Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel.
| Autor: | Joblin C; IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France., Bron E; Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain.; LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France., Pinto C; Aix-Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille, France., Pilleri P; IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France., Le Petit F; LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France., Gerin M; LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France., Le Bourlot J; LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France.; Université Paris-Diderot, Paris, France., Fuente A; Observatorio Astronómico Nacional, Apdo. 112, 28803 Alcalá de Henares, Madrid, Spain., Berne O; IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France., Goicoechea JR; Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain., Habart E; Institut d'Astrophysique Spatiale (IAS), Université Paris Sud & CNRS, 91405 Orsay, France., Köhler M; Institut d'Astrophysique Spatiale (IAS), Université Paris Sud & CNRS, 91405 Orsay, France., Teyssier D; European Space Astronomy Centre, ESA, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain., Nagy Z; I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany., Montillaud J; Institut Utinam, CNRS UMR 6213, OSU THETA, Université de Franche-Comté, 41bis avenue de l'Observatoire, 25000 Besançon, France., Vastel C; IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France., Cernicharo J; Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain., Röllig M; I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany., Ossenkopf-Okada V; I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany., Bergin EA; Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA. |
|---|---|
| Jazyk: | angličtina |
| Zdroj: | Astronomy and astrophysics [Astron Astrophys] 2018 Jul; Vol. 615. Date of Electronic Publication: 2018 Jul 27. |
| DOI: | 10.1051/0004-6361/201832611 |
| Abstrakt: | Context: In bright photodissociation regions (PDRs) associated to massive star formation, the presence of dense "clumps" that are immersed in a less dense interclump medium is often proposed to explain the difficulty of models to account for the observed gas emission in high-excitation lines. Aims: We aim at presenting a comprehensive view of the modeling of the CO rotational ladder in PDRs, including the high-J lines that trace warm molecular gas at PDR interfaces. Methods: We observed the 12 CO and 13 CO ladders in two prototypical PDRs, the Orion Bar and NGC 7023 NW using the instruments onboard Herschel . We also considered line emission from key species in the gas cooling of PDRs (C + , O, H Results: A grid of models was run to explore the parameter space of only two parameters: thermal gas pressure and a global scaling factor that corrects for approximations in the assumed geometry. We conclude that the emission in the high-J CO lines, which were observed up to J Conclusions: Compiling data from the literature, we found that the gas thermal pressure increases with the intensity of the UV radiation field given by G |
| Databáze: | MEDLINE |
| Externí odkaz: |
|