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arXiv · 2608.16179

Star Formation in the H II Region Sh 2-205: 3D Morphology and Kinematics from Young Stars and Molecular Gas

Yiwei Dong·Chaojie Hao·Ye Xu·Yingjie Li·Zehao Lin·Dejian Liu·Yan Sun·Longhui Yang
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Abstract

Using Gaia astrometry of young stars combined with CO observations, we present the first systematic three-dimensional (3D) analysis of the structure, kinematics, and evolutionary history of the star-forming regions in the environs of the H II region Sh 2-205 (S205). S205 exhibits a complex morphology and coherent expansion on both global and subregional scales. We identify several O9-B1 stars and a 0.56 Myr old pulsar that are likely associated with the region. A momentum estimate suggests that feedback from these objects may account for the observed overall expansion. Trace-back analysis of the expansion, combined with color-magnitude diagram fitting for young star clusters, indicates at least two episodes of star formation. These results reveal a complex star-formation history of S205 and provide new insights into its 3D evolution.

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Yiwei Dong, Chaojie Hao, Ye Xu, Yingjie Li, Zehao Lin, Dejian Liu, Yan Sun, Longhui Yang. 2026-08-17. Star Formation in the H II Region Sh 2-205: 3D Morphology and Kinematics from Young Stars and Molecular Gas. https://arxiv.org/abs/2608.16179

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