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHα 198 and LkHα 225S

    Science.gov (United States)

    Matthews, Brenda C.; Graham, James R.; Perrin, Marshall D.; Kalas, Paul

    2007-12-01

    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity, and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHα 198 and LkHα 225S. Single-dish observations of 12CO J=1-0, 13CO J=1-0, N2H+ J=1-0, and CS J=2-1 were made over a field of 4.3'×4.3' for each species. 12CO J=1-0 data from FCRAO were combined with high-resolution BIMA array data to achieve a naturally weighted synthesized beam of 6.75''×5.5'' toward LkHα 198 and 5.7''×3.95'' toward LkHα 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of 2 improvement. The outflow around LkHα 198 resolves into at least four outflows, none of which are centered on LkHα 198-IR, but even at our resolution we cannot exclude the possibility of an outflow associated with this source. In the LkHα 225S region we find evidence for two outflows associated with LkHα 225S itself, and a third outflow is likely driven by this source. Identification of the driving sources is still resolution limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO J=1-0 is present in the environments of both stars along with cold, dense gas as traced by CS J=2-1 and (in LkHα 225S) N2H+ J=1-0. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.

  15. Exploring atmospheres of hot mini-Neptune and extrasolar giant planets orbiting different stars with application to HD 97658b, WASP-12b, CoRoT-2b, XO-1b, and HD 189733b

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, Y.; Kaltenegger, L., E-mail: miguel@mpia.de [Max Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany)

    2014-01-10

    We calculated an atmospheric grid for hot mini-Neptune and giant exoplanets that links astrophysical observable parameters—orbital distance and stellar type—with the chemical atmospheric species expected. The grid can be applied to current and future observations to characterize exoplanet atmospheres and serves as a reference to interpret atmospheric retrieval analysis results. To build the grid, we developed a one-dimensional code for calculating the atmospheric thermal structure and linked it to a photochemical model that includes disequilibrium chemistry (molecular diffusion, vertical mixing, and photochemistry). We compare the thermal profiles and atmospheric composition of planets at different semimajor axes (0.01 AU ≤ a ≤ 0.1 AU) orbiting F, G, K, and M stars. Temperature and UV flux affect chemical species in the atmosphere. We explore which effects are due to temperature and which are due to stellar characteristics, showing the species most affected in each case. CH{sub 4} and H{sub 2}O are the most sensitive to UV flux, H displaces H{sub 2} as the most abundant gas in the upper atmosphere for planets receiving a high UV flux. CH{sub 4} is more abundant for cooler planets. We explore vertical mixing, to inform degeneracies on our models and in the resulting spectral observables. For lower pressures, observable species like H{sub 2}O or CO{sub 2} can indicate the efficiency of vertical mixing, with larger mixing ratios for a stronger mixing. By establishing the grid, testing the sensitivity of the results, and comparing our model to published results, our paper provides a tool to estimate what observations could yield. We apply our model to WASP-12b, CoRoT-2b, XO-1b, HD189733b, and HD97658b.

  16. Evolution from protoplanetary to debris discs: The transition disc around HD 166191

    CERN Document Server

    Kennedy, G M; Lisse, C M; Ménard, F; Sitko, M L; Wyatt, M C; Bayliss, D D R; DeMeo, F E; Crawford, K B; Kim, D L; Rudy, R J; Russell, R W; Sibthorpe, B; Skinner, M A; Zhou, G

    2013-01-01

    HD 166191 has been identified by several studies as hosting a rare and extremely bright warm debris disc with an additional outer cool disc component. However, an alternative interpretation is that the star hosts a disc that is currently in transition between a full gas disc and a largely gas-free debris disc. With the help of new optical to mid-IR spectra and Herschel imaging, we argue that the latter interpretation is supported in several ways: i) we show that HD 166191 is co-moving with the ~4 Myr-old Herbig Ae star HD 163296, suggesting that the two have the same age, ii) the disc spectrum of HD 166191 is well matched by a standard radiative transfer model of a gaseous protoplanetary disc with an inner hole, and iii) the HD 166191 mid-IR silicate feature is more consistent with similarly primordial objects. We note some potential issues with the debris disc interpretation that should be considered for such extreme objects, whose lifetime at the current brightness is mush shorter than the stellar age, or i...

  17. Discovery of a magnetic field in the rapidly-rotating O-type secondary of the colliding-wind binary HD 47129 (Plaskett's star)

    CERN Document Server

    Grunhut, J H; Leutenegger, M; Petit, V; Rauw, G; Neiner, C; Martins, F; Cohen, D H; Gagné, M; Ignace, R; Mathis, S; de Mink, S E; Moffat, A F J; Owocki, S; Shultz, M; Sundqvist, J

    2012-01-01

    We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star), in the context of the Magnetism in Massive Stars (MiMeS) survey. Eight independent Stokes $V$ observations were acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope and the Narval spectropolarimeter at the T\\'elescope Bernard Lyot. Using Least-Squares Deconvolution we obtain definite detections of signal in Stokes $V$ in 3 observations. No significant signal is detected in the diagnostic null ($N$) spectra. The Zeeman signatures are broad and track the radial velocity of the secondary component; we therefore conclude that the rapidly-rotating secondary component is the magnetized star. Correcting the polarized spectra for the line and continuum of the (sharp-lined) primary, we measured the longitudinal magnetic field from each observation. The longitudinal field of the secondary is variable...

  18. Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. V. Oxygen abundance in the metal-poor giant HD 122563 from OH UV lines

    CERN Document Server

    Prakapavičius, D; Dobrovolskas, V; Klevas, J; Steffen, M; Bonifacio, P; Ludwig, H -G; Spite, M

    2016-01-01

    Although oxygen is an important tracer of the early Galactic evolution, its abundance trends with metallicity are still relatively poorly known at [Fe/H] < -2.5. This is in part due to a lack of reliable oxygen abundance indicators in the metal-poor stars, in part due to shortcomings in 1D LTE abundance analyses. In this study we determined the oxygen abundance in the metal-poor halo giant HD 122563 using a 3D hydrodynamical CO5BOLD model atmosphere. Our main goal was to understand whether a 3D LTE analysis may help to improve the reliability of oxygen abundances determined from OH UV lines in comparison to those obtained using standard 1D LTE methodology. The oxygen abundance in HD 122563 was determined using 71 OH UV lines located in the wavelength range between 308-330 nm. The analysis was done using a high-resolution VLT UVES spectrum with a 1D LTE spectral line synthesis performed using the SYNTHE package and classical ATLAS9 model atmosphere. Subsequently, a 3D hydrodynamical CO5BOLD, and 1D hydrosta...

  19. IMPROVED V I log(gf) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J. E.; Wood, M. P.; Den Hartog, E. A.; Feigenson, T. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Sneden, C. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Cowan, J. J., E-mail: jelawler@wisc.edu, E-mail: mpwood@wisc.edu, E-mail: eadenhar@wisc.edu, E-mail: tfeigenson@wisc.edu, E-mail: chris@verdi.as.utexas.edu, E-mail: cowan@nhn.ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2015-01-01

    New emission branching fraction measurements for 836 lines of the first spectrum of vanadium (V I) are determined from hollow cathode lamp spectra recorded with the National Solar Observatory 1 m Fourier transform spectrometer (FTS) and a high-resolution echelle spectrometer. The branching fractions are combined with recently published radiative lifetimes from laser-induced fluorescence measurements to determine accurate absolute atomic transition probabilities for the 836 lines. The FTS data are also used to extract new hyperfine structure A coefficients for 26 levels of neutral vanadium. These new laboratory data are applied to determine the V abundance in the Sun and metal-poor star HD 84937, yielding log ε(V) = 3.956 ± 0.004 (σ = 0.037) based on 93 V I lines and log ε(V) = 1.89 ± 0.03 (σ = 0.07) based on nine V I lines, respectively, using the Holweger-Müller 1D model. These new V I abundance values for the Sun and HD 84937 agree well with our earlier determinations based upon V II.

  20. IMPROVED V II log(gf) VALUES, HYPERFINE STRUCTURE CONSTANTS, AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

    Energy Technology Data Exchange (ETDEWEB)

    Wood, M. P.; Lawler, J. E.; Den Hartog, E. A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Sneden, C. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Cowan, J. J., E-mail: mpwood@wisc.edu, E-mail: jelawler@wisc.edu, E-mail: eadenhar@wisc.edu, E-mail: chris@verdi.as.utexas.edu, E-mail: cowan@nhn.ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2014-10-01

    New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Two spectrometers, independent radiometric calibration methods, and independent data analysis routines enable a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log ε(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = –2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.

  1. Chemical surface inhomogeneities in late B-type stars with Hg and Mn peculiarity I Spot evolution in HD 11753 on short and long time scales

    CERN Document Server

    Korhonen, H; Briquet, M; Soriano, M Flores; Hubrig, S; Savanov, I; Hackman, T; Ilyin, I V; Eulaers, E; Pessemier, W

    2013-01-01

    Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods: High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. Results: We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals som...

  2. Improved V II log($gf$) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

    CERN Document Server

    Wood, M P; Hartog, E A Den; Sneden, C; Cowan, J J

    2014-01-01

    New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Use of two spectrometers, independent radiometric calibration methods, and independent data analysis routines enables a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used t...

  3. Improved Ni I log(gf) Values and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

    CERN Document Server

    Wood, M P; Sneden, C; Cowan, J J

    2014-01-01

    Atomic transition probability measurements for 371 Ni I lines in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrograph are combined with published radiative lifetimes to determine these transition probabilities. Generally good agreement is found in comparisons to previously reported Ni I transition probability measurements. Use of the new echelle spectrograph, independent radiometric calibration methods, and independent data analysis routines enable a reduction of systematic errors and overall improvement in transition probability uncertainty over previous measurements. The new Ni I data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ni abundances. Lines covering a wide range of wavelength and excitation potential are used to search for non-LTE effects.

  4. Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188

    CERN Document Server

    Stateva, I; Budaj, J

    2011-01-01

    We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abundances of several elements were determined. We conclude that all six stars are Am stars. These stars were put into the context of other Am binaries with 10 < Porb < 200 days and their abundance anomalies discussed in the context of possible tidal effects. There is clear anti-correlation of the Am peculiarities with v sin i. However, there seems to be also a correlation with the eccentricity and may be with the orbital period. The dependence on the temperature, age, mass, and microturbulence was studied as well. The ...

  5. Improved Cr II log(gf) Values and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

    Science.gov (United States)

    Lawler, J. E.; Sneden, C.; Nave, G.; Den Hartog, E. A.; Emrahoğlu, N.; Cowan, J. J.

    2017-01-01

    New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr ii) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr+ are reported. The goals of this study are to improve transition probability measurements in Cr ii and reconcile solar and stellar Cr abundance values based on Cr i and Cr ii lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Radiative lifetimes from this study and earlier publications are used to convert the BFs into absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log ε in the Sun and metal-poor star HD 84937. The mean result in the Sun is = 5.624 ± 0.009 compared to = 5.644 ± 0.006 on a scale with the hydrogen abundance log ε(H) = 12 and with the uncertainty representing only line-to-line scatter. A Saha (ionization balance) test on the photosphere of HD 84937 is also performed, yielding = 3.417 ± 0.006 and 0 eV)> = 3.374 ± 0.011 for this dwarf star. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V, and Sc) appear to have a similar (or correlated) production history—other iron-peak elements appear not to be associated with Cr.

  6. HD 95881: A gas rich to gas poor transition disk?

    CERN Document Server

    Verhoeff, A P; Acke, B; van Boekel, R; Pantin, E; Waters, L B F M; Tielens, A G G M; Ancker, M E van den; Mulders, G D; de Koter, A; Bouwman, J

    2010-01-01

    Context. Based on the far infrared excess the Herbig class of stars is divided into a group with flaring circumstellar disks (group I) and a group with flat circumstellar disks (group II). Dust sedimentation is generally proposed as an evolution mechanism to transform flaring disks into flat disks. Theory predicts that during this process the disks preserve their gas content, however observations of group II Herbig Ae stars demonstrate a lack of gas. Aims. We map the spatial distribution of the gas and dust around the group II Herbig Ae star HD 95881. Methods. We analyze optical photometry, Q-band imaging, infrared spectroscopy, and K and N-band interferometric spectroscopy. We use a Monte Carlo radiative transfer code to create a model for the density and temperature structure which quite accurately reproduces all the observables. Results. We derive a consistent picture in which the disk consists of a thick puffed up inner rim and an outer region which has a flaring gas surface and is relatively void of 'vis...

  7. Know The Star, Know the Planet. IV. A Stellar Companion to the Host star of the Eccentric Exoplanet HD 8673b

    CERN Document Server

    Roberts,, Lewis C; Neyman, Christopher R; Wu, Yanqin; Riddle, Reed L; Shelton, J Christopher; Angione, John; Baranec, Christoph; Bouchez, Antonin; Bui, Khanh; Burruss, Rick; Burse, Mahesh; Chordia, Pravin; Croner, Ernest; Das, Hillol; Dekany, Richard G; Guiwits, Stephen; Hale, David; Henning, John; Law, Shrinivas Kulkarni Nicholas; McKenna, Dan; Milburn, Jennifer; Palmer, Dean; Punnadi, Sujit; Ramaprakash, A N; Roberts, Jennifer E; Tendulkar, Shriharsh P; Trinh, Thang; Troy, Mitchell; Truong, Tuan; Zolkower, Jeff

    2015-01-01

    HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identi?ed a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of ?lters with the aim of con?rming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of ?lters. The measured di?erential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to...

  8. NEWLY DISCOVERED PLANETS ORBITING HD 5319, HD 11506, HD 75784 AND HD 10442 FROM THE N2K CONSORTIUM

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, Matthew J.; Fischer, Debra A.; Brewer, John M. [Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Payne, Matthew J.; Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Isaacson, Howard T. [Department of Astronomy, University of California, Berkeley, Berkeley, California 94720 (United States)

    2015-01-20

    Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 M {sub Jup}) orbiting stars monitored as part of the Next 2000 target stars (N2K) Doppler Survey program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer planet has an orbital period of 1627.5 days, and the newly discovered inner planet orbits in 223.6 days. A planet has also been discovered orbiting HD 75784 with an orbital period of 341.7 days. There is evidence for a longer period signal; however, several more years of observations are needed to put tight constraints on the Keplerian parameters for the outer planet. Lastly, an additional planet has been detected orbiting HD 10442 with a period of 1043 days.

  9. Newly Discovered Planets Orbiting HD 5319, HD 11506, HD 75784 and HD 10442 from the N2K Consortium

    Science.gov (United States)

    Giguere, Matthew J.; Fischer, Debra A.; Payne, Matthew J.; Brewer, John M.; Johnson, John Asher; Howard, Andrew W.; Isaacson, Howard T.

    2015-01-01

    Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 M Jup) orbiting stars monitored as part of the Next 2000 target stars (N2K) Doppler Survey program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer planet has an orbital period of 1627.5 days, and the newly discovered inner planet orbits in 223.6 days. A planet has also been discovered orbiting HD 75784 with an orbital period of 341.7 days. There is evidence for a longer period signal; however, several more years of observations are needed to put tight constraints on the Keplerian parameters for the outer planet. Lastly, an additional planet has been detected orbiting HD 10442 with a period of 1043 days. Based on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO and NASA.

  10. Magnetic fields and differential rotation on the pre-main sequence II: The early-G star HD 141943 - coronal magnetic field, H-alpha emission and differential rotation

    CERN Document Server

    Marsden, S C; Vélez, J C Ramírez; Alecian, E; Brown, C J; Carter, B D; Donati, J F; Dunstone, N; Hart, R; Semel, M; Waite, I A

    2011-01-01

    Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at three observing epochs (2007, 2009 and 2010). The observations were obtained using the 3.9-m Anglo-Australian telescope with the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. The brightness and surface magnetic field topologies (given in Paper I) were used to determine the star's surface differential rotation and reconstruct the coronal magnetic field of the star. The coronal magnetic field at the 3 epochs shows on the largest scales that the field structure is dominated by the dipole component with possible evidence for the tilt of the dipole axis shifting between observations. We find very high levels of differential rotation on HD 141943 (~8 times the solar value for the magnetic features and ~5 times solar for the brightness features) similar to that evidenced by another young early-G star, HD 171488. These results indicate that a significant increase in the level of differe...

  11. Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium

    CERN Document Server

    Giguere, Matthew J; Payne, Matthew J; Brewer, John M; Johnson, John Asher; Howard, Andrew W; Isaacson, Howard T

    2014-01-01

    Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly-discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 MJup) orbiting stars monitored as part of the N2K program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously-unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly-discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer pla...

  12. Simultaneous intensive photometry and high resolution spectroscopy of $\\delta$ Scuti stars; 3, Mode identifications and physical calibrations in HD 2724

    CERN Document Server

    Bossi, M; Núñez, N S

    1998-01-01

    On the basis of our new simultaneous photometry and spectroscopy (885 uvby differential measurements in 11 nights and 154 spectrograms of the FeII 4508 A region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit of pulsational models to our data, we estimate the inclination of rotational axis to be about 50 deg. and get a reliable identification of 4 modes as well as useful bits of information about the others: no retrograde mode is visible, whereas the star seems to show a certain preference for purely sectorial prograde oscillations. Finally, the attribution of our lowest frequency to the radial fundamental pulsation allows a new calibration of physical parameters. In particular, the gravity can be determined with unusual accuracy and the luminosity evaluation becomes more consistent with the Hipparcos astrometry.

  13. Calculation of the Masses of the Binary Star HD 93205 by Application of the Theory of the Apsidal Motion

    CERN Document Server

    Benvenuto, O G; Althaus, L G; Barba, R H; Morrell, N I

    2002-01-01

    We present a method to calculate masses for components of both eclipsing and non-eclipsing binary systems as long as their apsidal motion rates are available. The method is based on the fact that the equation that gives the rate of apsidal motion is a supplementary equation that allows the computation of the masses of the components, if the radii and the internal structure constants of them can be obtained from theoretical models. For this reason the use of this equation makes the method presented here model dependent. We apply this method to calculate the mass of the components of the non-eclipsing massive binary system HD 93205 (O3V+O8V), which is suspected to be a very young system. To this end, we computed a grid of evolutionary models covering the mass range of interest, and taking the mass of the primary (M_1) as the only independent variable, we solve the equation of apsidal motion for M_1 as a function of the age of the system. The mass of the primary we find ranges from M_1= 60+-19 msun for ZAMS mode...

  14. The circumstellar shell of the post-ABB star HD 56126: the 12C12C/12C13C isotope ratio and12C16O column density

    NARCIS (Netherlands)

    Barker, E.J.; Lambert, D.L.

    1998-01-01

    We have made the first detection of circumstellar absorption lines of the 12C13C A 1Πu-X 1∑g+ (Phillips) system 1-0 band and the 12C16O X 1∑+ first-overtone 2-0 band in the spectrum of the post-AGB star HD 56126 (IRAS 07134+1005). All current detections of circumstellar molecular absorption lines to

  15. Very Low-Mass Stellar and Substellar Companions to Solar-like Stars From MARVELS VI: A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

    CERN Document Server

    Ma, Bo; Wolszczan, Alex; Muterspaugh, Matthew W; Lee, Brian; Henry, Gregory W; Schneider, Donald P; Martin, Eduardo L; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; da Costa, Luiz Nicolaci; Jiang, Peng; Fiorenzano, A F Martinez; Hernandez, Jonay I Gonzalez; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C; Wan, Xiaoke; Wang, Ji; Wisniewski, John P; Zhao, Bo; Zucker, Shay

    2016-01-01

    We report the detections of a giant planet (MARVELS-7b) and a brown dwarf candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. It is the first close binary system with more than one substellar circum-primary companion discovered to the best of our knowledge. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using ET at Kitt Peak National Observatory, HRS at HET, the "Classic" spectrograph at the Automatic Spectroscopic Telescope at Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period brown dwarf in this binary. HD 87646 is a close binary with a separation of $\\sim22$ AU between the two stars, estimated using the Hipparcos catalogue and our newly acquired AO image from PALAO on the 200-inch Hale Telescope at Palomar. The primary star in the binary, HD 87646...

  16. Sparse aperture masking at the VLT II. Detection limits for the eight debris disks stars $\\beta$ Pic, AU Mic, 49 Cet, $\\eta$ Tel, Fomalhaut, g Lup, HD181327 and HR8799

    CERN Document Server

    Gauchet, L; Lagrange, A -M; Ehrenreich, D; Bonnefoy, M; Girard, J H; Boccaletti, A

    2016-01-01

    Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse Aperture masking (SAM) is a high angular resolution technique strongly contributing to probe the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims. We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low mass companions, or to set detection limits. Methods. We observed eight stars presenting debris disks ( $\\beta$ Pictoris, AU Microscopii, 49 Ceti, $\\eta$ Telescopii, Fomalhaut, g Lupi, HD181327 and HR8799) with SAM technique on the NaCo ins...

  17. Identifying gaps in flaring Herbig Ae/Be disks using spatially resolved mid-infrared imaging. Are all group I disks transitional?

    CERN Document Server

    Maaskant, K M; Waters, L B F M; Tielens, A G G M; Dominik, C; Min, M; Verhoeff, A; Meeus, G; Ancker, M E van den

    2013-01-01

    *Context The evolution of young massive protoplanetary disks toward planetary systems is expected to include the formation of gaps and the depletion of dust and gas. *Aims A special group of flaring disks around Herbig Ae/Be stars do not show prominent silicate emission features. We focus our attention on four key Herbig Ae/Be stars to understand the structural properties responsible for the absence of silicate feature emission. *Methods We investigate Q- and N-band images taken with Subaru/COMICS, Gemini South/T-ReCS and VLT/VISIR. Our radiative transfer modeling solutions require a separation of inner- and outer- disks by a large gap. From this we characterize the radial density structure of dust and PAHs in the disk. *Results The inner edge of the outer disk has a high surface brightness and a typical temperature between ~100-150 K and therefore dominates the emission in the Q-band. We derive radii of the inner edge of the outer disk of 34, 23, 30 and 63 AU for HD97048, HD169142, HD135344B and Oph IRS 48 r...

