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arXiv 1909.04262astro-ph.GA
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M33中巨分子云的ALMA观测I:解析可能由螺旋激波形成的巨分子丝中的恒星形成活动

ALMA Observations of Giant Molecular Clouds in M33 I: Resolving Star Formation Activities in the Giant Molecular Filaments Possibly Formed by a Spiral Shock

Kazuki Tokuda, Kazuyuki Muraoka, Hiroshi Kondo, Atsushi Nishimura, Tomoka Tosaki, Sarolta Zahorecz, Sachiko Onodera, Rie E. Miura, Kazufumi Torii, Nario Kuno, S… 展开作者

Kazuki Tokuda, Kazuyuki Muraoka, Hiroshi Kondo, Atsushi Nishimura, Tomoka Tosaki, Sarolta Zahorecz, Sachiko Onodera, Rie E. Miura, Kazufumi Torii, Nario Kuno, Shinji Fujita, Hidetoshi Sano, Toshikazu Onishi, Kazuya Saigo, Yasuo Fukui, Akiko Kawamura, Kengo Tachihara

摘要:

本文报道了用ALMA对M33中最大质量的巨分子云之一GMC-16的分子谱线和连续谱的观测结果,其角分辨率为0 $''$ 44 $\times$ 0 $''$ 27($\sim$ 2 pc $\times$ 1 pc).我们发现,在$^{12}$ CO和$^{13}$ CO($J$ = 2-1)中,GMC是由几种典型结构组成的。典型的长度、宽度和总质量分别为$\sim$ 50-70 pc、$\sim$ 5-6 pc和$\sim$ 10 $^{5}$ $M_{\odot}$,这与银河系GMC中所见的巨分子细丝(GMF)一致。巨磁纤维的伸长大致垂直于星系的旋转方向,几个H $\;$ { \sc ii}区域位于相对于细丝的下游侧,偏移量为$\sim$ 10-20 pc。这些观测结果表明,巨磁流体被认为是由星系螺旋激波产生的。1.3 mm连续谱和C $^{18}$ O($J$ = 2-1)观测在几个对流云的交汇处发现了一个$\sim$ 2 pc的致密团块,它被称为$"$中心丝,$"$可能是由云-云碰撞形成的。在M33中的原恒星外流的一个强有力的候选者也被确定在团的中心。我们已经成功地解决了秒差距尺度的本地恒星形成活动,其中银河系尺度的运动学可能会导致形成的父恒星云。

英文摘要:

We report molecular line and continuum observations toward one of the most massive giant molecular clouds (GMCs), GMC-16, in M33 using ALMA with an angular resolution of 0$''$44 $\times$ 0$''$27 ($\sim$2 pc $\times$ 1 pc). We have found that the GMC is composed of several filamentary structures in $^{12}$CO and $^{13}$CO ($J$ = 2-1). The typical length, width, and total mass are $\sim$50-70 pc, $\sim$5-6 pc, and $\sim$10$^{5}$ $M_{\odot}$, respectively, which are consistent with those of giant molecular filaments (GMFs) as seen in the Galactic GMCs. The elongations of the GMFs are roughly perpendicular to the direction of the galaxy's rotation, and several H$\;${\sc ii} regions are located at the downstream side relative to the filaments with an offset of $\sim$10-20 pc. These observational results indicate that the GMFs are considered to be produced by a galactic spiral shock. The 1.3 mm continuum and C$^{18}$O ($J$ = 2-1) observations detected a dense clump with the size of $\sim$2 pc at the intersection of several filamentary clouds, which is referred to as the $"$hub filament,$"$ possibly formed by a cloud-cloud collision. A strong candidate for protostellar outflow in M33 has also been identified at the center of the clump. We have successfully resolved the parsec-scale local star formation activity in which the galactic scale kinematics may induce the formation of the parental filamentary clouds.

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