Issue |
A&A
Volume 454, Number 1, July IV 2006
|
|
---|---|---|
Page(s) | 221 - 231 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20064887 | |
Published online | 03 July 2006 |
The high-mass star-forming region IRAS 18182-1433
1
Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany e-mail: beuther@mpia-hd.mpg.de
2
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA e-mail: name@cfa.harvard.edu
3
Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México
Received:
20
January
2006
Accepted:
23
March
2006
Aims.We present mm line and continuum observations at high spatial resolution characterizing the physical and chemical properties of the young massive star-forming region IRAS 18182-1433.
Methods.The region was observed with the Submillimeter Array in the 1.3 mm band. The data are complemented with short-spacing information from single-dish CO(2–1) observations. SiO(1–0) data from the VLA are added to the analysis.
Results.Multiple massive outflows emanate from the mm continuum peak. The
CO(2–1) data reveal a quadrupolar outflow system consisting of two
outflows inclined by ~90°. One outflow exhibits a
cone-like red-shifted morphology with a jet-like blue-shifted
counterpart where a blue counter-cone can only be tentatively
identified. The SiO(1–0) data suggest the presence of a third outflow.
Analyzing the 12CO/13CO line ratios indicates decreasing CO line opacities with increasing velocities. Although we observe a
multiple outflow system, the mm continuum peak remains single-peaked at
the given spatial resolution (~13 500 AU). The other seven
detected molecular species – also high-density tracers like CH3CN,
CH3OH, HCOOCH3 – are all ~1- offset from the mm
continuum peak, but spatially associated with a strong molecular outflow
peak and a cm emission feature indicative of a thermal jet. This spatial
displacement between the molecular lines and the mm continuum emission
could be either due to an unresolved sub-source at the position of the
cm feature, or the outflow/jet itself alters the chemistry of the core
enhancing the molecular abundances toward that region. A temperature
estimate based on the CH3CN
lines suggests temperatures
of the order of 150 K. A velocity analysis of the high-density tracing
molecules reveals that at the given spatial resolution none of them
shows any coherent velocity structure which would be consistent with a
rotating disk. We discuss this lack of rotation signatures and attribute
it to intrinsic difficulties to observationally isolate massive
accretion disks from the surrounding dense gas envelopes and the
molecular outflows.
Key words: stars: formation / ISM: jets and outflows / ISM: molecules / stars: early-type / stars: individual: IRAS 18182-1433 / stars: winds, outflows
© ESO, 2006
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