  18. Detailed Abundances of Planet-Hosting Wide Binaries. II. HD80606 + HD80607

    CERN Document Server

    Mack, Claude E; Schuler, Simon C; Hebb, Leslie; Pepper, Joshua A

    2016-01-01

    We present a detailed chemical abundance analysis of 15 elements in the planet-hosting wide binary system HD80606 + HD80607 using Keck/HIRES spectra. As in our previous analysis of the planet-hosting wide binary HD20782 + HD20781, we presume that these two G5 dwarf stars formed together and therefore had identical primordial abundances. In this binary, HD80606 hosts an eccentric ($e\\approx0.93$) giant planet at $\\sim$0.5 AU, but HD80607 has no detected planets. If close-in giant planets on eccentric orbits are efficient at scattering rocky planetary material into their host stars, then HD80606 should show evidence of having accreted rocky material while HD80607 should not. Here we show that the trends of abundance versus element condensation temperature for HD80606 and HD80607 are statistically indistinguishable, corroborating the recent result of Saffe et al. This could suggest that both stars accreted similar amounts of rocky material; indeed, our model for the chemical signature of rocky planet accretion i...

  19. Gas modelling in the disc of HD 163296

    CERN Document Server

    Tilling, I; Meeus, G; Mora, A; Montesinos, B; Riviere-Marichalar, P; Eiroa, C; Thi, W -F; Isella, A; Roberge, A; Martin-Zaidi, C; Kamp, I; Pinte, C; Sandell, G; Vacca, W D; Ménard, F; Mendigutía, I; Duchêne, G; Dent, W R F; Aresu, G; Meijerink, R; Spaans, M

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~ 4 Myr, with evidence of a circumstellar disc extending out to ~ 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [OI]63mic line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the 12CO 3-2, 2-1 and 13CO J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, ...

  20. Two Small Planets Transiting HD 3167

    CERN Document Server

    Vanderburg, Andrew; Duev, Dmitry A; Jensen-Clem, Rebecca; Latham, David W; Mayo, Andrew W; Baranec, Christoph; Berlind, Perry; Kulkarni, Shrinivas; Law, Nicholas M; Nieberding, Megan N; Riddle, Reed; Salama, Maissa

    2016-01-01

    We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R_e and an ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has a radius of 2.9 R_e and orbits its host star every 29.85 days. At a distance of just 45.8 +/- 2.2 pc, HD 3167 is one of the closest and brightest stars hosting multiple transiting planets, making HD 3167 b and c well suited for follow-up observations. The star is chromospherically inactive and slowly rotating, ideal for radial velocity observations to measure the planets' masses. The outer planet is large enough that it likely has a thick gaseous envelope which could be studied via transmission spectroscopy. Planets transiting bright, nearby stars like HD 3167 are valuable objects to study leading up to the launch of the James Webb Space Telescope.

  1. The complex circumstellar environment of HD 142527

    NARCIS (Netherlands)

    Verhoeff, A.P.; Min, M.; Pantin, E.; Waters, L.B.F.M.; Tielens, A.G.G.M.; Honda, M.; Fujiwara, H.; Bouwman, J.; van Boekel, R.; Dougherty, S.M.; de Koter, A.; Dominik, C.; Mulders, G.D.

    2011-01-01

    Context. The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD 142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of

  2. Toward Understanding The B[e] Phenomenon. VI. Nature and Spectral Variations of HD 85567.

    Science.gov (United States)

    Khokhlov, S. A.; Miroshnichenko, A. S.; Mennickent, R.; Cabezas, M.; Zhanabaev, Z. Zh.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; Nysewander, M. C.; LaCluyze, A. P.

    2017-01-01

    We report the results of high-resolution (R ∼ 80,000) spectroscopic observations of the emission-line object HD 85567, which has been classified as an FS CMa type object or a pre-main-sequence star. The main goal is to put more constraints on the object’s fundamental parameters, as well as on its nature and evolutionary state. Absorption lines in the spectrum of HD 85567 were found to be similar to those of mid-B-type dwarfs and correspond to the following fundamental parameters: Teff = 15,000 ± 500 K, v\\sin i=31+/- 3 km s‑1, and {log} g∼ 4.0. The interstellar extinction, AV = 0.50 ± 0.02 mag, was measured using the strengths of some diffuse interstellar bands. We also obtained UBV(RI)c images of a 10‧ × 10‧ region around the object. Photometry of projectionally close stars was used to derive an interstellar extinction law in this direction and resulted in a distance of 1300 ± 100 pc to the object and a luminosity of log L/L⊙ = 3.3 ± 0.2. We found no significant radial velocity variations of the absorption lines in the spectra of HD 85567 obtained during two-month-long periods of time in 2012 and 2015. Our analysis of the spectroscopic and photometric data available for the star led us to a conclusion that it cannot be a pre-main-sequence Herbig Ae/Be star. We argue that the circumstellar gas and dust were produced during the object’s evolution as most likely a binary system, which contains an undetected secondary component and is unlikely to be a merger product. This paper is partly based on observations obtained at the 1.5 m telescope of the Cerro Tololo Interamerican Observatory under CNTAC proposal 2012A–016.

  3. The Multiple System HD 27638

    CERN Document Server

    Torres, G

    2005-01-01

    We report spectroscopic observations of HD 27638B, the secondary in a visual binary in which the physically associated primary (separation approximately 19 arcsec) is a B9V star. The secondary shows strong Li 6708 absorption suggesting youth, and has attracted attention in the past as a candidate post-T Tauri star although this has subsequently been ruled out. It was previously known to be a double-lined spectroscopic binary (F8+G6) with a period of 17.6 days, and to show velocity residuals indicating a more distant massive third companion with a period of at least 8 years. Based on our radial velocity measurements covering more than two cycles of the outer orbit, along with other measurements, we derive an accurate triple orbital solution giving an outer period of 9.447 +/- 0.017 yr. The third object is more massive than either of the other two components of HD 27638B, but is not apparent in the spectra. We derive absolute visual magnitudes and effective temperatures for the three visible stars in HD 27638. ...

  4. PDS 144: The First Confirmed Herbig Ae - Herbig Ae Wide Binary

    CERN Document Server

    Hornbeck, J B; Perrin, M D; Wisniewski, J P; Tofflemire, B M; Brown, A; Holtzman, J A; Arraki, K; Hamaguchi, K; Woodgate, B; Petre, R; Daly, B; Grogin, N A; Bonfield, D G; Williger, G M; Lauroesch, J T; 10.1088/0004-637X/744/1/54

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5.35" on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83\\circ inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N - the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 \\pm 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7\\circ \\pm 6\\circ on the sky. By combining proper motion data and the absence of a dark mid-plane wit...

  5. Sparse aperture masking at the VLT. II. Detection limits for the eight debris disks stars β Pic, AU Mic, 49 Cet, η Tel, Fomalhaut, g Lup, HD 181327 and HR 8799

    Science.gov (United States)

    Gauchet, L.; Lacour, S.; Lagrange, A.-M.; Ehrenreich, D.; Bonnefoy, M.; Girard, J. H.; Boccaletti, A.

    2016-10-01

    Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse aperture masking (SAM) is a high angular resolution technique strongly contributing to probing the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims: We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low-mass companions, or to set detection limits. Methods: We observed eight stars presenting debris disks (β Pictoris, AU Microscopii, 49 Ceti, η Telescopii, Fomalhaut, g Lupi, HD 181327, and HR 8799) with SAM technique on the NaCo instrument at the Very Large Telescope (VLT). Results: No close companions were detected using closure phase information under 0.5'' of separation from the parent stars. We obtained magnitude detection limits that we converted to Jupiter masses detection limits using theoretical isochrones from evolutionary models. Conclusions: We derived upper mass limits on the presence of companions in the area of a few times the telescope's diffraction limits around each target star. Based on observations collected at the European Southern Observatory (ESO) during runs 087.C-0450(A), 087.C-0450(B) 087.C-0750(A), 088.C-0358(A).All magnitude detection limits maps are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A31

  6. Gas in the protoplanetary disc of HD 169142: Herschel's view

    CERN Document Server

    Meeus, G; Woitke, P; Montesinos, B; Mendigutía, I; Riviere-Marichalar, P; Eiroa, C; Mathews, G S; Vandenbussche, B; Howard, C D; Roberge, A; Sandell, G; Duchêne, G; Ménard, F; Grady, C A; Dent, W R F; Kamp, I; Augereau, J C; Thi, W F; Tilling, I; Alacid, J M; Andrews, S; Ardila, D R; Aresu, G; Barrado, D; Brittain, S; Ciardi, D R; Danchi, W; Fedele, D; de Gregorio-Monsalvo, I; Heras, A; Huelamo, N; Krivov, A; Lebreton, J; Liseau, R; Martin-Zaidi, C; Mora, A; Morales-Calderon, M; Nomura, H; Pantin, E; Pascucci, I; Phillips, N; Podio, L; Poelman, D R; Ramsay, S; Riaz, B; Rice, K; Solano, E; Walker, H; White, G J; Williams, J P; Wright, G

    2010-01-01

    In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the Open Time Key Project GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 micron, [CII] 157.7 micron, CO 72.8 and 90.2 micron, and o-H2O 78.7 and 179.5 micron. We only detect the [OI] 63.2 micron line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and 12/13CO data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ...

  7. Dust and Polycyclic Aromatic Hydrocarbon in the Pre-Transitional Disk around HD 169142

    CERN Document Server

    Seok, Ji Yeon

    2015-01-01

    The pre-transitional disk around the Herbig Ae star HD 169142 shows a complex structure of possible ongoing planet formation in dust thermal emission from the near infrared (IR) to millimeter wavelength range. Also, a distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 $\\mu$m, commonly attributed to polycyclic aromatic hydrocarbons (PAHs), are detected prominently in the HD 169142 disk. We model the spectral energy distribution (SED) as well as the PAH emission features of the HD 169142 disk simultaneously with porous dust and astronomical-PAHs taking into account the spatially resolved disk structure. Our porous dust model consisting of three distinct components that are primarily concentrated in the inner ring, middle ring, and outer disk, respectively, provides an excellent fit to the entire SED, and the PAH model closely reproduces the observed PAH features. The accretion of ice mantles onto porous dust aggregates occurs between ~16 AU and 60 AU, which overlaps with the spatial e...

  8. HD 12098 and Other Results from Nainital–Cape Survey

    Indian Academy of Sciences (India)

    V. Girish

    2005-06-01

    Nainital;Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere.We discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD 12098 and briefly discuss the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.

  9. Hardware Implementation of AES

    Directory of Open Access Journals (Sweden)

    Aakrati Chaturvedi

    2014-01-01

    Full Text Available The Advanced Encryption Standard algorithm can be efficiently programmed in software and implemented in hardware. Field Programmable Gate Array (FPGA devices are considered as efficient and cost effective solution for hardware. This research is in context to efficient hardware implementation of AES algorithm with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. This research is in context to efficient hardware implementation of AES algorithm with 128-192-256 key all in one module with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. The software part has been created, processed and simulated through Xilinx ISE 9.2. A compact design approach has been chosen to implement the algorithm with minimal hardware. As for hardware, Spartan 3AN family device (XC3S700A device is used

  10. AE3D

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-20

    AE3D solves for the shear Alfven eigenmodes and eigenfrequencies in a torodal magnetic fusion confinement device. The configuration can be either 2D (e.g. tokamak, reversed field pinch) or 3D (e.g. stellarator, helical reversed field pinch, tokamak with ripple). The equations solved are based on a reduced MHD model and sound wave coupling effects are not currently included.

  11. The Pan-Pacific Planet Search VI: Giant planets orbiting HD 86950 and HD 222076

    CERN Document Server

    Wittenmyer, Robert A; Zhao, Jinglin; Marshall, J P; Butler, R P; Tinney, C G; Wang, Liang; Johnson, John Asher

    2016-01-01

    We report the detection of two new planets orbiting the K giants HD 86950 and HD 222076, based on precise radial velocities obtained with three instruments: AAT/UCLES, FEROS, and CHIRON. HD 86950b has a period of 1270$\\pm$57 days at $a=2.72\\pm$0.08 AU, and m sin $i=3.6\\pm$0.7 Mjup. HD 222076b has $P=871\\pm$19 days at $a=1.83\\pm$0.03 AU, and m sin $i=1.56\\pm$0.11 Mjup. These two giant planets are typical of the population of planets known to orbit evolved stars. In addition, we find a high-amplitude periodic velocity signal ($K\\sim$50 m/s) in HD 29399, and show that it is due to stellar variability rather than Keplerian reflex motion. We also investigate the relation between planet occurrence and host-star metallicity for the 164-star Pan-Pacific Planet Search sample of evolved stars. In spite of the small sample of PPPS detections, we confirm the trend of increasing planet occurrence as a function of metallicity found by other studies of planets orbiting evolved stars.

  12. The Pan-Pacific Planet Search. VI. Giant Planets Orbiting HD 86950 and HD 222076

    Science.gov (United States)

    Wittenmyer, Robert A.; Jones, M. I.; Zhao, Jinglin; Marshall, J. P.; Butler, R. P.; Tinney, C. G.; Wang, Liang; Johnson, John Asher

    2017-02-01

    We report the detection of two new planets orbiting the K giants HD 86950 and HD 222076, based on precise radial velocities obtained with three instruments: AAT/UCLES, FEROS, and CHIRON. HD 86950b has a period of 1270 ± 57 days at a=2.72+/- 0.08 au, and m sin i=3.6+/- 0.7 {M}{Jup}. HD 222076b has P=871+/- 19 days at a=1.83+/- 0.03 au, and m sin i=1.56+/- 0.11 {M}{Jup}. These two giant planets are typical of the population of planets known to orbit evolved stars. In addition, we find a high-amplitude periodic velocity signal (K∼ 50 m s‑1) in HD 29399 and show that it is due to stellar variability rather than Keplerian reflex motion. We also investigate the relation between planet occurrence and host-star metallicity for the 164-star Pan-Pacific Planet Search (PPPS) sample of evolved stars. In spite of the small sample of PPPS detections, we confirm the trend of increasing planet occurrence as a function of metallicity found by other studies of planets orbiting evolved stars.

  13. Ground-based near-infrared imaging of the HD141569 circumstellar disk

    CERN Document Server

    Boccaletti, A; Marchis, F; Hanh, J

    2003-01-01

    We present the first ground-based near-infrared image of the circumstellar disk around the post-Herbig Ae/Be star HD141569A initially detected with the HST. Observations were carried out in the near-IR (2.2 $\\mu$m) at the Palomar 200-inch telescope using the adaptive optics system PALAO. The main large scale asymmetric features of the disk are detected on our ground-based data. In addition, we measured that the surface brightness of the disk is slightly different than that derived by HST observations (at 1.1 $\\mu$m and 1.6 $\\mu$m). We interpret this possible color-effect in terms of dust properties and derive a minimal

  14. Differential asteroseismic study of seismic twins observed by CoRoT; Comparison of HD 175272 with HD 181420

    CERN Document Server

    Ozel, N; Dupret, M A; Bruntt, H; Barban, C; Deheuvels, S; Garc'\\ia, R A; Michel, E; Samadi, R; Baudin, F; Mathur, S; Régulo, C; Auvergne, M; Morel, P; Pichon, B

    2013-01-01

    The CoRoT short asteroseismic runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report the observation and modeling of the F5V star HD 175272. Our aim is to define a method for extracting as much information as possible from a noisy oscillation spectrum. We followed a differential approach that consists of using a well-known star as a reference to characterize another star. We used classical tools such as the envelope autocorrelation function to derive the global seismic parameters of the star. We compared HD 175272 with HD 181420 through a linear approach, because they appear to be asteroseismic twins. The comparison with the reference star enables us to substantially enhance the scientific output for HD 175272. First, we determined its global characteristics through a detailed seismic analysis of HD 181420. Second, with our differential approach, we measured the difference of mass, radius and age between HD 175272 and HD 181420. We have deve...

  15. Variability of Disk Emission in Pre-Main Sequence and Related Stars. III. Exploring Structural Changes in the Pre-transitional Disk in HD 169142

    CERN Document Server

    Wagner, Kevin R; Grady, Carol A; Whitney, Barbara A; Swearingen, Jeremy R; Champney, Elizabeth H; Johnson, Alexa N; Werren, Chelsea; Russell, Ray W; Schneider, Glenn H; Momose, Munetake; Muto, Takayuki; Inoue, Akio K; Lauroesch, James T; Brown, Alexander; Fukagawa, Misato; Currie, Thayne M; Hornbeck, Jeremy; Wisniewski, John P; Woodgate, Bruce E

    2014-01-01

    We present near-IR and far-UV observations of the pre-transitional (gapped) disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space Telescope. The combination of our data along with existing data sets into the broadband spectral energy distribution reveals variability of up to 45% between ~1.5-10 {\\mu}m over a maximum timescale of 10 years. All observations known to us separate into two distinct states corresponding to a high near-IR state in the pre-2000 epoch and a low state in the post-2000 epoch, indicating activity within the <1 AU region of the disk. Through analysis of the Pa {\\beta} and Br {\\gamma} lines in our data we derive a mass accretion rate in May 2013 of (1.5 - 2.7) x 10^-9 Msun/yr. We present a theoretical modeling analysis of the disk in HD 169142 using Monte-Carlo radiative transfer simulation software to explore the conditions and perhaps signs of planetary formation in our collection of 24 years of observations. We find that shifting the outer edge (r = 0.3 AU) of t...

  16. Asteroseismic modelling of the Binary HD 176465

    CERN Document Server

    Nsamba, B; Campante, T L; Reese, D R; White, T R; Hernández, A García; Jiang, C

    2016-01-01

    The detection and analysis of oscillations in binary star systems is critical in understanding stellar structure and evolution. This is partly because such systems have the same initial chemical composition and age. Solar-like oscillations have been detected by Kepler in both components of the asteroseismic binary HD 176465. We present an independent modelling of each star in this binary system. Stellar models generated using MESA (Modules for Experiments in Stellar Astrophysics) were fitted to both the observed individual frequencies and complementary spectroscopic parameters. The individual theoretical oscillation frequencies for the corresponding stellar models were obtained using GYRE as the pulsation code. A Bayesian approach was applied to find the probability distribution functions of the stellar parameters using AIMS (Asteroseismic Inference on a Massive Scale) as the optimisation code. The ages of HD 176465 A and HD 176465 B were found to be 2.81 $\\pm$ 0.48 Gyr and 2.52 $\\pm$ 0.80 Gyr, respectively. ...

  17. MID-INFRARED IMAGING OF THE TRANSITIONAL DISK OF HD 169142: MEASURING THE SIZE OF THE GAP

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Mathematics and Physics, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Maaskant, Koen; Waters, L. B. F. M.; Dominik, C.; Mulders, G. D. [Astronomical Institute Anton Pannekoek, University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Okamoto, Y. K. [Institute of Astrophysics and Planetary Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Kataza, H. [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Fukagawa, M. [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Min, M. [Astronomical Institute Utrecht, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Yamashita, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Fujiyoshi, T.; Fujiwara, H. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Miyata, T.; Sako, S. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Sakon, I.; Onaka, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-06-20

    The disk around the Herbig Ae star HD 169142 was imaged and resolved at 18.8 and 24.5 {mu}m using Subaru/COMICS. We interpret the observations using a two-dimensional radiative transfer model and find evidence for the presence of a large gap. The mid-infrared images trace dust that is emitted at the onset of a strong rise in the spectral energy distribution (SED) at 20 {mu}m, and are therefore very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23{sup +3}{sub -5} AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the near-infrared, and an optically thin, geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a strong case for classification as a transitional disk, though improved imaging surveys are needed to support this speculation.

  18. Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap

    CERN Document Server

    Honda, M; Okamoto, Y K; Kataza, H; Fukagawa, M; Waters, L B F M; Dominik, C; Tielens, A G G M; Mulders, G D; Min, M; Yamashita, T; Fujiyoshi, T; Miyata, T; Sako, S; Sakon, I; Fujiwara, H; Onaka, T

    2012-01-01

    The disk around the Herbig Ae star HD\\,169142 was imaged and resolved at 18.8 and 24.5\\,$\\mu$m using Subaru/COMICS. We interpret the observations using a 2D radiative transfer model and find evidence for the presence of a large gap. The MIR images trace dust that emits at the onset of the strong rise in the spectral energy distribution (SED) at 20\\,$\\mu$m, therefore are very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23$^{+3}_{-5}$\\,AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the NIR and an optically thin geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a support for classifi...

  19. Sensitive survey for 13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars II: Stars in $\\rho$ Oph and upper Scorpius

    CERN Document Server

    Reboussin, L; Simon, M; Grosso, N; Wakelam, V; Di Folco, E; Dutrey, A; Piétu, V

    2015-01-01

    We attempt to determine the molecular composition of disks around young low-mass stars in the $\\rho$ Oph region and to compare our results with a similar study performed in the Taurus-Auriga region. We used the IRAM 30 m telescope to perform a sensitive search for CN N=2-1 in 29 T Tauri stars located in the $\\rho$ Oph and upper Scorpius regions. $^{13}$CO J=2-1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular cloud. The bandpass also contains two transitions of ortho-H$_2$CO, one of SO, and the C$^{17}$O J=2-1 line, which provides complementary information on the nature of the emission. Contamination by molecular cloud in $^{13}$CO and even C$^{17}$O is ubiquitous. The CN detection rate appears to be lower than for the Taurus region, with only four sources being detected (three are attributable to disks). H$_2$CO emission is found more frequently, but appears in general to be due to the surrounding cloud. The weaker emission than in Taurus may sugges...

  20. AES i ARM procesori

    Directory of Open Access Journals (Sweden)

    Danijela D. Protić

    2013-12-01

    Full Text Available Potreba za zaštitom informacija dovodi do velikih problema u izradi prenosivih uređaja kojima su limitirani snaga, memorija i energija. Ukoliko se takvim uređajima dodaju koprocesori, koji treba da obavljaju funkcije kriptozaštite, njihove se dimenzije povećavaju, pojavljuje se nefleksibilnost pa cena uređaja raste i do nekoliko puta. Na drugoj strani, algoritmi za zaštitu podataka su često memorijski zahtevni, a zbog velikog broja operacija koje je potrebno izvršavati u procesima šifrovanja i dešifrovanja, koprocesori često uspore rad osnovnog procesora. Za jedan od standarda za kriptozaštitu, AES, NIST je prihvatio Rijndaelov blokovski algoritam sa dužinom ulaznog i izlaznog bloka od 128 b, i dužinama šifarskog ključa od 128 b, 192 b i 256 b. Zbog karakteristika male potrošnje, 32-bitske arhitekture i brzog izvršavanja instrukcija, ARM procesori mogu da realizuju kriptozaštitu podataka, između ostalog i AES-om, a da ne opterete glavne procese u sistemima u kojima se koriste. Tehnologija ARM-a zaštićena je kao intelektualna svojina, pa je veliki broj proizvođača koristi za razvoj sopstvenih proizvoda, što je rezultovalo činjenicom da je u svetu proizvedeno preko 2 milijarde čipova koji su bazirani na ovoj tehnologiji. U radu su prikazane mogućnosti za poboljšanja u izvršenju algoritma AES primenom najnovijih verzija ARM procesora.

