Browsing by Author "Guenther, David B."

Browsing by Author "Guenther, David B."

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    Evolution, structure, and seismology of intermediate-mass stars 
    Guenther, David B. (American Astronomical Society, 2002-04)
    The interior structure, the evolution, and the p-mode oscillation spectra of stellar models between 2.0 and 5 M[subscript circled dot] are presented. Interior details, including convective core and envelope growth and ...

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    Evolutionary influences on the structure of red-giant acoustic oscillation spectra from 600d of Kepler observations 
    Guenther, David B.; Gruberbauer, Michael; Kallinger, T.; Hekker, S.; Mosser, B.; De Ridder, J.; Bedding, T. R.; Elsworth, Y. P.; Stello, D.; Basu, S. (EDP Sciences, 2012-05)
    Context. It was recently discovered that the period spacings of mixed pressure/gravity dipole modes in red giants permit a distinction between the otherwise unknown evolutionary stage of these stars. The Kepler space mission ...

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    Evolutionary model and oscillation frequencies for [alpha] Ursae Majoris: a comparison with observations 
    Guenther, David B.; Demarque, P.; Buzasi, D.; Catanzarite, J.; Laher, R.; Conrow, T.; Kreidl, T. (American Astronomical Society, 2000-02)
    Inspired by the observations of low-amplitude oscillations of [alpha] Ursae Majoris A by Buzasi et al. using the WIRE satellite, a grid of stellar evolutionary tracks has been constructed to derive physically consistent ...

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    Evolutionary models and pulsation analysis of selected MOST and MONS target stars : [Epsilon] Eridani, [Beta] Hydri, and [Beta] Geminorum 
    MacDonald, Peter A. (Halifax, N.S. : Saint Mary's University, 2001)
    Stellar evolution models and their associated non-radial pulsation spectra are presented for the nearby stars [varepsilon] Eridani (K2 V), β Hydri (G2 IV), β Geminorum (K2 III). This analysis was performed in preparation ...

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    The [gamma]-ray binary LS 5039: mass and orbit constraints from MOST observations 
    Sarty, Gordon E.; Szalai, Tamas; Kiss, Laszlo L.; Matthews, Jaymie M.; Wu, Kinwah; Kuschnig, Rainer; Guenther, David B.; Moffat, Anthony F. J.; Rucinski, Slavek M.; Sasselov, Dimitar (Wiley-Blackwell, 2011-02)
    The results of a coordinated space-based photometric and ground-based spectroscopic observing campaign on the enigmatic γ-ray binary LS 5039 are reported. 16 d of observations from the MOST satellite have been combined ...

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    Global parameter and helioseismic tests of solar variability models 
    Guenther, David B.; Li, L. H.; Basu, S.; Sofia, S.; Robinson, F. J.; Demarque, P. (American Astronomical Society and IOP Publishing, 2003-07-10)
    We construct models of the structure and evolution of the Sun which include variable magnetic fields and turbulence. The magnetic effects are (1) magnetic pressure, (2) magnetic energy, and (3) magnetic modulation to ...

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    HR 5907: discovery of the most rapidly rotating magnetic early B-type star by the MiMeS collaboration 
    Guenther, David B.; Grunhut, J. H.; Rivinius, Th.; Wade, G. A.; Townsend, R. H. D.; Marcolino, W. L. F.; Bohlender, D. A.; Szeifert, Th.; Petit, V.; Matthews, J. M. (Oxford University Press, 2012-01)
    We report the discovery and analysis of a very strong magnetic field in the rapidly rotating early B-type star HR 5907, based on observations obtained as part of the Magnetism in Massive Stars (MiMeS) project. We infer a ...

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    Inclusion of turbulence in solar modeling 
    Guenther, David B.; Li, L. H.; Robinson, F. J.; Demarque, P.; Sofia, S. (American Astronomical SocietyIOP Publishing, 2002-03-10)
    The general consensus is that in order to reproduce the observed solar p-mode oscillation frequencies, turbulence should be included in solar models. However, until now there has not been any well-tested efficient method ...

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    Looking for giant earths in the HD 209458 system: a search for transits in MOST space-based photometry 
    Guenther, David B.; Croll, Bryce; Matthews, Jaymie M.; Rowe, Jason F.; Kuschnig, Rainer; Walker, Andrew; Gladman, Brett; Sasselov, Dimitar; Cameron, Chris; Walker, Gordon A. H. (American Astronomical Society, 2007-04)
    We have made a comprehensive transit search for exoplanets down to about 2 Earth radii in the HD 209458 system, based on nearly uninterrupted broadband optical photometry obtained with the MOST (Microvariability and ...

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    Looking for super-Earths in the HD 189733 system: a search for transits in MOST space-based photometry 
    Croll, Bryce; Matthews, Jaymie M.; Rowe, Jason F.; Gladman, Brett; Miller-Ricci, Eliza; Sasselov, Dimitar; Walker, Gordon A. H.; Kuschnig, Rainer; Lin, Douglas N. C.; Guenther, David B. (American Astronomical Society, 2007-12-20)
    We have made a comprehensive transit search for exoplanets down to [similar or equal to]1.5-2 Earth radii in the HD 189733 system, based on 21 days of nearly uninterrupted broadband optical photometry obtained with the ...

