A Mid-Infrared Search for Variable Stars in the Milky Way Galaxy

Type Conference Paper
Names Brian H. Brooks, R. A. Benjamin, B. L. Babler, the GLIMPSE Team
Proceedings Title American Astronomical Society
Conference Name AAS Meeting #223, #156.06
Date January 1, 2014
URL http://adsabs.org/2014AAS.22315606B
Library Catalog labs.adsabs.harvard.edu
Abstract Using the Spitzer Space Telescope and the onboard IRAC (Infrared Array Camera) instrument, we have matched 27,703,930 mid-infrared sources detected in the overlap regions of the GLIMPSE (the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) (2004-2005) and Deep GLIMPSE (2012-2013) surveys. Most sources are measured at wavelengths of 3.6 and 4.5 microns with Galactic coordinates | l | < 65 deg and | b | < 1 deg. Of the matched infrared sources, 100,998 showed evidence of greater than 2 sigma variability in multiple bands in the same direction. We present an analysis of this population, presenting their magnitude, color, spatial, and environmental properties. We find two notable features. First, the population of variable stars is bimodal in apparent magnitude, with a minimum at m=9-10 mid-infrared magnitudes. Second, we find several factor-of-two spatial overdensities of variable stars at selected points along the Galactic plane. In addition, we present the 10-sigma variability list which contains 1060 variable stars, all of which were visually verified, and describe incidental discovery of several new proper motion stars. This work was supported by NSF REU Site Grant to the University of Wisconsin-Madison.
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