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An extremely X-ray luminous proto-Herbig Ae/Be star in the Serpens star forming region *
Received 16 November 1998 / Accepted 2 March 1999
We present near-infrared spectra for the highly obscured, optically invisible young stellar object EC 95 in the Serpens molecular cloud, from which we recently could detect strong X-ray emission with ROSAT. Its location in the HR diagram suggests this object to be an extremely young ( yr old) intermediate-mass () star, which is most likely the progenitor of a B-type or early A-type main sequence star. The only reasonable explanation for its extremely strong X-ray emission ( erg/sec) seems to be coronal, i.e. magnetic activity; this view is also supported by the strong radio emission of EC 95. This is quite surprising, since one usually does not expect a magnetic field on intermediate-mass stars, which are thought to lack surface convection zones, the prerequisite for a solar-like dynamo effect. A possible explanation might be that EC 95 currently goes through a short period of deuterium shell burning, which causes convection near the stellar surface and might give rise to a dynamo effect and a corona.
Key words: stars: coronae stars: individual: EC 95: J182958+011247 stars: individual: EC 95: J182958+011252 stars: magnetic fields stars: pre-main sequence X-rays: stars
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Online publication: April 19, 1999