AAS 199th meeting, Washington, DC, January 2002
Session 66. Extra-Solar Planets and Vega
Oral, Tuesday, January 8, 2002, 10:00-11:30am, International Ballroom Center

## [66.05] Millimeter-wave Aperture Synthesis Imaging of Vega: Evidence for a Ring Arc at 95 AU

D.W. Koerner (University of Pennsylvania), A.I. Sargent (California Institute of Technology), N.A] Ostroff (University of Pennsylvania)

We present the first millimeter-wave aperture synthesis map of dust around a main sequence star. A 3'' resolution image of 1.3 mm continuum emission from Vega reveals a clump of emission 12'' from the star at PA 45\circ, consistent with the location of maximum 850 \mum emission in a lower resolution JCMT/SCUBA map. The flux density is 4.0±0.9 mJy. Adjacent 1.3 mm peaks with flux densities 3.4±1.0 mJy and 2.8±0.9 mJy are located 14'' and 13'' from the star at PA 67\circ and 18\circ, respectively. An arc-like bridge connects the two strongest peaks. There is an additional 2.4 ±0.8 mJy peak to the SW 11'' from the star at PA 215\circ and a marginal detection, 1.4±0.5 mJy, at the stellar position, consistent with photospheric emission. An extrapolation from the 850 \mum flux, assuming F1.3mm-0.85mm \propto \lambda-2.8, agrees well with the total detected flux for Vega at 1.3 mm, and implies a dust emissivity index, \beta, of 0.8 We conclude that we have detected all but a very small fraction of the dust imaged by SCUBA in our aperture synthesis map and that these grains are largely confined to segments of a ring of radius 95 AU.