The Hunt for Nearby White Dwarfs

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White Dwarfs (WDs) serve as test beds to probe into astrophysically interesting questions such as (1) the ages of star clusters and Galactic components (i.e. disk, halo), (2) Galactic evolution, (3) halo dark matter constituents, (4) stellar structure theory, and (5) stellar evolution theory. The nearby WD population provides the brightest and most easily studied representatives.
How confident are we that all of the nearest WDs have been identified? In an effort to answer this question, we have begun an initiative to identify and characterize new nearby WDs, particularly in the southern hemisphere. We identify new WDs using medium resolution (R 1000) optical spectroscopy, and estimate physical parameters and distances using optical photometry combined with 2MASS near-infrared photometry. For objects within 25 pc (Catalogue of Nearby Stars, and NStars Database horizons), we determine a trigonometric parallax via CTIOPI (Cerro Tololo Inter-American Observatory Parallax Investigation).
Of the 43 new WD systems discovered so far, 21 are likely within 25 pc, a volume that contains 107 WDs with trigonometric parallaxes. A spectroscopic observing run in December will likely increase these values. Interesting objects include two that are likely double degenerates including one with a magnetic component, one that is a cool (T$_{eff}$ 5000 K) likely mixed atmosphere WD with deficient flux at near-infrared wavelengths, and three that are metal-rich. Observations are underway via the Hubble Space Telescope to resolve four potential double degenerates (the new magnetic WD and three other previously known WDs) for dynamical mass determinations.
All ground-based observations are obtained as part of the SMARTS (Small and Moderate Aperture Research Telescope System) Consortium at CTIO. We wish to thank NASA's Space Interferometry Mission, the National Science Foundation, the Space Telescope Science Institute, and GSU for their continued support.

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