Universität zu Köln

Trevino-Morales, S. P., Fuente, A., Sanchez-Monge, A., Pilleri, P., Goicoechea, J. R., Ossenkopf-Okada, V., Roueff, E., Rizzo, J. R., Gerin, M., Berne, O., Cernicharo, J., Gonzalez-Garcia, M., Kramer, C., Garcia-Burillo, S. and Pety, J. (2016). The first CO+ image I. Probing the HI/H-2 layer around the ultracompact HII region Mon R2. Astron. Astrophys., 593. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

The CO+ reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. We compared the CO+ distribution with other species present in photon-dominated regions (PDR), such as [CIIi] 158 mu m, H-2 S(3) rotational line at 9.3 mu m, polycyclic aromatic hydrocarbons (PAHs), and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [CII] emission. This confirms that the CO+ emission arises from a narrow dense layer of the HI/H-2 interface. We determined the CO+ fractional abundance relative to C+ toward three positions. The abundances range from 0.1 to 1.9 x 10(-10) and are in good agreement with the previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO+ linewidth is larger than those found in molecular gas tracers, and their central velocity are blueshifted with respect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photoevaporating clump surfaces.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Trevino-Morales, S. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fuente, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanchez-Monge, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pilleri, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Goicoechea, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ossenkopf-Okada, V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roueff, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rizzo, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gerin, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Berne, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cernicharo, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gonzalez-Garcia, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kramer, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Garcia-Burillo, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pety, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-263598
DOI:	10.1051/0004-6361/201628899
Journal or Publication Title:	Astron. Astrophys.
Volume:	593
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PHOTON-DOMINATED REGIONS; INTERSTELLAR-MEDIUM; MONOCEROS R2; PHOTODISSOCIATION REGIONS; COLLISIONAL EXCITATION; REACTIVE IONS; ORION BAR; CHEMISTRY; H-2; HYDROCARBONS Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26359