EDP Sciences
Press Release
Free access
Issue A&A
Volume 486, Number 3, August II 2008
Page(s) 971 - 984
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:200809568
Published online 04 June 2008

A&A 486, 971-984 (2008)
DOI: 10.1051/0004-6361:200809568

Two extremely luminous WN stars in the Galactic center with circumstellar emission from dust and gas

A. Barniske, L. M. Oskinova, and W.-R. Hamann

Potsdam University, Am Neuen Palais 10, Potsdam 14469, Germany
    e-mail: lida@astro.physik.uni-potsdam.de

Received 12 February 2008 / Accepted 22 May 2008

Context. The central region of our Galaxy contains a large population of young massive stars. These stars are concentrated in three large star clusters, as well as being scattered in the field. Strong ionizing radiation and stellar winds of massive stars are the essential feedback agents that determine the physics of the ISM in the Galactic center.
Aims. The aim is to study relatively isolated massive WN-type stars in the Galactic center in order to explore their properties and their influence on the ISM.
Methods. The K-band spectra of two WN stars in the Galactic center, WR 102ka and WR 102c, are exploited to infer the stellar parameters and to compute synthetic stellar spectra using the Potsdam Wolf-Rayet (PoWR) model atmosphere code. These models are combined with dust-shell models for analyzing the Spitzer IRS spectra of these objects. Archival IR images complement the interpretation.
Results. We report that WR 102ka and WR 102c are among the most luminous stars in the Milky Way. They critically influence their immediate environment by strong mass loss and intense UV radiation, and thus set the physical conditions for their compact circumstellar nebula. The mid-IR continua for both objects are dominated by dust emission. For the first time we report the presence of dust in the close vicinity of WN stars. Also for the first time, we have detected lines of pure-rotational transitions of molecular hydrogen in a massive-star nebula. A peony-shaped nebula around WR 102ka is resolved at 24 $\mu$m by the Spitzer MIPS camera. We attribute the formation of this IR-bright nebula to the recent evolutionary history of WR 102ka.

Key words: stars: Wolf-Rayet -- HII regions -- Galaxy: center -- stars: individual: WR 102ka -- stars: individual: WR 102c

© ESO 2008

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.

Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

Mirror sites: CDS | EDP Sciences
  RSS feeds
© The European Southern Observatory (ESO)