Spectroscopic Discovery of Brown Dwarf-like Secondary Stars in the Cataclysmic Variables LL Andromedae and EF Eridani
Abstract
Infrared spectroscopic observations of LL Andromedae and EF Eridani are presented. Our K-band spectrum of LL And reveals the presence of methane absorption in the secondary star indicating an effective temperature <~1300 K, similar to a ``T''-type methane brown dwarf. The secondary star in EF Eri is seen to be warmer with an effective temperature of ~1650 K and a spectroscopic classification consistent with an L4-5 star. Both secondaries have theoretical mass estimates of 0.04-0.055 Msolar (40-55 MJup). Our IR spectroscopic observations of LL And and EF Eri provide the first direct proof of the theoretical prediction that post-period minimum cataclysmic variables contain brown dwarf-like secondary stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2001
- DOI:
- 10.1086/319499
- arXiv:
- arXiv:astro-ph/0101572
- Bibcode:
- 2001ApJ...550L..57H
- Keywords:
-
- Stars: Binaries: General;
- Stars: Novae;
- Cataclysmic Variables;
- Stars: Individual: Constellation Name: EF Eridani;
- Stars: Individual: Constellation Name: LL Andromedae;
- Stars: Low-Mass;
- Brown Dwarfs;
- Astrophysics
- E-Print:
- 8 pages, 2 figures. Accepted in Astrophysical Journal Letters