======================================================================== 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. 2 Jul 4, 2000 Recently submitted papers: -------------------------- 1) New star clusters projected close to the Galactic Centre (Dutra & Bica, A&A) 2) Is the Galactic center populated with young star clusters? (Zwart, ASPC) ........................................................................ 3) VIIth Catalogue of Galactic Wolf-Rayet Stars (van der Hucht) 4) Deuterium at the Galactic Center (Lubowich, Nature, Press Release) P.S.: The last paper was picked up by chance as a press release, we do not have the original abstract. This is a reminder that if you have a Galactic Center paper, please submit the abstract to GCNEWS irrespective of which journal you submit to. There is still the believe that submitting to Nature, for example, ensures automatic recognition, however, experience shows that many of these papers are as much overlooked (or even more, because of the short shelf-life and delayed/incomplete ADS abstracts) than others. ------------------------------------------------------------------------ Email : dutra@if.ufrgs.br Title : New star clusters projected close to the Galactic Centre Author(s): C.M. Dutra (1) and E. Bica (1) Institute: (1) Universidade Federal do Rio Grande do Sul, IF, CP 15051, Porto Alegre 91501-970, RS, Brazil Paper : A&A, in press EPrint : astro-ph/0006409 Abstract: We carried out a systematic search for new star clusters in a field of 5^o *5^o centred close to the Galactic Nucleus using the infrared JHK_s 2MASS Survey archive. In addition we searched for embedded clusters in the directions of HII regions and dark clouds for | l |<=4^o. As a result we present a list of 58 IR star clusters or candidates. We provide positions, sizes and reddening estimated from 100 micron dust emission. Their angular distribution together with previously catalogued objects in the region and possible relation with star forming complexes are also discussed. ------------------------------------------------------------------------ Email : spz@oeroeboeroe.bu.edu Title : Is the Galactic center populated with young star clusters? Author(s): Simon Portegies Zwart Institute: (1) Dept. of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA Paper : to appear in Dynamics of Star Clusters and the Milky Way, eds. R.Spurzem et al. (ASP Conference Series) EPrint : astro-ph/0006428 Abstract: We study the evolution and observability of young and compact star clusters near the Galactic center, such as the Arches cluster and the Quintuplet. The star clusters are modeled with a combination of techniques; using direct \nbody integration to calculate the motions of all stars and detailed stellar and binary evolution to follow the evolution of the stars. The modeled star clusters dissolve within 10 to 60 million years in the tidal field of the Galaxy. The projected stellar density in the modeled clusters drops within 5% to 70% of the lifetime to a level comparable to the projected background density towards the Galactic center. And it will be very hard to distinguished these clusters at later age among the background stars. This effect is more severe for clusters at larger distance from the Galactic center but in projection at the same distance. Based on these arguments we conclude that the Galactic center easily hides 10 to 40 clusters with characteristics similar to the Arches and the Quintuplet cluster. ------------------------------------------------------------------------ Dear colleagues, Please find at my ftp site ftp://saturn.sron.nl/pub/karelh/UPLOADS/7thWRCat.dir/7thWRCAT.ps the long overdue VIIth Catalogue of Galactic Wolf-Rayet Stars, which is about to be submitted to New Astronomy Reviews. Karel A. van der Hucht ------------------------------------------------------------------------ Press-Release (taken from AIP): NEW MEASUREMENTS OF DEUTERIUM at the center of our Milky Way galaxy confirm theoretical models that most deuterium, the heavy isotope of hydrogen containing one proton and one neutron, is primordial (made at the time of the big bang) and not subsequently created in galaxies or stars. A Hofstra-Williams-Colgate-Manchester (UK) team of astronomers have used the National Radio Astronomy Observatory 12-m radio telescope to scan a huge molecular cloud only 30 light years from the galactic center. In particular they look at the spectra of hydrogen cyanide (HCN) and its deuterium counterpart DCN. In general stars are expected to be net consumers (not producers) of deuterium: they burn it into helium. But the galactic center is the Times Square of the Milky Way; it is the scene of jets, bursts, x-ray and gamma sources, a massive black hole, filaments, arcs, and other material-processing objects. From their observed ratio of deuterium-to-hydrogen D/H, the researchers (Don Lubowich, Jay Pasachoff, Tom Balonek, and Tom Millar) deduce three things: (1) The D/H ratio is higher than you would expect in the absence of a source of virginal unprocessed material (high in D, low in heavier elements). This demonstrates that matter comparatively rich in D is indeed raining down with the cloud onto the plane of our galaxy (see figure at www.aip.org/physnews/graphics). In other words, the infalling matter is to the galaxy what comets are to our solar system: specimens of relatively unprocessed, primitive material. (2) For all that, the D/H ratio at the galactic center is lower than in all other places in the galaxy. This is important evidence confirming that D is not made in stars and that what D we see is made by the big bang. (3) From models of D production in quasars, the observed D/H ratio suggests that the Milky Way could not have harbored a quasar for at least a billion years and probably not for four billion years. (Lubowich et al., Nature, 29 June 2000.) (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 ========================================================================