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Title:
The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems
Authors:
Subasavage, John P.; Henry, Todd J.; Bergeron, P.; Dufour, P.; Hambly, Nigel C.; Beaulieu, Thomas D.
Affiliation:
AA(Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106, USA ), AB(Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106, USA ), AC(Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada ), AD(Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada ), AE(Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK ), AF(Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106, USA )
Publication:
The Astronomical Journal, Volume 134, Issue 1, pp. 252-261. (AJ Homepage)
Publication Date:
07/2007
Origin:
UCP
Astronomy Keywords:
solar neighborhood, stars: distances, stars: evolution, stars: statistics, white dwarfs
DOI:
10.1086/518739
Bibliographic Code:
2007AJ....134..252S

Abstract

We present spectra for 33 previously unclassified white dwarf systems brighter than V=17, primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect that three of these systems are unresolved double degenerates. We obtained VRI photometry for these 33 objects, as well as for 23 known white dwarf systems without trigonometric parallaxes, also primarily in the southern hemisphere. For the 56 objects, we converted the photometry values to fluxes and fit them to a spectral energy distribution using the spectroscopy to determine which model to use (i.e., pure hydrogen, pure helium, or metal-rich helium), resulting in estimates of Teff and distance. Eight of the new and 12 of the known systems are estimated to be within the NStars and Catalogue of Nearby Stars horizons of 25 pc, constituting a potential 18% increase in the nearby white dwarf sample. Trigonometric parallax determinations are under way via CTIOPI for these 20 systems. One of the DCs is cool, so it displays absorption in the near-infrared. Using the distance determined via trigonometric parallax, we are able to constrain the model-dependent physical parameters and find that this object is most likely a mixed H/He atmosphere white dwarf similar to other cool white dwarfs identified in recent years with significant absorption in the infrared due to collision-induced absorptions by molecular hydrogen.

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Part 1     Part  2     Part  3     Part  4     Part  5     Part  6     Part  7     Part  8     Part  9     Part 10     Part 11     Part 12     Part 13     Part 14     Part 15     Part 16     Part 17     Part 18     Part 19     Part 20     Part 21     Part 22     Part 23    

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