Cool Stars 14 - Submitted Abstract # 106
This version created on 05 October 2006

X-ray and optical emission in protostellar jets:  model predictions
and comparison with observations


Rosaria Bonito, Universita' di Palermo - INAF Osservatorio Astronomico di Palermo
Fabio Favata, Astrophysics Div. - Research and Science Support Dept. of ESA
Malcolm Fridlund, Astrophysics Div. - Research and Science Support Dept. of ESA
Rene Liseau, Stockholm Observatory, AlbaNova University Center
Giuseppina Micela, INAF Osservatorio Astronomico di Palermo
Salvatore Orlando, INAF Osservatorio Astronomico di Palermo
Giovanni Peres, Universita' di Palermo - INAF Osservatorio Astronomico di Palermo
Robert Rosner, Center for Astrophysical Thermonuclear Flashes, University of Chicago
Salvatore Sciortino, INAF Osservatorio Astronomico di Palermo

We investigate the mechanisms causing the X-ray emission recently
detected from Herbig - Haro (HH) objects by analyzing variability in
the X-ray band, as detected with Chandra for HH 154, the nearest HH
object from which X-ray emission has been detected.  A detailed
comparison between our 2005 deep Chandra observation with previous
2001 Chandra data shows for the first time the proper motion and the
complex morphology of the X-ray source associated with a protostellar
jet.  The source consists of both an unresolved, point-like component,
without detectable proper motion over 4 yr, and an elongated component
in agreement with a shock moving away from the parent star at about
460  km/s.  We have also studied HST observations in H-alpha and [S
II] made at three epochs (1996, 1998, 2005) deriving the morphology
and the evolution of the larger knotty structure within the jet.  The
X-ray emission is co-located with optical knots having true velocity
of about 500  km/s according to HST optical spectroscopy and imaging.
In order to explain the mechanisms governing the relevant X-ray
emission, we developed a hydrodynamic numerical model (including
thermal conduction and radiative losses) of a continuous supersonic
protostellar jet.  The model predicts X-ray emission due to the shock
forming at the head of the jet;  also the X-ray source should move at
about 500  km/s, consistent with the velocity of the observed extended
X-ray component.

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