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arXiv 2210.04786astro-ph.GA
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III NGC 300中的MUSE拥挤场3D光谱。表征极微弱的HII区域和扩散电离气体

MUSE crowded field 3D spectroscopy in NGC 300 III. Characterizing extremely faint HII regions and diffuse ionized gas

Genoveva Micheva, Martin M. Roth, Peter M. Weilbacher, Christophe Morisset, N. Castro, A. Monreal Ibero, Azlizan A. Soemitro, Michael V. Maseda, Matthias Steinm… 展开作者

Genoveva Micheva, Martin M. Roth, Peter M. Weilbacher, Christophe Morisset, N. Castro, A. Monreal Ibero, Azlizan A. Soemitro, Michael V. Maseda, Matthias Steinmetz, Jarle Brinchmann

摘要:

HII和扩散电离气体(DIG)的物理性质之间存在已知的差异,但文献中大多数研究区域都相对明亮。我们在螺旋星系NGC 300中收集了390个HII区域的微弱样本,中值$\log_{10}Hα$ =34.7,从金属丰度、密度、消光和运动学方面推导出它们的物理性质,并对DIG的性质进行了比较分析。我们使用了NGC 300中9个场的MUSE数据,覆盖了0到~450 arcsec(~4投影kpc)的银河中心距离,包括旋臂和旋臂间区域。我们将数据分箱在树状图叶和提取所有强星云发射线。我们确定了HII和DIG区域,并比较了它们的电子密度,金属丰度,消光和运动学性质。我们还测试了无监督机器学习算法区分HII和DIG区域的有效性。HII区和DIG区的天然气密度接近所有气田的低密度极限。DIG中的平均速度分散高于HII区域,这可以通过DIG比HII气体热1.8 kK来解释。DIG的电离参数比HII气体低,DIG的比例在15- 77%之间,有强有力的证据表明,低质量的恒星和激波对DIG的电离有贡献。大部分的DIG是一致的,没有灭绝和氧金属丰度是无法区分的HII气体。我们观察到一个平坦的金属丰度分布在中心区域,没有梯度的迹象。极暗的HII和DIG区域之间的差异遵循与它们更明亮的表亲相同的趋势和相关性。然而,HII和DIG是如此异质,以至于每个类内的差异大于两个类之间的差异。

英文摘要:

There are known differences between the physical properties of HII and diffuse ionized gas (DIG), but most of the studied regions in the literature are relatively bright. We compiled a faint sample of 390 HII regions with median $\log_{10}Hα$=34.7 in the spiral galaxy NGC300, derived their physical properties in terms of metallicity, density, extinction, and kinematics, and performed a comparative analysis of the properties of the DIG. We used MUSE data of nine fields in NGC300, covering a galactocentric distance of zero to ~450 arcsec (~4 projected kpc), including spiral arm and inter-arm regions. We binned the data in dendrogram leaves and extracted all strong nebular emission lines. We identified HII and DIG regions and compared their electron densities, metallicity, extinction, and kinematic properties. We also tested the effectiveness of unsupervised machine-learning algorithms in distinguishing between the HII and DIG regions. The gas density in the HII and DIG regions is close to the low-density limit in all fields. The average velocity dispersion in the DIG is higher than in the HII regions, which can be explained by the DIG being 1.8 kK hotter than HII gas. The DIG manifests a lower ionization parameter than HII gas, and the DIG fractions vary between 15-77%, with strong evidence of a contribution by hot low-mass evolved stars and shocks to the DIG ionization. Most of the DIG is consistent with no extinction and an oxygen metallicity that is indistinguishable from that of the HII gas.We observe a flat metallicity profile in the central region, without a sign of a gradient. The differences between extremely faint HII and DIG regions follow the same trends and correlations as their much brighter cousins. HII and DIG are so heterogeneous, however, that the differences within each class are larger than the differences between the two classes.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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