/ftp/cats/J_AJ/138/1681



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J/AJ/138/1681             WD within 20pc of the Sun                (Sion+, 2009)
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	table1.dat table3.dat table4.dat
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Query from: http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/AJ/138/1681
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Beginning of ReadMe : J/AJ/138/1681 WD within 20pc of the Sun (Sion+, 2009) ================================================================================ The white dwarfs within 20 parsecs of the Sun: kinematics and statistics. Sion E.M., Holberg J.B., Oswalt T.D., McCook G.P., Wasatonic R. <Astron. J., 138, 1681-1689 (2009)> =2009AJ....138.1681S ================================================================================ ADC_Keywords: Stars, white dwarf ; Stars, distances ; Space velocities ; Stars, ages ; Spectral types ; Stars, nearby Keywords: stars: kinematics - stars: statistics - techniques: photometric - techniques: spectroscopic - white dwarfs Abstract: We present the kinematical properties, distribution of spectroscopic subtypes, and stellar population subcomponents of the white dwarfs within 20pc of the Sun. We find no convincing evidence of halo white dwarfs in the total 20pc sample of 129 white dwarfs nor is there convincing evidence of genuine thick disk subcomponent members within 20 parsecs. Virtually, the entire 20pc sample likely belongs to the thin disk. The total DA to non-DA ratio of the 20pc 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 20pc sample yields a revised local space density of white dwarfs of (4.9+/-0.5)x10^-3^pc^-3^ and a corresponding mass density of (3.3+/-0.3)x10^-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. Description: The local sample of 129 white dwarfs within 20pc is mainly the same as in Holdberg et al., 2008, Cat. J/AJ/135/1225 (124 stars). In this work, we use the enlarged local sample to examine the kinematical properties, distribution of spectroscopic subtypes, and stellar population subcomponents of the white dwarfs sampled in this volume of space around the Sun.

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