Physical Sciences and Mathematics Commons^™

Rotational And Cyclical Variability In Γ Cassiopeiae. Ii. Fifteen Seasons, Gregory W. Henry, Myron A. Smith

Information Systems and Engineering Management Research Publications

The B0.5 IVe star γ Cas is of great interest because it is the prototype of a small group of classical Be stars having hard X-ray emission of unknown origin. We discuss results from ongoing B and V observations of the γ Cas star–disk system acquired with an Automated Photometric Telescope during the observing seasons 1997–2011. In an earlier study, Smith, Henry, & Vishniac showed that light variations in γ Cas are dominated by a series of comparatively prominent cycles with amplitudes of 0.02–0.03 mag and lengths of 2–3 months, superimposed on a 1.21 day periodic signal some five times …

The Relationship Between Γ Cassiopeiae’S X-Ray Emission And Its Circumstellar Environment Ii. Geometry And Kinematics Of The Disk From Mirc And Vega Instruments On The Chara Array, Philippe Stee, O. Delaa, John D. Monnier, Anthony Meilland, Karine Perraut, Denis Mourard, Xiao Che, Gail H. Schaefer, Ettore Pedretti, Myron A. Smith, Raimundo Lopes De Oliveira, Christian Motch, Gregory W. Henry, Noel D. Richardson, Karen S. Bjorkman, R. Bücke, E. Pollmann, Juan Zorec, Douglas R. Gies, Theo A. Ten Brummelaar, Harold A. Mcalister, Nils H. Turner, Judit Sturmann, Laszlo Sturmann, Stephen T. Ridgway

Information Systems and Engineering Management Research Publications

Context.γ Cas is thought to be the prototype of classical Be stars and is the most studied object among this group. However, as for all Be stars, the origin and the physics of its circumstellar disk responsible for the observed near IR-excess, emission lines, and peculiar X-ray emission is still being debated.

Aims. We constrain the geometry and kinematics of its circumstellar disk from the highest spatial resolution ever achieved on this star. This investigation is a part of a large multi-technique observing campaign to obtain the most complete picture of γ Cas which emphasizes the relation of the …

Spectro-Interferometric Observations Of Classical Nova V458 Vul 2007, Samira Rajabi, Matthew W. Muterspaugh, Benjamin F. Lane, Martin M. Sirk, Stanley Browne, Askari Ghasempour, Samuel P. Halverson, John G. Kelly, Michael Williamson

Information Systems and Engineering Management Research Publications

We used the Palomar Testbed Interferometer (PTI) to resolve 2.2 μm emission from the classical nova V458 Vul 2007 over the course of several days following its discovery on 2007 August 8.54 UT. We also obtained K-band photometric data and spectra of the nova during the early days of the outburst. We also used photometric measurements from the AAVSO database. This is a unique data set offering a three-technique approach: high-resolution imaging, spectroscopy, and photometry. Our analysis shows that the nova ejecta can be modeled as an inclined disk at low inclination, i.e., low ellipticity which is consistent with the …

Absolute Properties Of The Eclipsing Binary Star V335 Serpentis, Claud H. Sandberg Lacy, Francis C. Fekel, Antonio Claret

Information Systems and Engineering Management Research Publications

V335 Ser is now known to be an eccentric double-lined A1+A3 binary star with fairly deep (0.5 mag) partial eclipses. Previous studies of the system are improved with 7456 differential photometric observations from the URSA WebScope and 5666 from the NFO WebScope, and 67 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope. From dates of minima, the apsidal period is about 880 years. Accurate (better than 2%) masses and radii are determined from analysis of the two new light curves and the radial velocity curve. Theoretical models match the absolute properties of the stars at …

Spot Activity Of Lq Hydra From Photometry Between 1988 And 2011, Jyri J. Lehtinen, Lauri Jetsu, Thomas Hackman, Perttu Kajatkari, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Aims. We investigate the spot activity of the young magnetically active main sequence star LQ Hya. Our aims are to identify possible active longitudes, estimate the differential rotation, and study long and short term changes in the activity.

