ROSAT observations of the flare star CC ERI
Abstract
The flare/spotted spectroscopic binary star CC Eri was observed with the Position Sensitive Proportional Counter (PSPC) on the X-ray satellite ROSAT on 1990 July 9-11 and 1992 January 26-27. During the observations, the source was variable on time-scales from a few minutes to several hours, with the X-ray (0.2-2 keV) luminosity in the range ~(2.5-6.8)x10^29 erg s^-1. An X-ray flare-like event, which has a 1-h characteristic rise time and a 2-h decay time, was observed from CC Eri on 1990 July 10, 16:14-21:34 (UT). The X-ray spectrum of the source can be described by current thermal plasma codes with two temperature components or with a continuous temperature distribution. The spectral results show that plasma at T_e~10^7K exists in the corona of CC Eri. The variations in the observed source flux and spectra can be reproduced by a flare, adopting a magnetic reconnection model. Comparisons with an unheated model, late in the flare, suggest that the area and volume of the flare are substantially larger than in a solar two-ribbon flare, while the electron pressure is similar. The emission measure and temperature of the non-flaring emission, interpreted as the average corona, lead to an electron pressure similar to that in a well-developed solar active region. Rotational modulation of a spot-related active region requires an unphysically large X-ray flux in a concentration area.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 1995
- DOI:
- arXiv:
- arXiv:astro-ph/9409044
- Bibcode:
- 1995MNRAS.272...11P
- Keywords:
-
- STARS;
- CORONAE-STARS;
- FLARE-STARS;
- INDIVIDUAL;
- CC ERI-STARS;
- LATE-TYPE-STARS;
- ROTATION-X-RAYS;
- STARS.;
- Astrophysics
- E-Print:
- 14 pages, compressed and uuencoded postscript file, to be published in MNRAS