Universität zu Köln

Heyer, Mark ORCID: 0000-0002-3871-010X, Goldsmith, Paul F., Simon, Robert, Aladro, Rebeca ORCID: 0000-0002-1316-1343 and Ricken, Oliver (2022). Searching for Converging Flows of Atomic Gas onto a Molecular Cloud. Astrophys. J., 941 (1). BRISTOL: IOP Publishing Ltd. ISSN 1538-4357

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Abstract

We present new observations of [C ii] (2) P (3/2) -> (2) P (1/2) fine structure line emission from an isolated molecular cloud using the upGREAT instrument on board SOFIA. These data are analyzed together with archival CO J=1-0 and H i 21 cm emission spectra to investigate the role of converging atomic gas flows in the formation of molecular clouds. Bright [C ii] emission is detected throughout the mapped area that likely originates from photodissociation regions excited by UV radiation fields produced by newborn stars within the cloud. Upon spatial averaging of the [C ii] spectra, we identify weak [C ii] emission within velocity intervals where the H i 21 cm line is brightest; these are blueshifted relative to velocities of the CO and bright [C ii] emission by 4 km s(-1). The brightness temperatures, velocity dispersions, and alignment with H i 21 cm velocities connect this [C ii] emission component to the cold, neutral atomic gas of the interstellar medium, known as the cold, neutral medium (CNM). We propose that this CNM feature is an accretion flow onto the farside of the existing molecular cloud. The mass infall rate is 3.2 x 10(-4) M (circle dot) yr(-1). There is no direct evidence of a comparable redshifted component in the [C ii] or H i 21 cm spectral lines that would indicate the presence of a converging flow.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Heyer, Mark UNSPECIFIED orcid.org/0000-0002-3871-010X UNSPECIFIED Goldsmith, Paul F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Simon, Robert UNSPECIFIED UNSPECIFIED UNSPECIFIED Aladro, Rebeca UNSPECIFIED orcid.org/0000-0002-1316-1343 UNSPECIFIED Ricken, Oliver UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-684026
DOI:	10.3847/1538-4357/aca097
Journal or Publication Title:	Astrophys. J.
Volume:	941
Number:	1
Date:	2022
Publisher:	IOP Publishing Ltd
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language C-II; SUBMILLIMETER; EMISSION; REGIONS; GALAXY Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/68402