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arXiv 2307.04590astro-ph.GA
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核周电离星团的物理性质。I. NGC 7742

Physical properties of circumnuclear ionising clusters. I. NGC 7742

S. Zamora, A. I. Díaz

AI总结:

该研究基于IFS观测分析NGC 7742星系环中88个电离星团及其HII区,测定光子发射率、密度、金属丰度、温度、年龄与质量,揭示其恒星族群及气体物理性质。

摘要:

本工作旨在利用IFS观测推导正面旋涡星系NGC 7742环中CNSFRs的物理性质。我们选取了88个独立的电离星团,它们为分布在该星系环上的HII区提供能量;这些HII区可能起源于一次小并合事件。对于HII区,Lyman连续谱光子发射率介于0.025至1.5×10^51之间,这表明这些区域由星团电离。它们的电子密度、电离参数、填充因子和电离氢质量所显示的数值与其他针对类似区域的研究结果一致;由硫示踪得到的金属丰度被发现处于太阳值的0.25至2.4倍之间,其中大多数区域显示出略低于太阳值的丰度。电离星团的等效温度相对较低,低于40000 K,这与所推导的高元素丰度相符。星团中的年轻恒星族群由电离族群和非电离族群贡献,二者年龄分别约为5 Ma和300 Ma。在校正了底层非电离族群的贡献后,电离星团的质量平均值为3.5×10^4 M⊙,与电离气体质量相当,约为经校正的测光质量的20%。

英文摘要:

This work aims to derive the physical properties of the CNSFRs in the ring of the face-on spiral NGC 7742 using IFS observations. We have selected 88 individual ionising clusters that power HII regions populating the ring of the galaxy that may have originated in a minor merger event. For the HII regions the rate of Lyman continuum photon emission is between 0.025 and 1.5 10$^{51}$ which points to these regions being ionised by star clusters. Their electron density, ionisation parameter, filling factor and ionised hydrogen mass show values consistent with those found in other studies of similar regions and their metal abundances as traced by sulphur have been found to be between 0.25 and 2.4 times solar, with most regions showing values slightly below solar. The equivalent temperature of the ionising clusters is relatively low, below 40000 K which is consistent with the high elemental abundances derived. The young stellar population of the clusters has contributions of ionising and non-ionising populations with ages around 5 Ma and 300 Ma respectively. The masses of ionising clusters once corrected for the contribution of underlying non-ionising populations were found to have a mean value of 3.5 $\times$ 10$^4$ M$_{\odot}$, comparable to the mass of ionised gas and about 20 \% of the corrected photometric mass.

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