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From: Simon Portegies Zwart  spz@science.uva.nl 
To: gcnews@zia.aoc.nrao.edu
Subject: submission of astro-ph/0403147


\documentstyle[11pt,newpasp,psfig]{article}
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% astro-ph/0403147
\newcommand{\msun}{\mbox{${\rm M}_\odot$}}
\newcommand{\rsun}{\mbox{${\rm R}_\odot$}}
\newcommand{\Rgc}{\mbox{${R_{\rm GC}}$}}
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\markboth{Portegies Zwart}{YDCs in the Galactic Center}
\begin{document}
\title{Life and Death of Young Dense Star Clusters near the Galactic 
Center}

\author{Simon F. Portegies Zwart}
\affil{Astronomical Institute `Anton Pannekoek',
       University of Amsterdam, Kruislaan 403, the Netherlands and
       Institute for Computer Science, University of Amsterdam, Kruislaan 
403
}
\author{Stephen L.\ W.\ McMillan}
\affil{Department of Physics, Drexel University, Philadelphia, PA 19104, 
USA}

\author{Holger Baumgardt}
\affil{Institute of Advanced Physical and Chemical Research  RIKEN,
       2-1 Hirosawa, Wako-shi, Saitama 351-019, Japan}

\begin{abstract}
We discuss the structural change and degree of mass segregation of
young dense star clusters within about 100\,pc of the Galactic center.
In our calculations, which are performed with GRAPE-6, the equations
of motion of all stars and binaries are calculated accurately but the
external potential of the Galaxy is solved (semi)analytically.  The
simulations are preformed to model the Arches star cluster.  We find
that star clusters with are less strongly perturbed by the tidal field
and dynamical friction are much stronger affected by mass segregation;
resulting in a significant pile-up of massive stars in the cluster
center. At an age of about 3.5\,Myr more than 90 per cent of the stars
more massive than $\sim 10$\,\msun\, are concentrated within the
half-mass radius of the surviving cluster.  Star clusters which are
strongly perturbed by the tidal field of the parent Galaxy are much
less affected by mass segregation.
\end{abstract}