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 peony.tex A&A 486/3, 2008, in press
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% NASA/Spitzer Press Release
% http://www.spitzer.caltech.edu/Media/releases/ssc2008-13/
% astro-ph > arXiv:0807.2476

\documentclass{aa}  
\begin{document}
\titlerunning{Two extremely luminous WN stars in the Galatic Center}
\title{Two extremely luminous WN stars in the Galactic center with 
circumstellar emission from dust and gas}

\author{A. Barniske, L.\,M. Oskinova, and W.-R. Hamann}
          
\offprints{lida@astro.physik.uni-potsdam.de}

\institute{Potsdam University, Am Neuen Palais 10, Potsdam, 14469 Germany
}

\date{Received 12 February 2008 / Accepted  22 May 2008}

% \abstract{}{}{}{}{} 
% 5 {} token are mandatory
\abstract
% 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 heading (mandatory)
{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 heading (mandatory)
{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 {{\em Spitzer}} IRS spectra of
these objects. Archival IR images complement the interpretation.  }
%
% results heading (mandatory) 
{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
{{\em Spitzer}} MIPS camera. We attribute the formation of this IR-bright 
nebula to the recent evolutionary history of WR\,102ka.  }
%
% conclusions heading (optional), leave it empty if necessary 
{}

\keywords{stars: Wolf-Rayet -- HII regions -- Galaxy: center -- 
stars: individual: \ka\ --  stars: individual: \wrc\ }

\end{document}