Herschel observations in the ultracompact HII region Mon R2

被引：15

作者：

Fuente, A. ^{[1
]}

Berne, O. ^{[2
]}

Cernicharo, J. ^{[3
]}

Rizzo, J. R. ^{[3
]}

Gonzalez-Garcia, M. ^{[4
]}

Goicoechea, J. R. ^{[3
]}

Pilleri, P. ^{[5
,6
]}

Ossenkopf, V. ^{[7
,8
]}

Gerin, M. ^{[9
]}

Guesten, R. ^{[10
]}

Akyilmaz, M. ^{[7
]}

Benz, A. O. ^{[11
]}

Boulanger, F. ^{[12
]}

Bruderer, S. ^{[11
]}

Dedes, C. ^{[11
]}

France, K. ^{[13
]}

Garcia-Burillo, S. ^{[14
]}

Harris, A. ^{[15
]}

Joblin, C. ^{[5
,6
]}

Klein, T. ^{[10
]}

Kramer, C. ^{[4
]}

Le Petit, F. ^{[16
,31
]}

Lord, S. D. ^{[17
]}

Martin, P. G. ^{[13
]}

Martin-Pintado, J. ^{[3
]}

Mookerjea, B. ^{[18
]}

Neufeld, D. A. ^{[19
]}

Okada, Y. ^{[7
]}

Pety, J. ^{[20
]}

Phillips, T. G. ^{[21
]}

Roellig, M. ^{[7
]}

Simon, R. ^{[7
]}

Stutzki, J. ^{[7
]}

van der Tak, F. ^{[8
,22
]}

Teyssier, D. ^{[23
]}

Usero, A. ^{[14
]}

Yorke, H. ^{[24
]}

Schuster, K. ^{[20
]}

Melchior, M. ^{[25
]}

Lorenzani, A. ^{[26
]}

Szczerba, R. ^{[27
]}

Fich, M. ^{[28
]}

McCoey, C. ^{[28
,29
]}

Pearson, J. ^{[24
]}

Dieleman, P. ^{[30
]}

机构：

[1] OAN, Alcala De Henares 28803, Madrid, Spain

[2] Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands

[3] CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain

[4] IRAM, E-18012 Granada, Spain

[5] Univ Toulouse, UPS, CESR, F-31062 Toulouse 4, France

[6] CNRS, UMR 5187, F-31028 Toulouse, France

[7] Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany

[8] SRON Netherlands Inst Space Res, NL-9700 AB Groningen, Netherlands

[9] Observ Paris, LERMA, F-75014 Paris, France

[10] Max Planck Inst Radioastron, D-53121 Bonn, Germany

[11] ETH, Inst Astron, CH-8093 Zurich, Switzerland

[12] Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France

[13] Univ Toronto, Dept Astron & Astrophys, Toronto, ON M5S 3H8, Canada

[14] OAN, Madrid 28014, Spain

[15] Univ Maryland, Dept Astron, College Pk, MD 20742 USA

[16] Observ Paris, LUTH, F-92190 Meudon, France

[17] IPAC Caltech, Pasadena, CA 91125 USA

[18] Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India

[19] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA

[20] Inst RadioAstron Millimetr, F-38406 St Martin Dheres, France

[21] CALTECH, Pasadena, CA 91125 USA

[22] Univ Groningen, Kapteyn Astron Inst, NL-9700 AB Groningen, Netherlands

[23] European Space Astron Ctr, Madrid 28080, Spain

[24] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA

[25] FHNW, Inst 4D Technol, CH-5210 Windisch, Switzerland

[26] Osservatorio Astrofis Arcetri INAF, I-50100 Florence, Italy

[27] Nicholas Copernicus Astron Ctr, PL-87100 Torun, Poland

[28] Univ Waterloo, Dept Phys & Astron, Waterloo, ON N2L 3G1, Canada

[29] Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada

[30] SRON Netherlands Inst Space Res, NL-9747 AD Groningen, Netherlands

[31] Univ Paris 07, F-92190 Meudon, France

来源：

ASTRONOMY & ASTROPHYSICS | 2010年 / 521卷

关键词：

ISM: structure; ISM: kinematics and dynamics; ISM: molecules; HII regions; submillimeter: ISM; MONOCEROS R2; CLOUD CORE; PHOTODISSOCIATION; SAGITTARIUS-B2; KINEMATICS; OUTFLOW;

D O I：

10.1051/0004-6361/201015093

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Monoceros R2, at a distance of 830 pc, is the only ultracompact Hii region (UC Hii) where the photon-dominated region (PDR) between the ionized gas and the molecular cloud can be resolved with Herschel. Therefore, it is an excellent laboratory to study the chemistry in extreme PDRs (G0 > 105 in units of Habing field, n > 106 cm-3). Aims. Our ultimate goal is to probe the physical and chemical conditions in the PDR around the UC Hii Mon R2. Methods. HIFI observations of the abundant compounds 13CO, C18O, o-H2 18O, HCO+, CS, CH, and NH have been used to derive the physical and chemical conditions in the PDR, in particular the water abundance. The modeling of the lines has been done with the Meudon PDR code and the non-local radiative transfer model described by Cernicharo et al. Results. The 13CO, C18O, o-H18 2 O, HCO+ and CS observations are well described assuming that the emission is coming from a dense (n = 5 x 106 cm-3, N(H2) > 1022 cm-2) layer of molecular gas around the Hii region. Based on our o-H18 2 O observations, we estimate an o-H2O abundance of similar to 2 x 10-8. This is the average ortho-water abundance in the PDR. Additional H18 2 O and/ or water lines are required to derive the water abundance profile. A lower density envelope (n similar to 105 cm-3, N(H2) = 2-5 x 1022 cm-2) is responsible for the absorption in the NH 11. 02 line. The emission of the CH ground state triplet is coming from both regions with a complex and self-absorbed profile in the main component. The radiative transfer modeling shows that the 13CO and HCO+ line profiles are consistent with an expansion of the molecular gas with a velocity law, ve = 0.5 x (r/ Rout)-1 km s-1, although the expansion velocity is poorly constrained by the observations presented here. Conclusions. We determine an ortho-water abundance of similar to 2 x 10-8 in Mon R2. Because shocks are unimportant in this region and our estimate is based on H18 2 O observations that avoids opacity problems, this is probably the most accurate estimate of the water abundance in PDRs thus far.

引用

页数：5

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