An extremely X-ray luminous proto-Herbig Ae/Be star in the
Serpens star forming region
Astronomy & Astrophysics, 345, 583 (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 (~ 2 x 10^5 yr old)
intermediate-mass (~ 4 M_sun) 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 (L_x ~ 1.2 x 10^33 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
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