  1. Hubble Space Telescope Observations of the HD 202628 Debris Disk

    Science.gov (United States)

    Krist, John E.; Stapelfeldt, Karl R.; Bryden, Geoffrey; Plavchan, Peter

    2012-01-01

    A ring-shaped debris disk around the G2V star HD 202628 (d = 24.4 pc) was imaged in scattered light at visible wavelengths using the coronagraphic mode of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The ring is inclined by approx.64deg from face-on, based on the apparent major/minor axis ratio, with the major axis aligned along PA = 130deg. It has inner and outer radii (> 50% maximum surface brightness) of 139 AU and 193 AU in the northwest ansae and 161 AU and 223 AU in the southeast ((Delta)r/r approx. = 0.4). The maximum visible radial extent is approx. 254 AU. With a mean surface brightnesses of V approx. = 24 mag arcsec.(sup -2), this is the faintest debris disk observed to date in reflected light. The center of the ring appears offset from the star by approx.28 AU (deprojected). An ellipse fit to the inner edge has an eccentricity of 0.18 and a = 158 AU. This offset, along with the relatively sharp inner edge of the ring, suggests the influence of a planetary-mass companion. There is a strong similarity with the debris ring around Fomalhaut, though HD 202628 is a more mature star with an estimated age of about 2 Gyr. We also provide surface brightness limits for nine other stars in our study with strong Spitzer excesses around which no debris disks were detected in scattered light (HD 377, HD 7590, HD 38858, HD 45184, HD 73350, HD 135599, HD 145229, HD 187897, and HD 201219).

  2. The Pan-Pacific Planet Search. IV. Two super-Jupiters in a 3:5 resonance orbiting the giant star HD33844

    CERN Document Server

    Wittenmyer, Robert A; Butler, R P; Horner, Jonathan; Wang, Liang; Robertson, Paul; Jones, M I; Jenkins, J S; Brahm, R; Tinney, C G; Mengel, M W; Clark, J

    2015-01-01

    We report the discovery of two giant planets orbiting the K giant HD 33844 based on radial velocity data from three independent campaigns. The planets move on nearly circular orbits with semimajor axes $a_b=1.60\\pm$0.02 AU and $a_c=2.24\\pm$0.05 AU, and have minimum masses (m sin $i$) of $M_b=1.96\\pm$0.12 Mjup and $M_c=1.76\\pm$0.18 Mjup. Detailed N-body dynamical simulations show that the two planets remain on stable orbits for more than $10^6$ years for low eccentricities, and are most likely trapped in a mutual 3:5 mean-motion resonance.

  3. PDS 144: The First Confirmed Herbig Ae-Herbig Ae Wide Binary

    Science.gov (United States)

    Hornbeck, J. B.; Grady, C. A.; Perrin, M. D.; Wisniewski, J. P.; Tofflemire, B. M.; Brown, A.; Holtzman, J. A.; Arraki, K.; Hamaguchi, K.; Woodgate, B.; Petre, R.; Daly, B.; Grogin, N. A.; Bonfield, D. G.; Williger, G. M.; Lauroesch, J. T.

    2012-01-01

    PDS 144 is a pair of Herbig Ae stars that are separated by 5farcs35 on the sky. It has previously been shown to have an A2Ve Herbig Ae star viewed at 83° inclination as its northern member and an A5Ve Herbig Ae star as its southern member. Direct imagery revealed a disk occulting PDS 144 N—the first edge-on disk observed around a Herbig Ae star. The lack of an obvious disk in direct imagery suggested PDS 144 S might be viewed face-on or not physically associated with PDS 144 N. Multi-epoch Hubble Space Telescope imagery of PDS 144 with a 5 year baseline demonstrates PDS 144 N & S are comoving and have a common proper motion with TYC 6782-878-1. TYC 6782-878-1 has previously been identified as a member of Upper Sco sub-association A at d = 145 ± 2 pc with an age of 5-10 Myr. Ground-based imagery reveals jets and a string of Herbig-Haro knots extending 13' (possibly further) which are aligned to within 7° ± 6° on the sky. By combining proper motion data and the absence of a dark mid-plane with radial velocity data, we measure the inclination of PDS 144 S to be i = 73° ± 7°. The radial velocity of the jets from PDS 144 N & S indicates they, and therefore their disks, are misaligned by 25° ± 9°. This degree of misalignment is similar to that seen in T Tauri wide binaries.

  4. THE DIVERSE ORIGINS OF NEUTRON-CAPTURE ELEMENTS IN THE METAL-POOR STAR HD 94028: POSSIBLE DETECTION OF PRODUCTS OF i-PROCESS NUCLEOSYNTHESIS

    Energy Technology Data Exchange (ETDEWEB)

    Roederer, Ian U. [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Karakas, Amanda I. [Research School of Astronomy and Astrophysics, The Australian National University, Canberra ACT 2611 (Australia); Pignatari, Marco [E.A. Milne Centre for Astrophysics, Department of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); Herwig, Falk, E-mail: iur@umich.edu, E-mail: amanda.karakas@monash.edu, E-mail: mpignatari@gmail.com, E-mail: fherwig@uvic.ca [Joint Institute for Nuclear Astrophysics and Center for the Evolution of the Elements (JINA-CEE) (United States)

    2016-04-10

    We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = −1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = −0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy.

  5. NEAR-INFRARED SPECTROSCOPY OF POST-AGB STARS

    NARCIS (Netherlands)

    OUDMAIJER, RD; WATERS, LBFM; VANDERVEEN, WECJ; GEBALLE, TR

    1995-01-01

    The results of a medium resolution near-infrared spectral survey of 18 post-AGB candidate stars are presented. Most of the stars have near-infrared hydrogen lines in absorption, which is normal for their spectral types. Three stars, HD 101584, HD 179821 and HD 170756 have the CO first overtone bands

  6. Pro Tools HD

    CERN Document Server

    Camou, Edouard

    2013-01-01

    An easy-to-follow guide for using Pro Tools HD 11 effectively.This book is ideal for anyone who already uses ProTools and wants to learn more, or is new to Pro Tools HD and wants to use it effectively in their own audio workstations.

  7. Pre-main-sequence binaries with tidally disrupted discs: the Br gamma in HD 104237

    CERN Document Server

    Garcia, P J V; Dougados, C; Bacciotti, F; Clausse, J -M; Massi, F; Mérand, A; Petrov, R; Weigelt, G

    2013-01-01

    Active pre-main-sequence binaries with separations of around ten stellar radii present a wealth of phenomena unobserved in common systems. The study of these objects is extended from Classical T Tauri stars to the Herbig Ae star HD 104237. Spectro-interferometry with the VLTI/AMBER is presented. It is found that the K-band continuum squared visibilities are compatible with a circumbinary disc with a radius of ~0.5 AU. However, a significant fraction (~50 per cent) of the flux is unresolved and not fully accounted by the stellar photospheres. The stars probably don't hold circumstellar discs, in addition to the circumbinary disk, due to the combined effects of inner magnetospheric truncation and outer tidal truncation. This unresolved flux likely arises in compact structures inside the tidally disrupted circumbinary disc. Most ($\\gtrsim 90$ per cent) of the Br gamma line emission is unresolved. The line-to-continuum spectro-astrometry shifts in time, along the direction of the Ly alpha jet known to be driven b...

  8. Gaps in the HD169142 protoplanetary disk revealed by polarimetric imaging: Signs of ongoing planet formation?

    CERN Document Server

    Quanz, Sascha P; Buenzli, Esther; Garufi, Antonio; Schmid, Hans Martin; Wolf, Sebastian

    2013-01-01

    We present H-band VLT/NACO polarized light images of the Herbig Ae/Be star HD169142 probing its protoplanetary disk as close as ~0.1" to the star. Our images trace the face-on disk out to ~1.7" (~250 AU) and reveal distinct sub-structures for the first time: 1) the inner disk (<20 AU) appears to be depleted in scattering dust grains; 2) an unresolved disk rim is imaged at ~25 AU; 3) an annular gap extends from ~40 - 70 AU; 4) local brightness asymmetries are found on opposite sides of the annular gap. We discuss different explanations for the observed morphology among which ongoing planet formation is a tempting - but yet to be proven - one. Outside of ~85 AU the surface brightness drops off roughly r^{-3.3}, but describing the disk regions between 85-120 AU / 120-250 AU separately with power-laws r^{-2.6} / r^{-3.9} provides a better fit hinting towards another discontinuity in the disk surface. The flux ratio between the disk integrated polarized light and the central star is ~4.1 * 10^{-3}. Finally, com...

  9. Diagnosing the Structure of the HD 163296 Protoplanetary Disk Via Coronagraphic Imaging Polarimetry

    Science.gov (United States)

    Kowalski, Adam F.; Wisniewski, John P.; Clampin, M.; Grady, C. A.; Sitko, M. L.; Bjorkman, K. S.; Fukagawa, M.; Hines, D. C.; Katoh, E.; Whitney, B. A.

    2008-01-01

    Coronagraphic imaging polarimetry is a high contrast imaging technique which can diagnose both the spatial distribution and size distribution of dust grains which comprise primordial protoplanetary disks. It can therefore be a useful tool to test our understanding of how the structure of young disks evolves through the era of gas giant planet formation. We report our initial analysis of the H-band polarized and total intensity of the nearby Herbig Ae star HD 163296, and characterize the morphology of the scattered light disk in the context of previous optical HST coronagraphic imagery. Our observations were obtained as part of a multi-epoch campaign designed to diagnose and correlate the behavior of the inner and outer regions of select protoplanetary disks. This campaign will help test recent suggestions (Sitko et al. 2008; Wisniewski et al. 2008) that that HD 163296 dis experiences the novel phenomenon of time-variable self-shadowing, whereby occasional changes in the scale height of the inner disk wall induces changes in the illumination of the outer disk.

  10. The SPHERE view of the planet-forming disk around HD100546

    CERN Document Server

    Garufi, Antonio; Schmid, Hans Martin; Mulders, Gijs D; Avenhaus, Henning; Boccaletti, Anthony; Ginski, Christian; Langlois, Maud; Stolker, Tomas; Augereau, Jean-Charles; Benisty, Myriam; Lopez, Bruno; Dominik, Carsten; Gratton, Raffaele; Henning, Thomas; Janson, Markus; Menard, Francois; Meyer, Michael R; Pinte, Christophe; Sissa, Elena; Vigan, Arthur; Zurlo, Alice; Bazzon, Andreas; Buenzli, Esther; Bonnefoy, Mickael; Brandner, Wolfgang; Chauvin, Gael; Cheetham, Anthony; Cudel, Maxime; Desidera, Silvano; Feldt, Markus; Galicher, Raphael; Kasper, Markus; Lagrange, Anne-Marie; Lannier, Justine; Maire, Anne-Lise; Mesa, Dino; Mouillet, David; Peretti, Sebastien; Perrot, Clement; Salter, Graeme; Wildi, Francois

    2016-01-01

    We image with unprecedented spatial resolution and sensitivity disk features that could be potential signs of planet-disk interaction. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD100546 in scattered light. We obtain the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyze with the Pynpoint package. The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to ADI processing) resembles a morphology newly observed in inclined disks. Given the cav...

  11. Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA

    Science.gov (United States)

    Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M.; De Gregorio-Monsalvo, Itziar; Manara, Carlo F.; Natta, Antonella; Pérez, Laura M.; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

    2016-12-01

    We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the 12CO, 13CO, and C 18O J =2 -1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

  12. Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA.

    Science.gov (United States)

    Isella, Andrea; Guidi, Greta; Testi, Leonardo; Liu, Shangfei; Li, Hui; Li, Shengtai; Weaver, Erik; Boehler, Yann; Carperter, John M; De Gregorio-Monsalvo, Itziar; Manara, Carlo F; Natta, Antonella; Pérez, Laura M; Ricci, Luca; Sargent, Anneila; Tazzari, Marco; Turner, Neal

    2016-12-16

    We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the ^{12}CO, ^{13}CO, and C^{18}O J=2-1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.

  13. The circumstellar shell of the post-AGB star HD 56126 the $^{12}C ^{12}C \\/ ^{12}C ^{13}C$isotope ratio and $^{12}C ^{16}O$ column density

    CERN Document Server

    Bakker, E J; Lambert, Eric J. Bakker & David L.

    1998-01-01

    We have made the first detection of circumstellar absorption lines of the 12C13C (Phillips) system 1-0 band and the 12C16O first-overtone 2-0 band in the spectrum of the post-AGB star HD56126 (IRAS07134+1005). The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C12C/12C13C=36+-13, 12C16O/(12C12C+12C13C)=606+-230, and 12C16O/(12C14N+13C14N)=475+-175. The isotopic exchange reaction for 12C12C is too slow to significantly alter the 12C12C/12C13C ratio and the 12C12C to 12C13C ratio a good measure of half the carbon isotope ratio: 12C/13C=2 X 12C12C/12C13C=72+-26. A fit of the 12C12C excitation model of van Dishoeck & Black (1982) to the relative population distribution of 12C12C yields n sigma / I = 3.3 +- 1.0 X 1e-14. At r=1e16cm this translates in n=1.7e7cm-3 and dM/dt=2.5e-4Msol/year.

  14. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    Science.gov (United States)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  15. References: AePW publications

    Data.gov (United States)

    National Aeronautics and Space Administration — This page is the repository for the publications resulting from the AePW. This includes the special sessions at conferences: AIAA ASM 2012, Grapevine TX; AIAA SDM...

  16. ALMA Reveals the Anatomy of the mm-sized Dust and Molecular Gas in the HD 97048 Disk

    Science.gov (United States)

    Walsh, Catherine; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Maud, Luke T.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

    2016-11-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ˜ mm wavelengths. We present the first spatially resolved ˜ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°-40°. HD 97048 is another source for which the large (˜ mm-sized) dust grains are more centrally concentrated than the small (˜μm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10-20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  17. HD Radio技术

    Institute of Scientific and Technical Information of China (English)

    李栋

    2007-01-01

    HD Radio技术于2002年被美国FCC批准为美国AM与FM波段的数字广播标准。它在不影响现有模拟广播的前提下.使用现有模拟广播的频谱提供高清晰度的数字声音广播与数据业务。HD Radio基于IBOC(带内同频道)技术,是由iBiquity Digital公司开发的。

  18. AE Recorder Characteristics and Development.

    Energy Technology Data Exchange (ETDEWEB)

    Partridge, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Curtis, Shane Keawe [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McGrogan, David Paul [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    The Anomalous Environment Recorder (AE Recorder) provides a robust data recording capability for multiple high-shock applications including earth penetrators. The AE Recorder, packaged as a 2.4" di ameter cylinder 3" tall, acquires 12 accelerometer, 2 auxiliary, and 6 discrete signal channels at 250k samples / second. Recording depth is 213 seconds plus 75ms of pre-trigger data. The mechanical, electrical, and firmware are described as well as support electro nics designed for the first use of the recorder.

  19. Gas lines from the 5-Myr old optically thin disk around HD141569A. Herschel observations and modeling

    CERN Document Server

    Thi, Wing-Fai; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Menard, Francois; Martin-Zaïdi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, Williams; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean

    2013-01-01

    At the distance of 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of OI at 63 and 145 micron and the CII line at 157 micron with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 micron, and 12CO fundamental ro-vibrational and pure rotational J=3-2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. The models suggest that the oxygen lines are emitted from the inner disk around HD141569A, whereas the [CII] line emission is more extended. The CO submillimeter fl...

  20. ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk

    CERN Document Server

    Walsh, Catherine; Meeus, Gwendolyn; Dent, William R F; Maud, Luke; Aikawa, Yuri; Millar, Tom J; Nomura, Hideko

    2016-01-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially-resolved observations at ~ mm wavelengths. We present the first spatially-resolved ~ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ~ 640 au. The ALMA data reveal a circular-symmetric dusty disk extending to ~ 350 au, and a molecular disk traced in CO J=3-2 emission, extending to ~ 750 au. The CO emission arises from a flared layer with an opening angle ~ 30 deg - 40 deg. HD 97048 is another source for which the large (~ mm-sized) dust grains are more centrally concentrated than the small (~ {\\mu}m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modelling suggests a decrement in continuum emission within ~ 50 au, consistent with the cavity size determined from mid-infrared imaging (34 +/- 4 au). The extracted continuum intensity profiles show ring-l...

  1. Kepler Observations of the Asteroseismic Binary HD 176465

    CERN Document Server

    White, T R; Aguirre, V Silva; Ball, W H; Bedding, T R; Chaplin, W J; Christensen-Dalsgaard, J; Garcia, R A; Gizon, L; Stello, D; Aigrain, S; Antia, H M; Appourchaux, T; Bazot, M; Campante, T L; Creevey, O L; Davies, G R; Elsworth, Y P; Gaulme, P; Handberg, R; Hekker, S; Houdek, G; Howe, R; Huber, D; Karoff, C; Marques, J P; Mathur, S; McQuillan, A; Metcalfe, T S; Mosser, B; Nielsen, M B; Régulo, C; Salabert, D; Stahn, T

    2016-01-01

    Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0$\\pm$0.5 Gyr old. The two components of HD 176465 are young phy...

  2. The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars

    Indian Academy of Sciences (India)

    Santosh Joshi

    2005-06-01

    The ``Nainital–Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

  3. HD148937: a multiwavelength study of the third Galactic member of the Of?p class

    CERN Document Server

    Naze, Y; Rauw, G; Martins, F; Pollock, A M T; Bond, H E

    2008-01-01

    Three Galactic O-type stars belong to the rare class of Of?p objects: HD108, HD191612, and HD148937. The first two stars show a wealth of phenomena, including magnetic fields and strong X-ray emission, light variability, and dramatic periodic spectral variability. We present here the first detailed optical and X-ray study of the third Galactic Of?p star, HD148937. Spectroscopic monitoring has revealed low-level variability in the Balmer and HeII4686 lines, but constancy at HeI and CIII4650. The Ha line exhibits profile variations at a possible periodicity of ~7d. Model atmosphere fits yield T_{eff}=41000+-2000K, log(g)=4.0+-0.1, Mdot_{sph}1700km/s), and an order-of-magnitude overluminosity compared to normal O stars (log [L_X^unabs/L_BOL] ~ -6).

  4. 10 micron spectroscopy of younger stars in the rho Ophiuchi cloud

    Science.gov (United States)

    Hanner, M. S.; Brooke, T. Y.; Tokunaga, A. T.

    1995-01-01

    Spectra in the 10 micrometer region were obtained of 14 young stars associated with the central core of the rho Oph dark cloud complex. Silicate dust emission and absorption features can be fairly well reproduced with simple models using the emissivity of the silicates in the Orion Trapezium region, believed to be typical of molecular cloud dust. A spectrum of the Trapezium star theta(sup 1) Ori D was obtained to define the emissivity more precisely. The emissivity of silicate dust around the late-type giant Mu Cep does not improve the fits to the absorption features and provides a poorer match to the emission features. None of the sources display a strong 11.2 micrometer peak like that seen in comet Halley and attributed to crystalline olivine. A broad weak feature near 11.2 micrometer, possibly related to the comet feature, may be present in the emission spectrum of the Herbig Ae star HD 150193. Absorption features toward two of the objects are narrower than would be expected from Trapezium-like silicates, suggesting differences in the composition of the silicates. The relation between the silicate extinction band depth and H2O ice band depths is determined for the deeply embedded objects. One late-type object, Elias 14, clearly shows the 11.25 micrometer aromatic hydrocarbon emission feature, possibly excited by the nearby B star, HD 147889, though the latter does not exhibit the feature.

  5. Chemical compositions of four barium stars

    CERN Document Server

    Liang, Y C; Chen, Y Q; Qiu, H M; Zhang, B

    2003-01-01

    Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and HD 98839 are studied based on high resolution, high signal-to-noise Echelle spectra. Results show that all of them are disk stars. Their \\alpha and iron peak elements are similar to the solar abundances. The neutron-capture process elements are overabundant relative to the Solar. The heavy-element abundances of the strong Ba star HD 50082 are higher than those of other three mild Ba stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD 26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun (+0.75,-0.78M_sun), respectively, which are consistent with the average mass of mild Ba stars. We also calculate the theoretical abundances of Ba stars by combining the AGB stars nucleosynthesis and wind accretion formation scenario of Ba binary systems. The comparisons between the observed abundance patterns of the sample stars with the th...

  6. HD 285507b

    DEFF Research Database (Denmark)

    Quinn, Samuel N.; White, Russel J.; Latham, David W.;

    2014-01-01

    We report the discovery of the first hot Jupiter in the Hyades open cluster. HD 285507b orbits a V = 10.47 K4.5V dwarf (M * = 0.734 M ☉; R * = 0.656 R ☉) in a slightly eccentric () orbit with a period of days. The induced stellar radial velocity corresponds to a minimum companion mass of M Psin i...... confidence that the planet does not transit. HD 285507b joins a small but growing list of planets in open clusters, and its existence lends support to a planet formation scenario in which a high stellar space density does not inhibit giant planet formation and migration. We calculate the circularization...... timescale for HD 285507b to be larger than the age of the Hyades, which may indicate that this planet's non-zero eccentricity is the result of migration via interactions with a third body. We also demonstrate a significant difference between the eccentricity distributions of hot Jupiters that have had time...

  7. CHEMICAL IMAGING OF THE CO SNOW LINE IN THE HD 163296 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Chunhua; Öberg, Karin I.; Andrews, Sean M.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Hughes, A. Meredith [Van Vleck Observatory, Astronomy Department, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Hogherheijde, Michiel [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); D’Alessio, Paola [Centro de Radioastronomi´a y Astrofísica, Universidad Nacional Autónoma de México, 58089 Morelia, Michoacán, México (Mexico)

    2015-11-10

    The condensation fronts (snow lines) of H{sub 2}O, CO, and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density is expected to drop substantially, based solely on CO emission profiles, is challenging. This has prompted an exploration of chemical signatures of CO freeze-out. We present ALMA Cycle 1 observations of the N{sub 2}H{sup +} J = 3−2 and DCO{sup +} J = 4−3 emission lines toward the disk around the Herbig Ae star HD 163296 at ∼0.″5 (60 AU) resolution, and evaluate their utility as tracers of the CO snow line location. The N{sub 2}H{sup +} emission is distributed in a ring with an inner radius at 90 AU, corresponding to a midplane temperature of 25 K. This result is consistent with a new analysis of optically thin C{sup 18}O data, which implies a sharp drop in CO abundance at 90 AU. Thus N{sub 2}H{sup +} appears to be a robust tracer of the midplane CO snow line. The DCO{sup +} emission also has a ring morphology, but neither the inner nor the outer radius coincide with the CO snow line location of 90 AU, indicative of a complex relationship between DCO{sup +} emission and CO freeze-out in the disk midplane. Compared to TW Hya, CO freezes out at a higher temperature in the disk around HD 163296 (25 versus 17 K in the TW Hya disk), perhaps due to different ice compositions. This highlights the importance of actually measuring the CO snow line location, rather than assuming a constant CO freeze-out temperature for all disks.

