Issue |
A&A
Volume 431, Number 3, March I 2005
|
|
---|---|---|
Page(s) | 993 - 1005 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20041595 | |
Published online | 16 February 2005 |
Subarcsecond mid-infrared and radio observations of the W3 IRS5 protocluster
1
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
Observations at mid-infrared (4.8–17.65 μm) and radio
(0.7–1.3 cm) wavelengths are used to constrain the structure of the
high-mass star-forming region W3 IRS5 on 01 (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
© ESO, 2005
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