3D structure of HII region Sh2-235 from tunable-filter optical observations

Abstract

We present observations of the H-alpha, H-beta, [SII] 6716, 6731 and [NII] 6583 emission lines in the galactic HII region Sh2-235 with the Mapper of Narrow Galaxy Lines (MaNGaL), a tunable filter at the 1-m telescope of Special Astrophysical Observatory of the Russian Academy of Sciences. We show that the HII region is obscured by neutral material with AV = 2-4 mag. The area with the highest AV is situated to the south-west from the ionizing star and coincides with a maximum detected electron density of >=300 cm(-3). The combination of these results with archive AKARI far-infrared data allows us to estimate the contribution of the front and rear walls to the total column density of neutral material in S235, and explain the three-dimensional structure of the region. The HII region consist of a denser, more compact portion deeply embedded in the neutral medium and the less dense and obscured gas. The front and rear walls of the HII region are inhomogeneous, with the material in the rear wall having a higher column density. We find a two-sided photodissociation region in the dense clump S235 East 1, illuminated by a UV field with G0=50-70 and 200 Habing units in the western and eastern parts, respectively.

arXiv commentaccepted to MNRAS

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Cited by in corpus (8)

• Mapper of Narrow Galaxy Lines (MaNGaL): new tunable filter imager for Caucasian telescopes
• The PDR structure and kinematics around the compact HII regions S235A and S235C with [CII], [13CII], [OI] and HCO+ line profiles
• Dark cloud-type chemistry in PDRs with moderate UV field
• Magnetic fields and Star Formation around HII regions: The S235 complex
• The Distribution of UV Radiation Field in the Molecular Clouds of Gould Belt
• Ethynyl around the HII regions S255 and S257
• Near infrared view on the photodissociation regions S255, S257, NGC7538 and S140
• 3D structure of HII regions in the star-forming complex S254-S258