Volume 653, September 2021
|Number of page(s)||22|
|Section||Interstellar and circumstellar matter|
|Published online||16 September 2021|
Globules and pillars in Cygnus X
III. Herschel and upGREAT/SOFIA far-infrared spectroscopy of the globule IRAS 20319+3958 in Cygnus X★
I. Physik. Institut, University of Cologne,
Zülpicher Str. 77,
2 RAL Space, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK
3 ESO, Karl Schwarzschild Str. 2, 85748 Garching, Germany
4 Nordic Optical Telescope, Rambla José Ana Fernández Pérez 7, 38711 Breña Baja, Spain
5 Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
6 Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA
7 Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, allée G. Saint-Hilaire, 33615 Pessac, France
8 Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
9 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
10 SOFIA-USRA, NASA Ames Research Center, MS 232-12, Moffett Field, CA 94035, USA
11 DLR, Rutherfordstraße 2, 12489 Berlin-Adlershof, Germany
Accepted: 13 August 2021
IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240 M⊙, length ~1.5 pc) with an internal H II region 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 a Herschel/HIFI [C II] 158 μm map of the whole globule and a large set of other FIR lines (mid-to high-J CO lines observed with Herschel/PACS and SPIRE, the [O I] 63 μm line and the 12CO 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-τ PDR 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 II region cavity and the external PDR. The modelled internal UV field of ~2500 G° is similar to what we obtained from the Herschel FIR 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 ~150–600 G° 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 140 G°.
Key words: ISM: atoms / ISM: clouds / HII regions / photon-dominated region / ISM: molecules / ISM: kinematics and dynamics
The [C II] data shown in Figs. 4 and 5 (FITS files) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/653/A108
© ESO 2021
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.