Mid-IR observations of circumstellar disks. II. Vega-type stars and a post-main sequence object
Abstract
We present spectral energy distributions and new N-band photometry and spectroscopy for a sample of six main sequence stars and one post-MS object using the ESO TIMMI2 camera at La Silla observatory (Chile). All objects are thought to possess circumstellar material and for the majority of the targets this is their first N-band spectroscopic observation. The emission spectra (observed in three cases), modelled with a mixture of silicates consisting of different grain sizes and composition, confirm the suspected presence of disks around these targets. The most important discovery is that HD 113766, a young Vega-type star, is host to highly processed dust which is probably second generation. It is the first time a Vega-type star with such highly evolved dust has been observed. Silicate emission of basically unevolved dust is seen in case of the post-MS object HD 41511 and the Vega-type star HD 172555. In addition, to study the cold dust, we observed a subsample at 1200 μm with the bolometer array SIMBA at the SEST in La Silla but we only got upper limits for those five objects. This shows that these Vega-type stars have a smaller amount of dust than their precursors, the T Tauri and Herbig Ae/Be stars.
Based on observations collected at the European Southern Observatory, La Silla, Chile (70.C-0468, 71.C-0001).- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2005
- DOI:
- 10.1051/0004-6361:20041490
- Bibcode:
- 2005A&A...431..175S
- Keywords:
-
- stars: circumstellar matter;
- stars: planetary systems: protoplanetary disks;
- infrared: stars;
- techniques: spectroscopic;
- submillimeter