XMM-NEWTON/RGS First View of Coronas of Two Luminous Cool Stars
Abstract
Two single cool stars, β Dra (G2Ib--IIa, HD 159181) and α TrA (K2 II--III, HD 150798) offer a contrast in the structure and evolution of their outer atmospheres. Alpha TrA is a well-known hybrid object, from a class of cool luminous single stars originally identified based on the presence of strong C IV emission accompanied by absorption features at low and high velocities indicating a massive stellar wind and circumstellar material. The atmosphere of Beta Dra appears to be similar to the solar coronal example with high temperature emission, but lacking a massive cool wind. X-Ray observations can help to delineate structure and evolution of stellar coronae from the solar example through the intermediate hybrid configuration. Spectra of these stars obtained with XMM/Newton under the Guest Investigator program contain emission lines of many elements and ionic species. An emission measure distribution is constructed from a line-based analysis. Differences in structure, density, and element abundance between the coronas of these luminous stars are quantified. This research is supported in part by a NASA Grant NAG5-9977 to the Smithsonian Astrophysical Observatory.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AAS...201.1202D