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X-RAY EMISSION AND CORONA OF THE YOUNG INTERMEDIATE-MASS BINARY ?1 Ori E
- Source :
- The Astrophysical Journal; December 2009, Vol. 707 Issue: 2 p942-953, 12p
- Publication Year :
- 2009
-
Abstract
- th1 Ori E is a young, moderate mass binary system, a rarely observed case of spectral-type G-giants of about 3 solar masses, which are still collapsing toward the main sequence, where they presumably become X-ray faint. We have obtained high-resolution X-ray spectra with Chandra and find that the system is very active and similar to coronal sources, having emission typical of magnetically confined plasma. It has a broad temperature distribution with a hot component and significant high energy continuum; narrow emission lines from H- and He-like ions, as well as a range of Fe ions, and relative luminosity, Lx /L bol = 10-3, at the saturation limit. Density, while poorly constrained, is consistent with the low density limits, our upper limits being ne < 1013 cm-3 for Mg XI and ne < 1012 cm-3 for Ne IX. Coronal elemental abundances are sub-solar, with Ne being the highest at about 0.4 times solar. We find a possible trend in Trapezium hot plasmas toward low relative abundances of Fe, O, and Ne, which is hard to explain in terms of the dust depletion scenarios of low-mass young stars. Variability was unusually low during our observations relative to other coronally active stars. Qualitatively, the emission is similar to post-main-sequence G-stars. Coronal structures could be compact or comparable to the dimensions of the stellar radii. From comparison to X-ray emission from similar mass stars at various evolutionary epochs, we conclude that the X-rays in th1 Ori E are generated by a convective dynamo, present during contraction, but which will vanish during the main-sequence epoch possibly to be resurrected during post-main-sequence evolution.
Details
- Language :
- English
- ISSN :
- 0004637X and 15384357
- Volume :
- 707
- Issue :
- 2
- Database :
- Supplemental Index
- Journal :
- The Astrophysical Journal
- Publication Type :
- Periodical
- Accession number :
- ejs20237585