======================================================================== G C N E W S * Newsflash * - The Newsletter for Galactic Center Research - gcnews@mpifr-bonn.mpg.de http://www.mpifr-bonn.mpg.de/gcnews ======================================================================== Vol. 12, No. 7 Sep 5, 2000 Recently submitted papers: -------------------------- 1) AST/RO Observations of Atomic Carbon near the Galactic Center (Ojha et al., ApJ) 2) N-BODY SIMULATIONS OF COMPACT YOUNG CLUSTERS NEAR THE GALACTIC CENTER (Kim et al., ApJ) ------------------------------------------------------------------------ Email : rojha@cfa.harvard.edu Title : AST/RO Observations of Atomic Carbon near the Galactic Center Author(s): Roopesh Ojha(1), Antony A. Stark(1), Henry H. Hsieh(1), Adair P. Lane(1), Richard A. Chamberlin(2), Thomas M. Bania(3), Alberto D. Bolatto(3), James M. Jackson(3), Gregory A. Wright(4) Institute: (1) Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 78; Cambridge MA 02138 (2) Caltech Submillimeter Obs., 111 Nowelo Street Hilo, HI 96720 (3) Astronomy Department, Boston University, 725 Commonwealth Avenue Boston, MA 02215 (4) Bell Laboratories, Holmdel, NJ 07733 Paper : ApJ, submitted EPrint : astro-ph/0008439 Abstract: We present a coarsely-sampled map of the region |l|<=2^o, |b|<= 0.1^o in the 492 GHz (^3P_1->^3P_0) fine structure transition of neutral carbon, observed with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). The distribution of [CI] emission is similar on the large scale to that of CO J=1->0. On average, the ratio of the integrated intensities, I_[C I]/I_^12CO, is higher in the Galactic disk than in the Galactic Center region. This result is accounted for by the absorption of ^12CO within the clouds located in the outer Galactic disk. I_[C I]/I_^12CO is surprisingly uniform over the variety of environments near the Galactic Center. On average, [\ionC1] is optically thin (or as optically thin as ^13CO (J=1->0)) even in the dense molecular clouds of the Galactic Center region. ------------------------------------------------------------------------ Email : sskim@astro.ucla.edu Title : N-BODY SIMULATIONS OF COMPACT YOUNG CLUSTERS NEAR THE GALACTIC CENTER Author(s): Sungsoo S. Kim(1), Donald F. Figer(2), Hyung Mok Lee(3), and Mark Morris(1) Institute: (1) Division of Astronomy, University of California, Los Angeles, CA, 90095-1562; sskim@astro.ucla.edu; morris@astro.ucla.edu (2) Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218; figer@stsci.edu (3) Astronomy Program, SEES, Seoul National University, Seoul 151-742, Korea; hmlee@astro.snu.ac.kr Paper : ApJ, Dec 20, 2000, in press Weblink : http://www.astro.ucla.edu/~sskim/nbody.ps Abstract: We investigate the dynamical evolution of compact young star clusters (CYCs) near the Galactic center (GC) using Aarseth's Nbody6 codes. The relatively small number of stars in the cluster (5,000-20,000) makes real-number N-body simulations for these clusters feasible on current workstations. Using Fokker-Planck (F-P) models, Kim, Morris, \& Lee (1999) have made a survey of cluster lifetimes for various initial conditions, and have found that clusters with a mass ~< 2 * 10^4 M_sun evaporate in 10 Myr. These results were, however, to be confirmed by N-body simulations because some extreme cluster conditions, such as strong tidal forces and a large stellar mass range participating in the dynamical evolution, might violate assumptions made in F-P models. Here we find that, in most cases, the CYC lifetimes of previous F-P calculations are 5-30 % shorter than those from the present N-body simulations. The comparison of projected number density profiles and stellar mass functions between N-body simulations and HST/NICMOS observations by Figer et al. (1999) suggests that the current tidal radius of the Arches cluster is 1.0 pc, and the following parameters for the initial conditions of that cluster: total mass of 2 * 10^4 M_sun and mass function slope for intermediate-to-massive stars of 1.75 (the Salpeter function has 2.35). We also find that the lower stellar mass limit, the presence of primordial binaries, the amount of initial mass segregation, and the choice of initial density profile (King or Plummer models) do not significantly affect the dynamical evolution of CYCs. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Angela Cotera Heino Falcke (cotera@ipac.caltech.edu) (hfalcke@mpifr-bonn.mpg.de) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please send the (La)Tex file of your paper to gcnews@mpifr-bonn.mpg.de ========================================================================