Gonzalez Delgado, David

Contact Email: delgado@astro.su.se
Institute: Stockholm Observatory
First Coauthor: Hans Olofsson
Institute: Stockholm Observatory
Second Coauthor: Fredrik Schoier
Institute: Leiden Observatory
Research URL:http://www.astro.su.se
Presenting Thesis: Yes
Subject Area: Stellar Atmospheres, Circumstellar Material
Waveband: Radio
Technique: Spectroscopy
Presentation: Poster Display
Title: Modelling of circumstellar envelopes around O-rich stars
Abstract: Using a detailed radiative transfer analysis, combined with an energy balance equation for the gas, we have performed extensive modelling of circumstellar CO radio line emission from a large sample of semiregular and irregular oxygen-rich stars. We determine some of the basic parameters that characterize circumstellar envelopes (CSEs), e.g., the stellar mass loss rate, the gas expansion velocity, and the kinetic temperature structure of the gas. We assume a spherically symmetric CSE with a smooth gas density distribution, created by a continuous mass loss, which expands with a constant velocity. A reliable mass loss rate determination for an individual star requires, in addition to a detailed radiative transfer analysis, good observational constraints in the form of multi-line observations and radial brightness distributions