AAS 205th Meeting, 9-13 January 2005
Session 170 White Dwarfs and Hot Subdwarfs
Oral, Thursday, January 13, 2005, 2:00-3:30pm, Sunrise

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[170.01] Photometric Analysis of Halo White Dwarf Candidates

M. T. Ruiz (Departamento de Astronomia, Universidad de Chile), P. Bergeron (Departement de Physique, Universite de Montreal), M. Hamuy (Carnegie Observatories), S. K. Leggett (UKIRT, Joint Astronomy Centre), M. J. Currie, C. -P. Lajoie (Departement de Physique, Universite de Montreal), P. Dufour (Starlink Project, Rutherford Laboratory)

A detailed analysis of 32 Halo white dwarf candidates identified by Oppenheimer et al. is presented, based on model atmosphere fits to observed energy distributions, built from optical BVRI and infrared JHK magnitudes. Effective temperatures and atmospheric compositions for all objects have been determined, as well as their masses and cooling ages for those with measured trigonometric parallaxes. The sample is compared with other Halo white dwarf candidates and Disk white dwarfs to study the nature of these objects in terms of reduce proper motion diagrams, tangential velocities, and stellar ages. We confirm the conclusions of an earlier analysis, based on photographic magnitudes of the same sample, that some white dwarfs born in the young Disk may have high velocities with respect to the Local Standard of Rest, and that total stellar ages must be derived in order to associate a white dwarf with the old Halo population.

M.T.R. received partial support from FONDECYT 1010404, and FONDAP 15010003. P.B. aknowledges partial support from NSERC Canada and Fund FQRNT (Quebec).

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© 2004. The American Astronomical Society.