  8. Unveiling the gas and dust disk structure in HD 163296 using ALMA observations

    CERN Document Server

    de Gregorio-Monsalvo, I; Dent, W; Pinte, C; López, C; Klaassen, P; Hales, A; Cortés, P; Rawlings, M G; Tachihara, K; Testi, L; Takahashi, S; Chapillon, E; Mathews, G; Juhasz, A; Akiyama, E; Higuchi, A E; Saito, M; Nyman, L - Å; Phillips, N; Rodń, J; Corder, S; Van Kempen, T

    2013-01-01

    Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We have used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 microns, as well as the 3- dimensional radiative transfer code MCFOST to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at sub-millimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back- and the front-side of a flared disk. Continuum emission at 850 microns reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirms the need for a sharp outer edge to the dust disk. The models for the ...

  9. Resolving the CO Snow Line in the Disk around HD 163296

    CERN Document Server

    Qi, Chunhua; Oberg, Karin I; Wilner, David J; Hughes, A Meredith; Andrews, Sean M; Ayala, Sandra

    2011-01-01

    We report Submillimeter Array (SMA) observations of CO (J=2--1, 3--2 and 6--5) and its isotopologues (13CO J=2--1, C18O J=2--1 and C17O J=3--2) in the disk around the Herbig Ae star HD 163296 at ~2" (250 AU) resolution, and interpret these data in the framework of a model that constrains the radial and vertical location of the line emission regions. First, we develop a physically self-consistent accretion disk model with an exponentially tapered edge that matches the spectral energy distribution and spatially resolved millimeter dust continuum emission. Then, we refine the vertical structure of the model using wide range of excitation conditions sampled by the CO lines, in particular the rarely observed J=6--5 transition. By fitting 13CO data in this structure, we further constrain the vertical distribution of CO to lie between a lower boundary below which CO freezes out onto dust grains (T ~ 19 K) and an upper boundary above which CO can be photodissociated (the hydrogen column density from the disk surface ...

  10. Is the X-ray pulsating companion of HD 49798 a possible type Ia supernova progenitor?

    CERN Document Server

    Liu, Dong-Dong; Wu, Cheng-Yuan; Wang, Bo

    2015-01-01

    HD 49798 (a hydrogen depleted subdwarf O6 star) with its massive white dwarf (WD) companion has been suggested to be a progenitor candidate of type Ia supernovae (SNe Ia). However, it is still uncertain whether the companion of HD 49798 is a carbon-oxygen (CO) WD or an oxygen-neon (ONe) WD. A CO WD will explode as an SN Ia when its mass grows approach to Chandrasekhar mass, while the outcome of an accreting ONe WD is likely to be a neutron star. We followed a series of Monte Carlo binary population synthesis approach to simulate the formation of ONe WD + He star systems. We found that there is almost no orbital period as large as HD 49798 with its WD companion in these ONe WD + He star systems based on our simulations, which means that the companion of HD 49798 might not be an ONe WD. We suggest that the companion of HD 49798 is most likely a CO WD, which can be expected to increase its mass to the Chandrasekhar mass limit by accreting He-rich material from HD 49798. Thus, HD 49798 with its companion may prod...

  11. Detailed photospheric abundances of 28 Peg and HD 202240

    CERN Document Server

    Elmasli, Asli; Kilicoglu, Tolgahan; Unal, Kubraozge; Nasolo, Yahya; Albayrak, Berahitdin

    2015-01-01

    The atmospheric parameters and chemical abundances of two neglected A-type stars, 28 Peg and HD 202240, were derived using high resolution spectra obtained at the TUBITAK National Observatory. We determined the photospheric abundances of eleven elements for 28 Peg and twenty for HD 202240, using equivalent-width measurement and spectral synthesis methods. Their abundance patterns are in good agreement with those of chemically normal A-type stars having similar atmospheric parameters. We pinpoint the position of these stars on the H-R diagram and estimate their masses and ages as; $2.60\\pm0.10\\ M_\\odot$ and $650\\pm50\\ Myr$ for 28 Peg and $4.50\\pm0.09\\ M_\\odot$ and $150\\pm10\\ Myr$ for HD 202240. To compare our abundance determinations with those of stars having similar ages and atmospheric parameters, we select members of open clusters. We notice that our target stars exhibit similar abundance patterns with these members.

  12. HD 210111: a new lambda Bootis type SB system

    CERN Document Server

    Paunzen, E; Fraga, L; Pintado, O

    2012-01-01

    The small group of lambda Bootis stars comprises late B to early F-type stars, with moderate to extreme (up to a factor 100) surface underabundances of most Fe-peak elements and solar abundances of lighter elements (C, N, O, and S). The main mechanisms responsible for this phenomenon are atmospheric diffusion, meridional mixing and accretion of material from their surroundings. Especially spectroscopic binary (SB) systems with lambda Bootis type components are very important to investigate the evolutionary status and accretion process in more details. For HD 210111, also delta Scuti type pulsation was found which gives the opportunity to use the tools of asteroseismology for further investigations. The latter could result in strict constraints for the amount of diffusion for this star. Together with models for the accretion and its source this provides a unique opportunity to shed more light on these important processes. We present classification and high resolution spectra for HD 210111. A detailed investiga...

  13. Optical and ultraviolet spectroscopy of three F + B binary stars

    Science.gov (United States)

    Bopp, Bernard W.; Dempsey, Robert C.; Parsons, Sidney B.

    1991-01-01

    Optical and ultraviolet spectroscopy is presented for three F + B objects that are members of the first group of strongly interacting, F II + B systems. The data obtained confirm that HD 59771, HD 242257, and CoD -30 5135 are all binary star systems consisting of a luminous F-type component and a B star. Strong, variable H-alpha emission is seen in all the stars. It is found that the UV spectrum of HD 59771 resembles the spectrum of HD 207739. CoD -30 5135 has the most dramatic mid-UV spectrum seen among the scores of observed cool + hot star systems.

  14. Optical spectrophotometry of oscillations and flickering in AE Aquarii

    Science.gov (United States)

    Welsh, William F.; Horne, Keith; Oke, J. B.

    1993-01-01

    We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

  15. What next for the Likely Pre-Supernova, HD 179821?

    CERN Document Server

    Jura, M; Werner, M W

    2001-01-01

    We have used the Owens Valley Radio Observatory Millimeter Array to obtain a map of the J = (1-0) CO emission from the circumstellar shell around HD 179821, a highly evolved G-type star which will probably explode as a supernova in the next 100,000 yr. Very approximately, the gas presents as a circular ring with azimuthal variations in the CO brightness by about a factor of 2. Until about 1600 years ago, the star was a red hypergiant losing about 0.0003 M(Sun)/yr at an average outflow speed of 32 km/s. We propose that when HD 179821 explodes as a supernova, it may resemble Kepler's supernova remnant and thus some of the anisotropies in supernova remnants may be intrinsic. If the factors which cause the anisotropic mass loss in HD 179821 persist to the moment when the star explodes as a supernova, the newly-born pulsar may receive a momentum "kick" leading to a space motion near 700 km/s. Independent of the angular asymmetries, the radially detached shell around HD 179821 may be representative of environments ...

  16. Resolving Close Encounters: Stability in the HD 5319 and HD 7924 Planetary Systems

    CERN Document Server

    Kane, Stephen R

    2016-01-01

    Radial velocity searches for exoplanets have detected many multi-planet systems around nearby bright stars. An advantage of this technique is that it generally samples the orbit outside of inferior/superior conjunction, potentially allowing the Keplerian elements of eccentricity and argument of periastron to be well characterized. The orbital architectures for some of these systems show signs of close planetary encounters that may render the systems unstable as described. We provide an in-depth analysis of two such systems: HD 5319 and HD 7924, for which the scenario of coplanar orbits results in rapid destabilization of the systems. The poorly constrained periastron arguments of the outer planets in these systems further emphasizes the need for detailed investigations. An exhaustive scan of parameters space via dynamical simulations reveals specific mutual inclinations between the two outer planets in each system that allow for stable configurations over long timescales. We compare these configurations with ...

  17. The Discovery of HD 37605c and a Dispositive Null Detection of Transits of HD 37605b

    CERN Document Server

    Wang, Sharon Xuesong; Cochran, William; Kane, Stephen R; Henry, Gregory W; Payne, Matthew J; Endl, Michael; MacQueen, Phillip J; Valenti, Jeff A; Antoci, Victoria; Dragomir, Diana; Matthews, Jaymie M; Howard, Andrew W; Marcy, Geoffrey W; Isaacson, Howard; Ford, Eric B; Mahadevan, Suvrath; von Braun, Kaspar

    2012-01-01

    We report the radial-velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P~55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of ~7.5 years with a low eccentricity and an Msini of ~3.4 MJup. Our discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS) effort to provide precise ephemerides to long-period planets for transit follow-up. With a total of 137 radial velocity observations covering almost eight years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using the predicted ephemeris, we performed a transit search for HD 37605b with the photometric data taken by the T12 ...

  18. Implications of the non-detection of X-ray emission from HD 149427

    CERN Document Server

    Stute, Matthias

    2011-01-01

    HD 149427 is a very enigmatic object. It has been classified either as a planetary nebula or as a D'-type symbiotic star. Its distance is also highly uncertain. Furthermore, HD 149427 is a potential jet source. We report the non-detection of X-ray emission from HD 149427 and explore the implications to its nature. We observed the object with XMM-Newton with an effective exposure time of 33.5 ks. The upper limit for the flux of the X-ray emission in the soft band (2 keV) it is about 10^-14 erg/s/cm^2. We discuss the implication of our results in light of the possible natures of HD 149427 -- being a planetary nebula or a symbiotic star, close or very distant. The derived upper limits on the mass accretion rate of the white dwarf are untypical for symbiotic stars and may favor the picture of HD 149427 being a young PN. HD 149427 might be a symbiotic star in hibernation -- if a symbiotic star at all. We estimate the possible mass-loss rate and kinetic luminosity of the jet and find no contradiction with our upper...

  19. Biclique cryptanalysis of the full AES

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Khovratovich, Dmitry; Rechberger, Christian

    2011-01-01

    Since Rijndael was chosen as the Advanced Encryption Standard (AES), improving upon 7-round attacks on the 128-bit key variant (out of 10 rounds) or upon 8-round attacks on the 192/256-bit key variants (out of 12/14 rounds) has been one of the most difficult challenges in the cryptanalysis of block...... ciphers for more than a decade. In this paper, we present the novel technique of block cipher cryptanalysis with bicliques, which leads to the following results: The first key recovery method for the full AES-128 with computational complexity 2126.1. The first key recovery method for the full AES-192...... with computational complexity 2189.7. The first key recovery method for the full AES-256 with computational complexity 2254.4. Key recovery methods with lower complexity for the reduced-round versions of AES not considered before, including cryptanalysis of 8-round AES-128 with complexity 2124.9. Preimage search...

  20. Chemical abundances for A-and F-type supergiant stars

    Science.gov (United States)

    Molina, R. E.; Rivera, H.

    2016-04-01

    We present the stellar parameters and elemental abundances of a set of A-F-type supergiant stars HD 45674, HD 180028, HD 194951 and HD 224893 using high resolution (R≈ 42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD 45674 and HD 224893. We reaffirm the abundances for HD 180028 and HD 194951 studied previously by Luck. Alpha-elements indicate that the objects belong to the thin disc population. Their abundances and their location on the Hertzsprung-Russell diagram seem to indicate that HD 45675, HD 194951 and HD 224893 are in the post-first dredge-up (post-1DUP) phase, and that they are moving in the red-blue loop region. HD 180028, on the contary, shows typical abundances of Population I, but its evolutionary status cannot be satisfactorily defined.

  1. Chemical abundances for A-and F-type supergiant stars

    CERN Document Server

    Molina, R E

    2016-01-01

    We present the stellar parameters and elemental abundances of a set of A--F-type supergiant stars HD\\,45674, HD\\,180028, HD\\,194951 and HD\\,224893 using high resolution ($R$\\,$\\sim$\\,42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD\\,45674 and HD\\,224893. We reaffirm the abundances for HD\\,180028 and HD\\,194951 studied previously by Luck (2014) respectively. Alpha-elements indicates that objects belong to the thin disc population. From their abundances and its location on the Hertzsprung-Russell diagram seems point out that HD\\,45675, HD\\,194951 and HD\\,224893 are in the post-first dredge-up (post-1DUP) phase and they are moving in the red-blue loop region. HD~180028, on the contary, shows typical abundances of the population I but its evolutionary status could not be satisfactorily defined.

  2. The Puzzling Spectrum of HD 94509

    CERN Document Server

    Cowley, C R; Hubrig, S

    2015-01-01

    The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmo...

  3. Stability and Formation of the Resonant System HD 73526

    CERN Document Server

    Sándor, Z; Klagyivik, P

    2007-01-01

    Based on radial velocity measurements it has been found recently that the two giant planets detected around the star HD 73526 are in 2:1 resonance. However, as our numerical integration shows, the derived orbital data for this system result in chaotic behavior of the giant planets, which is uncommon among the resonant extrasolar planetary systems. We intend to present regular (non-chaotic) orbital solutions for the giant planets in the system HD 73526 and offer formation scenarios based on combining planetary migration and sudden perturbative effects such as planet-planet scattering or rapid dispersal of the protoplanetary disk. A comparison with the already studied resonant system HD 128311, exhibiting similar behavior, is also done. The new sets of orbital solutions have been derived by the Systemic Console (www.oklo.org). The stability of these solutions has been investigated by the Relative Lyapunov indicator, while the migration and scattering effects are studied by gravitational N-body simulations apply...

  4. Chromosome isolation by flow sorting in Aegilops umbellulata and Ae. comosa and their allotetraploid hybrids Ae. biuncialis and Ae. geniculata.

    Directory of Open Access Journals (Sweden)

    István Molnár

    Full Text Available This study evaluates the potential of flow cytometry for chromosome sorting in two wild diploid wheats Aegilops umbellulata and Ae. comosa and their natural allotetraploid hybrids Ae. biuncialis and Ae. geniculata. Flow karyotypes obtained after the analysis of DAPI-stained chromosomes were characterized and content of chromosome peaks was determined. Peaks of chromosome 1U could be discriminated in flow karyotypes of Ae. umbellulata and Ae. biuncialis and the chromosome could be sorted with purities exceeding 95%. The remaining chromosomes formed composite peaks and could be sorted in groups of two to four. Twenty four wheat SSR markers were tested for their position on chromosomes of Ae. umbellulata and Ae. comosa using PCR on DNA amplified from flow-sorted chromosomes and genomic DNA of wheat-Ae. geniculata addition lines, respectively. Six SSR markers were located on particular Aegilops chromosomes using sorted chromosomes, thus confirming the usefulness of this approach for physical mapping. The SSR markers are suitable for marker assisted selection of wheat-Aegilops introgression lines. The results obtained in this work provide new opportunities for dissecting genomes of wild relatives of wheat with the aim to assist in alien gene transfer and discovery of novel genes for wheat improvement.

  5. The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry

    CERN Document Server

    Pascual, N; Meeus, G; Marshall, J P; Mendigutía, I; Sandell, G

    2016-01-01

    Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of disc host stars observed by the Herschel Open Time Key Programme `Gas in Protoplanetary Systems'. We present Herschel/PACS far-infrared imaging observations of 22 Herbig Ae/Bes and 5 debris discs, combined with ancillary photometry spanning ultraviolet to sub-millimetre wavelengths. From these measurements we determine the diagnostics of disc evolution, along with the total excess, in three regimes spanning near-, mid-, and far-infrared wavelengths. Using appropriate statistical tests, these diagnostics are examined for correlations. We find that the far-infrared flux, where the disc becomes optically thin, is correlated with the millimetre flux, which provides a meas...

  6. Radiation thermo-chemical models of protoplanetary discs. IV. Modelling CO ro-vibrational emission from Herbig Ae discs

    NARCIS (Netherlands)

    Thi, W. F.; Kamp, I.; Woitke, P.; van der Plas, G.; Bertelsen, R.; Wiesenfeld, L.

    2013-01-01

    Context. The carbon monoxide (CO) ro-vibrational emission from discs around Herbig Ae stars and T Tauri stars with strong ultraviolet emissions suggests that fluorescence pumping from the ground X1Σ+ to the electronic A1Π state of CO should be taken into account in disc models. Aims: We wish to unde

  7. Radiation thermo-chemical models of protoplanetary discs IV. Modelling CO ro-vibrational emission from Herbig Ae discs

    NARCIS (Netherlands)

    Thi, W. F.; Kamp, I.; Woitke, P.; van der Plas, G.; Bertelsen, R.; Wiesenfeld, L.

    2013-01-01

    Context. The carbon monoxide (CO) ro-vibrational emission from discs around Herbig Ae stars and T Tauri stars with strong ultraviolet emissions suggests that fluorescence pumping from the ground X-1 Sigma(+) to the electronic A(1)Pi state of CO should be taken into account in disc models. Aims. We w

  8. AE Aquarii represents a new subclass of Cataclysmic Variables

    CERN Document Server

    Ikhsanov, N R

    2012-01-01

    We analyze properties of the unique nova-like star AE Aquarii identified with a close binary system containing a red dwarf and a very fast rotating magnetized white dwarf. It cannot be assigned to any of the three commonly adopted sub-classes of Cataclysmic Variables: Polars, Intermediate Polars, and Accreting non-magnetized White Dwarfs. Our study has shown that the white dwarf in AE Aqr is in the ejector state and its dipole magnetic moment is $\\mu ~ 1.5 \\times 10^{34} G cm^3$. It switched into this state due to intensive mass exchange between the system components during a previous epoch. A high rate of disk accretion onto the white dwarf surface resulted in temporary screening of its magnetic field and spin-up of the white dwarf to its present spin period. Transition of the white dwarf to the ejector state had occurred at a final stage of the spin-up epoch as its magnetic field emerged from the accreted plasma due to diffusion. In the frame of this scenario AE Aqr represents a missing link in the chain of...

  9. Radio detection of the young binary HD 160934

    CERN Document Server

    Azulay, R; Marcaide, J M; Marti-Vidal, I; Arroyo-Torres, B

    2013-01-01

    Precise determination of dynamical masses of pre-main-sequence (PMS) stars is essential to calibrate stellar evolution models that are widely used to derive theoretical masses of young low-mass objects. Binary stars in young, nearby loose associations are particularly good candidates for this calibration since all members share a common age. Interestingly, some of these young binaries present a persistent and compact radio emission, which makes them excellent targets for astrometric VLBI studies. We aim to monitor the orbital motion of the binary system HD 160934, a member of the AB Doradus moving group. We observed HD 160934 with the Very Large Array and the European VLBI Network at 8.4 and 5 GHz, respectively. The orbital information derived from these observations was analyzed along with previously reported orbital measurements. We show that the two components of the binary, HD 160934 A and HD 160934 c, display compact radio emission at VLBI scales, providing precise information on the relative orbit. Revi...

  10. Radio detection of the young binary HD 160934

    Science.gov (United States)

    Azulay, R.; Guirado, J. C.; Marcaide, J. M.; Martí-Vidal, I.; Arroyo-Torres, B.

    2014-01-01

    Context. Precise determination of dynamical masses of pre-main-sequence (PMS) stars is essential to calibrate stellar evolution models that are widely used to derive theoretical masses of young low-mass objects. Binary stars in young, nearby loose associations are particularly good candidates for this calibration since all members share a common age. Interestingly, some of these young binaries present a persistent and compact radio emission, which makes them excellent targets for astrometric VLBI studies. Aims: We aim to monitor the orbital motion of the binary system HD 160934, a member of the AB Doradus moving group. Methods: We observed HD 160934 with the Very Large Array and the European VLBI Network at 8.4 and 5 GHz, respectively. The orbital information derived from these observations was analyzed along with previously reported orbital measurements. Results: We show that the two components of the binary, HD 160934 A and HD 160934 c, display compact radio emission at VLBI scales, providing precise information on the relative orbit. Revised orbital elements were estimated. Conclusions: Future VLBI monitoring of this pair should determine precise model-independent mass estimates for the A and c components, which will serve as calibration tests for PMS evolutionary models.

  11. Dynamic AES – Extending the Lifetime?

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2014-01-01

    proven that AES is vulnerable to side-channelattacks, related sub-key attacks and biclicque attacks. This paper introducesa new dynamic version of AES where the main flow is depending on theTNAF (τ -adic Non-Adjacent Form) value. This new approach can preventside-channel attacks, related sub-key attacks...

  12. GMRT search for 150 MHz radio emission from the transiting extrasolar planets HD 189733 b and HD 209458 b

    Science.gov (United States)

    Lecavelier Des Etangs, A.; Sirothia, S. K.; Gopal-Krishna; Zarka, P.

    2011-09-01

    We report a sensitive search for meter-wavelength emission at 150 MHz from two prominent transiting extrasolar planets, HD 189733 b and HD 209458 b. To distinguish any planetary emission from possible stellar or background contributions, we monitored these systems just prior to, during, and after the planet's eclipse behind the host star. No emission was detected from HD 209458 b with a 3σ upper limit of 3.6 mJy. For HD 189733 b we obtain a 3σ upper limit of 2.1 mJy and a marginal 2.7σ detection of ~1900 ± 700 μJy from a direction just 13″ from the star's coordinates (i.e., within the beam), but its association with the planet remains unconfirmed. Thus, the present GMRT observations provide unprecedentedly tight upper limits for meter wavelength emissions from these nearest two transiting-type exoplanets. We point out possible explanations of the non-detections and briefly discuss the resulting constraints on these systems. Data for this observations can be retrieved electronically on the GMRT archive server http://ncra.tifr.res.in/~gmrtarchive and upon request to archive@gmrt.ncra.tifr.res.in.

