======================================================================== 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. 13, No. 14 Jun 28, 2001 Recently submitted papers: -------------------------- 2 micron Narrow-band Adaptive Optics Imaging in the Arches Cluster (Blum et al., AJ) ------------------------------------------------------------------------ Email : rblum@noao.edu Title : 2 micron Narrow-band Adaptive Optics Imaging in the Arches Cluster Author(s): R. D. Blum(1,2), D. Schaerer(1,3), A. Pasquali(4), M. Heydari-Malayeri(5), P. S. Conti(6), W. Schmutz(7) Institute: (1) Visiting Astronomer, Canada-France-Hawaii-Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France, and the University of Hawaii (2) Cerro Tololo Interamerican Observatory, Casilla 603, La Serena, Chile, rblum@noao.edu (3) Laboratoire d'Astrophysique, Observatoire Midi-Pyrenees, 14 Av. E. Belin F-31400, Toulouse, France,schaerer@ast.obs-mip.fr (4) ESO/Space Telescope European Coordinating Facility, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany, apasqual@eso.org (5) DEMIRM, Observatoire de Paris, 61 Avenue de l'Observatoire, F-75014 Paris, France, heydari@obspm.fr (6) JILA, University of Colorado,Campus Box 440, Boulder, CO, 80309, USA,pconti@jila.colorado.edu (7) Physikalisch-Meteorologisches Observatorium, 7260 Davos, Switzerland, wschmutz@pmodwrc.ch Paper : AJ, accepted EPrint : astro-ph/0106496 Web : ftp://ftp.ctio.noao.edu/pub/blum/arches.ps.gz Abstract: Canada-France-Hawaii-Telescope adaptive optics bonnette images through narrow-band filters in the K-band are presented for the Arches cluster. Continuum fluxes, line fluxes, and equivalent widths are derived from high angular resolution images, some near diffraction limited, for the well known massive stars in the Arches cluster. Images were obtained in the lines of HeI 2.06 micron , HI Br gamma (2.17 micron ), and HeII 2.19 micron as well as continuum positions at 2.03 micron , 2.14 micron, and 2.26 micron. In addition, fluxes are presented for HI Pa-alpha (1.87 micron ) and a nearby continuum position (1.90 micron ) from Hubble Space Telescope archival data. The 2 micron and Pa-alpha data reveal two new emission-line stars and three fainter candidate emission-line objects. Indications for a spectral change of one object between earlier observations in 1992/1993 and our data from 1999 are found. The ratio of HeII 2.19 micron to Br gamma emission exhibits a narrow distribution among the stars, suggesting a narrow evolutionary spread centered predominantly on spectral types O4 If or Wolf-Rayet stars of the WN7 sub-type. From the approximate spectral types of the identified emission-line stars and comparisons with evolutionary models we infer a cluster age between 2 and 4.5 Myr. ------------------------------------------------------------------------ (Older versions of the Newsflash can be found at the gcnews web-page) ======================================================================== Edited by Angela Cotera Heino Falcke & Sera Markoff (cotera@as.arizona.edu) (hfalcke,smarkoff@mpifr-bonn.mpg.de) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For Abstract submission please send the (La)Tex file of your paper to gcnews@mpifr-bonn.mpg.de ========================================================================