Abstract
This paper presents the first X-ray observations of the late-type dwarf flare star Gliese 890 using the low-energy (LE) and the medium energy (ME) detectors of the Exosat Observatory. A steady X-ray emission, most probably of coronal origin, is detected. No flaring activity is observed in X-ray observations. A combined spectral fit to the LE and ME data was carried out, and an X-ray plasma temperature of 1.4 + or - 0.3 keV and the equivalent hydrogen column density of (7.5 + or - 4.7) x 10 to the 19th/sq cm using the plasma emission models given by Raymond and Smith. The X-ray luminosity in the 0.1-4.0 keV energy band is 4.1 x 10 to the 29th ergs/sec. The X-ray luminosity and the temperature are typical of a slowly rotating dMe type flare star and do not show any effect of the fast rotation, possibly suggesting a saturation effect of the dynamo action. 29 refs.
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