Universität zu Köln

Goicoechea, J. R., Pabst, C. H. M., Kabanovic, S., Santa-Maria, M. G., Marcelino, N., Tielens, A. G. G. M., Hacar, A., Berne, O., Buchbender, C., Cuadrado, S., Higgins, R., Kramer, C., Stutzki, J., Suri, S., Teyssier, D. and Wolfire, M. (2020). Molecular globules in the Veil bubble of Orion: IRAM 30 m (CO)-C-12, (CO)-C-13, and (CO)-O-18 (2-1) expanded maps of Orion A? Astron. Astrophys., 639. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Strong winds and ultraviolet (UV) radiation from O-type stars disrupt and ionize their molecular core birthplaces, sweeping up material into parsec-size shells. Owing to dissociation by starlight, the thinnest shells are expected to host low molecular abundances and therefore little star formation. Here, we expand previous maps made with observations using the IRAM 30 m telescope (at 11 '' similar or equal to 4500 AU resolution) and present square-degree (CO)-C-12 and (CO)-C-13 (J = 2-1) maps of the wind-driven Veil bubble that surrounds the Trapezium cluster and its natal Orion molecular core (OMC). Although widespread and extended CO emission is largely absent from the Veil, we show that several CO globules exist that are blueshifted in velocity with respect to OMC and are embedded in the [CII] 158 mu m-bright shell that confines the bubble. This includes the first detection of quiescent CO at negative local standard of rest velocities in Orion. Given the harsh UV irradiation conditions in this translucent material, the detection of CO globules is surprising. These globules are small (R-g = 7100 AU), not massive (M-g = 0.3 M-circle dot), and are moderately dense: n(H) = 4 x 10(4) cm(-3) (median values). They are confined by the external pressure of the shell, P-ext/k greater than or similar to 10(7) cm(-3) K, and are likely magnetically supported. They are either transient objects formed by instabilities or have detached from pre-existing molecular structures, sculpted by the passing shock associated with the expanding shell and by UV radiation from the Trapezium. Some represent the first stages in the formation of small pillars, others of isolated small globules. Although their masses (M-g <M-Jeans) do not suggest they will form stars, one globule matches the position of a known young stellar object. The lack of extended CO in the Veil shell demonstrates that feedback from massive stars expels, agitates, and reprocesses most of the disrupted molecular cloud gas, thereby limiting the star-formation rate in the region. The presence of molecular globules is a result of this feedback.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Goicoechea, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pabst, C. H. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kabanovic, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Santa-Maria, M. G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Marcelino, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tielens, A. G. G. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hacar, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Berne, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Buchbender, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cuadrado, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Higgins, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kramer, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Stutzki, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Suri, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Teyssier, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wolfire, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-327936
DOI:	10.1051/0004-6361/202037455
Journal or Publication Title:	Astron. Astrophys.
Volume:	639
Date:	2020
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 INTERSTELLAR CLOUDS; COMETARY GLOBULES; MAGNETIC-FIELDS; BOK GLOBULES; RADIATION; PHOTODISSOCIATION; NEBULA; EMISSION; CARBON; CO Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/32793