AAS 200th meeting, Albuquerque, NM, June 2002
Session 72. Degenerates
Display, Thursday, June 6, 2002, 9:20am-4:00pm, SW Exhibit Hall

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[72.03] Resolving Close Double Degenerates with HST/FGS1r

E.P. Nelan, R. B. Makidon (STScI), R. Saffer (Villanova)

We report on the results of high angular resolution interferometric survey of cool white dwarfs with HST's FGS1r (Cycle 10 proposal 9169). Our goal was to discover binary WD systems suitable for follow up studies to derive visual orbits and physical masses for both components. To maximize our prospects of success, we chose cool WD "primaries" since potential companions could not be much cooler and fainter. Our sample included (but was not limited to) WDs with spectroscopic indications of binarity. Based upon the incidence of duplicity among G-dwarfs, their period distribution, and the effects of common envelope (CE) evolution, we expected to discover ~6 wide systems in a survey of 60 stars. Instead we found only 2 wide systems (sep > 0.100"). But most interestingly, we found 3 systems with angular separations less than 0.030", indicating projected physical separations of less than ~0.7 A.U. This implies that these 3 objects are post-CE systems. But given that they did not spiral down to unresolvable, short period systems, that enjoyed a large value for alpha CE.

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

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