THE MASS LOSS RETURN FROM EVOLVED STARS TO THE LARGE MAGELLANIC CLOUD: EMPIRICAL RELATIONS FOR EXCESS EMISSION AT 8 AND 24 {mu}m

Journal Article · Mon Jun 15 04:00:00 EDT 2009 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/137/6/4810; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21255733

Srinivasan, Sundar ^[1]; Meixner, Margaret; Leitherer, Claus; Vijh, Uma; Gordon, Karl D; Sewilo, Marta ^[2]; Volk, Kevin ^[3]; Blum, Robert D; Harris, Jason ^[4]; Babler, Brian L; Bracker, Steve; Meade, Marilyn ^[5]; Block, Miwa; Engelbracht, Charles W; For, Bi-Qing; Misselt, Karl A ^[6]; Cohen, Martin ^[7]; Hora, Joseph L ^[8]; Indebetouw, Remy ^[9]; Markwick-Kemper, Francisca ^[10]

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1. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
3. Gemini Observatory, 670 North A'ohoku Place, Hilo, HI 96720 (United States)
4. National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States)
5. Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)
6. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
7. Radio Astronomy Laboratory, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)
8. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
9. Astronomy Department, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903-0818 (United States)
10. Jodrell Bank Centre of Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

We present empirical relations describing excess emission from evolved stars in the Large Magellanic Cloud (LMC) using data from the Spitzer Space Telescope Surveying the Agents of a Galaxy's Evolution (SAGE) survey which includes the Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 {mu}m and Multiband Imaging Photometer (MIPS) 24, 70, and 160 {mu}m bands. We combine the SAGE data with the Two Micron All Sky Survey (2MASS; J, H, and K {sub s}) and the optical Magellanic Cloud Photometric Survey (MCPS; U, B, V, and I) point source catalogs in order to create complete spectral energy distributions (SEDs) of the asymptotic giant branch (AGB) star candidates in the LMC. AGB star outflows are among the main producers of dust in a galaxy, and this mass loss results in an excess in the fluxes observed in the 8 and 24 {mu}m bands. The aim of this work is to investigate the mass loss return by AGB stars to the interstellar medium of the LMC by studying the dependence of the infrared excess flux on the total luminosity. We identify oxygen-rich, carbon-rich, and extreme AGB star populations in our sample based on their 2MASS and IRAC colors. The SEDs of oxygen- and carbon-rich AGB stars are compared with appropriate stellar photosphere models to obtain the excess flux in all the IRAC bands and the MIPS 24 {mu}m band. Extreme AGB stars are dominated by circumstellar emission at 8 and 24 {mu}m; thus we approximate their excesses with the flux observed in these bands. We find about 16,000 O-rich, 6300 C-rich, and 1000 extreme sources with reliable 8 {mu}m excesses, and about 4500 O-rich, 5300 C-rich, and 960 extreme sources with reliable 24 {mu}m excesses. The excesses are in the range 0.1 mJy to 5 Jy. The 8 and 24 {mu}m excesses for all three types of AGB candidates show a general increasing trend with luminosity. The color temperature of the circumstellar dust derived from the ratio of the 8 and 24 {mu}m excesses decreases with an increase in excess, while the 24 {mu}m optical depth increases with excess. The extreme AGB candidates are the major contributors to the mass loss, and we estimate the total AGB mass loss return to the LMC to be (5.9-13) x 10{sup -3} M {sub sun} yr{sup -1}.

• OSTI ID: 21255733
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 137; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ASYMPTOTIC SOLUTIONS
CAMERAS
CARBON
CARBON STARS
CATALOGS
COLOR
DUSTS
EMISSION
ENERGY SPECTRA
GALACTIC EVOLUTION
LUMINOSITY
MAGELLANIC CLOUDS
OXYGEN
PHOTOMETERS
PHOTOSPHERE
POINT SOURCES
TELESCOPES