Methods. Our analysis is based on 24 years of Johnson V-band photometry of LQ Hya obtained with the T3 0.4 m Automated Telescope at the Fairborn Observatory. We use the previously published continuous period search (CPS) method to model the evolution of the light curve of LQ Hya. The CPS fits a Fourier series model to short overlapping subsets …

Absolute Properties Of The Eclipsing Binary Star Bf Draconis, Claud H. Sandberg Lacy, Guillermo Torres, Francis C. Fekel, Jeffrey A. Sabby, Antonio Claret

Information Systems and Engineering Management Research Publications

BF Dra is now known to be an eccentric double-lined F6+F6 binary star with relatively deep (0.7 mag) partial eclipses. Previous studies of the system are improved with 7494 differential photometric observations from the URSA WebScope and 9700 from the NFO WebScope, 106 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory, and 31 accurate radial velocities from the CfA. Very accurate (better than 0.6%) masses and radii are determined from analysis of the two new light curves and four radial velocity curves. Theoretical models …

The Relationship Between Γ Cassiopeiae’S X-Ray Emission And Its Circumstellar Environment, Myron A. Smith, Raimundo Lopes De Oliveira, Christian Motch, Gregory W. Henry, Noel D. Richardson, Karen S. Bjorkman, Philippe Stee, Denis Mourard, John D. Monnier, Xiao Che, R. Bücke, E. Pollmann, Douglas R. Gies, Gail Schaefer, Theo A. Ten Brummelaar, Harold Mcalister, Nils H. Turner, Judit Sturmann, Laszlo Sturmann, Stephen T. Ridgway

Information Systems and Engineering Management Research Publications

γ Cas is the prototypical classical Be star and is recently best known for its variable hard X-ray emission. To elucidate the reasons for this emission, we mounted a multiwavelength campaign in 2010 centered around four XMM-Newton observations. The observational techniques included long baseline optical interferometry (LBOI) from two instruments at CHARA, photometry carried out by an automated photometric telescope and Hα observations. Because γ Cas is also known to be in a binary, we measured radial velocities from the Hα line and redetermined its period as 203.55 ± 0.20 days and its eccentricity as near zero. The LBOI observations …

Third Component Search And Abundances Of The Very Dusty Short-Period Binary Bd +20°307, Francis C. Fekel, Maria J. Cordero, Raphael Galicher, Benjamin Zuckerman, Carl Melis, Alycia J. Weinberger

Information Systems and Engineering Management Research Publications

We have obtained near-infrared adaptive optics imaging and collected additional radial velocity observations to search for a third component in the extremely dusty short-period binary system BD +20°307. Our image shows no evidence for a third component at separations greater than 19 AU. Our four seasons of radial velocities have a constant center-of-mass velocity and are consistent with the systemic velocities determined at two earlier epochs. Thus, the radial velocities also provide no support for a third component. Unfortunately, the separation domains covered by our imaging and radial velocity results do not overlap. Thus, we examined the parameters for possible …

Asteroseismology Of The Nearby Sn-Ii Progenitor: Rigel. I. The Most High-Precision Photometry And Radial Velocity Monitoring, Ehsan Moravveji, Edward F. Guinan, Matt Shultz, Michael H. Williamson, Andres Moya

Information Systems and Engineering Management Research Publications

Rigel (β Ori, B8 Ia) is a nearby blue supergiant displaying α Cyg type variability, and is one of the nearest Type II supernova progenitors. As such it is an excellent test bed to study the internal structure of pre-core-collapse stars. In this study, for the first time, we present 28 days of high-precision MOST photometry and over six years of spectroscopic monitoring. We report 19 significant pulsation modes of signal-to-noise ratio, S/N ≳ 4.6 from radial velocities, with variability timescales ranging from 1.21 to 74.7 days, which are associated with high-order low-degree gravity modes. While the radial velocity variations …