The β Pictoris circumstellar disk. XVII. Physical and chemical parameters of the disk.
Abstract
New high resolution spectroscopic observations in the visible as well as archival HST UV data are used to investigate some physical and chemical properties of the disk around β Pictoris . A number of circumstellar lines are detected for the first time: Fe I , as well as weak lines of Fe II , Mn II and Zn II . Reliable estimates of the total gaseous abundance of Fe I , Fe II , Zn II and Mn II are given for the stable part of the gaseous disk, enabling to investigate its chemical composition. The various observed metallic abundances are found to be close to solar ones, which may indicate that evaporation processes of refractory or cometary bodies occur to produce this gas. These observations also enable to derive other important information for the gaseous disk: the electronic densities range between 10^3^ and 10^6^cm^-3^; the total Hydrogen density column is 1-2x10^19^cm^-2^, assuming that volatiles in the gaseous disk have solar system abundances; assuming that the hydrogen depletion is similar to the cometary ones would reduce the estimated column density by a factor of 10^3^ to 10^4^. Tentative estimates of the abundance of some refractory elements in the gas phase during two variable events are also given. In these two cases, we show that these events produce infalling gas with solar abundances, which strongly favours the Falling Evaporating Bodies (FEB) scenario.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1995
- Bibcode:
- 1995A&A...296..499L
- Keywords:
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- STARS: CIRCUMSTELLAR MATTER;
- STARS: {BETA} PICTORIS;
- COMETS: GENERAL