PI: Wei-Chun Jao, Georgia State University, email@example.com
Address: Physics Department, P.O. Box 4106, Atlanta, GA 30302, USA
CoI: Todd Henry, Georgia State University
CoI: John Subasavage, CTIO
Title: Fingerprinting a Mysterious Unseen Companion in the Solar Neighborhood
Abstract: We propose to use GMOS at Gemini-South to acquire a blue spectrum of a peculiar binary system discovered by the CTIOPI project. This system has the largest photocentric perturbation (~200 mas) among more than 500 systems we have observed for up to 10 years. Our red spectrum indicates that the primary is a red dwarf of type M5.0V, while our UBVRI photometry is consistent with combined light from the M5.0V star plus a cool (4500K) white dwarf secondary. However, the white dwarf has abnormally high flux at U compared to known cool white dwarfs. In addition, the GALEX mission indicates that this system has a very strong near-UV flux. Observations made via this proposal will allow us to confirm the nature of the mysterious unseen companion and model its physical properties, including its temperature and atmosphere abundance. Our continuing parallax observations and radial velocity measurements by Phoenix at Gemini-South (already scheduled) will yield a dynamical mass for a white dwarf cooler than 5000K for the first time.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360