First GLIMPSE Results on the Stellar Structure of the Galaxy
| Autor: | Michael J. Wolff, E. P. Mercer, Marilyn R. Meade, Remy Indebetouw, Richard Ignace, Henry A. Kobulnicky, Dan P. Clemens, T. M. Bania, John S. Mathis, Brian Babler, John M. Dickey, Laura Chomiuk, B. Uzpen, Susan R. Stolovy, Barbara A. Whitney, Mark G. Wolfire, Christer Watson, Ed Churchwell, Milton Cohen, James M. Jackson, S. Bracker, Robert A. Benjamin |
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| Rok vydání: | 2005 |
| Předmět: |
Physics
Point source Star formation Extinction (astronomy) Astrophysics (astro-ph) FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Galaxy Space and Planetary Science Stellar structure Astrophysics::Earth and Planetary Astrophysics Astrophysics::Galaxy Astrophysics |
| DOI: | 10.48550/arxiv.astro-ph/0508325 |
| Popis: | The GLIMPSE (Galactic Legacy Mid-Plane Survey Extraordinaire) Point Source Catalog of ~ 30 million mid-infrared sources towards the inner Galaxy, 10 < |l| < 65 degrees and |b| < 1 degree, was used to determine the distribution of stars in Galactic longitude, latitude, and apparent magnitude. The counts versus longitude can be approximated by the modified Bessel function N=N_0*(l/l_0)*K_1(l/l_0), where l_0 is insensitive to limiting magnitude, band choice, and side of Galactic center: l_0= 17-30 degrees with a best fit value in the the 4.5 micron band of l_0=24 +/- 4 degrees. Modeling the source distribution as an exponential disk yields a radial scale length of H= 3.9 +/- 0.6 kpc. There is a pronounced north-south asymmetry in source counts for |l| < 30 degrees, with ~ 25% more stars in the north. For l=10-30 degrees, there is a strong enhancement of stars of m= 11.5-13.5 mag. A linear bar passing through the Galactic center with half-length R_bar=4.4 +/- 0.5 kpc, tilted by phi=44 +/- 10 degrees to the Sun-Galactic Center line, provides the simplest interpretation of this data. We examine the possibility that enhanced source counts at l=26-28 degrees, 31.5-34 degrees, and 306-309 degrees are related to Galactic spiral structure. Total source counts are depressed in regions where the counts of red objects (m_K-m_[8.0] >3) peak. In these areas, the counts are reduced by extinction due to molecular gas and/or high diffuse backgrounds associated with star formation. Accepted for publication in Astrophysical Journal Letters. Version with full res figures and info on GLIMPSE Point Source Catalog at http://www.astro.wisc.edu/glimpse |
| Databáze: | OpenAIRE |
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