Quantitative Spectroscopy of the HeI Cluster in the Galactic Center

F. Najarro(1) A. Krabbe(2), R. Genzel(2), D. Lutz(2), R. P. Kudritzki(1,3) & D.J. Hillier(4)

(1) Institut für Astronomie und Astrophysik der Universität München, Scheinerstr. 1, 81679 München, Germany
(2) Max-Planck-Institut für extraterrestrische Physik, 85740 Garching bei München, Germany
(3) Max-Planck-Institut für Astrophysik, 85740 Garching bei München, Germany
(4) Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA

Paper: Accepted by A&A

Weblink: ftp://ftp.usm.uni-muenchen.de/pub/paco/gcpap_aa.ps.gz


We present results on quantitative infrared spectroscopy of the brightest HeI emission line stars in the Galactic center. The observed HeI and H broad emission lines are caused by extremely strong stellar winds (Mdot ~ 5 to 80 * 10^-5 M_sun/yr) with relatively small outflow velocities (v_inf ~ 300 to 1000 km/sec ). The effective temperatures of the objects range from 17,000 K to 30,000 K with corresponding stellar luminosities of 1 to 30 * 10^5 L_sun. Strongly enhanced helium abundances (NHe/NH>.5) are found. These results indicate that the HeI emission line stars are evolved blue supergiants close to the evolutionary stage of Wolf-Rayet stars. They power the central parsec and belong to a young stellar cluster of massive stars which formed a few million years ago.)

Preprints available from the authors at paco@usmu01.usm.uni-muenchen.de , or the raw TeX (no figures) if you click here.

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