New results on the helium stars in the galactic center using BEAR spectro-imagery
Abstract
Integral field spectroscopy of the central parsec of the Galactic Center was obtained at 2.06 mu m using BEAR, an imaging Fourier Transform Spectrometer, at a spectral resolution of 74 km s-1. Sixteen stars were confirmed as ``helium stars" by detecting the He I 2.058 mu m line in emission, providing a homogeneous set of fully resolved line profiles. These observations allow us to discard some of the earlier detections of such stars in the central cluster and to add three new stars. The sources detected in the BEAR data were compared with adaptive optics images in the K band to determine whether the emission was due to single stars. Two sub-classes of almost equal number are clearly identified from the width of their line profiles, and from the brightness of their continuum. The first class is characterized by very broad line profiles (FWHM =~ 1000 km s-1) and by their relative faintness. The other, brighter in K by an average factor of ~ 9, has a much narrower emission component of width =~ 200 km s-1. Most of the emission lines show a P Cygni profile. From these results, we propose that the latter group is formed of stars in or near the LBV phase, and the other one of stars at the WR stage. The division into two groups is also shown by their spatial distribution, with the narrow-line stars in a compact central cluster (
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2001
- DOI:
- 10.1051/0004-6361:20000227
- arXiv:
- arXiv:astro-ph/0011215
- Bibcode:
- 2001A&A...366..466P
- Keywords:
-
- INSTRUMENTATION: SPECTROGRAPH;
- TECHNIQUES: RADIAL VELOCITIES;
- INFRARED: STARS;
- GALAXY: CENTER;
- STARS: EARLY-TYPE;
- STARS: WOLF-RAYET;
- Astrophysics
- E-Print:
- 16 pages, 9 figures. To be published in Astronomy &