GLIMPSE360: Mapping the Galaxy's "Edge"

Type Conference Paper
Names Robert A. Benjamin, B. Whitney, M. Meade, B. Babler, C. Watson, E. Churchwell, GLIMPSE360 team
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #217, #241.14
Volume 43
Pages 24114
Date January 1, 2011
Short Title GLIMPSE360
Library Catalog NASA ADS
Abstract We present compelling new evidence for the "truncation" of the Galactic stellar disk at R=13.4 ±0.4 kpc using data from the Spitzer Space Telescope's Warm Mission program GLIMPSE 360, a mid-infrared survey at 3.6 and 4.5 microns of the outer Galactic disk and warp, from galactic longitude l=65 to 265 degrees. The truncation is detected as a drop-off in the number of red giant stars per square degree fainter than a certain magnitude. Our average truncation distance is in excellent agreement with previous measurements of the truncation distance. By mapping the changing apparent magnitude of the dropoff as a function of Galactic longtiude, we are able to determine, for the first time, the variation in the truncation radius as a function of Galactic azimuth. Using TRILEGAL models of Galactic starcounts, we also constrain whether there is a sharp or more gradual dropoff in the density of the Galactic stellar disk beyond the truncation radius. This research was supported by NASA/JPL contract 1368014 and NASA ATP grant NNX10AI70G to the University of Wisconsin-Whitewater.
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