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    The mass of the planet-hosting giant star [beta] Geminorum determined from its p-mode oscillation spectrum 
    Guenther, David B.; Hatzes, A. P.; Zechmeister, M.; Matthews, J.; Kuschnig, R.; Walker, G. A. H.; Dollinger, M.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D. (EDP Sciences, 2012-07)
    Aims. Our aim is to use precise radial velocity measurements and photometric data to derive the frequency spacing of the p-mode oscillation spectrum of the planet-hosting star [beta] Gem. This spacing along with the ...

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    Matching stellar models to oscillation data 
    Guenther, David B.; Brown, Kevin I. T. (American Astronomical Society, 2004-01)
    We describe a method to match stellar models to a set of low-l p-mode oscillation frequencies. The method provides a quality of fit measure similar to that obtained from a [subscript X][superscript 2] fit. With a sufficiently ...

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    Modeling convective core overshoot and diffusion in Procyon constrained by asteroseismic data 
    Guenther, David B.; Demarque, P.; Gruberbauer, Michael (IOP Publishing Limited, 2014-06-01)
    We compare evolved stellar models, which match Procyon’s mass and position in the HR diagram, to current groundbased asteroseismic observations. Diffusion of helium and metals along with two conventional core overshoot ...

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    MOST detects corotating bright spots on the mid-O-type giant Xi Persei 
    Ramiaramanantsoa, Tahina; Moffat, Anthony F. J.; Chene, Andre-Nicolas; Richardson, Noel D.; Henrichs, Huib F.; Desforges, Sebastien; Antoci, Victoria; Rowe, Jason F.; Matthews, Jaymie M.; Kuschnig, Rainer; Guenther, David B. (Oxford University Press, 2014-06)
    We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei in 2011 November . ...

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    MOST detects g- and p-modes in the B supergiant HD 163899 (B2 Ib/II ) 
    Saio, H.; Kuschnig, R.; Gautschy, A.; Cameron, Chris; Walker, G. A. H.; Matthews, J. M.; Guenther, David B.; Moffat, A. F .J.; Rucinski, S. M.; Sasselov, D. (American Astronomical Society, 2006-10-20)
    The Microvariability and Oscillations of Stars (MOST ) satellite observed the B supergiant HD 163899 (B2 Ib/ II ) for 37 days as a guide star and detected 48 frequencies [less than tilde] 2.8 cycles day [superscript minus ...

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    MOST detects SPBe pulsations in HD 127756 and HD 217543: asteroseismic rotation rates independent of v sin i[superscript 1] 
    Guenther, David B.; Cameron, Chris; Saio, H.; Kuschnig, R.; Walker, G. A. H.; Matthews, J. M.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W. (American Astronomical Society, 2008-09)
    The MOST (Microvariability and Oscillations of Stars ) satellite has discovered SPBe (slowly pulsating Be) oscillations in the stars HD 127756 (B1/B2 Vne) and HD 217543 (B3 Vpe). For HD 127756, 30 significant frequencies ...

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    MOST detects transits of HD 97658b, a warm, likely volatile-rich super-Earth 
    Dragomir, Diana; Matthews, Jaymie M.; Eastman, Jason D.; Cameron, Chris; Howard, Andrew W.; Guenther, David B.; Kuschnig, Rainer; Moffat, Anthony F. J.; Rowe, Jason F.; Rucinski, Slavek M. (IOP Publishing Limited, 2013-07-20)
    Through photometric monitoring of the extended transit window of HD 97658b with the MOST space telescope, we have found that this exoplanet transits with an ephemeris consistent with that predicted from radial velocity ...

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    MOST finds no coherent oscillations in the hot carbon-rich Wolf-Rayet star HD 165763 (WR 111) 
    Guenther, David B.; Moffat, A. F. J.; Marchenko, S. V.; Zhilyaev, B. E.; Rowe, J. F.; Muntean, V.; Chene, A.-N.; Matthews, J. M.; Kuschnig, R.; Rucinski, S. M. (American Astronomical SocietyIOP Publishing, 2008-05-20)
    We have photometrically monitored the V = 8 mag Galactic Population I WC5 star WR 111 for 3 weeks nonstop using the MOST microsatellite. Each of the ∼27,000 data points has a precision of ∼3 mmag. We find no coherent Fourier ...

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    MOST light-curve analysis of the [gamma] Doradus pulsator HR8799, showing resonances and amplitude variations 
    Sodor, A.; Chene, A. -N.; De Cat, P.; Bognar, Zs.; Wright, D. J.; Marois, C.; Walker, G. A. H.; Matthews, J. M.; Kallinger, T.; Rowe, J. F.; Guenther, David B. (EDP Sciences, 2014-08)
    Context. The central star of the HR 8799 system is a γ Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the ...

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    MOST observations of [sigma] Ori E: challenging the centrifugal breakout narrative 
    Guenther, David B.; Townsend, R. H. D.; Rivinius, Th.; Rowe, J. F.; Moffat, A. F. J.; Matthews, J. M.; Bohlender, D.; Neiner, C.; Telting, J. H.; Kallinger, T. (American Astronomical SocietyIOP Science, 2013-05-20)
    We present results from three weeks’ photometric monitoring of the magnetic helium-strong star [sigma] Ori E using the Microvariability and Oscillations of Stars microsatellite. The star’s light curve is dominated by ...