Year: 2021
Type: article
Abstract: IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240M⊙, length ~1.5 pc) with an internal H IIregion created by the stellar feedback of embedded intermediate-mass stars, in particular, one Herbig Be star. In Schneider et al. 2012, (A&A, 542, L18) and Djupvik et al. 2017, (A&A, 599, A37), we proposed that the emission of the far-infrared (FIR) lines of [C II] at 158 μm and [O I] at 145 μm in the globule head are mostly due to an internal photodissociation region (PDR). Here, we present aHerschel/HIFI [C II] 158 μm map of the whole globule and a large set of other FIR lines (mid-to high-JCO lines observed withHerschel/PACS and SPIRE, the [O I] 63 μm line and the12CO 16→15 line observed with upGREAT on SOFIA), covering the globule head and partly a position in the tail. The [C II] map revealed that the whole globule is probably rotating. Highly collimated, high-velocity [C II] emission is detected close to the Herbig Be star. We performed a PDR analysis using the KOSMA-τPDR code for one position in the head and one in the tail. The observed FIR lines in the head can be reproduced with a two-component model: an extended, non-clumpy outer PDR shell and a clumpy, dense, and thin inner PDR layer, representing the interface between the H IIregion cavity and the external PDR. The modelled internal UV field of ~2500G°is similar to what we obtained from theHerschelFIR fluxes, but lower than what we estimated from the census of the embedded stars. External illumination from the ~30 pc distant Cyg OB2 cluster, producing an UV field of ~150–600G°as an upper limit, is responsible for most of the [C II] emission. For the tail, we modelled the emission with a non-clumpy component, exposed to a UV-field of around 140G°.
Source: Astronomy and Astrophysics
Authors: N. Schneider, M. Röllig, E. T. Polehampton, F. Comerón, A. A. Djupvik, Z. Makai, C. Buchbender, R. Simon, S. Bontemps, R. Güsten, G. White, Y. Okada, A. Parikka, N. Rothbart
Institutions: University of Cologne, Rutherford Appleton Laboratory, European Southern Observatory, Aarhus University, Nordic Optical Telescope, West Virginia University, Centre National de la Recherche Scientifique, Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, Max Planck Institute for Radio Astronomy, The Open University, Ames Research Center, Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Agence Nationale de la Recherche
OpenAlex ID: W3194074748