Program: GS-2012A-Q-36

Our ongoing trigonometric parallax investigation of nearby stars (CTIOPI) has uncovered two intriguing white dwarf systems. Both systems have accurate parallaxes (better than 5%) that lie within 50 pc of the Sun. They are elevated on the H-R Diagram indicating that they are significantly overluminous compared to a single white dwarf at the same temperature. Follow-up spectroscopy using the Goodman Spectrograph on SOAR has revealed radial velocity variations on time scales of hours and days, respectively, for the two targets. The implications are that at least one component in each system is a low-mass white dwarf that can provide insight into the details of close binary evolution. Once an accurate orbit is measured, the masses of each component can be constrained to further understand the origin and fate of the system. We propose to robustly determine the orbital periods of these systems, constrain masses, and ultimately characterize how these systems came to be and better predict what they might become.