ALMA reveals molecular cloud N55 in the Large Magellanic Cloud as a site of massive star formation
N Naslim, K. Tokuda, T. Onishi, F. Kemper, T. Wong, O. Morata, S. Takada, R. Harada, A. Kawamura, K. Saigo, R. Indebetouw, S. C. Madden, S. Hony, M. Meixner
利用阿塔卡玛大毫米波阵的$^{12}$ CO(1-0)和$^{13}$ CO(1-0)观测资料,给出了大麦云云N55的分子云性质。我们对分子气体的性质进行了详细的研究,以了解N55的云性质与银河系云的不同。在N55中,大多数CO发射出现团簇,并且具有YSO的分子核显示出更大的线宽和质量。大质量团块与高质量和中等质量的YSO有关。团簇质量由局部热力学平衡和$^{12}$ CO和$^{13}$ CO排放的维里分析确定。这些质量估计得出的结论是:(a)团块处于自引力维里平衡,(b)$^{12}$ CO(1-0)到H $_2$的转换因子X $_{\rm CO}$为6.5 $\times$ 10 $^{20}$ cm $^{-2}$(K km s $^{-1}$)$^{-1}$。N55团簇的CO到H的$_2$转换因子在$\sim$ 0.67 pc的空间尺度下测量,这比猎户座云在类似空间尺度下的X $_{\rm CO}$值高出约两倍。N55的核心质量函数清楚地显示出低于200 M $_{\odot}$的周转,将低质量端与高质量端分开。$^{12}$ CO质谱的低质量端符合指数0.5 $\pm$ 0.1的幂律,而对于$^{13}$ CO,符合指数0.6 $\pm$ 0.2的幂律。在高质量端,核心质谱符合功率指数为2.0 $\pm$ 0.3的$^{12}$ CO,与2.5 $\pm$ 0.4的$^{13}$ CO。这种幂律行为的核心质量函数在N55是一致的许多银河系云。
英文摘要:
We present the molecular cloud properties of N55 in the Large Magellanic Cloud using $^{12}$CO(1-0) and $^{13}$CO(1-0) observations obtained with Atacama Large Millimeter Array. We have done a detailed study of molecular gas properties, to understand how the cloud properties of N55 differ from Galactic clouds. Most CO emission appears clumpy in N55, and molecular cores that have YSOs show larger linewidths and masses. The massive clumps are associated with high and intermediate mass YSOs. The clump masses are determined by local thermodynamic equilibrium and virial analysis of the $^{12}$CO and $^{13}$CO emissions. These mass estimates lead to the conclusion that, (a) the clumps are in self-gravitational virial equilibrium, and (b) the $^{12}$CO(1-0)-to-H$_2$ conversion factor, X$_{\rm CO}$, is 6.5$\times$10$^{20}$cm$^{-2}$(K km s$^{-1}$)$^{-1}$. This CO-to-H$_2$ conversion factor for N55 clumps is measured at a spatial scale of $\sim$0.67 pc, which is about two times higher than the X$_{\rm CO}$ value of Orion cloud at a similar spatial scale. The core mass function of N55 clearly show a turnover below 200M$_{\odot}$, separating the low-mass end from the high-mass end. The low-mass end of the $^{12}$CO mass spectrum is fitted with a power law of index 0.5$\pm$0.1, while for $^{13}$CO it is fitted with a power law index 0.6$\pm$0.2. In the high-mass end, the core mass spectrum is fitted with a power index of 2.0$\pm$0.3 for $^{12}$CO, and with 2.5$\pm$0.4 for $^{13}$CO. This power-law behavior of the core mass function in N55 is consistent with many Galactic clouds.