  13. Planet host stars in open clusters

    Science.gov (United States)

    Yang, XiaoLing; Chen, YuQin; Zhao, Gang

    2015-03-01

    We have compiled a list of all planet host star candidates reported in the literature, which are likely to be cluster members, and we checked their memberships by the spatial location, radial velocity, proper motion and photometric criteria. We found that only six stars, BD-13 2130, HD 28305, Kepler-66, Kepler-67, Pr0201 and Pr0211, are planet orbiting stars in open clusters to date. Two stars, HD 70573 and HD 89744, belong to moving groups and one star, TYC 8975-2606-1, may not be a planet host star, while three stars, HD 16175, HD 46375 and HD 108874 are not members of open clusters. We note that all these six planetary systems in the stellar cluster environment are younger than ˜1 Gyr, which might indicate that the planetary system in open cluster can not survive for a long time, and we speculate that close stellar encounters between member stars in open cluster can potentially destroy, or at least strongly affect, the presence of planetary systems.

  14. Low-amplitude and long-period radial velocity variations in giants HD 3574, 63 Cygni, and HD 216946 (Research Note)

    CERN Document Server

    Lee, B -C; Park, M -G; Hatzes, A P; Kim, K -M

    2014-01-01

    Aims. We study the low-amplitude and long-period variations in evolved stars using precise radial velocity measurements. Methods. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from September 2004 to May 2014 as part of the exoplanet search program at the Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the detection of low-amplitude and long-period orbital radial velocity variations in three evolved stars, HD 3574, 63 Cyg, and HD 216946. They have periods of 1061, 982, and 1382 days and semi-amplitudes of 376, 742, and 699 m/s, respectively.

  15. Searching for stable orbits in the HD 10180 planetary system

    Directory of Open Access Journals (Sweden)

    Laskar J.

    2011-02-01

    Full Text Available A planetary system with at least seven planets has been found around the star HD 10180. However, the traditional Keplerian and n-body fits to the data provide an orbital solution that becomes unstable very quickly, which may quest the reliability of the observations. Here we show that stable orbital configurations can be obtained if general relativity and long-term dissipation raised by tides on the innermost planet are taken into account.

  16. B- and A-Type Stars in the Taurus-Auriga Star-Forming Region

    Science.gov (United States)

    Mooley, Kunal; Hillenbrand, Lynne; Rebull, Luisa; Padgett, Deborah; Knapp, Gillian

    2013-01-01

    We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud, (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey, and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region. We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), t Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.

  17. HST/ACS Coronagraphic Observations of the HD 163296 Circumstellar Disk: Evidence of Time-Variable Self-Shadowing?

    Science.gov (United States)

    Wisniewski, J.; Dowling, Lorraine; Clampin, Mark; Grady, C.; Ardila, D.; Golimowski, D.; Illingworth, G.; Krist, J.

    2007-01-01

    We present Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) coronagraphic observations of the Herbig Ae star HD 163296. HD 163296's scattered light disk was resolved in the F606W and F814W filters in observations obtained In 2003 and in the F435W filter in observations obtained in 2004. Analysis of single-epoch data indicates that the disk (V-I) color is redder than the observed stellar (V-I) color. This spatially uniform red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition. Both of these processes would be consistent with the observed flat geometry of the outer disk, as diagnosed by the observed r$(exp -3)$ power law behavior of its median azimuthally averaged disk surface brightness, which suggest that grain evolution is occurring. Comparison of ACS and STIS epoch scattered light data reveals differences in the observed disk surface brightnesses, of order 1 mag arcsec$(exp -2)$, in both V and white-light filter bandpasses. Along with the observed variability in the visibility and surface brightness of the ansa(e) in the disk, and spectropolarimetric variability of the system, these results suggest that the resolved scattered light disk is variable, a phenomenon not previously observed in any other Herbig protoplanetary system We speculate that the observed behavior might be attributable to the variable inflation of the scale height of the inner disk wall, which results in variable self-shadowing of the outer disk.

  18. Recent results on the hierarchical triple system HD 150136

    Science.gov (United States)

    Gosset, E.; Berger, J. P.; Absil, O.; Le Bouquin, J. B.; Sana, H.; Mahy, L.; De Becker, M.

    2013-06-01

    HD 150136 is a hierarchical triple system, non-thermal radio emitter, made of three O stars totalling some 130 solar masses. The 2.67-day inner orbit is rather well-known. Recent works derived a good approximation for the outer orbit with a period of 3000 days. We report here on interferometric observations that allow us to angularly resolve the outer orbit. First evidences for an astrometric displacement are given. The determination of the outer system orbit gives access to the inclinations of the systems and to the masses, including the one of the O3-O3.5 primary star.

  19. Waveform Analysis of AE in Composites

    Science.gov (United States)

    Prosser, William H.

    1998-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been developed to evaluate damage mechanisms in the testing of composite materials. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. Much more precise source location can also be obtained in comparison to conventional, threshold crossing arrival time determination techniques. Two successful examples of the application of Modal AE are presented in this work. In the first, the initiation of transverse matrix cracking in cross-ply, tensile coupons was monitored. In these tests, it was documented that the same source mechanism, matrix cracking, can produce widely different AE signal amplitudes dependent on laminate stacking sequence and thickness. These results, taken together with well known propagation effects of attenuation and dispersion of AE signals in composite laminates, cast further doubt on the validity of simple amplitude or amplitude distribution analysis for AE source determination. For the second example, delamination propagation in composite ring specimens was monitored. Pressurization of these composite rings is used to simulate the stresses in a composite rocket motor case. AE signals from delamination propagation were characterized by large amplitude flexural plate mode components which have long signal durations because of the large dispersion of this mode.

  20. Kepler Observations of the Asteroseismic Binary HD 176465

    DEFF Research Database (Denmark)

    White, T. R.; Benomar, O.; Silva Aguirre, V.

    2016-01-01

    Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we...... analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two...... stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous...

  1. Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE

    CERN Document Server

    Ginski, C; Pinilla, P; Dominik, C; Boccaletti, A; de Boer, J; Benisty, M; Biller, B; Feldt, M; Garufi, A; Keller, C U; Kenworthy, M; Maire, A L; Ménard, F; Mesa, D; Milli, J; Min, M; Pinte, C; Quanz, S P; van Boekel, R; Bonnefoy, M; Chauvin, G; Desidera, S; Gratton, R; Girard, J H V; Keppler, M; Kopytova, T; Lagrange, A -M; Langlois, M; Rouan, D; Vigan, A

    2016-01-01

    We studied the well known circumstellar disk around the Herbig Ae/Be star HD 97048 with high angular resolution to reveal undetected structures in the disk, which may be indicative of disk evolutionary processes such as planet formation. We used the IRDIS near-IR subsystem of the extreme adaptive optics imager SPHERE at the ESO/VLT to study the scattered light from the circumstellar disk via high resolution polarimetry and angular differential imaging. We imaged the disk in unprecedented detail and revealed four ring-like brightness enhancements and corresponding gaps in the scattered light from the disk surface with radii between 39 au and 341 au. We derived the inclination and position angle as well as the height of the scattering surface of the disk from our observational data. We found that the surface height profile can be described by a single power law up to a separation ~270 au. Using the surface height profile we measured the scattering phase function of the disk and found that it is well consistent ...

  2. New related-key rectangle attacks on reduced AES-192 and AES-256

    Institute of Scientific and Technical Information of China (English)

    WEI YongZhuang; HU YuPu

    2009-01-01

    In this paper, we examine the security of reduced AES-192 and AES-256 against related-key rectangle attacks by exploiting the weakness in the AES key schedule. We find the following two new attacks: 9-round reduced AES-192 with 4 related keys, and 10-round reduced AES-256 with 4 related keys. Our results show that related-key rectangle attack with 4 related keys on 9-round reduced AES-192 requires a data complexity of about 2101 chosen plaintexts and a time complexity of about 2174.8 encryptions, and moreover, related-key rectangle attack with 4 related keys on 10-round reduced AES-256 requires a data complexity of about 297.5 chosen plaintexts and a time complexity of about 2254 encryptions. These attacks are the first known attacks on 9-round reduced AES-192 and 10-round reduced AES-256 with only 4 related keys. Furthermore, we give an improvement of the 10-round reduced AES-192 attack presented at FSE2007, which reduces both the data complexity and the time complexity.

  3. The HARPS search for Earth-like planets in the habitable zone. I. Very low-mass planets around HD 20794, HD 85512, and HD 192310

    Science.gov (United States)

    Pepe, F.; Lovis, C.; Ségransan, D.; Benz, W.; Bouchy, F.; Dumusque, X.; Mayor, M.; Queloz, D.; Santos, N. C.; Udry, S.

    2011-10-01

    Context. In 2009 we started an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars within the dedicated HARPS-Upgrade GTO program. Aims: The goal of this campaign is to gather very-precise radial-velocity data with high cadence and continuity to detect tiny signatures of very-low-mass stars that are potentially present in the habitable zone of their parent stars. Methods: Ten stars were selected among the most stable stars of the original HARPS high-precision program that are uniformly spread in hour angle, such that three to four of them are observable at any time of the year. For each star we recorded 50 data points spread over the observing season. The data points consist of three nightly observations with a total integration time of 10 min each and are separated by two hours. This is an observational strategy adopted to minimize stellar pulsation and granulation noise. Results: We present the first results of this ambitious program. The radial-velocity data and the orbital parameters of five new and one confirmed low-mass planets around the stars HD 20794, HD 85512, and HD 192310 are reported and discussed, among which is a system of three super-Earths and one that harbors a 3.6 M⊕-planet at the inner edge of the habitable zone. Conclusions: This result already confirms previous indications that low-mass planets seem to be very frequent around solar-type stars and that this may occur with a frequency higher than 30%. Based on observations made with the HARPS instrument on ESO's 3.6 m telescope at the La Silla Observatory in the frame of the HARPS-Upgrade GTO program ID 086.C-0230.Tables 7-9 (RV data) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/534/A58

  4. Spectroscopic Binaries near the North Galactic Pole Paper 24: HD 106104, 109281, 109463 and 110743

    Indian Academy of Sciences (India)

    R. F. Griffin

    2001-06-01

    The four stars treated in this paper have been under observation with photoelectric radial-velocity spectrometers for many years. They have proved to be binaries with periods of 30, 1828, 1514 and 822 days respectively; the orbits are of modest eccentricity apart from that of HD 110743 which is indistinguishable from a circle. The mass functions are small, and no companion has been observed for any of the stars. HD 110743, a K dwarf, is much the nearest of the four, and its orbit is of short enough period for the photocentric motion to have been recognized by Hipparcos. An eleventh-magnitude star rather more than 1' away from HD 106104 is shown to be a genuine physical companion, with practically identical radial velocity, proper motion and distance modulus, although the projected separation is about 13,000 AU.

  5. Calculating Auroral Oval Pattern by AE Index

    Institute of Scientific and Technical Information of China (English)

    CHEN Anqin; LI Jiawei; YANG Guanglin; WANG Jingsong

    2008-01-01

    The relationship between the auroral oval pattern, i.e., location, size, shape, and intensity, and the auroral electrojet activity index (AE index) is studied. It is found that the maximal auroral intensity is elliptically distributed, and the lengths of semimajor and semiminor axes are positively correlated to AE.The intensity along the normal of the auroral oval can be satisfyingly described by a Gaussian distribution,and the maximum and the full width at half maximum of the Gaussian distribution are both positively correlated to AE. Based on these statistical results, a series of experimental formulas as a function of AE are developed to calculate the location, size, shape, and intensity of the auroral oval. These formulas are validated by the auroral images released by SWPC/NOAA.

  6. HD depletion in starless cores

    CERN Document Server

    Sipilä, O; Harju, J

    2013-01-01

    Aims: We aim to investigate the abundances of light deuterium-bearing species such as HD, H2D+ and D2H+ in a gas-grain chemical model including an extensive description of deuterium and spin state chemistry, in physical conditions appropriate to the very centers of starless cores. Methods: We combine a gas-grain chemical model with radiative transfer calculations to simulate density and temperature structure in starless cores. The chemical model includes deuterated forms of species with up to 4 atoms and the spin states of the light species H2, H2+ and H3+ and their deuterated forms. Results: We find that HD eventually depletes from the gas phase because deuterium is efficiently incorporated to grain-surface HDO, resulting in inefficient HD production on grains. HD depletion has consequences not only on the abundances of e.g. H2D+ and D2H+, whose production depends on the abundance of HD, but also on the spin state abundance ratios of the various light species, when compared with the complete depletion model ...

  7. Masking a Compact AES S-box

    Science.gov (United States)

    2007-08-07

    Lecture Notes in Computer Science , pages 309–18, 2001. [2] D. Canright. A very compact S-box for AES. In CHES2005, volume 3659 of Lecture Notes in Computer Science , pages...et al., editor, CHES2003, volume 2779 of Lecture Notes in Computer Science , pages 319–333. Springer, 2003. [4] Jovan Dj. Golić and Christophe Tymen...Multiplicative masking and power analysis of AES. In CHES 2002, volume 2523 of Lecture

  8. Spectroscopic variability of two Oe stars

    CERN Document Server

    Rauw, G; Naze, Y; Eversberg, T; Alves, F; Arnold, W; Bergmann, T; Viegas, N G Correia; Fahed, R; Fernando, A; Gonzalez-Perez, J N; Carreira, L F Gouveia; Hempelmann, A; Hunger, T; Knapen, J H; Leadbeater, R; Dias, F Marques; Mittag, M; Moffat, A F J; Reinecke, N; Ribeiro, J; Romeo, N; Gallego, J Sanchez; Santos, E M Dos; Schanne, L; Schmitt, J H M M; Schroeder, K -P; Stahl, O; Stober, Ba; Stober, Be; Vollmann, K

    2015-01-01

    The Oe stars HD45314 and HD60848 have recently been found to exhibit very different X-ray properties: whilst HD60848 has an X-ray spectrum and emission level typical of most OB stars, HD45314 features a much harder and brighter X-ray emission, making it a so-called gamma Cas analogue. Monitoring the optical spectra could provide hints towards the origin of these very different behaviours. We analyse a large set of spectroscopic observations of HD45314 and HD60848, extending over 20 years. We further attempt to fit the H-alpha line profiles of both stars with a simple model of emission line formation in a Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and He I 5876 emission lines are observed for both stars. In the case of HD60848, we find a time lag between the variations in the equivalent widths of these lines. The emission lines are double peaked with nearly identical strengths of the violet and red peaks. The H-alpha profile of this star can be successfully reproduced by our mod...

  9. HD 80606: searching for the chemical signature of planet formation

    Science.gov (United States)

    Saffe, C.; Flores, M.; Buccino, A.

    2015-10-01

    Context. Binary systems with similar components are ideal laboratories that allow several physical processes to be tested, such as the possible chemical pattern imprinted by the planet formation process. Aims: We explore the probable chemical signature of planet formation in the remarkable binary system HD 80606-HD 80607. The star HD 80606 hosts a giant planet with ~4 MJup detected by both transit and radial velocity techniques, which is one of the most eccentric planets detected to date. We study condensation temperature Tc trends of volatile and refractory element abundances to determine whether there is a depletion of refractories, which could be related to the terrestrial planet formation. Methods: We carried out a high-precision abundance determination in both components of the binary system via a line-by-line, strictly differential approach. First, we used the Sun as a reference and then we used HD 80606. The stellar parameters Teff, log g, [Fe/H] and vturb were determined by imposing differential ionization and excitation equilibrium of Fe I and Fe II lines, with an updated version of the program FUNDPAR, together with plane-parallel local thermodynamic equilibrium (LTE) ATLAS9 model atmospheres and the MOOG code. Then, we derived detailed abundances of 24 different species with equivalent widths and spectral synthesis with the program MOOG. The chemical patterns were compared with the solar-twins Tc trends of Meléndez et al. (2009, AJ, 704, L66) and with a sample of solar-analogue stars with [Fe/H] ~ +0.2 dex from Neves et al. (2009, A&A, 497, 563). The Tc trends were also compared mutually between both stars of the binary system. Results: From the study of Tc trends, we concluded that the stars HD 80606 and HD 80607 do not seem to be depleted in refractory elements, which is different for the case of the Sun. Then, following the interpretation of Meléndez et al. (2009), the terrestrial planet formation would have been less efficient in the components of

  10. Planetary companions orbiting M giants HD 208527 and HD 220074

    CERN Document Server

    Lee, B -C; Park, M -G

    2012-01-01

    Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) is used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 +/- 5.8 and 672.1 +/- 3.7 days. The RV variations are not apparently related to the surface inhomogeneities and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 +/- 0.4 and 1.2 +/- 0.3 M_Sun, we obtain the minimum masses for the exoplanets of 9.9 +/- 1.7 and 11.1 +/- 1.8 M_Jup around HD 208527 and HD 220074 with an orbital semi-major axis of 2.1 +/- 0.2 and 1.6 +/- 0.1 AU and an eccentricity of 0.08 and 0.14, respectively. We also find that the previously known spectral class...

  11. The Physical Properties of HD 3651B: An Extrasolar Nemesis?

    CERN Document Server

    Burgasser, A J

    2006-01-01

    I present detailed analysis of the near infrared spectrum of HD 3651B, a faint, co-moving wide companion to the nearby planet-hosting star HD 3651. These data confirm the companion as a brown dwarf with spectral type T8, consistent with the analysis of Luhman et al. Application of the semi-empirical technique of Burgasser, Burrows & Kirkpatrick indicates that HD 3651B has Teff = 790+/-30 K and log g = 5.0+/-0.3 for a metallicity of [M/H] = 0.12+/-0.04, consistent with a mass M = 0.033+/-0.013 M_sun and an age of 0.7-4.7 Gyr. The surface gravity, mass and age estimates of this source are all highly sensitive to the assumed metallicity; however, a supersolar metallicity is deduced by direct comparison of spectral models to the observed absolute fluxes. The age of HD 3651B is somewhat better constrained than that of the primary, with estimates for the latter ranging over ~2 Gyr to >12 Gyr. As a widely orbiting massive object to a known planetary system that could potentially harbor terrestrial planets in its...

  12. The Transiting Exocomets in the HD 172555 System

    Science.gov (United States)

    Grady, C. A.; Brown, A.; Kamp, I.; Roberge, A.; Riviere-Marichalar, P.; Welsh, B.

    2017-01-01

    The Earth is thought to have formed dry, in a part of the Solar Nebula deficient in organic material, and to have acquired its organics and water through bombardment by minor bodies. Observations of this process in well-dated systems can provide insight into the probable origin and composition of the bombarding parent bodies. Transiting cometary activity has previously been reported in Ca II for the late-A member of the 241 Myr old Pictoris Moving Group member, HD 172555(Kiefer et al. 2014). We present HST STIS and COS spectra of HD 172555 demonstrating that the star has chromospheric emission and variable in falling gas features in transitions of silicon and carbon ions at times when no Fe II absorption is seen in the UV data, and no Ca II absorption is seen in contemporary optical spectra. The lack of CO absorption and stable gas absorption at the system velocity is consistent with the absence of a cold Kuiper belt analog (Riviere-Marichalar et al. 2012) in this system. The presence of infall in some species at one epoch and others at different epochs suggests that, like Pictoris, there may be more than one family of exocomets. If perturbed into star-grazing orbits by the same mechanism as for Pic, these data suggest that the wide planet frequency among A-early F stars in the PMG is at least 37.5, well above the frequency estimated for young moving groups independent of host star spectral type.

  13. THE DISCOVERY OF HD 37605c AND A DISPOSITIVE NULL DETECTION OF TRANSITS OF HD 37605b

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Sharon Xuesong; Wright, Jason T.; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Cochran, William; Endl, Michael; MacQueen, Phillip J. [McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Kane, Stephen R.; Von Braun, Kaspar [NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Boulevard, Box 9501, Nashville, TN 37209 (United States); Payne, Matthew J.; Ford, Eric B. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Antoci, Victoria; Dragomir, Diana; Matthews, Jaymie M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T1Z1 (Canada); Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard, E-mail: xxw131@psu.edu, E-mail: jtwright@astro.psu.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2012-12-10

    We report the radial velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P {approx} 55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of {approx}7.5 years with a low eccentricity and an Msin i of {approx}3.4 M{sub Jup}. Our discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey effort to provide precise ephemerides to long-period planets for transit follow-up. With a total of 137 radial velocity observations covering almost 8 years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using the predicted ephemeris, we performed a transit search for HD 37605b with the photometric data taken by the T12 0.8 m Automatic Photoelectric Telescope (APT) and the MOST satellite. Though the APT photometry did not capture the transit window, it characterized the stellar activity of HD 37605, which is consistent of it being an old, inactive star, with a tentative rotation period of 57.67 days. The MOST photometry enabled us to report a dispositive null detection of a non-grazing transit for this planet. Within the predicted transit window, we exclude an edge-on predicted depth of 1.9% at the >>10{sigma} level, and exclude any transit with an impact parameter b > 0.951 at greater than 5{sigma}. We present the BOOTTRAN package for calculating Keplerian orbital parameter uncertainties via bootstrapping. We made a comparison and found consistency between our orbital fit parameters calculated by the RVLIN package and error bars by BOOTTRAN with those produced by a Bayesian analysis using MCMC.

  14. A Herschel view of IC 1396 A: Unveiling the different sequences of star formation

    CERN Document Server

    Sicilia-Aguilar, Aurora; Getman, Konstantin; Henning, Thomas; Merin, Bruno; Eiroa, Carlos; Riviere-Marichalar, Pablo; Currie, Thayne

    2013-01-01

    The IC1396A globule in the young cluster Tr37, hosting many young stars and protostars, is assumed to be a site of triggered star formation. We mapped IC1396A with Herschel/PACS at 70 and 160 micron. The Herschel maps trace in great detail the very embedded protostellar objects and the structure of the cloud. PACS data reveal a previously unknown Class 0 object (IC1396A-PACS-1) located behind the ionization front. IC1396A-PACS-1 is not detectable with Spitzer, but shows marginal X-ray emission. The data also allowed to study three of the Class I intermediate-mass objects within the cloud. We derived approximate cloud temperatures to study the effect and potential interactions between the protostars and the cloud. The Class 0 object is associated with the densest and colder part of IC1396A. Heating in the cloud is dominated by the winds and radiation of the O6.5 star HD 206267 and, to a lesser extent, by the effects of the Herbig Ae star V 390 Cep. The surroundings of the Class I and Class II objects embedded ...

  15. Dynamical Study of the Exoplanet Host Binary System HD 106515

    Science.gov (United States)

    Rica, F. M.; Barrena, R.; Henríquez, J. A.; Pérez, F. M.; Vargas, P.

