NOAO >   Observing Info >   Approved Programs >   2010A-0290

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Proposal Information for 2010A-0290


PI: Terry D. Oswalt, Florida Institute of Technology, toswalt@fit.edu
Address: Physics Department, 150 West University Boulevard, Melbourne, FL 32940, USA

CoI: Jingkun Zhao, National Astronomical Obs. of China
CoI: Jay Holberg, University of Arizona

Title: An Investigation of Post-main-sequence Mass Loss Using Wide Binary Stars

Abstract: We propose a study of widely separated binary stars that contain normal lower main sequence stars with distant non-interacting white dwarf (WD) companions. The physical separations of these wide pairs are typically 10^3 A.U., implying that they have evolved as single coeval stars. The ages of the white dwarfs, which span the entire history of the Solar neighborhood, are relatively easy to determine from their observed spectra. As stars evolve to the WD stage, most lose well over half their original mass. This initial-to-final mass relation is one of the weakest links in our understanding of stellar evolution and how matter is recycled into the interstellar medium. It is well established that stellar chromospheric activity declines with age in Solar-type stars. Stellar ages may also be estimated by isochrone fitting in color magnitude diagrams or via stellar rotation rate obtained from long-term photometric observations. These techniques yield their best precision in different age regimes. Subtracting the cooling time for a white dwarf companion from the total age of a main sequence companion given by any of these methods gives its progenitor main sequence lifetime, hence its initial mass. Using the above approach we propose to (a) independently calibrate the initial-to-final mass relation for white dwarf stars; and (b) refine and extend the empirical chromospheric activity vs. age relation for main sequence stars to as close to the age of the Galaxy's disk (~10 Gy) as possible.


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