TAMING THE INVISIBLE MONSTER: SYSTEM PARAMETER CONSTRAINTS FOR {epsilon} AURIGAE FROM THE FAR-ULTRAVIOLET TO THE MID-INFRARED
- Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
- National Optical Astronomy Observatory, Tucson, AZ 85719 (United States)
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208 (United States)
We have assembled new Spitzer Space Telescope IRAC observations of the mysterious binary star {epsilon} Aurigae, along with archival far-ultraviolet to mid-infrared data, to form an unprecedented spectral energy distribution (SED) spanning 3 orders of magnitude in wavelength from 0.1 {mu}m to 100 {mu}m. The observed SED can be reproduced using a three-component model consisting of a 2.2{sup +0.9}{sub -0.8} M{sub sun} F-type post-asymptotic giant branch star, and a 5.9 {+-} 0.8 M{sub sun} B5{+-}1 type main-sequence star that is surrounded by a geometrically thick, but partially transparent, disk of gas and dust. At the nominal HIPPARCOS parallax distance of 625 pc, the model normalization yields a radius of 135 {+-} 5 R{sub sun} for the F star, consistent with published interferometric observations. The dusty disk is constrained to be viewed at an inclination of i {approx_gt} 87{sup 0}, and has an effective temperature of 550 {+-} 50 K with an outer radius of 3.8 AU and a thickness of 0.95 AU. The dust content of the disk must be largely confined to grains larger than {approx}10 {mu}m in order to produce the observed gray optical-infrared eclipses and the lack of broad dust emission features in the archival Spitzer mid-infrared spectra. The total mass of the disk, even considering a potential gaseous contribution in addition to the dust that produces the observed infrared excess, is <<1 M{sub sun}. We discuss evolutionary scenarios for this system that could lead to the current status of the stellar components and suggest possibilities for its future evolution, as well as potential observational tests of our model.
- OSTI ID:
- 21448919
- Journal Information:
- Astrophysical Journal, Vol. 714, Issue 1; Other Information: DOI: 10.1088/0004-637X/714/1/549; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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