The X-Ray View of the Low-Mass Stars in the Solar Neighborhood
Abstract
We present the results of a complete and sensitive X-ray survey of all known stars of spectral type K and M in the immediate solar vicinity with distances less than 7 pc. The X-ray data were obtained primarily from the ROSA T all-sky survey (RASS); those program stars not detected in the RASS data were subsequently studied with the ROSAT pointed observation program. These new X-ray observations resulted in a detection rate of almost 94% for all K and M stars within 6 pc around the Sun, and 87% for K and M dwarfs within 7 pc around the Sun. The resulting X-ray luminosity distribution function can be well described by a log-normal distribution; the largest and smallest X-ray luminosities from our sample stars differ by almost four orders of magnitude. We show the existence of a correlation between total emitted X-ray luminosity and spectral hardness, such that more luminous objects tend to have larger spectral hardness, thus implying higher coronal temperatures. A comparison with Einstein data shows the lack of significant variability in excess of a factor of 2 in our sample stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1995
- DOI:
- 10.1086/176149
- Bibcode:
- 1995ApJ...450..392S
- Keywords:
-
- STARS: CORONAE;
- STARS: LATE-TYPE;
- X-RAYS: STARS