NOAO >   Observing Info >   Approved Programs >   2005B-0108

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Proposal Information for 2005B-0108


PI: Philip Massey, Lowell Observatory, Phil.Massey@lowell.edu
Address: 1400 W. Mars Hill Rd, Flagstaff, Az 86001

CoI: Kathy Eastwood, Northern Arizona University
CoI: Douglas Gies, George State University
CoI: Nidia Morrell, Las Campanas Observatory
CoI: Virpi Niemela, Univ. Nacional de La Plata
CoI: Laura Penny, College of Charleston

Title: Taking Things to the Extreme: Using High Mass Stars to Resolve the Mass Discrepancy

Abstract: \vskip -0.2in The mass of a star is arguably its most fundamental property, and yet for high-mass stars there is a long-standing systematic difference between the masses determined from stellar evolutionary models, and those found from stellar atmosphere models. For the hottest stars, this mass discrepancy may amount to a factor of two or more. This proposal seeks to resolve this discrepancy by using high-mass binaries. This will allow the Co-Is to make critical comparisons between the masses determined by these two indirect methods with those found from simple Newtonian physics using the orbit solutions. More than simply identifying which approach gives the right answer, the results of this study will provide needed guidance to our theoretician colleagues both to know in what areas the models are reliable, and in what areas further improvement is needed. The approach will be to identify eclipsing binary systems photometrically in the first year, using frequent imaging of OB associations and clusters known to contain a wealth of high-mass stars, both in the Milky Way and in the Magellanic Clouds. This is the goal of the present proposal. Once these systems are identified, we will obtain radial velocities for orbits, and the high S/N data needed for stellar atmosphere modeling, using the facilities of Las Campanas. The observational program outlined here is ambitious, but all of the pieces are in place; the critical first step is to identify eclipsing systems, which can be readily accomplished with the 1.3-m synoptic queue.


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



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