We report on high dispersion spectroscopy of the Ha absorption line of
the cool DA white dwarf G 29 -38. This is the star for which a recently detected
infrared excess has been suggested to be due to a possible brown dwarf companion by
Zuckerman and Becklin (1986, 1987). Three echelle spectra obtained at the Multiple
Mirror Telescope and at the Kitt Peak Mayall 4m telescope in 1987 December show
no evidence for radial velocity variations larger than -'1.1 ± 8.7 km s -1 and are used
to derive a weighted heliocentric radial velocity Vr = 33.7 ± 4.3 km s -1 for the white
dwarf. No emission component from the hypothesized secondary star is detected.
These negative results do not constitute strong evidence against the companion
hypothesis, since the expected orbital velocity of the white dwarf component could
be quite small, and the companion's line emission could be too faint to be detected.
However, the observation of a sharp absorption line core restricts the possible rotation
of the white dwarf to < 40 km s -1 and ensures that any surface magnetic field has
a strength < 105 gauss. These results make it unlikely that the DA white dwarf
has previously been in a cataclysmic variable accretion phase.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/623899 |
| Date | 10 1900 |
| Creators | Liebert, J., Saffer, R. A., Pilachowski, C. A. |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | Steward Observatory, The University of Arizona (Tucson, Arizona) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Article |
| Source | Steward Observatory Parker Library SO QB 4 .S752 ARCH |
| Rights | Copyright © All Rights Reserved. |
| Relation | Preprints of the Steward Observatory #839, http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1989AJ.....97..182L&db_key=AST&data_type=HTML&format=&high=3ed65e9cd000634 |
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