Infrared mapping of the dust disc around VEGA

Abstract

ISOPHOT has been used to perform high-resolution 60-μm scans of Vega, and these have been compared with those from gammaDra, to obtain a Gaussian width of 22+/-2 arcsec. The dust disc around Vega has been mapped, resolving it at 60 and 90 μm with ISOPHOT. At 90 μm a Gaussian width of 36+/-3 arsec has been derived. In addition, multi-filter photometry is presented, at 25, 60, 80, 100, 120, 150, 170 and 200 mum. The data are fitted by a modified blackbody with a temperature of 73 K [Q(lambda)~1/lambda^1.1]. The dust disc has a luminosity L_IR/L_*~3x10^-5. Using a distance of 7.8 pc, 22 arcsec corresponds to a distance of 86 au, and 36 arcsec to a distance of 140 au.