The 1.2 mm image of the β Pictoris disk^*

¹ Stockholm Observatory, SCFAB, Roslagstullsbacken 21, 106 91 Stockholm, Sweden e-mail: alexis@astro.su.se, olofsson@astro.su.se, pawel@astro.su.se
² ESTEC/ESA, PO Box 299, 2200AG Noordwijk, The Netherlands e-mail: malcolm.fridlund@esa.int
³ Lick Observatory, University of California Santa Cruz, CA 95064, USA e-mail: taku@ucolick.org

Corresponding author: R. Liseau, rene@astro.su.se

Received: 26 July 2002
Accepted: 5 February 2003

Abstract

We present millimeter imaging observations in the 1200 μm continuum of the disk around . With the 25 beam, the  disk is unresolved perpendicularly to the disk plane (10), but slightly resolved in the northeast-southwest direction (26). Peak emission is observed at the stellar position. A secondary maximum is found 1000 AU along the disk plane in the southwest, which does not positionally coincide with a similar feature reported earlier at 850 μm. Arguments are presented which could be seen in support of the reality of these features. The observed submm/mm emission is consistent with thermal emission from dust grains, which are significantly larger than those generally found in the interstellar medium, including mm-size particles, and thus more reminiscent of the dust observed in protostellar disks. Modelling the observed scattered light in the visible and the emission in the submm/mm provides evidence for the particles dominating the scattering in the visible/NIR and those primarily responsible for the thermal emission at longer wavelengths belonging to different populations.