    2017-01-01

    HD 106515 AB (STF1619 AB) is a high common proper motion and common radial velocity binary star system composed of two G-type bright stars located at 35 pc and separated by about 7 arcsec. This system was observed by the Hipparcos satellite with a precision in distance and proper motion of 3 and 2%, respectively. The system includes a circumprimary planet of nearly 10 Jupiter masses and a semimajor axis of 4.59 AU, discovered using the radial velocity method. The observational arc of 21° shows a small curvature that evidences HD 106515 AB is a gravitationally bound system. This work determines the dynamical parameters for this system which reinforce the bound status of both stellar components. We determine orbital solutions from instantaneous position and velocity vectors. In addition, we provide a very preliminary orbital solution and a distribution of the orbital parameters, obtained from the line of sight (z). Our results show that HD 106515 AB presents an orbital period of about 4 800 years, a semimajor axis of 345 AU and an eccentricity of about 0.42. Finally, we use an N-body numerical code to perform simulations and reproduce the longer term octupole perturbations on the inner orbit.

  16. The structure and kinematics of the ISM around HD 192281

    Science.gov (United States)

    Arnal, E. M.; Cichowolski, S.; Pineault, S.; Testori, J. C.; Cappa, C. E.

    2011-08-01

    Aims: This work aims at investigating the interaction of HD 192281 (O5 Vn((f))p) with its local ISM. The purpose is to analyse the effects that a massive star has on the structure and kinematics of its surrounding gas. Methods: To carry out this study, we used high-resolution radio continuum and 21-cm H i line data from the Canadian Galactic Plane Survey (CGPS). This data base was complemented with radio continuum, infrared, and molecular data retrieved from available surveys. Given that HD 192281 is very likely a runaway star, we attempt to establish whether the observed H i distribution can be interpreted in terms of a simple bow shock model. Results: Analysis of the H i data shows the presence of an H i feature likely to be associated with HD 192281. This feature remains detectable from ~5 to -10 km s-1. At the most negative radial velocities, the shape of the H i feature is highly reminiscent of a bow shock structure seen projected onto the plane of the sky. This feature has counterparts at radio-continuum, infrared, and CO emissions. The analysis of the radio continuum data suggests a thermal spectrum for the gas related to this structure.

  17. Is the HD 15115 circumstellar disk really asymmetrical?

    Science.gov (United States)

    Mazoyer, J.; Boccaletti, A.; Augereau, J.-C.; Lagrange, A.-M.; Galicher, R.; Baudoz, P.

    2014-09-01

    Similarly to beta Pictoris, HD 15115 is a young and nearby (45.2 pc) star that hosts a debris disk. This debris disk was first imaged in 2007 (Kalas et al., 2007) in visible using HST and in H band using the Keck observatory. The disk appeared edge-on and showed an asymmetry between its west and east parts. This detection was later observed in J band using HST / Nicmos data (Debes et al., 2008) and in Ks and L' using LBT (Rodigas et al. 2012). These observations confirmed the asymmetric nature of HD 15115 debris disk. We present here the results of the analysis of data from the Gemini / NICI archival system from 2009 and 2011 in H and K bands. We use newly developed differential treatment algorithms on these data (ADI, LOCI, KLIP) to subtract the light of the star and image the disk up to 1 arc second (30 AU). From this analysis, we find an inclination of 86 (confirming previous conclusions about HD 15115). We derive the disk position angle and spine and photometry and only find a brightness asymmetry in these elements. We also present evidence of an ring at 2 arc seconds (60 AU), with a rather sharp inner edge, and no sign of an asymmetry. With this radius and inclination, we create disk models (Augereau et al. 1999) and put constraints on the disk parameters, using either the position angle, spine and photometry or forward modeling.

  18. 15 CFR 758.2 - Automated Export System (AES).

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Automated Export System (AES). 758.2... CLEARANCE REQUIREMENTS § 758.2 Automated Export System (AES). The Census Bureau's Foreign Trade Statistics...) electronically using the Automated Export System (AES). In order to use AES, you must apply directly to...

  19. DIRECT IMAGING OF AN ASYMMETRIC DEBRIS DISK IN THE HD 106906 PLANETARY SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Kalas, Paul G.; Wang, Jason J.; Duchene, Gaspard; Dong, Ruobing; Graham, James R.; Rosa, Robert J. De [Astronomy Department, University of California, Berkeley CA 94720-3411 (United States); Rajan, Abhijith; Patience, Jennifer [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287 (United States); Millar-Blanchaer, Maxwell A.; Chilcote, Jeffrey [Department of Astronomy and Astrophysics, University of Toronto, Toronto ON M5S 3H4 (Canada); Chen, Christine [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Fitzgerald, Michael P. [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095 (United States); Macintosh, Bruce [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Murray-Clay, Ruth [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Matthews, Brenda; Marois, Christian; Draper, Zachary H.; Lawler, Samantha [National Research Council of Canada Herzberg, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Rameau, Julien; Doyon, René [Institut de Recherche sur les Exoplanetes, Département de Physique, Université de Montréal, Montréal QC H3C 3J7 (Canada); and others

    2015-11-20

    We present the first scattered light detections of the HD 106906 debris disk using the Gemini/Gemini Planet Imager in the infrared and Hubble Space Telescope (HST)/Advanced Camera for Surveys in the optical. HD 106906 is a 13 Myr old F5V star in the Sco–Cen association, with a previously detected planet-mass candidate HD 106906b projected 650 AU from the host star. Our observations reveal a near edge-on debris disk that has a central cleared region with radius ∼50 AU, and an outer extent >500 AU. The HST data show that the outer regions are highly asymmetric, resembling the “needle” morphology seen for the HD 15115 debris disk. The planet candidate is oriented ∼21° away from the position angle of the primary’s debris disk, strongly suggesting non-coplanarity with the system. We hypothesize that HD 106906b could be dynamically involved in the perturbation of the primary’s disk, and investigate whether or not there is evidence for a circumplanetary dust disk or cloud that is either primordial or captured from the primary. We show that both the existing optical properties and near-infrared colors of HD 106906b are weakly consistent with this possibility, motivating future work to test for the observational signatures of dust surrounding the planet.

  20. Radial velocities of population II binary stars. II

    CERN Document Server

    Bartkevicius, A

    2006-01-01

    Here we publish the second list of radial velocities for 91 Hipparcos stars, mostly high transverse velocity binaries without previous radial velocity measurements. The measurements of radial velocities are done with a CORAVEL-type radial velocity spectrometer with an accuracy better than 1 km/s. We also present the information on eight new radial velocity variables - HD 29696, HD 117466AB, BD +28 4035AB, BD +30 2129A, BD +39 1828AB, BD +69 230A, BD +82 565A and TYC 2267-1300-1 - found from our measurements. Two stars (HD 27961AB and HD 75632AB) are suspected as possible radial velocity variables.

  1. Attacks and countermeasures on AES and ECC

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2013-01-01

    is foreseeable while the rounds are performed. ECC (Elliptic Curve Cryptography) is used as a public key crypto system with the key purpose of creating a private shared between two participants in a communication network. Attacks on ECC include the Pohlig-Hellman attack and the Pollard's rho attack. Furthermore......AES (Advanced Encryption Standard) is widely used in LTE and Wi-Fi communication systems. AES has recently been exposed to new attacks which have questioned the overall security of AES. The newest attack is a so called biclique attack, which is using the fact that the content of the state array...... side-channels attacks can be applied to ECC. This paper reflects an ongoing research in the field of countermeasures against the attacks mentioned above....

  2. [Modern spectral estimation of ICP-AES].

    Science.gov (United States)

    Zhang, Z; Jia, Q; Liu, S; Guo, L; Chen, H; Zeng, X

    2000-06-01

    The inductively coupled plasma atomic emission spectrometry (ICP-AES) and its signal characteristics were discussed using modern spectral estimation technique. The power spectra density (PSD) was calculated using the auto-regression (AR) model of modern spectra estimation. The Levinson-Durbin recursion method was used to estimate the model parameters which were used for the PSD computation. The results obtained with actual ICP-AES spectra and measurements showed that the spectral estimation technique was helpful for the better understanding about spectral composition and signal characteristics.

  3. AES ALGORITHM IMPLEMENTATION IN PROGRAMMING LANGUAGES

    Directory of Open Access Journals (Sweden)

    Luminiţa DEFTA

    2010-12-01

    Full Text Available Information encryption represents the usage of an algorithm to convert an unknown message into an encrypted one. It is used to protect the data against unauthorized access. Protected data can be stored on a media device or can be transmitted through the network. In this paper we describe a concrete implementation of the AES algorithm in the Java programming language (available from Java Development Kit 6 libraries and C (using the OpenSSL library. AES (Advanced Encryption Standard is an asymmetric key encryption algorithm formally adopted by the U.S. government and was elected after a long process of standardization.

  4. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633

    Science.gov (United States)

    Mikulášek, Zdeněk; Paunzen, Ernst; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hümmerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janík, Jan; Jagelka, Miroslav

    2016-07-01

    We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.

  5. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633

    CERN Document Server

    Mikulasek, Zdenek; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hummerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janik, Jan; Jagelka, Miroslav

    2016-01-01

    We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.

  6. Refined Properties of the HD 130322 Planetary System

    CERN Document Server

    Hinkel, Natalie R; Henry, Gregory W; Feng, Y Katherina; Boyajian, Tabetha; Wright, Jason; Fischer, Debra A; Howard, Andrew W

    2015-01-01

    Exoplanetary systems closest to the Sun, with the brightest host stars, provide the most favorable opportunities for characterization studies of the host star and their planet(s). The Transit Ephemeris Refinement and Monitoring Survey uses both new radial velocity measurements and photometry in order to greatly improve planetary orbit uncertainties and the fundamental properties of the star, in this case HD 130322. The only companion, HD 130322b, orbits in a relatively circular orbit, e = 0.029 every ~10.7 days. Radial velocity measurements from multiple sources, including 12 unpublished from the Keck I telescope, over the course of ~14 years have reduced the uncertainty in the transit midpoint to ~2 hours. The transit probability for the b-companion is 4.7%, where M_p sin i = 1.15 M_J and a = 0.0925 AU. In this paper, we compile photometric data from the T11 0.8m Automated Photoelectric Telescope at Fairborn Observatory taken over ~14 years, including the constrained transit window, which results in a dispos...

  7. Resolving the inner regions of the HD 97048 circumstellar disk with VLT/NACO polarimetric differential imaging

    Science.gov (United States)

    Quanz, S. P.; Birkmann, S. M.; Apai, D.; Wolf, S.; Henning, T.

    2012-02-01

    Context. Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. Because most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disks on these scales to constrain the conditions for planet formation. Aims: Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD 97048 in polarized light. Methods: We used VLT/NACO to observe HD 97048 in polarimetric differential imaging (PDI) mode in the H and Ks band. This technique offers high-contrast capabilities at very small inner working angles and probes the dust grains on the surface layer of the disk that act as the scattering surface. Results: We spatially resolve the disk around HD 97048 in polarized flux in both filters on scales between ~0.1″-1.0″ corresponding to the inner ~16-160 AU. Fitting isophots to the flux calibrated H-band image between 13-14 mag/arcsec2 and 14-15 mag/arcsec2, we derive an apparent disk inclination angle of 34° ± 5° and 47° ± 2°, respectively. The disk position angle in both brightness regimes is almost identical and roughly 80°. Along the disk major axis the surface brightness of the polarized flux drops from ~11 mag/arcsec2 at ~0.1″ (~16 AU) to ~15.3 mag/arcsec2 at ~ 1.0″ (~160 AU). The brightness profiles along the major axis are fitted with power-laws falling off as ∝ r - 1.78 ± 0.02 in H and ∝ r - 2.34 ± 0.04 in Ks. Because the surface brightness decreases more rapidly in Ks compared to H, the disks becomes relatively bluer at larger separations, possibly indicating changing dust grain properties as a function of radius. Conclusions: We imaged for the first time the inner ~0.1″-1.0″ (~16-160 AU) of the surface layer of the HD 97048 circumstellar disk in scattered light, which demonstrates the power of ground-based imaging polarimetry. Our data fill an

  8. Atomic-AES: A compact implementation of the AES encryption/decryption core

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco

    2016-01-01

    D that require access to both the AES encryption and decryption modules. In this paper we look to investigate whether the basic circuit of Moradi et al. can be tweaked to provide dual functionality of encryption and decryption (ENC/DEC) while keeping the hardware overhead as low as possible. As a result, we...... report an 8-bit serialized AES circuit that provides the functionality of both encryption and decryption and occupies around 2645 GE with a latency of 226 cycles. This is a substantial improvement over the next smallest AES ENC/DEC circuit (Grain of Sand) by Feldhofer et al. which takes around 3400 gates...

  9. Large HI structures linked to southern O-type stars

    CERN Document Server

    Martín, M C; Romero, G A

    2008-01-01

    In our search for interstellar bubbles around massive stars we analyze the environs of the O-type stars HD 38666, HD 124979, HD 163758, and HD 171589. The location of the stars, which are placed far from the galactic plane, favors the formation of large wind bubbles. We investigate the distribution of the neutral and ionized gas based on HI, CO, and radio continuum data, and that of the interstellar dust based on far infrared IRIS images. Here we report the discovery of neutral gas cavities and slowly expanding shells associated with the four massive stars. IR and optical counterparts were also detected for some of the stars. We discuss the probability that the features have originated in the action of the stellar winds on the surrounding gas.

  10. Effective temperatures, rotational velocities, microturbulent velocities and abundances in the atmospheres of the Sun,. HD1835 and HD10700

    CERN Document Server

    Pavlenko, Ya V; Jones, H R A; Ivanyuk, O; Pinfield, D J

    2012-01-01

    We describe our procedure to determine effective temperatures, rotational velocities, microturbulent velocities, and chemical abundances in the atmospheres of Sun-like stars. We use independent determinations of iron abundances using the fits to the observed Fe I and Fe II atomic absorption lines. We choose the best solution from the fits to these spectral features for the model atmosphere that provides the best confidence in the determined log N(Fe), Vt, and vsini. First, we compute the abundance of iron for a set of adopted microturbulent velocities. To determine the most self-consistent effective temperature and microturbulent velocity in any star's atmosphere, we used an additional constraint where we minimise the dependence of the derived abundances of Fe I and Fe II on the excitation potential of the corresponding lines. We analyse the spectra of the Sun and two well known solar type stars, HD1835 and HD10700 to determine their abundances, microturbulent velocity and rotational velocity. For the Sun abu...

  11. Bayesian frequency analysis of HD 201433 observations with BRITE

    CERN Document Server

    Kallinger, T

    2016-01-01

    Multiple oscillation frequencies separated by close to or less than the formal frequency resolution of a data set are a serious problem in the frequency analysis of time series data. We present a new and fully automated Bayesian approach that searches for close frequencies in time series data and assesses their significance by comparison to no signal and a mono-periodic signal. We extensively test the approach with synthetic data sets and apply it to the 156 days-long high-precision BRITE photometry of the SPB star HD 201433, for which we find a sequence of nine statistically significant rotationally split dipole modes.

  12. The MiMeS survey of Magnetism in Massive Stars: magnetic analysis of the O-type stars

    Science.gov (United States)

    Grunhut, J. H.; Wade, G. A.; Neiner, C.; Oksala, M. E.; Petit, V.; Alecian, E.; Bohlender, D. A.; Bouret, J.-C.; Henrichs, H. F.; Hussain, G. A. J.; Kochukhov, O.; MiMeS Collaboration

    2017-02-01

    We present the analysis performed on spectropolarimetric data of 97 O-type targets included in the framework of the Magnetism in Massive Stars (MiMeS) Survey. Mean least-squares deconvolved Stokes I and V line profiles were extracted for each observation, from which we measured the radial velocity, rotational and non-rotational broadening velocities, and longitudinal magnetic field Bℓ. The investigation of the Stokes I profiles led to the discovery of two new multiline spectroscopic systems (HD 46106, HD 204827) and confirmed the presence of a suspected companion in HD 37041. We present a modified strategy of the least-squares deconvolution technique aimed at optimizing the detection of magnetic signatures while minimizing the detection of spurious signatures in Stokes V. Using this analysis, we confirm the detection of a magnetic field in six targets previously reported as magnetic by the MiMeS collaboration (HD 108, HD 47129A2, HD 57682, HD 148937, CPD-28 2561, and NGC 1624-2), as well as report the presence of signal in Stokes V in three new magnetic candidates (HD 36486, HD 162978, and HD 199579). Overall, we find a magnetic incidence rate of 7 ± 3 per cent, for 108 individual O stars (including all O-type components part of multiline systems), with a median uncertainty of the Bℓ measurements of about 50 G. An inspection of the data reveals no obvious biases affecting the incidence rate or the preference for detecting magnetic signatures in the magnetic stars. Similar to A- and B-type stars, we find no link between the stars' physical properties (e.g. Teff, mass, and age) and the presence of a magnetic field. However, the Of?p stars represent a distinct class of magnetic O-type stars.

  13. Three Temperate Neptunes Orbiting Nearby Stars

    CERN Document Server

    Fulton, Benjamin J; Weiss, Lauren M; Sinukoff, Evan; Petigura, Erik A; Isaacson, Howard; Hirsch, Lea; Marcy, Geoffrey W; Henry, Gregory W; Grunblatt, Samuel K; Huber, Daniel; von Braun, Kaspar; Boyajian, Tabetha S; Kane, Stephen R; Wittrock, Justin; Horch, Elliott P; Ciardi, David R; Howell, Steve B; Wright, Jason T; Ford, Eric B

    2016-01-01

    We present the discovery of three modestly-irradiated, roughly Neptune-mass planets orbiting three nearby Solar-type stars. HD 42618 b has a minimum mass of $15.4 \\pm 2.4$ M$_{\\oplus}$, a semi-major axis of 0.55 AU, an equilibrium temperature of 337 K, and is the first planet discovered to orbit the solar analogue host star, HD 42618. We also discover new planets orbiting the known exoplanet host stars HD 164922 and HD 143761 ($\\rho$ CrB). The new planet orbiting HD 164922 has a minimum mass of $12.9 \\pm 1.6$ M$_{\\oplus}$ and orbits interior to the previously known Jovian mass planet orbiting at 2.1 AU. HD 164922 c has a semi-major axis of 0.34 AU and an equilibrium temperature of 418 K. HD 143761 c orbits with a semi-major axis of 0.44 AU, has a minimum mass of $25 \\pm 2$ M$_{\\oplus}$, and is the warmest of the three new planets with an equilibrium temperature of 445 K. It orbits exterior to the previously known warm Jupiter in the system. A transit search using space-based CoRoT data and ground-based photom...

  14. AE8/AP8 Implementations in AE9/AP9, IRBEM, and SPENVIS

    Science.gov (United States)

    2014-02-18

    period applies to orbit generation only; AE8/AP8 utilizes geomagnetic field models from other epochs as specified in the table below.) SHIELDOSE2 model...Cain, J. C., S. J. Hendricks, R. A. Langel, and W. V. Hudson (1967), A proposed model for the international geomagnetic reference field, 1965, J...trapped particle fluxes with the NASA models AP-8 and AE-8, Radiat. Meas., 26, pp. 947-952. International Association of Geomagnetism and Aeronomy

  15. Radio emission from rapidly-rotating cool giant stars

    Science.gov (United States)

    Drake, Stephen A.; Walter, Frederick M.; Florkowski, David R.

    1990-01-01

    The results of a VLA program are reported to examine the radio continuum emission from 11 rapidly-rotating cool giant stars, all of which were originally believed to be single stars. Six of the 11 stars were detected as radio sources, including FK Com and HR 9024, for which there exist multifrequency observations. HD 199178, UZ Lib (now known to be a binary system), and HD 82558, for which there is only 6-cm data. The radio properties of these stars are compared with those of the active, rapidly rotating evolved stars found in the RS CVn binary systems.

  16. An investigation of four chemically peculiar stars with photometric periods below 12 h

    Science.gov (United States)

    Hümmerich, Stefan; Bernhard, Klaus; Paunzen, Ernst; Hambsch, Franz-Josef; Bohlsen, Terry; Powles, Jonathan

    2017-04-01

    We present an investigation of three chemically peculiar (CP) stars and one CP star candidate that exhibit photometric periods below 12 h. New spectroscopic observations have been acquired that confirm the peculiar nature of all objects. HD 77013 and HD 81076 are classical CP1 (Am) stars, HD 67983 is a marginal CP1 (Am:) star and HD 98000 is a CP2 (Ap) star. We have procured observations from the ASAS-3 and SuperWASP archives and obtained additional photometry in order to verify the results from the sky survey data. We have derived astrophysical parameters and investigated the positions of our target stars in the MBol versus log Teff diagram, from which information on evolutionary status has been derived. We present period analyses and discuss each object in detail. From the available data, we propose pulsational variability as the underlying mechanism for the variability in HD 67983, HD 77013 and HD 81076, which offer the opportunity to study the interaction of atomic diffusion and pulsation. HD 67983 and HD 77013 exhibit multiperiodic variability in the γ Doradus frequency realm; HD 81076 is a δ Scuti star. The CP2 star HD 98000 exhibits monoperiodic variability with a frequency of f ≈ 2.148 cycles d-1 (P ≈ 0.466 d), which we interpret as the rotational period. If this assumption is correct, HD 98000 is the α2 Canum Venaticorum variable with the shortest period hitherto observed and thus a very interesting object that might help to investigate the influence of rotational mixing on chemical peculiarities.

  17. Refined Parameters of the Planet Orbiting HD 189733

    Science.gov (United States)

    Bakos, G. Á.; Knutson, H.; Pont, F.; Moutou, C.; Charbonneau, D.; Shporer, A.; Bouchy, F.; Everett, M.; Hergenrother, C.; Latham, D. W.; Mayor, M.; Mazeh, T.; Noyes, R. W.; Queloz, D.; Pál, A.; Udry, S.

    2006-10-01

    We report on the BVRI multiband follow-up photometry of the transiting extrasolar planet HD 189733b. We revise the transit parameters and find a planetary radius of RP=1.154+/-0.033RJ and an inclination of iP=85.79d+/-0.24d. The new density (~1 g cm-3) is significantly higher than the former estimate (~0.75 g cm-3) this shows that from the current sample of nine transiting planets, only HD 209458 (and possibly OGLE-10b) have anomalously large radii and low densities. We note that due to the proximity of its parent star, HD 189733b currently has one of the most precise radius determinations among extrasolar planets. We calculate new ephemerides, P=2.218573+/-0.000020 days and T0=2453629.39420+/-0.00024 (HJD), and estimate the timing offsets of the 11 distinct transits with respect to the predictions of a constant orbital period, which can be used to reveal the presence of additional planets in the system.

