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Full-Text Articles in Physical Sciences and Mathematics
Absolute Dimensions Of The G7+K7 Eclipsing Binary Star Im Virginis: Discrepancies With Stellar Evolution Models, Juan Carlos Morales, Guillermo Torres, Laurence A. Marschall, William C. Brehm
Absolute Dimensions Of The G7+K7 Eclipsing Binary Star Im Virginis: Discrepancies With Stellar Evolution Models, Juan Carlos Morales, Guillermo Torres, Laurence A. Marschall, William C. Brehm
Physics and Astronomy Faculty Publications
We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IMVir, composed of a G7-type primary and a K7 secondary.With these observations, we derive accurate absolute masses and radii of M1 = 0.981 + 0.012M, M2 = 0.6644 + 0.0048M, R1 = 1.061 + 0.016R, and R2 = 0.681 + 0.013R for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 + 100 K and 4250 + 130 K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory.We find that …
Optical Photometry And Spectroscopy Of The Suspected "Cool Algol" Av Delphini: Determination Of The Physical Properties, Jeff A. Mader, Laurence A. Marschall, Guillermo Torres, Akbar H. Rizvi
Optical Photometry And Spectroscopy Of The Suspected "Cool Algol" Av Delphini: Determination Of The Physical Properties, Jeff A. Mader, Laurence A. Marschall, Guillermo Torres, Akbar H. Rizvi
Physics and Astronomy Faculty Publications
We present new spectroscopic and BVRI photometric observations of the double-lined eclipsing binary AV Del ( period = 3:85 days) conducted over six observing seasons. A detailed radial velocity and light-curve analysis of the optical data shows the system to be most likely semidetached, with the less massive and cooler star filling its Roche lobe. The system is probably a member of the rare class of ‘‘cool Algol’’ systems, which are distinguished from the ‘‘classical’’ Algol systems in that the mass-gaining component is also a late-type star rather than a B- or A-type star. By combining the spectroscopic and photometric …
Optical Photometry And X-Ray Monitoring Of The "Cool Algol" Bd+05˚706: Determination Of The Physical Properties, Guillermo Torres, Jeff A. Mader, Laurence A. Marschall, Ralph Neuhauser, Alaine S. Duffy
Optical Photometry And X-Ray Monitoring Of The "Cool Algol" Bd+05˚706: Determination Of The Physical Properties, Guillermo Torres, Jeff A. Mader, Laurence A. Marschall, Ralph Neuhauser, Alaine S. Duffy
Physics and Astronomy Faculty Publications
We present new photometric observations in the BVRI bands of the double-lined eclipsing binary BD +05706 conducted over three observing seasons, as well as new X-ray observations obtained with ROSAT covering a full orbital cycle (P = 18.9 days). A detailed light-curve analysis of the optical data shows the system to be semidetached, confirming indications from an earlier analysis by Torres et al. (published in 1998), with the less massive and cooler star filling its Roche lobe. The system is a member of the rare class of cool Algol systems, which are different from the ‘‘ classical ’’ Algol systems …
New Rotation Periods In The Pleiades: Interpreting Activity Indicators, Anita Krishnamurthi, D. M. Terndrup, M. H. Pinsonneault, K. Sellgren, John R. Stauffer, Rudolph Schild, D. E. Backman, K. B. Beisser, D. B. Dahari, Amil Dasgupta, J. T. Hagelgans, M. A. Seeds, Rajan Anand '98, Bentley D. Laaksonen '95, Laurence A. Marschall, T. Ramseyer
New Rotation Periods In The Pleiades: Interpreting Activity Indicators, Anita Krishnamurthi, D. M. Terndrup, M. H. Pinsonneault, K. Sellgren, John R. Stauffer, Rudolph Schild, D. E. Backman, K. B. Beisser, D. B. Dahari, Amil Dasgupta, J. T. Hagelgans, M. A. Seeds, Rajan Anand '98, Bentley D. Laaksonen '95, Laurence A. Marschall, T. Ramseyer
Physics and Astronomy Faculty Publications
We present results of photometric monitoring campaigns of G, K and M dwarfs in the Pleiades carried out in 1994, 1995 and 1996. We have determined rotation periods for 18 stars in this cluster. In this paper, we examine the validity of using observables such as X-ray activity and amplitude of photometric variations as indicators of angular momentum loss. We report the discovery of cool, slow rotators with high amplitudes of variation. This contradicts previous conclusions about the use of amplitudes as an alternate diagnostic of the saturation of angular momentum loss. We show that the X-ray data can be …
Rotational Periods And Starspot Activity Of Young Solar-Type Dwarfs In The Open Cluster Ic 4665, S. Allain, C. Prosser, Laurence A. Marschall, Bentley D. Laaksonen
Rotational Periods And Starspot Activity Of Young Solar-Type Dwarfs In The Open Cluster Ic 4665, S. Allain, C. Prosser, Laurence A. Marschall, Bentley D. Laaksonen
Physics and Astronomy Faculty Publications
We present the results of a V-band photometric monitoring survey of 15 late-type dwarfs in the young open cluster IC 4665. Low-amplitude periodic light variations are found for 8 stars and ascribed to the modulation by starspots that cover typically a few percent of the stellar disk. Periods range from 0.6 to 3.7d, translating to equatorial velocities between 13 and 93 km.s-1. That no period longer than 4d was detected suggests a relative paucity of extremely slow rotators (Veq << 10 km.s-1) among late-type dwarfs in IC 4665. The fractional number of slow rotators in IC 4665 is similar to that of Alpha Per cluster, suggesting that IC 4665 is close in age to Alpha Per (~50 Myr).