NGC 6334 and NGC 6357: Hα kinematics and the nature of the H II regions⋆
Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de
Marseille), UMR 7326,
2 Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia, WV 26506, USA
3 Adjunct Astronomer at the National Radio Astronomy Observatory, PO Box 2, Green Bank, WV 24944, USA
4 LAB/OASU, UMR 5804, CNRS, Université de Bordeaux, 33270 Floirac, France
5 I. Physik. Institut, University of Cologne, 50931 Cologne, Germany
6 IAS, CNRS & Université Paris Sud, Bâtiment 121, 91405 Orsay, France
7 Laboratoire d’Astrophysique de Grenoble, Université Joseph Fourier, CNRS, BP 53, 38041 Grenoble Cedex, France
8 International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
9 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
10 School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
Received: 27 June 2014
Accepted: 18 December 2015
Aims. NGC 6334 and NGC 6357 are amongst the most active, optically visible Galactic star-forming complexes. They are composed of several H ii regions that have a significant impact on their surrounding. The aim of this paper is to present a kinematic study of the optical H ii regions that belong to NGC 6334 and NGC 6357.
Methods. We use Fabry-Perot interferometer observations of the Hα line, which cover NGC 6334 and NGC 6357. These observations allow us to analyse the Hα line profiles to probe the kinematics of the ionised gas of both regions. We complement the Hα observations with multi-wavelength data to specify the nature of the H ii regions.
Results. We determine the dynamical nature of the optical H ii regions that belongs to NGC 6334 and NGC 6357. In NGC 6334, GUM 61 is an expanding wind shell-like H ii region, GUM 64b exhibits a champagne flow, GM1-24 is the Hα counterpart of two larger regions and H ii 351.2+0.5 is, in fact, composed of two H ii regions. In NGC 6357, H ii 353.08+0.28 and H ii 353.09+0.63 are probably stellar wind-shaped bubble H ii regions, while H ii 353.42+0.45 is a classical photo-ionised H ii region. We suggest that, at large scale, star-formation seems to be triggered where large/old H ii regions intersect. Inversely, stellar formation seems to have already started in the NGC 6334 north-east filament, irrespective of any evident external H ii region impact. While NGC 6357 shows more complicated kinematics, NGC 6334 is characterised by a more active stellar formation.
Key words: HII regions / ISM: individual objects: NGC 6334 / ISM: individual objects: NGC 6357 / ISM: kinematics and dynamics
The Hα data (FITS cubes) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A135
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