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A&A 413, 669-679 (2004)
DOI: 10.1051/0004-6361:20034151
A large X-ray flare from the Herbig Ae star V892 Tau
G. Giardino1, F. Favata1, G. Micela2 and F. Reale31 Astrophysics Division - Research and Science Support Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
2 INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
3 Università di Palermo - Dipartimento di Scienze Fisiche ed Astronomiche, Piazza del Parlamento 1, 90134 Palermo, Italy
(Received 1 August 2003 / Accepted 30 September 2003 )
Abstract
We report the XMM-Newton observation of a large X-ray flare from
the Herbig Ae star V892 Tau. The apparent low mass companion of
V892 Tau, V892 Tau NE, is unresolved by XMM-Newton. Nevertheless there is
compelling evidence from combined XMM-Newton and Chandra data that the
origin of the flare is the Herbig Ae star V892 Tau. During the
flare the X-ray luminosity of V892 Tau increases by a factor of
, while the temperature of the plasma increases from
keV to
keV. From the scaling of the flare
event, based on hydrodynamic modeling, we conclude that a 500 G
magnetic field is needed in order to confine the plasma. Under the
assumptions that a dynamo mechanism is required to generate such a
confining magnetic field and that surface convection is a necessary
ingredient for a dynamo, our findings provide indirect evidence for
the existence of a significant convection zone in the stellar
envelope of Herbig Ae stars.
Key words: stars: flare -- stars: coronae -- stars: formation -- stars: pre-main sequence -- stars: individual: V892 Tau
Offprint request: G. Giardino, ggiardin@rssd.esa.int
SIMBAD Objects in preparation
© ESO 2004