X-rays at the End of the Main Sequence
Abstract
We present results from XMM-Newton and Chandra observations of very low-mass stars. These X-ray observations quite frequently detect, besides large flares, also their quasi-quiescent emission. Our analysis shows that stars down to the bottom of the main sequence are able to generate X-ray emission at high activity levels of log LX/Lbol = -3 … -4, similar to more massive stars operating a solar-type dynamo. However, in very low-mass stars the highly active phase may persist over Gyr, significantly longer than for more massive stars or brown dwarfs. We further discuss examples of strong X-ray flares produced by these stars. Altogether, the X-ray properties require the presence of an efficient dynamo mechanism that is capable of generating the igneous coronae of very low-mass stars.
- Publication:
-
16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
- Pub Date:
- December 2011
- Bibcode:
- 2011ASPC..448.1231R