The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics

TL;DR

This study analyzes the kinematics, distribution, and composition of white dwarfs within 20 parsecs, finding most belong to the thin disk, with some showing signs of planetary debris accretion, and providing updated density estimates.

Contribution

It provides a comprehensive kinematic and statistical analysis of nearby white dwarfs, including new data, revised density estimates, and insights into planetary debris around these stars.

Findings

No evidence of halo white dwarfs within 20 pc.

Approximately 15% of white dwarfs show signs of accreting circumstellar material.

Revised local white dwarf density: 4.9 ± 0.5 x 10^{-3} M_sun/yr.

Abstract

We present the kinematical properties, distribution of spectroscopic subtypes, 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 5 new stars to the 20 pc sample yields a revised local space density of white dwarfs of $4.9\pm0.5 \times 10^{-3}$ M$_{\sun}$/yr and a corresponding mass density of $3.3\pm0.3 \times 10^{-3}$ M$_{\sun}$/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.