تقرير
Serendipitous X-ray Sources in the Chandra HRC Field around Alpha Centauri
| العنوان: | Serendipitous X-ray Sources in the Chandra HRC Field around Alpha Centauri |
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| المؤلفون: | Ayres, Thomas R. |
| سنة النشر: | 2018 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | For more than a decade, Alpha Centauri AB (G2V+K1V) has been observed by Chandra, in a long-term program to follow coronal (T~1MK) activity cycles of the two sunlike stars. Over 2008.4-2017.8, nineteen HRC-I exposures were taken, each about 10 ks in duration, and spaced about six months apart. Beyond monitoring the AB X-ray luminosities, the HRC-I sequence represents a unique decadal record of the dozen, or so, serendipitous X-ray sources in the Alpha Cen field, which is at low Galactic latitude and thus dominated by nearby stars. For the present study, the ten brightest candidates were considered. Only a handful of these were persistent; most were variable, some highly so, flaring in a few epochs, weak or absent in the others. All ten X-ray sources have Gaia objects within about 2 arcseconds; mostly late-type dwarfs, but a few giants. However, two of the proposed optical counterparts have statistically significant offsets, and possible conflicts between the X-ray and optical properties. Another of the candidates brightened a factor of 100 in X-rays during a single exposure, briefly attaining super-flare status. The Gaia counterpart is anomalously blue for its absolute G-magnitude, and likely is a WD+dM pair. To the extent that the low Galactic latitude field is representative, the Chandra time-domain view emphasizes that the high-energy stellar sky is biased toward transient sources, so any snapshot survey surely will miss many of the most interesting objects. Comment: to be published in AJ |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-3881/aaea62 |
| URL الوصول: | http://arxiv.org/abs/1810.11674 |
| رقم الأكسشن: | edsarx.1810.11674 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-3881/aaea62 |
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