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.

中文翻译：

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来自可调滤光片光学观测的 H ii 区域 Sh2-235 的 3D 结构

我们使用窄星系线映射器 (MaNGaL) 展示了对银河系 HII 区域 Sh2-235 中 H-alpha、H-beta、[SII] 6716、6731 和 [NII] 6583 发射线的观察结果，这是一个可调滤波器俄罗斯科学院特殊天体物理天文台1米望远镜。我们表明 HII 区域被 AV = 2-4 mag 的中性物质遮蔽。具有最高 AV 的区域位于电离星的西南方向，与检测到的最大电子密度 >=300 cm(-3) 相吻合。将这些结果与存档的 AKARI 远红外数据相结合，我们可以估计前后壁对 S235 中性物质总柱密度的贡献，并解释该区域的三维结构。HII 区域由更密集的、更致密的部分深深嵌入中性介质中，而密度较小且被遮蔽的气体较少。HII 区的前后壁是不均匀的，后壁中的材料具有更高的柱密度。我们在密集的团块 S235 East 1 中发现了一个两侧的光解区域，在西部和东部分别由 G0=50-70 和 200 Habing 单位的紫外线场照射。