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First Glimpse Results on the Stellar Structure of the Galaxy

Citation

Benjamin, RA and Churchwell, E and Babler, BL and Indebetouw, R and Meade, MR and Whitney, BA and Watson, C and Wolfire, MG and Wolff, MJ and Ignace, R and Bania, TM and Bracker, S and Clemens, DP and Chomiuk, L and Cohen, M and Dickey, JM and Jackson, JM and Kobulnicky, HA and Mercer, EP and Mathis, JS and Stolovy, SR and Uzpen, B, First Glimpse Results on the Stellar Structure of the Galaxy, The Astrophysical Journal, 630, (2 II) pp. L149-L152. ISSN 0004-637X (2005) [Refereed Article]

DOI: doi:10.1086/491785

Abstract

The GLIMPSE (Galactic Legacy Mid-Plane Survey Extraordinaire) Point Source Catalog of ∼30 million mid-infrared sources toward the inner Galaxy, 10 ≤ |l| ≤ 65 and |b| ≤ 1, was used to determine the distribution of stars in Galactic longitude, l, latitude, b, and apparent magnitude, m. 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 with a best-fit value in the 4.5 μm band of l 0 = 24 4. 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, with ∼25% more stars in the north. For l = 10-30, 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 φ = 44 10 to the Sun-Galactic center line, provides the simplest interpretation of these data. We examine the possibility that enhanced source counts at l = 26-28, 31.5-34, and 306-309 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, high diffuse backgrounds associated with star formation, or both.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Dickey, JM (Professor John Dickey)
ID Code:39314
Year Published:2005
Web of Science® Times Cited:224
Deposited By:Physics
Deposited On:2005-08-01
Last Modified:2012-04-20
Downloads:0

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