Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii
Abstract
We report Chandra detections of coronal X-rays from the early G supergiants α Aquarii (HD 209750: G2 Ib) and β Aquarii (HD 204867: G0 Ib). Previous ROSAT observations of these archetypical ``hybrid chromosphere'' stars were inconclusive, in the case of α Aqr owing to a 38' mispointing, and for β Aqr because of a small positional discrepancy of the apparent source. The Chandra High Resolution Camera (HRC-I), with its superior spatial resolution and sensitivity, has obtained a positive detection of α Aqr and recovered faint emission at the location of β Aqr, now well separated from the stronger source to the southeast that dominated the earlier ROSAT image. The coronal LX/LC IV luminosity ratios of both supergiants are extremely depressed relative to early G main-sequence stars, continuing the ``X-ray deficiency syndrome'' originally identified in late F/early G luminosity class III giants of the Hertzsprung gap.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2005
- DOI:
- 10.1086/431977
- Bibcode:
- 2005ApJ...627L..53A
- Keywords:
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- Stars: Coronae;
- Stars: Individual: Henry Draper Number: HD 31910;
- Stars: Individual: Henry Draper Number: HD 159181;
- Stars: Individual: Henry Draper Number: HD 204867;
- Stars: Individual: Henry Draper Number: HD 209750;
- X-Rays: Stars