AAS 203rd Meeting, January 2004
Session 13 Disks Around Young Stars
Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall

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[13.04] A Resolved Circumstellar Disk around the Herbig Ae Star HD 100546 in the Thermal Infrared

W. M. Liu, P. M. Hinz, M. R. Meyer, E. E. Mamajek, W. F. Hoffmann (Steward Observatory), J. L. Hora (Harvard-Smithsonian Center for Astrophysics)

We present mid-infrared nulling interferometric and direct imaging observations of the Herbig Ae star HD 100546 obtained with the Magellan I (Baade) 6.5 m telescope. The observations show resolved circumstellar emission at 10.3, 11.7, 12.5, 18.0, and 24.5 microns. Through the nulling observations (10.3, 11.7 and 12.5 microns), we detect a circumstellar disk, with an inclination of 45 ±15 degrees with respect to a face-on disk, a semimajor axis position angle of 150 ±10 degrees (E of N), and a spatial extent of about 25 AU. The direct images (18.0 and 24.5 microns) show evidence for cooler dust with a spatial extent of 30-40 AU from the star. The direct images also show evidence for an inclined disk with a similar position angle as the disk detected by nulling. This morphology is consistent with models in which a flared circumstellar disk dominates the emission. However, the similarity in relative disk size we derive for different wavelengths suggests that the disk may have a large inner gap, possibly cleared out by the formation of a giant protoplanet. The existence of a protoplanet in the system also provides a natural explanation for the observed difference between HD 100546 and other Herbig Ae stars.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.