AAS 201st Meeting, January, 2003
Session 119. White Dwarfs
Poster, Thursday, January 9, 2003, 9:20am-4:00pm, Exhibit Hall AB

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[119.04U] Cool Companions to White Dwarfs from the 2MASS Second Incremental Data Release

H. Taylor (UW), S. Wachter, D. W. Hoard (SSC/Caltech), R. Wilcox, K. Hansen, S. Finkelstein (UW)

We present near-IR magnitudes for all objects in the Catalog of Spectroscopically Identified White Dwarfs (WDs) by McCook & Sion that are contained in the 2-Micron All Sky Survey (2MASS) Second Incremental Data Release. Because WDs have traditionally been identified and studied via observations in the blue part of the spectrum, comparatively little is known about their infrared properties. WDs are promising targets in the search for low mass stellar and sub-stellar companions. Since WDs are less luminous than main sequence stars, the brightness contrast compared to a potential faint companion is significantly reduced. Most importantly, the markedly different spectral energy distributions of the WDs and low mass companions makes the detection and separation of the two components relatively straightforward even with simple broad-band multi-color photometry. We show that the near-IR color-color diagram is an effective means of selecting candidate binary stars containing a WD and a low mass main sequence star and identify 47 new binary candidates from our sample. We also compared a sample of simulated WD + red dwarf binaries with our 2MASS data. The colors of the simulated binaries are dominated by the low mass companion through the late-M to early-L spectral types. As the spectral type of the companion becomes progressively later, however, the colors of unresolved binaries become progressively bluer. Binaries containing the lowest mass companions will be difficult to distinguish from single WDs solely on the basis of their near-IR colors.

The author(s) of this abstract have provided an email address for comments about the abstract: hoard@ipac.caltech.edu

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.