T. M. Gledhill, K. P. Forde
Some evolved stars in the pre-planetary nebula phase produce
highly-collimated molecular outflows that resemble the accretion-driven jets
and outflows from pre-main sequence stars. We show that IRAS 16342-3814 (the
Water Fountain Nebula) is such an object and present K-band integral field
spectroscopy revealing a fast (> 150 km/s) bipolar H2 outflow. The H2 emission
is shock excited and may arise in fast-moving clumps, accelerated by the
previously observed precessing jet. The total luminosity in H2 is 0.37
L$_{\odot}$ which is comparable with that of accretion-powered outflows from
Class 0 protostars. We also detect CO overtone bandhead emission in the
scattered continuum, indicating hot molecular gas close to the centre, a
feature also observed in a number of protostars with active jets. It seems
likely that the jet and outflow in IRAS 16342-3814 are powered by accretion
onto a binary companion.
View original:
http://arxiv.org/abs/1112.0877
No comments:
Post a Comment