Issue |
A&A
Volume 465, Number 3, April III 2007
|
|
---|---|---|
Page(s) | 887 - 898 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20065931 | |
Published online | 05 February 2007 |
The interaction of young massive stars with their environment *,**
A millimeter and submillimeter line study of NGC 6334 FIR II
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: dennyzhang998@hotmail.com
2
Purple Mountain Observatory, Chinese Academy of Sciences, NanJing 210008, PR China
3
Center for Astrophysics, GuangZhou University, GuangZhou 510006, PR China
4
Instituto de Radioastronomía Millimétrica (IRAM), Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
5
Department of Physics, Tamkang University, 251-37 Tamsui, Taipeh County, Taiwan
6
Im Acker 21b, 56072 Koblenz, Germany
Received:
29
June
2006
Accepted:
7
January
2007
Using the 15-m Swedish ESO Sub-millimeter Telescope (SEST), CO, HCN, and HCO+ observations of the galactic star-forming region NGC 6334 FIR II
are presented, complemented by [C i] 3PP0 and 3P
P1 data from the Atacama Pathfinder Experiment (APEX 12-m
telescope). Embedded in the extended molecular cloud and associated with the H ii region NGC 6334–D, there is a molecular “void”.
[C i] correlates well with 13CO and other molecular lines and shows no rim brightening relative to molecular cloud regions farther off
the void. While an interpretation in terms of a highly clumped cloud morphology is possible, with photon dominated regions (PDRs) reaching deep into
the cloud, the data do not provide any direct evidence for a close association of [C i] with PDRs. Kinetic temperatures are ~40-50 K
in the molecular cloud and
200 K toward the void. CO and [C i] excitation temperatures are similar. A comparison of molecular and
atomic fine structure line emission with the far infrared and radio continuum as well as the distribution of 2.2
m H2 emission indicates
that the well-evolved H ii region expands into a medium that is homogeneous on pc-scales. If the H2 emission is predominantly shock
excited, both the expanding ionization front (classified as subsonic, “D-type”) and the associated shock front farther out (traced by H2)
can be identified, observationally confirming for the first time a classical scenario that is predicted by evolutionary models of Hii
regions. Integrated line intensity ratios of the observed molecules are determined, implying a mean C18O/C17O abundance ratio of
4.13 ± 0.13 that reflects the 18O/17O isotope ratio. This ratio is consistent with values determined in nearby clouds. Right
at the edge of the void, however, the oxygen isotope ratio might be smaller.
Key words: ISM: abundances / ISM: atoms / ISM: H ii regions / ISM: individual objects: NGC 6334 FIR II / ISM: molecules / radio lines: ISM
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.