Research Note
Quiescent X-ray emission from the M9 dwarf LHS 2065
Universität Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: jrobrade@hs.uni-hamburg.de
Received:
6
May
2008
Accepted:
20
June
2008
Aims. X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere.
Methods. We investigate an archival XMM-Newton observation of LHS 2065, an ultracool dwarf with spectral type M9.
Results. We clearly detect LHS 2065 at soft X-ray energies in less than 1 h effective exposure time above the 3σ level with the PN and MOS1 detector.
No flare signatures are present and we attribute
the X-ray detection to quasi-quiescent activity. From the PN data we derived an X-ray luminosity of 
erg/s in the 0.3–0.8 keV band,
the corresponding activity level of log LX/
points to a rather active star.
Indications for minor variability and possible accompanying spectral changes
are present, however the short exposure time and poor data quality prevents a more detailed analysis.
Conclusions. LHS 2065 is one of the coolest and least massive stars that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona.
Key words: stars: coronae / stars: individual LHS 2065 / stars: late-type / X-rays: stars
© ESO, 2008