NOAO >   Observing Info >   Approved Programs >   2009B-0240

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Proposal Information for 2009B-0240


PI: Stephen J. Williams, Georgia State University, swilliams@chara.gsu.edu
Address: Physics Department, P.O. Box 4106, Atlanta, GA 30302-4106, USA

CoI: Douglas R. Gies, Georgia State University
CoI: Rachel A. Matson, Georgia State University
CoI: Laura R. Penny, College of Charleston

Title: Weighing the Most Massive Stars of the Magellanic Clouds

Abstract: In a recent study of the FUV spectra of massive O-type stars in the Magellanic Clouds (undertaken to determine their projected rotational velocities), we discovered a number of double-lined, spectroscopic binaries. Two of these new binaries contain stars classified as O2 types, among the most massive stars known. Our goal in this proposal is to obtain the first radial velocity curves for these new massive binaries using the SOAR telescope and Goodman spectrograph. We would use these measurements to obtain orbital elements, extract the individual spectra in the blue-green range, and determine the effective temperatures and gravities through comparison with model spectra. This will allow us to place the stars correctly in the theoretical H-R diagram based upon their effective temperature and luminosity. Those systems with large derived mass functions (and hence high orbital inclination) will be targets of subsequent photometric study to fit the light curve, estimate inclination, and determine masses.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2009B-0240

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