  18. The dust, planetesimals and planets of HD 38529

    CERN Document Server

    Moro-Martin, Amaya; Carpenter, John M; Hillenbrand, Lynne A; Wolf, Sebastian; Meyer, Michael R; Hollenbach, David J; Najita, Joan; Henning, Thomas

    2007-01-01

    HD 38529 is a post-main sequence G8III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having Msin(i) of 0.8 MJup and 12.2 MJup, semimajor axes of 0.13 AU and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 micron of 4.7, a small excess at 33 micron (S/N=2.6) and no excess <30 micron. We discuss the distribution of the potential dust-producing planetesimals from the study of the dynamical perturbations of the two known planets, considering in particular the effect of secular resonances. We identify three dynamically stable niches at 0.4-0.8 AU, 20-50 AU and beyond 60 AU. We model the spectral energy distribution of HD 38529 to find out which of these niches show signs of harboring dust-producing plantesimals. The secular analysis, together with the SED modeling resuls, suggest that the planetesimals responsible for most of the du...

  19. Resolved Imaging of the HD191089 Debris Disc

    CERN Document Server

    Churcher, Laura J; Smith, Rachel

    2010-01-01

    Two thirds of the F star members of the 12 Myr old Beta Pictoris Moving Group (BPMG) show significant excess emission in the mid-infrared, several million years after the expected dispersal of the protoplanetary disc. Theoretical models of planet formation suggest that this peak in the mid-infrared emission could be due to the formation of Pluto-sized bodies in the disc, which ignite the collisional cascade and enhance the production of small dust. Here we present resolved mid-infrared imaging of the disc of HD191089 (F5V in the BPMG) and consider its implications for the state of planet formation in this system. HD191089 was observed at 18.3 microns using T-ReCS on Gemini South and the images were compared to models of the disc to constrain the radial distribution of the dust. The emission observed at $18.3\\umu m$ is shown to be significantly extended beyond the PSF at a position angle of 80 degrees. This is the first time dust emission has been resolved around HD191089. Modelling indicates that the emission...

  20. HD 98800: A 10-Myr-Old Transition Disk

    CERN Document Server

    Furlan, E; Calvet, N; Forrest, W J; D'Alessio, P; Hartmann, L; Watson, D M; Green, J D; Najita, J; Chen, C H

    2007-01-01

    We present the mid-infrared spectrum, obtained with the Spitzer Infrared Spectrograph (IRS), of HD 98800, a quadruple star system located in the 10-Myr-old TW Hydrae association. It has a known mid-infrared excess that arises from a circumbinary disk around the B components of the system. The IRS spectrum confirms that the disk around HD 98800 B displays no excess emission below about 5.5 micron, implying an optically thick disk wall at 5.9 AU and an inner, cleared-out region; however, some optically thin dust, consisting mainly of 3-micron-sized silicate dust grains, orbits the binary in a ring between 1.5 and 2 AU. The peculiar structure and apparent lack of gas in the HD 98800 B disk suggests that this system is likely already at the debris disks stage, with a tidally truncated circumbinary disk of larger dust particles and an inner, second-generation dust ring, possibly held up by the resonances of a planet. The unusually large infrared excess can be explained by gravitational perturbations of the Aa+Ab p...

  1. Photometric Variability of Four Coronally Active Stars

    Indian Academy of Sciences (India)

    J. C. Pandey; K. P. Singh; R. Sagar; S. A. Drake

    2002-03-01

    We present photometric observations of four stars that are optical counterparts of soft X-ray/EUV sources, namely 1ES 0829+15.9, 1ES0920-13.6, 2RE J110159+223509 and 1ES 1737+61.2. We have discovered periodic variability in two of the stars, viz., MCC 527 (1ES 0829+15.9; Period = 0.828 ± 0.0047) and HD 81032 (1ES 0920-13.6; Period = ∼ 57.02 ± 0.560 days). HD 95559 (2RE J110159+223509) is found to show a period of 3. HD 160934 (1ES1737+61.2) also shows photometric variability but needs to be monitored further for finding its period. These stars most likely belong to the class of chromospherically active stars.

  2. The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b.

    Science.gov (United States)

    Ballester, Gilda E; Sing, David K; Herbert, Floyd

    2007-02-01

    About ten per cent of the known extrasolar planets are gas giants that orbit very close to their parent stars. The atmospheres of these 'hot Jupiters' are heated by the immense stellar irradiation. In the case of the planet HD 209458b, this energy deposition results in a hydrodynamic state in the upper atmosphere, allowing for sizeable expansion and escape of neutral hydrogen gas. HD 209458b was the first extrasolar planet discovered that transits in front of its parent star. The size of the planet can be measured using the total optical obscuration of the stellar disk during an observed transit, and the structure and composition of the planetary atmosphere can be studied using additional planetary absorption signatures in the stellar spectrum. Here we report the detection of absorption by hot hydrogen in the atmosphere of HD 209458b. Previously, the lower atmosphere and the full extended upper atmosphere of HD 209458b have been observed, whereas here we probe a layer where the escaping gas forms in the upper atmosphere of HD 209458b.

  3. Direct imaging of an asymmetric debris disk in the HD 106906 planetary system

    CERN Document Server

    Kalas, Paul G; Wang, Jason J; Millar-Blanchaer, Maxwell A; Duchene, Gaspard; Chen, Christine; Fitzgerald, Michael P; Dong, Ruobing; Graham, James R; Patience, Jennifer; Macintosh, Bruce; Murray-Clay, Ruth; Matthews, Brenda; Rameau, Julien; Marois, Christian; Chilcote, Jeffrey; De Rosa, Robert J; Doyon, René; Draper, Zachary H; Lawler, Samantha; Ammons, S Mark; Arriaga, Pauline; Bulger, Joanna; Cotten, Tara; Follette, Katherine B; Goodsell, Stephen; Greenbaum, Alexandra; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Konapacky, Quinn; Lafreniere, David; Larkin, James E; Long, Douglas; Maire, Jérôme; Marchis, Franck; Metchev, Stan; Morzinski, Katie M; Nielsen, Eric L; Oppenheimer, Rebecca; Perrin, Marshall D; Pueyo, Laurent; Rantakyrö, Fredrik T; Ruffio, Jean-Baptiste; Saddlemyer, Leslie; Savransky, Dmitry; Schneider, Adam C; Sivaramakrishnan, Anand; Soummer, Rémi; Song, Inseok; Thomas, Sandrine; Vasisht, Gautam; Ward-Duong, Kimberly; Wiktorowicz, Sloane J; Wolff, Schuyler G

    2015-01-01

    We present the first scattered light detections of the HD 106906 debris disk using Gemini/GPI in the infrared and HST/ACS in the optical. HD 106906 is a 13 Myr old F5V star in the Sco-Cen association, with a previously detected planet-mass candidate HD 106906b projected 650 AU from the host star. Our observations reveal a near edge-on debris disk that has a central cleared region with radius $\\sim$50 AU, and an outer extent $>$500 AU. The HST data show the outer regions are highly asymmetric, resembling the ''needle'' morphology seen for the HD 15115 debris disk. The planet candidate is oriented $\\sim$21$\\deg$ away from the position angle of the primary's debris disk, strongly suggesting non-coplanarity with the system. We hypothesize that HD 106906b could be dynamically involved in the perturbation of the primary's disk, and investigate whether or not there is evidence for a circumplanetary dust disk or cloud that is either primordial or captured from the primary. We show that both the existing optical prope...

  4. A Massive Substellar Companion to the Massive Giant HD 119445

    CERN Document Server

    Omiya, Masashi; Han, Inwoo; Lee, Byeong-Cheol; Sato, Bun'ei; Kambe, Eiji; Kim, Kang-Min; Yoon, Tae Seog; Yoshida, Michitoshi; Masuda, Seiji; Toyota, Eri; Urakawa, Seitaro; Takada-Hidai, Masahide

    2009-01-01

    We detected a brown dwarf-mass companion around the intermediate-mass giant star HD 119445 (G6III) using the Doppler technique. This discovery is the first result from a Korean-Japanese planet search program based on precise radial velocity measurements. The radial velocity of this star exhibits a periodic Keplerian variation with a period, semi-amplitude and eccentricity of 410.2 days, 413.5 m/s and 0.082, respectively. Adopting a stellar mass of 3.9 M_solar, we were able to confirm the presence of a massive substellar companion with a semimajor axis of 1.71 AU and a minimum mass of 37.6 M_Jup, which falls in the middle of the brown dwarf-mass region. This substellar companion is the most massive ever discovered within 3 AU of a central intermediate-mass star. The host star also ranks among the most massive stars with substellar companions ever detected by the Doppler technique. This result supports the current view of substellar systems that more massive substellar companions tend to exist around more massi...

  5. The Dushak–Erekdag Survey of roAp Stars

    Indian Academy of Sciences (India)

    Tatyana Dorokhova; Nikolay Dorokhov

    2005-06-01

    The search of roAp stars at Mt. Dushak–Erekdag Observatory was started in 1992 using the 0.8m Odessa telescope equipped with a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD+8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.

  6. AES Water Architecture Study Interim Results

    Science.gov (United States)

    Sarguisingh, Miriam J.

    2012-01-01

    The mission of the Advanced Exploration System (AES) Water Recovery Project (WRP) is to develop advanced water recovery systems in order to enable NASA human exploration missions beyond low earth orbit (LEO). The primary objective of the AES WRP is to develop water recovery technologies critical to near term missions beyond LEO. The secondary objective is to continue to advance mid-readiness level technologies to support future NASA missions. An effort is being undertaken to establish the architecture for the AES Water Recovery System (WRS) that meets both near and long term objectives. The resultant architecture will be used to guide future technical planning, establish a baseline development roadmap for technology infusion, and establish baseline assumptions for integrated ground and on-orbit environmental control and life support systems (ECLSS) definition. This study is being performed in three phases. Phase I of this study established the scope of the study through definition of the mission requirements and constraints, as well as indentifying all possible WRS configurations that meet the mission requirements. Phase II of this study focused on the near term space exploration objectives by establishing an ISS-derived reference schematic for long-duration (>180 day) in-space habitation. Phase III will focus on the long term space exploration objectives, trading the viable WRS configurations identified in Phase I to identify the ideal exploration WRS. The results of Phases I and II are discussed in this paper.

  7. Five New Transits of the Super-Neptune HD 149026

    CERN Document Server

    Winn, Joshua N; Torres, Guillermo; Holman, Matthew J

    2007-01-01

    We present new photometry of HD 149026 spanning five transits of its "super-Neptune" planet. In combination with previous data, we improve upon the determination of the planet-to-star radius ratio: R_p/R_star = 0.0491^{+0.0018}_{-0.0005}. We find the planetary radius to be 0.71 +/- 0.05 R_Jup, in accordance with previous theoretical models invoking a high metal abundance for the planet. The limiting error is the uncertainty in the stellar radius. Although we find agreement among four different ways of estimating the stellar radius, the uncertainty remains at 7%. We also present a refined transit ephemeris and a constraint on the orbital eccentricity and argument of pericenter, e cos(omega) = -0.0014 +/- 0.0012, based on the measured interval between primary and secondary transits.

  8. Study of HD 169392A observed by CoRoT and HARPS

    CERN Document Server

    Mathur, S; Catala, C; Benomar, O; Davies, G R; Garcia, R A; Salabert, D; Ballot, J; Mosser, B; Regulo, C; Chaplin, W J; Elsworth, Y; Handberg, R; Hekker, S; Mantegazza, L; Michel, E; Poretti, E; Rainer, M; Roxburgh, I W; Samadi, R; Steslicki, M; Uytterhoeven, K; Verner, G A; Auvergne, M; Baglin, A; Forteza, S Barcelo; Baudin, F; Cortes, T Roca

    2012-01-01

    The numerous results obtained with asteroseismology thanks to space missions such as CoRoT and Kepler are providing a new insight on stellar evolution. After five years of observations, CoRoT is going on providing high-quality data. We present here the analysis of the double star HD169392 complemented by ground-based spectroscopic observations. This work aims at characterizing the fundamental parameters of the two stars, their chemical composition, the acoustic-mode global parameters including their individual frequencies, and their dynamics. We have analysed HARPS observations of the two stars to retrieve their chemical compositions. Several methods have been used and compared to measure the global properties of acoustic modes and their individual frequencies from the photometric data of CoRoT. The new spectroscopic observations and archival astrometric values suggest that HD169392 is a wide binary system weakly bounded. We have obtained the spectroscopic parameters for both components, suggesting the origin...

  9. 22 CFR 120.30 - The Automated Export System (AES).

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of... system for collection of export data for the Department of State. In accordance with this subchapter...

  10. The Transiting Exocomets in the HD 172555 System

    Science.gov (United States)

    Grady, C. A.; Brown, Alexander; Kamp, Inga; Roberge, Aki; Riviere-Marichalar, Pablo; Welsh, Barry

    2017-01-01

    The Earth is thought to have formed dry, in a part of the Solar Nebula deficient in organic material, and to have acquired its water and organics through bombardment by minor bodies. Observations of this process in well-dated systems can provide insight into the probable origin and composition of the bombarding parent bodies. Transiting cometary activity has previously been reported in Ca II for the late-A member of the ~23 Myr old Beta Pictoris Moving Group member, HD 172555. We present HST STIS and COS spectra of HD 172555 which demonstrate that the star has chromospheric emission and variable infalling gas features in transitions of silicon and carbon ions at times when no Fe II absorption is seen in the UV data, and no Ca II absorption is seen in contemporary optical spectra. We discuss apparent optical depths for the infall features. The lack of CO absorption and stable gas absorption at the system velocity is consistent with the absence of a cold Kuiper belt analog in this system. The presence of infall in some species at one epoch and others at different epochs suggests that, like beta Pictoris, there may be more than one family of exocomets. If perturbed into star-grazing orbits by the same mechanism as for beta Pic, these data suggest that the wide planet frequency among A-early F stars in the BPMG is at least 37.5%, well above the frequency estimated for young moving groups independent of host star spectral type.Support for this work was provided by NASA through grant Number HST-GO-13798 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

  11. A 12-Year Activity Cycle for HD 219134

    CERN Document Server

    Johnson, Marshall C; Cochran, William D; Meschiari, Stefano; Robertson, Paul; MacQueen, Phillip J; Brugamyer, Erik J; Caldwell, Caroline; Hatzes, Artie P; Ramírez, Ivan; Wittenmyer, Robert A

    2016-01-01

    The nearby (6.5 pc) star HD 219134 was recently shown by Motalebi et al. (2015) and Vogt et al. (2015) to host several planets, the innermost of which is transiting. We present twenty-seven years of radial velocity observations of this star from the McDonald Observatory Planet Search program, and nineteen years of stellar activity data. We detect a long-period activity cycle measured in the Ca II $S_{HK}$ index, with a period of $4230 \\pm 100$ days (11.7 years), very similar to the 11-year Solar activity cycle. Although the period of the Saturn-mass planet HD 219134 h is close to half that of the activity cycle, we argue that it is not an artifact due to stellar activity. We also find a significant periodicity in the $S_{HK}$ data due to stellar rotation with a period of 22.8 days. This is identical to the period of planet f identified by Vogt et al. (2015), suggesting that this radial velocity signal might be caused by rotational modulation of stellar activity rather than a planet. Analysis of our radial vel...

  12. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

    Hubrig, S.; Gonzalez, J. F.; Ilyin, I.

    2012-01-01

    Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... by applying the moment technique on spectral lines of inhomogeneously distributed elements separately. Furthermore, we present new determinations of the mean longitudinal magnetic field for the HgMn star HD 65949 and the hotter analog of HgMn stars, the PGa star HD 19400, using FORS 2 installed at the VLT. We...... also give new measurements of the eclipsing system ARAur with a primary star of HgMn peculiarity, which were obtained with the SOFIN spectropolarimeter installed at the Nordic Optical Telescope. Methods. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS...

  13. Search for gamma-ray emission from AE Aquarii with seven years of FERMI-LAT observations

    CERN Document Server

    Li, Jian; Rea, Nanda; Wilhelmi, Emma de Ona; Papitto, Alessandro; Hou, Xian; Mauche, Christopher W

    2016-01-01

    AE Aquarii (AE Aqr) is a cataclysmic binary hosting one of the fastest rotating (P$_{\\rm spin}$ = 33.08 s) white dwarfs known. Based on seven years of Fermi Large Area Telescope (LAT) Pass 8 data, we report on a deep search for gamma-ray emission from AE Aqr. Using X-ray observations from ASCA, XMM-Newton, Chandra, Swift, Suzaku, and NuSTAR, spanning 20 years, we substantially extend and improve the spin ephemeris of AE Aqr. Using this ephemeris, we searched for gamma-ray pulsations at the spin period of the white dwarf. No gamma-ray pulsations were detected above 3 $\\sigma$ significance. Neither phase-averaged gamma-ray emission nor gamma-ray variability of AE Aquarii is detected by Fermi-LAT. We impose the most restrictive upper limit to the gamma-ray flux from AE Aqr to date: $1.3\\times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ in the 100 MeV-300 GeV energy range, providing constraints on models.

  14. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    ZHANG LingQian; LIU ZhenXing; MA ZhiWei; W. BAUMJOHANN; WU Jian; M. DUNLOP; SHI JianKui; LU Li; WANG JiYe

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as e coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index end AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  15. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    W.; BAUMJOHANN; M.; DUNLOP

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  16. Chaotic appearance of the AE index

    Science.gov (United States)

    Shan, L.-H.; Hansen, P.; Goertz, C. K.; Smith, R. A.

    1991-01-01

    Results are reported from a stochastic analysis of a 5-day time series of the geomagnetic AE index during an active period. The original data, the power spectrum, and the autocorrelation function are shown, and the steps in the analysis are described in detail. It is found that the autocorrelation time scale is about 50 min, giving a correlation dimension (for the construction of a time series of m-dimensional vectors) of 2.4. This result is consistent with either colored-noise or deterministic-chaos magnetosphere models, indicating the need for further investigation.

  17. Tracing back the evolution of the candidate LBV HD168625

    CERN Document Server

    Mahy, L; Royer, P; Waelkens, C

    2016-01-01

    Aims. We obtained Herschel/PACS imaging and spectroscopic observations of the nebula surrounding the candidate LBV HD168625. By combining these data with optical spectra of the star, we want to constrain the abundances in the nebula and in the star and compare them to trace back its evolution. Methods. We use CMFGEN to determine the fundamental parameters and the CNO abundances of the central star whilst the abundances of the nebula are derived from the emission lines present in the Herschel/PACS spectrum. Result. The FIR images show a nebula composed of an elliptical ring/torus of ejecta with a ESE-WNW axis and of a second perpendicular bipolar structure composed of empty caps/rings. We detect equatorial shells composed of dust and ionized material with different sizes when observed at different wavelengths, and bipolar caps more of less separated from the central star in H$\\alpha$ and mid-IR images. This complex global structure seems to show 2 different inclinations: 40{\\deg} for the equatorial torus and 6...

  18. Simulation and Experimental Investigation on the AE Tomography to Improve AE Source Location in the Concrete Structure

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2014-01-01

    Full Text Available Acoustic emission (AE tomography, which is based on the time-travel tomography with AE events as its signal sources, is a new visualization tool for inspecting and locating the internal damages in the structures. In this paper, AE tomography is applied to examine a man-made damage in a typical heterogeneous concrete structure to validate its effectiveness. Firstly, the finite element (ABAQUS/Explicit simulation model of the concrete structure with one damaged circle in its center is built, and the simulated AE signals are obtained to establish the AE tomography. The results show that the damaged circle in the created model can be visualized clearly with the AE tomography in its original location. Secondly, the concrete specimen based on the FE model is fabricated, and the pencil lead break (PLB signal is taken as the exciting source for AE tomography. It is shown that the experimental results have good consistency with the FE simulation results, which also verifies the feasibility of the finite element model for AE tomography. Finally, the damage source location based on AE tomography is compared with the traditional time of arrival (TOA location method, and the better location accuracy is obtained with the AE tomography. The research results indicate that AE tomography has great potential in the application of structure damage detection.

  19. HD 65949: Rosetta stone or red herring

    Science.gov (United States)

    Cowley, C. R.; Hubrig, S.; Palmeri, P.; Quinet, P.; Biémont, É.; Wahlgren, G. M.; Schütz, O.; González, J. F.

    2010-06-01

    HD 65949 is a late B star with exceptionally strong HgII λ3984, but it is not a typical HgMn star. The ReII spectrum is of extraordinary strength. Abundances or upper limits are derived here for 58 elements based on a model with Teff = 13100K and log (g) = 4.0. Even-Z elements through nickel show minor deviations from solar abundances. Anomalies among the odd-Z elements through copper are mostly small. Beyond the iron peak, a huge scatter is found. Enormous enhancements are found for the elements rhenium through mercury (Z = 75-80). We note the presence of ThIII in the spectrum. The abundance pattern of the heaviest elements resembles the N = 126 r-process peak of solar material, though not in detail. An odd-Z anomaly appears at the triplet (Zr Nb Mo), and there is a large abundance jump between Xe (Z = 54) and Ba (Z = 56). These are signatures of chemical fractionation. We find a significant correlation of the abundance excesses with second ionization potentials for elements with Z > 30. If this is not a red herring (false lead), it indicates the relevance of photospheric or near-photospheric processes. Large excesses (4-6 dex) require diffusion from deeper layers with the elements passing through a number of ionization stages. That would make the correlation with second ionization potential puzzling. We explore a model with mass accretion of exotic material followed by the more commonly accepted differentiation by diffusion. That model leads to a number of predictions which challenge future work. New observations confirm the orbital elements of Gieseking and Karimie, apart from the systemic velocity, which has increased. Likely primary and secondary masses are near 3.3 and 1.6 Msolar, with a separation of ca. 0.25 au. New atomic structure calculations are presented in two appendices. These include partition functions for the first through third spectra of Ru, Re and Os, as well as oscillator strengths in the ReII spectrum. Based on observations obtained at the

  20. 撞瘪的AE86

    Institute of Scientific and Technical Information of China (English)

    王非

    2009-01-01

    你有爱AE86的朋友?我信你有,谁都有。问问他们,AE86出演过什么电影?他们会先笑你,然后告诉你:当然是"头文字D"。是啊,他们当然是想跟你聊藤原拓海。忘了给你这样答案的朋友,跟他们自己想的不一样,他们一点都不酷。看起来,他们丝毫未经过1980-90以前的indie movie潮流洗礼。他们知道Vincent Gallo是谁吗?或者Jim Jarmusch,或者Lars von Trier,或者Gus Van Sant?就连这些基本项,他们都未必知道(Sean Penn出演Gus Van Sant的Milk,今年都有Oscar the best actor可拿,早已征服主流),遑论更小众更独立的电影人。

  1. ASASSN-14ae: A Tidal Disruption Event at 200 Mpc

    CERN Document Server

    Holoien, Thomas W -S; Bersier, D; Kochanek, C S; Stanek, K Z; Shappee, B J; Grupe, D; Basu, U; Beacom, J F; Brimacombe, J; Brown, J S; Davis, A B; Jencson, J; Pojmanski, G; Szczygiel, D M

    2014-01-01

    ASASSN-14ae is a candidate tidal disruption event (TDE) found at the center of SDSS J110840.11+340552.2 ($d\\simeq200$ Mpc) by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global array of 14-cm telescopes. The host galaxy is an early type spiral with no signs of an active galactic nucleus (AGN) and with little recent star formation. We present follow-up photometric and spectroscopic observations of the source, including optical data from ground-based telescopes and ultraviolet and optical data from Swift. From blackbody fits to the host-subtracted spectral energy distribution, we find that the transient had a peak luminosity of $L\\simeq8\\times10^{43}$ erg s$^{-1}$ and a total integrated energy of $E\\simeq1.5\\times10^{50}$ ergs over the $\\sim3$ months of observations presented. The blackbody temperature of the transient remains roughly constant at $T\\sim20,000$ K while the luminosity declines by nearly 1.5 orders of magnitude during this time, a drop that is most consistent with an exponential, $L\\p...

