Deep Hα survey of the Milky Way - V. The 1=289° to 295° area

Abstract

An Hα study of the ionized hydrogen in the Galactic plane direction 1 = 290° has been undertaken. We describe and discuss the characteristics of the numerous filaments and emission patches observed. These appear linked to a major expanding HI bubble or shell over an area of several degrees. Thanks to morphological, kinematical and stellar distance considerations we have linked observed HII regions and molecular clouds into star-forming complexes which mainly trace the Carina arm. We show particularly that the HII regions Gum35 (G289.8-1.3), Gum38b (G291.6-0.5, NGC 3603) and Hf 58 (G291.9-0.7) can be directly linked to the farthest complexes at a distance 'd' of 8 and 9 kpc, while HII regions Gum37 (G290.6+0.3), Gum38a (G291.3-0.7) and the expanding shell can be linked to the closest complexes located between 2.6 and 2.9 kpc. Important internal motions have been identified in the Gum35, Gum37, Gum38a and Gum38b HII regions. The identification and analysis of these motions are essential for a good systemic velocity determination. We have also identified and delineated that part of the Galactic plane exhibiting velocity departures of Δ⊖ = 7 km s-1 (between 285° and 295° and d = 2.5 and 3 kpc).