Submitting Campus

Daytona Beach

Department

Physical Sciences

Document Type

Article

Publication/Presentation Date

10-30-2009

Abstract/Description

We present the kinematical properties, distribution of spectroscopic subtypes, and stellar population subcomponents of the white dwarfs within 20 pc of the Sun.We find no convincing evidence of halo white dwarfs in the total 20 pc sample of 129 white dwarfs nor is there convincing evidence of genuine thick disk subcomponent members within 20 parsecs. Virtually, the entire 20 pc sample likely belongs to the thin disk. The total DA to non-DA ratio of the 20 pc sample is 1.6, a manifestation of deepening envelope convection which transforms DA stars with sufficiently thin H surface layers into non-DAs. The addition of five new stars to the 20 pc sample yields a revised local space density of white dwarfs of (4.9±0.5)×10−3 pc−3 and a corresponding mass density of (3.3±0.3)×10−3 MꙨ pc−3.We find that at least 15% of the white dwarfs within 20 parsecs of the Sun (the DAZ and DZ stars) have photospheric metals that possibly originate from accretion of circumstellar material (debris disks) around them. If this interpretation is correct, this suggests the possibility that the same percentage have planets or asteroid-like bodies orbiting them.

Publication Title

The Astronomical Journal

DOI

https://doi.org/10.1088/0004-6256/138/6/1681

Publisher

IOP Publishing

Grant or Award Name

NSF grant AST05-07797, NSF grant AST-0807919

Additional Information

Dr. Oswalt was not affiliated with Embry-Riddle Aeronautical University at the time this paper was published.

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