A&A 440, 569-581 (2005)
DOI: 10.1051/0004-6361:20041828
A search for shock-excited optical emission from the outflows of massive young stellar objects
C. Alvarez1, 2, 3 and M. G. Hoare11 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
e-mail: alvarez@mpia-hd.mpg.de
2 Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands
3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
(Received 10 August 2004 / Accepted 28 May 2005)
Abstract
We have searched for optical shock-excited emission
lines in the outer parts of the bipolar outflows from massive young
stellar objects where the flow terminates and the extinction is
expected to be low. The Taurus Tunable Filter (TTF) at the
Anglo-Australian Telescope (AAT) was used to obtain narrow-band
(
) images of the
, [NII] 6583, and [SII] 6717/6731 lines around
Mon R2 IRS3
,
S255 IRS1
/3,
GL 961
and
GL 989
. No clear
examples of shocked emission were found. A bow shock feature in the
GL 989
region maybe related with the molecular outflow NGC 2264 D.
A weak optical bow-like
feature is seen in
GL 961
, but which of the stars in the cluster is the
driving source cannot be uniquely identified. Other emission line
features were found in Mon R2 and S255 that are consistent with an
HII region origin. The observed fluxes and the upper limits
were compared with predictions from radiative shock models
available in the literature. Any head-on collisions of a jet with
speeds of the order of 500 km s-1 should have been detected
if the extinction
mag. Estimates of the extinction
in the outer parts of the molecular clouds are somewhat lower than this,
although it is possible that it could be higher local to any interaction
regions due to swept up material. If the extinction is low, then the
shocks must either be slower (<150 km s-1) or very oblique
(>
), which would argue against the presence of highly collimated
jets from high mass young stellar objects.
Key words: stars: formation -- ISM: jets and outflows
SIMBAD Objects
© ESO 2005