EXPLORATIONS BEYOND THE SNOW LINE: SPITZER/IRS SPECTRA OF DEBRIS DISKS AROUND SOLAR-TYPE STARS
- Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States)
- NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States)
- Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Johns Hopkins University - Applied Physics Laboratory, SD/SRE, MP3-W155, 7707 Montpelier Road, Laurel, MD 20723 (United States)
- Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)
We have observed 152 nearby solar-type stars with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. Including stars that met our criteria but were observed in other surveys, we get an overall success rate for finding excesses in the long-wavelength IRS band (30-34 mum) of 11.8% +- 2.4%. The success rate for excesses in the short-wavelength band (8.5-12 mum) is approx1% including sources from other surveys. For stars with no excess at 8.5-12 mum, the IRS data set 3sigma limits of around 1000 times the level of zodiacal emission present in our solar system, while at 30-34 mum data set limits of around 100 times the level of our solar system. Two stars (HD 40136 and HD 10647) show weak evidence for spectral features; the excess emission in the other systems is featureless. If the emitting material consists of large (10 mum) grains as implied by the lack of spectral features, we find that these grains are typically located at or beyond the snow line, approx1-35 AU from the host stars, with an average distance of 14 +- 6 AU; however, smaller grains could be located at significantly greater distances from the host stars. These distances correspond to dust temperatures in the range approx50-450 K. Several of the disks are well modeled by a single dust temperature, possibly indicative of a ring-like structure. However, a single dust temperature does not match the data for other disks in the sample, implying a distribution of temperatures within these disks. For most stars with excesses, we detect an excess at both IRS and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. Only three stars in this sample show a MIPS 70 mum excess with no IRS excess, implying that very cold dust is rare around solar-type stars.
- OSTI ID:
- 21378423
- Journal Information:
- Astrophysical Journal, Vol. 705, Issue 1; Other Information: DOI: 10.1088/0004-637X/705/1/89; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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