On the Nature of the Fast-Moving Star S2 in the Galactic Center
Abstract
We analyze the properties of the star S2 orbiting the supermassive black hole at the center of the Galaxy. A high-quality SINFONI H- and K-band spectrum obtained from co-adding 23.5 hr of observation between 2004 and 2007 reveals that S2 is an early B dwarf (B0-B2.5 V). Using model atmospheres, we constrain its stellar and wind properties. We show that S2 is a genuine massive star and not the core of a stripped giant star, as sometimes speculated to resolve the problem of star formation so close to the supermassive black hole. We give an upper limit on its mass-loss rate and show that it is He enriched, possibly because of the presence of a magnetic field.
Based on observations collected at the ESO Very Large Telescope (programs 075.B-0547, 076.B-0259, 077.B-0503, 078.B-0520, and 179.B-0261).- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2008
- DOI:
- 10.1086/526768
- arXiv:
- arXiv:0711.3344
- Bibcode:
- 2008ApJ...672L.119M
- Keywords:
-
- Galaxy: center;
- stars: early-type;
- stars: fundamental parameters;
- Astrophysics
- E-Print:
- 4 pages, 5 figures, ApJ letters accepted