  2. Do Hydrogen-deficient Carbon Stars have Winds?

    CERN Document Server

    Geballe, T R; Clayton, Geoffrey C

    2009-01-01

    We present high resolution spectra of the five known hydrogen-deficient carbon (HdC) stars in the vicinity of the 10830 Angstrom line of neutral helium. In R Coronae Borealis (RCB) stars the He I line is known to be strong and broad, often with a P Cygni profile, and must be formed in the powerful winds of those stars. RCB stars have similar chemical abundances as HdC stars and also share greatly enhanced 18O abundances with them, indicating a common origin for these two classes of stars, which has been suggested to be white dwarf mergers. A narrow He I absorption line may be present in the hotter HdC stars, but no line is seen in the cooler stars, and no evidence for a wind is found in any of them. The presence of wind lines in the RCB stars is strongly correlated with dust formation episodes so the absence of wind lines in the HdC stars, which do not make dust, is perhaps to be expected.

  3. No hydrogen exosphere detected around the super-Earth HD 97658 b

    Science.gov (United States)

    Bourrier, V.; Ehrenreich, D.; King, G.; Lecavelier des Etangs, A.; Wheatley, P. J.; Vidal-Madjar, A.; Pepe, F.; Udry, S.

    2017-01-01

    The exoplanet HD 97658 b provides a rare opportunity to probe the atmospheric composition and evolution of moderately irradiated super-Earths. It transits a bright K star at a moderate orbital distance of 0.08 au. Its low density is compatible with a massive steam envelope that could photodissociate at high altitudes and become observable as escaping neutral hydrogen. Our analysis of three transits with HST/STIS at Lyman-α reveals no such signature, suggesting that the thermosphere of HD 97658 b is not hydrodynamically expanding and is subjected to a low escape of neutral hydrogen (core. We determine an average reference for the intrinsic Lyman-α line and X-EUV (XUV) spectrum of the star, and show that HD 97658 b is in mild conditions of irradiation compared to other known evaporating exoplanets with an XUV irradiation about three times lower than the evaporating warm Neptune GJ436 b. This could be the reason why the thermosphere of HD 97658 b is not expanding: the low XUV irradiation prevents an efficient photodissociation of any putative steam envelope. Alternatively, it could be linked to a low hydrogen content or inefficient conversion of the stellar energy input. The HD 97658 system provides clues for understanding the stability of low-mass planet atmospheres in terms of composition, planetary density, and irradiation. Our study of HD 97658 b can be seen as a control experiment of our methodology, confirming that it does not bias detections of atmospheric escape and underlining its strength and reliability. Our results show that stellar activity can be efficiently discriminated from absorption signatures by a transiting exospheric cloud. They also highlight the potential of observing the upper atmosphere of small transiting planets to probe their physical and chemical properties.

  4. Evidence for the Direct Detection of the Thermal Spectrum of the Non-Transiting Hot Gas Giant HD 88133 b

    Science.gov (United States)

    Piskorz, Danielle; Crockett, Nathan R.; Lockwood, Alexandra; Benneke, Björn; Blake, Geoffrey A.; Barman, Travis S.; Bender, Chad F.; Bryan, Marta; Carr, John S.; Fischer, Debra; Howard, Andrew; Isaacson, Howard T.; Johnson, John A.

    2016-10-01

    We target the thermal emission spectrum of the non-transiting gas giant HD 88133 b with high-resolution near-infrared spectroscopy, by treating the planet and its host star as a spectroscopic binary. For sufficiently deep summed flux observations of the star and planet across multiple epochs, it is possible to resolve the signal of the hot gas giant's atmosphere compared to the brighter stellar spectrum, at a level consistent with the aggregate shot noise of the full data set. To do this, we first perform a principal component analysis to remove the contribution of the Earth's atmosphere to the observed spectra. Then, we use a cross-correlation analysis to tease out the spectra of the host star and HD 88133 b to determine its orbit and identify key sources of atmospheric opacity. In total, six epochs of Keck NIRSPEC L band observations and three epochs of Keck NIRSPEC K band observations of the HD 88133 system were obtained. Based on an analysis of the maximum likelihood curves calculated from the multi-epoch cross correlation of the full data set with two atmospheric models, we report the direct detection of the emission spectrum of the non-transiting exoplanet HD 88133 b and measure a radial projection of its Keplerian orbital velocity, its true mass, its orbital inclination, and dominant atmospheric species. This, combined with eleven years of radial velocity measurements of the system, provides the most up-to-date ephemeris for HD 88133.

  5. Unravelling the Nature of HD 81032 – A New RS CVn Binary

    Indian Academy of Sciences (India)

    J. C. Pandey; K. P. Singh; S. A. Drake; R. Sagar

    2005-12-01

    BVR photometric and quasi-simultaneous optical spectroscopic observations of the star HD 81032 have been carried out during the years 2000–2004. A photometric period of 18.802 ± 0.07d has been detected for this star. A large group of spots with a migration period of 7.43 ± 0.07 years is inferred from the first three years of the data. H and CaII H and K emissions from the star indicate high chromospheric activity. The available photometry in the BVRIJHK bands is consistent with the spectral type of K0IV previously found for this star.We have also examined the spectral energy distribution of HD 81032 for the presence of an infrared colour excess using the 2MASS JHK and IRAS photometry, but found no significant excess in any band above the normal values expected for a star with this spectral type. We have also analyzed the X-ray emission properties of this star using data obtained by the ROSAT X-ray observatory during its All-Sky Survey phase. An X-ray flare of about 12 hours duration was detected during the two days of X-ray coverage obtained for this star. Its X-ray spectrum, while only containing 345 counts, is inconsistent with a single-temperature component solar-abundance coronal plasma model, but implies either the presence of two or more plasma components, non-solar abundances, or a combination of both of these properties. All of the above properties of HD 81032 suggest that it is a newly identified, evolved RS CVn binary.

  6. Dynamic nuclear polarization in solid HD

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    1996-12-31

    Polarized solid HD targets containing only polarizable nuclei provide the possibility to do nuclear physics experiments of overwhelming quality compared with conventional targets. Based on recent results of Solem and the experience with solid HD as a target material, an experimental setup is suggested for further investigation of dynamic polarization in HD. The influence of temperature, field, radiation dose and the concentrations of H{sub 2}, D{sub 2} and paramagnetic O{sub 2} impurities can be investigated in a systematic way. (K.A.). 18 refs.

  7. Stars resembling the Sun

    Science.gov (United States)

    Cayrel de Strobel, G.

    stars tightly neighbouring the Sun in mass, chemical composition and state of evolution. The surprising result is that the stars occupy in this HR Diagram a rather extended region around the Sun, many of them seem more evolved and older than the Sun, and only 4 of the evolved stars seem younger. The age of some stars in the sample is also discussed in terms of chromospheric activity and Li-content. Our conclusion is much the same as that contained in previous papers we have written on the subject: in spite of a much larger number of stars, we have not been able to nominate a single star of the sample for a ``perfect good solar twin''. Another aim in beginning, 25 years ago, this search for solar analogues, was to have ready a bunch of stars resembling the Sun and analysed spectroscopically in detail, in order that, when planets hunters of solar type stars, finally would have found such a specimen, we would have been able to immediately compare the physical parameters of this star to those of the Sun. We have been lucky enough: one of the good solar analogues we present herewith, is 51 Pegasi (HD 217014) which, according to the very recent observations by Mayor and Queloz (1995), has a planet orbiting around it. And what is more: two other stars possessing planets: 47 Ursae Majoris (HD 95128) and 70 Virginis (HD 117176), have just been discovered by Marcy and Butler (187th Meeting of the AAS, January 1996). One of them, 47 Ursae Majoris, is also included in the list of photometric solar analogues. The other star, 70 Virginis, has only been included after the ``Planets News'', because the colour index (B-V) of this star is slightly higher than the prescribted limit of the selection, (B-V = 0.71, instead, 0.69). It would have been a pity to leave the third '' planet star out of the competition.

  8. The SOPHIE search for northern extrasolar planets. II. A multiple planet system around HD 9446

    Science.gov (United States)

    Hébrard, G.; Bonfils, X.; Ségransan, D.; Moutou, C.; Delfosse, X.; Bouchy, F.; Boisse, I.; Arnold, L.; Desort, M.; Díaz, R. F.; Eggenberger, A.; Ehrenreich, D.; Forveille, T.; Lagrange, A.-M.; Lovis, C.; Pepe, F.; Perrier, C.; Pont, F.; Queloz, D.; Santos, N. C.; Udry, S.; Vidal-Madjar, A.

    2010-04-01

    We report the discovery of a planetary system around HD 9446, performed from radial velocity measurements secured with the spectrograph SOPHIE at the 193-cm telescope of the Haute-Provence Observatory for more than two years. At least two planets orbit this G5V, active star: HD 9446b has a minimum mass of 0.7 MJup and a slightly eccentric orbit with a period of 30 days, whereas HD 9446c has a minimum mass of 1.8 MJup and a circular orbit with a period of 193 days. As for most of the known multiple planet systems, the HD 9446-system presents a hierarchical disposition with a massive outer planet and a lighter inner planet. Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (program 07A.PNP.CONS). The full version of Table 1 (SOPHIE measurements of HD 9446) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/513/A69

  9. HD 16771: A lithium-rich giant in the red-clump stage

    CERN Document Server

    Reddy, Arumalla B S

    2016-01-01

    Aims: We report the discovery of a young lithium rich giant, HD 16771, in the core-helium burning phase that does not seem to fit existing proposals of Li synthesis near the luminosity function bump or during He-core flash. We aim to understand the nature of Li enrichment in the atmosphere of HD 16771 by exploring various Li enhancement scenarios. Methods: We have collected high-resolution echelle spectra of HD 16771 and derived stellar parameters and chemical abundances for 27 elements by either line equivalent widths or synthetic spectrum analyses. Results: HD 16771 is a Li-rich (log(n(Li))=+2.67+/-0.10 dex) intermediate mass giant star (M=2.4+/-0.1 Msun) with age=0.76+/-0.13 Gyr and located at the red giant clump. Kinematics and chemical compositions are consistent with HD 16771 being a member of the Galactic thin disk population. The non-detection of 6Li(< 3%), a low carbon isotopic ratio (12C/13C=12+/-2), and the slow rotation (vsini=2.8 km/s) all suggest that lithium might have been synthesized in th...

  10. Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546

    CERN Document Server

    Kama, M; van Dishoeck, E F; Hogerheijde, M; Folsom, C P; Miotello, A; Fedele, D; Belloche, A; Güsten, R; Wyrowski, F

    2016-01-01

    The composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two systems with a similar age and disk mass, but different central stars: HD 100546 and TW Hya. We combine our recent detections of C$^{0}$ in these disks with observations of other carbon reservoirs (CO, C$^{+}$, C$_{2}$H) and gas mass and warm gas tracers (HD, O$^{0}$), as well as spatially resolved ALMA observations and the spectral energy distribution. The disks are modelled with the DALI 2D physical-chemical code. Stellar abundances for HD 100546 are derived from archival spectra. Upper limits on HD emission from HD 100546 place an upper limit on the total disk mass of $\\leq0.1\\,M_{\\odot}$. The gas-phase carbon abundance in the atmosphere of this warm Herbig disk is at most moderately depleted compared to the interstellar medium, with [C]/[H]$_{\\rm gas}=(0.1-1.5)\\times 1...

  11. Discovery of Molecular Gas around HD 131835 in an APEX Molecular Line Survey of Bright Debris Disks

    Science.gov (United States)

    Moór, A.; Henning, Th.; Juhász, A.; Ábrahám, P.; Balog, Z.; Kóspál, Á.; Pascucci, I.; Szabó, Gy. M.; Vavrek, R.; Curé, M.; Csengeri, T.; Grady, C.; Güsten, R.; Kiss, Cs.

    2015-11-01

    Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10-40 Myr old systems. We used the APEX and IRAM 30 m radio telescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3-2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk at both 70 and 100 μm, with a characteristic radius of ˜170 AU. While in stellar properties HD 131835 resembles β Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young (≤40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of a detectable amount of gas in the most massive debris disks around young A-type stars is a common phenomenon. Our current data cannot conclude on the origin of gas in HD 131835. If the gas is secondary, arising from the disruption of planetesimals, then HD 131835 is a comparably young, and in terms of its disk, more massive analog of the β Pic system. However, it is also possible that this system, similar to HD 21997, possesses a hybrid disk, where the gas material is predominantly primordial, while the dust grains are mostly derived from planetesimals.

  12. DISCOVERY OF MOLECULAR GAS AROUND HD 131835 IN AN APEX MOLECULAR LINE SURVEY OF BRIGHT DEBRIS DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Moór, A.; Ábrahám, P.; Kóspál, Á.; Szabó, Gy. M.; Kiss, Cs. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, H-1525 Budapest (Hungary); Henning, Th.; Balog, Z. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Juhász, A. [Institute of Astronomy, Madingley Road, Cambridge CB3, OHA (United Kingdom); Pascucci, I. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Vavrek, R. [Herschel Science Centre, ESA/ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691, Madrid (Spain); Curé, M. [Instituto de Física y Astronomía, Universidad de Valparaíso (Chile); Csengeri, T.; Güsten, R. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Grady, C., E-mail: moor@konkoly.hu [NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States)

    2015-11-20

    Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10–40 Myr old systems. We used the APEX and IRAM 30 m radio telescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3–2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk at both 70 and 100 μm, with a characteristic radius of ∼170 AU. While in stellar properties HD 131835 resembles β Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young (≤40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of a detectable amount of gas in the most massive debris disks around young A-type stars is a common phenomenon. Our current data cannot conclude on the origin of gas in HD 131835. If the gas is secondary, arising from the disruption of planetesimals, then HD 131835 is a comparably young, and in terms of its disk, more massive analog of the β Pic system. However, it is also possible that this system, similar to HD 21997, possesses a hybrid disk, where the gas material is predominantly primordial, while the dust grains are mostly derived from planetesimals.

  13. Direct detection of the tertiary component in the massive multiple HD 150136 with VLTI

    Science.gov (United States)

    Sanchez-Bermudez, J.; Schödel, R.; Alberdi, A.; Barbá, R. H.; Hummel, C. A.; Maíz Apellániz, J.; Pott, J.-U.

    2013-06-01

    Context. Massive stars are of fundamental importance for almost all aspects of astrophysics, but there still exist large gaps in our understanding of their properties and formation because they are rare and therefore distant. It has been found that most O-stars are multiples. It may well be that almost all massive stars are born as triples or higher multiples, but their large distances require milliarcsecond angular resolution for a direct detection of the companions. Aims: HD 150136 is the nearest system to Earth with >100 M⊙ and provides a unique opportunity to study an extremely massive system. Recently, evidence for the existence of a third component in HD 150136, in addition to the tight spectroscopic binary that forms the main component, was found in spectroscopic observations. Our aim was to image and obtain astrometric and photometric measurements of this component using long-baseline optical interferometry to further constrain the nature of this component. Methods: We observed HD 150136 with the near-infrared instrument AMBER attached to the ESO VLT Interferometer, which provides an angular resolution of 2 mas. The recovered closure phases are robust to systematic errors and provide unique information on the source asymmetry. Therefore, they are of crucial relevance for both image reconstruction and model fitting of the source structure. Results: The third component in HD 150136 is clearly detected in the high-quality data from AMBER. It is located at a projected angular distance of 7.3 mas, or about 13 AU at the line-of-sight distance of HD 150136, at a position angle of 209 degrees east of north, and has a flux ratio of 0.25 with respect to the inner binary. Our findings agree with previous results and have permitted us to improve the orbital solutions of the tertiary around the inner system. Conclusions: We resolved the third component of HD 150136 in J, H and K filters. The luminosity and color of the tertiary agrees with the predictions and shows

  14. BOREAS AES Campbell Scientific Surface Meteorological Data

    Science.gov (United States)

    Atkinson, G. Barrie; Funk, Barrie; Knapp. David E. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    Canadian AES personnel collected data related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from 14 automated meteorology stations located across the BOREAS region. Included in this data are parameters of date, time, mean sea level pressure, station pressure, temperature, dew point, wind speed, resultant wind speed, resultant wind direction, peak wind, precipitation, maximum temperature in the last hour, minimum temperature in the last hour, pressure tendency, liquid precipitation in the last hour, relative humidity, precipitation from a weighing gauge, and snow depth. Temporally, the data cover the period of August 1993 to December 1996. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  15. Acoustic Emissions (AE) Electrical Systems' Health Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Acoustic Emissions (AE) are associated with physical events, such as thermal activity, dielectric breakdown, discharge inception, as well as crack nucleation and...

  16. Multiple Lookup Table-Based AES Encryption Algorithm Implementation

    Science.gov (United States)

    Gong, Jin; Liu, Wenyi; Zhang, Huixin

    Anew AES (Advanced Encryption Standard) encryption algorithm implementation was proposed in this paper. It is based on five lookup tables, which are generated from S-box(the substitution table in AES). The obvious advantages are reducing the code-size, improving the implementation efficiency, and helping new learners to understand the AES encryption algorithm and GF(28) multiplication which are necessary to correctly implement AES[1]. This method can be applied on processors with word length 32 or above, FPGA and others. And correspondingly we can implement it by VHDL, Verilog, VB and other languages.

  17. First HARPSpol discoveries of magnetic fields in massive stars

    CERN Document Server

    Alecian, E; Neiner, C; Wade, G A; de Batz, B; Henrichs, H; Grunhut, J H; Bouret, J -C; Briquet, M; Gagne, M; Naze, Y; Oksala, M E; Rivinius, T; Townsend, R H D; Walborn, N R; Weiss, W

    2011-01-01

    In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. In this Letter, we report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements are strongly varying for HD 130807 from $\\sim$-100 G to $\\sim$700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from $\\sim$-40 to -80 G, and from $\\sim$-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of the MiMeS objectives: the understanding ...

  18. FM-HD RADIO的应用

    Institute of Scientific and Technical Information of China (English)

    黄文海

    2014-01-01

    结合中央塔FM-HD RADIO发射机,就HD RADIO技术应用于FM频段部分的频谱结构、发射机改造等方面进行阐述,并利用北京地区的测试数据说明现阶段该技术在FM频段的应用.

  19. Analysis of Exoplanet HD 149026b Using BLISS Mapping

    CERN Document Server

    Stevenson, Kevin B; Fortney, Jonathan; Loredo, Thomas J; Hardy, Ryan A; Nymeyer, Sarah; Bowman, William C; Cubillos, Patricio; Bowman, M Oliver; Hardin, Matthew

    2011-01-01

    The dayside of HD 149026b is near the edge of detectability by the Spitzer Space Telescope. We report on eleven secondary-eclipse events at 3.6, 4.5, 3 x 5.8, 4 x 8.0, and 2 x 16 {\\mu}m plus three primary transit events at 8.0 {\\mu}m. Multiple observations at the longer wavelengths improved eclipse-depth signal-to-noise ratios by up to a factor of two and improved estimates of the planet-to-star radius ratio (Rp/Rs = 0.0517 +/- 0.0005). We also identify no significant deviations from a circular orbit and, using this model, report an improved period of 2.8758916 +/- 0.0000014 days. Chemical-equilibrium models find no indication of a temperature inversion in the dayside atmosphere of HD 149026b. Our best-fit model favors large amounts of CO and CO2, moderate heat redistribution (f=0.5), and a strongly enhanced metallicity. Brightness temperatures range from 1600 to 2000 K. These analyses use BiLinearly-Interpolated Subpixel Sensitivity (BLISS) mapping, a new technique to model two position-dependent systematics...

  20. A Six-Planet System Orbiting HD 219134

    CERN Document Server

    Vogt, Steven S; Meschiari, Stefano; Butler, R Paul; Henry, Gregory W; Wang, Songhu; Holden, Brad; Gapp, Cyril; Hanson, Russell; Arriagada, Pamela; Keiser, Sandy; Teske, Johanna; Laughlin, Gregory

    2015-01-01

    We present new, high-precision Doppler radial velocity (RV) data sets for the nearby K3V star HD 219134. The data include 175 velocities obtained with the HIRES Spectrograph at the Keck I Telescope, and 101 velocities obtained with the Levy Spectrograph at the Automated Planet Finder Telescope (APF) at Lick Observatory. Our observations reveal six new planetary candidates, with orbital periods of P=3.1, 6.8, 22.8, 46.7, 94.2 and 2247 days, spanning masses of msini=3.8, 3.5, 8.9, 21.3, 10.8 and 108 M_earth respectively. Our analysis indicates that the outermost signal is unlikely to be an artifact induced by stellar activity. In addition, several years of precision photometry with the T10 0.8~m automatic photometric telescope (APT) at Fairborn Observatory demonstrated a lack of brightness variability to a limit of ~0.0002 mag, providing strong support for planetary-reflex motion as the source of the radial velocity variations. The HD 219134 system, with its bright (V=5.6) primary provides an excellent opportun...