A&A 431, 993-1005 (2005)
DOI: 10.1051/0004-6361:20041595
Subarcsecond mid-infrared and radio observations of the W3 IRS5 protocluster
F. F. S. van der Tak1, P. G. Tuthill2 and W. C. Danchi31 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: vdtak@mpifr-bonn.mpg.de
2 School of Physics, University of Sydney, NSW 2006, Australia
3 NASA Goddard Space Flight Center, Infrared Astrophysics, Code 685, Greenbelt MD 20771, USA
(Received 5 July 2004 / Accepted 27 October 2004 )
Abstract
Observations at mid-infrared (4.8-17.65
m) and radio
(0.7-1.3 cm) wavelengths are used to constrain the structure of the
high-mass star-forming region W3 IRS5 on 0
1 (200 AU) scales. Two
bright mid-infrared sources are detected, as well as diffuse emission. The
bright sources have associated compact radio emission and probably are young
high-mass stars.
The measured sizes and estimated temperatures indicate that these
sources together can supply the observed far-infrared luminosity.
However, an optically thick radio source with a possible
mid-infrared counterpart may also contribute significant luminosity;
if so, it must be extremely deeply embedded.
The infrared colour temperatures of 350-390 K and low radio
brightness suggest gravitational confinement of the H II regions and
ongoing accretion at a rate of a few 10
-8
yr
-1 or more.
Variations in the accretion rate would explain the observed radio
variability.
The low estimated foreground extinction suggests the existence of a
cavity around the central stars, perhaps blown by stellar winds.
At least three radio sources without mid-infrared counterparts
appear to show proper motions of ~100 km s
-1, and may be deeply
embedded young runaway OB stars, but more likely are clumps in the
ambient material which are shock-ionized by the OB star winds.
Key words: stars: circumstellar matter -- stars: formation -- instrumentation: high angular resolution -- ISM: individual objects: W3 IRS5
SIMBAD Objects
© ESO 2005