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Star formation rates in the L 1482 filament of the California molecular cloud
Publications of the Astronomical Society of Japan ( IF 2.3 ) Pub Date : 2020-06-11 , DOI: 10.1093/pasj/psaa048
Toshihiro Omodaka 1 , Takumi Nagayama 2 , Kazuhito Dobashi 3 , James O Chibueze 4, 5 , Akifumi Yamabi 3 , Yoshito Shimajiri 6 , Shinnosuke Inoue 1 , Shota Hamada 1 , Kazuyoshi Sunada 2 , Yuji Ueno 2
Affiliation  

We measured the trigonometric parallax of the H2O maser source associated with the L 1482 molecular filament hosting the most massive young star, LkHα 101, in the California molecular cloud. The measured parallax is 1.879 ± 0.096 mas, corresponding to the distance of 532 ± 28 pc. This parallax is consistent with that of the nearby star cluster LkHα 101, which was recently measured with Gaia DR2. We found that the L 1482 molecular filament and the LkHα 101 cluster are located at the same distance within 3 ± 30 pc. We observed the southern parts of L 1482 molecular clouds including the H2O maser source, which is adjacent to LkHα 101, using the Nobeyama 45 m telescope in the J = 1–0 transitions of both 12CO and 13CO. The peak intensity of the 12CO line revealed the high excitation temperature region (60–70 K) due to heating by UV radiation from LkHα 101. We derived the column density of these molecular clouds assuming local thermodynamic equilibrium (LTE) from the 13CO emission. Using Dendrogam, we searched for small-scale, dense structures (cores) and identified 337 cores in the 13CO data. Gravitationally bound cores with a virial mass to LTE mass ratio ≤1.5 and young stars are concentrated in the high excitation temperature region. The column density in the warm region is five to six times larger than that of the surrounding colder molecular region. This suggests that the warm region has been compressed by a high-pressure wave and successive radiation-driven star formation is in progress in this warm region. In the cold molecular cloud to the north of the warm region, the cores are likely gravitationally unbound, which may be the reason why star formation is not active there.

中文翻译:

加利福尼亚分子云的L 1482灯丝中的恒星形成率

我们测量了与L 1482分子丝相关的H 2 O maser源的三角视差,该分子丝承载着加利福尼亚分子云中最大的年轻恒星LkHα101。测得的视差为1.879±0.096 mas,对应于532±28 pc的距离。该视差与附近的星团LkHα101的视差一致,最近用Gaia DR2对其进行了测量。我们发现L 1482分子丝和LkHα101簇位于3±30 pc内的相同距离处。我们使用Nobeyama 45 m望远镜在12 CO和13J = 1–0跃迁中观察了L 1482分子云的南部,包括与LkHα101相邻的H 2 O maser源。CO。的的峰强度12 CO线揭示了高激发温度区域(60〜70 K)由于从LkHα101 UV辐射来加热我们派生这些分子云的假设从本地热力学平衡(LTE)列密度13 CO排放。使用Dendrogam,我们搜索了小规模的密集结构(核心),并在13个核心中确定了337个核心CO数据。重力质量与LTE质量比≤1.5的引力束缚核和年轻恒星集中在高激发温度区域。温暖区域的色谱柱密度是周围较冷分子区域的色谱柱密度的五到六倍。这表明温暖的区域已被高压波压缩,并且在该温暖的区域中正在进行连续的辐射驱动恒星形成。在暖区北部的冷分子云中,核心很可能在重力作用下未结合,这可能是恒星形成在那里不活跃的原因。
更新日期:2020-08-04
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