AAS 195th Meeting, January 2000
Session 25. Stars and Disks
Oral, Wednesday, January 12, 2000, 10:00-11:30am, Regency V

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[25.02] A Single Circumbinary Disk in the HD 98800 Quadruple System

D.W. Koerner (University of Pennsylvania), E.L.N. Jensen (Swarthmore College), K. Cruz, T.B. Guild (University of Pennsylvania), K. Gultekin (U Maryland)

We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'', each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optical secondary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 146 K. With the assumption that the dust is in radiative equilibrium with the central stars, these characteristics require its location to be in a configuration that is circumbinary to the spectroscopic pair. A simple black-body fit underpredicts emission in the region of the broad silicate feature, however, and the feature itself requires a dust component with temperatures higher than 146 K by at least a factor of two. Further, the spectral slope at sub-millimeter wavelengths is flatter than expected for a collision-induced size-distribution of grains, suggesting a range of temperatures present at longer wavelengths. These facts suggest that the circumbinary dust is not confined to a narrow ring but is wide enough to exhibit a range of temperatures.

If you would like more information about this abstract, please follow the link to http://www.hep.upenn.edu/PORG/web/papers/koerner99b.ps. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser. [Previous] | [Session 25] | [Next]