NGC 6334 and NGC 6357: Hα kinematics and the nature of the H II regions

Aims. NGC 6334 and NGC 6357 are amongst the most active, optically visible Galactic star-forming complexes. They are composed of several El 11 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 H alpha line, which cover NGC 6334 and NGC 6357. These observations allow us to analyse the H alpha line profiles to probe the kinematics of the ionised gas of both regions. We complement the H alpha 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 H alpha 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 11 II regions, while H II 353.42+0.45 is a classical photo-ionised 11 II region. We suggest that, at large scale, star-formation seems to be triggered where large/old 1111 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.