Detection of a Hot Binary Companion of η Carinae
Abstract
We report the detection of a hot companion of η Carinae using high-resolution spectra (905-1180 Å) obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. Observations were obtained at two epochs of the 2024 day orbit: 2003 June, during ingress to the 2003.5 X-ray eclipse, and 2004 April, several months after egress. These data show that essentially all the far-UV flux from η Car shortward of Lyα disappeared at least 2 days before the start of the X-ray eclipse (2003 June 29), implying that the hot companion, η Car B, was also eclipsed by the dense wind or extended atmosphere of η Car A. Analysis of the far-UV spectrum shows that η Car B is a luminous, hot star. The N II λλ1084-1086 emission feature suggests that it may be nitrogen-rich. The observed far-UV flux levels and spectral features, combined with the timing of their disappearance, is consistent with η Car being a massive binary system.
Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by Johns Hopkins University under NASA contract NAS 5-32985.- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2005
- DOI:
- 10.1086/498268
- arXiv:
- arXiv:astro-ph/0510581
- Bibcode:
- 2005ApJ...633L..37I
- Keywords:
-
- Stars: Binaries: Eclipsing;
- Stars: Circumstellar Matter;
- Stars: Individual: Constellation Name: η Carinae;
- Stars: Mass Loss;
- Astrophysics
- E-Print:
- Astrophys.J.633:L37-L40,2005