Undersökning av döende stjärnor: Massförlust och molekyler för stjärnor på den asymptotiska jättegrenen

Abstract

The study aims to investigate the mass outflow from evolved stars. Emission lines from nine stars, observed under the project DEATHSTAR, were studied. The gasmass- loss rates were approximated using a simplified formula based on the rotational emission lines of 12CO. Furthermore, the project aims to determine the molecular composition of two of the nine stars, W Hya and R For. The calculated gas-mass-loss rates varied from 10−7 to 10−5M yr−1. The dust-mass and dust-mass-loss rate calculations were only attempted regarding the star W Hya, though no dust-mass and dust-mass-loss could be determined from the data. The observed emission spectra from W Hya and R For contained at least 16 and 17 molecular emission lines respectively. The outflow of W Hya is dominated by oxygen based molecules, while the outflow of R For contains carbon based molecules. Finally, the emission lines from 12CO for several stars show evidence of asymmetric envelopes. The obtained profile for R Hya hints at multiple velocity components and might warrant a more in-depth investigation in the future.