The Runaway White Dwarf LP400-22 Has a Companion
| Autor: | Kilic, Mukremin, Brown, Warren R., Prieto, Carlos Allende, Swift, B., Kenyon, S. J., Liebert, J., Agueros, M. A. |
|---|---|
| Rok vydání: | 2009 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/0004-637X/695/1/L92 |
| Popis: | We report the detection of a radial velocity companion to the extremely low mass white dwarf LP400-22. The radial velocity of the white dwarf shows variations with a semi-amplitude of 119 km/s and a 0.98776 day period, which implies a companion mass of M > 0.37 Msun. The optical photometry rules out a main sequence companion. Thus the invisible companion is another white dwarf or a neutron star. Using proper motion measurements and the radial velocity of the binary system, we find that it has an unusual Galactic orbit. LP400-22 is moving away from the Galactic center with a velocity of 396 km/s, which is very difficult to explain by supernova runaway ejection mechanisms. Dynamical interactions with a massive black hole like that in the Galactic center can in principle explain its peculiar velocity, if the progenitor was a triple star system comprised of a close binary and a distant tertiary companion. Until better proper motions become available, we consider LP400-22 to be most likely a halo star with a very unusual orbit. Comment: ApJ Letters, in press |
| Databáze: | arXiv |
| Externí odkaz: |
|