ALMA resolves molecular clouds in the metal poor Magellanic Bridge A
(节略)我们描述了麦哲伦桥A中的气体和尘埃排放,它具有最高的870 $μ$ m的排放超过单碟调查。利用ALMA望远镜,我们在1.3 mm连续谱和CO(2-1)谱线上以亚秒差距的分辨率绘制了麦哲伦桥A分子云。我们还用APEX在870 $μ$ m连续谱和CO(2-1)谱线上绘制了分辨率为6 pc的云图。我们将ALMA和APEX CO(2-1)线立方相结合来研究分子气体发射。麦哲伦桥A在尘埃和CO(2-1)排放中分裂成两个不同的分子云,我们称之为南北。根据我们拟合远红外线通量的最佳参数,北源的尘埃排放比南源冷约3 K,这与其不太发达的恒星形成有关。这两个尘埃源在LABOCA数据中都存在很大的亚毫米级过量:根据我们的最佳拟合,北源和南源与斯皮策/赫歇尔连续谱拟合的修改黑体(MBB)的过量分别为~7和~3。尽管如此,我们没有检测到相应的1.3毫米连续ALMA。我们的极限与MBB拟合的外推相容,因此我们不能独立地确认在该较长波长处的过量。CO(2-1)的排放量是在两个秒差距大小的云维里质量约400和700 Mo每个。它们的体积密度为~700-2600 cm $^{-3}$,大于银河系分子云的典型体积密度。对于北云和南云,CO到H2的转换因子分别为6.5和15 M $_{\odot}$(K km s $^{-1}$ pc $^2$)$^{-1}$,使用它们各自的维里质量和CO(2-1)光度计算。…
The First Detection of a Protostellar CO Outflow in the Small Magellanic Cloud with ALMA
原恒星外流是恒星形成过程中最显著的特征之一。过去几十年的观测研究已经成功地证明,外流是无处不在的低质量和高质量的原恒星在太阳金属量银河系的条件。然而,原恒星外流特性的环境依赖性仍然知之甚少,特别是在低金属度制度。在这里,我们报告的第一次检测到的分子外流的小麦哲伦云与0.2 $Z_{\odot}$,使用阿塔卡玛大型毫米/亚毫米阵列观测在0.1 pc的空间分辨率对大质量的原恒星Y246。在$\gtrsim$ 15 km s $^{-1}$处CO(3-2)发射的高速翼很好地说明了双极外流。流出物的评估属性(动量、机械力等)与银河系的对应物一致我们的研究结果表明,分子外流,即,小尺度吸积盘的路标,可能普遍与原恒星的金属丰度范围的$\sim$ 0.2-1 $Z_{\odot}$。
An ALMA view of molecular filaments in the Large Magellanic Cloud II: An early stage of high-mass star formation embedded at colliding clouds in N159W-South
An ALMA view of molecular filaments in the Large Magellanic Cloud I: The formation of high-mass stars and pillars in the N159E-Papillon Nebula triggered by a cloud-cloud collision
ALMA 0.1 pc View of Molecular Clouds Associated with High-Mass Protostellar Systems in the Small Magellanic Cloud: Are Low-Metallicity Clouds Filamentary or Not?
An ALMA study of the massive molecular clump N159W-North in the Large Magellanic Cloud: A possible gas flow penetrating one of the most massive protocluster systems in the Local Group
ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: The N83 Star-Forming Region
NASA Goddard Space Flight Center(美国宇航局戈达德太空飞行中心);University of Maryland, College Park(马里兰大学帕克分校);Center for Research and Exploration in Space Science and Technology, NASA Goddard Space Flight Center(空间科学与技术研究探索中心,美国宇航局戈达德太空飞行中心);Astrochemistry Laboratory, NASA Goddard Space Flight Center(天体化学实验室,美国宇航局戈达德太空飞行中心);Kagawa University(香川大学);University of Virginia(弗吉尼亚大学);Keele University(基尔大学)
ALMA Observations of Cold Methanol Gas in the Large Magellanic Cloud (LMC): N79 South GMC
S. N. Bose National Centre for Basic Sciences(S.N. 玻色基础科学国家中心);Institute of Science and Technology, Niigata University(新潟大学科学技术研究院);Rosseland Centre for Solar Physics, University of Oslo(奥斯陆大学罗斯兰太阳物理中心);Institute of Theoretical Astrophysics, University of Oslo(奥斯陆大学理论天体物理研究所);Institute of Science Tokyo(东京科学大学);RIKEN Pioneering Research Institute(理化学研究所先导研究本部);Institute of Astronomy Space and Earth Science(天文宇宙地球科学研究院)
ALMA CO Observations of Gamma-Ray Supernova Remnant N132D in the Large Magellanic Cloud: Possible Evidence for Shocked Molecular Clouds Illuminated by Cosmic-Ray Protons
ALMA CO Observations of Supernova Remnant N63A in the Large Magellanic Cloud: Discovery of Dense Molecular Clouds Embedded within Shock-Ionized and Photoionized Nebulae
The ${}^{13}\mathrm{CO}(2{-}1)/^{12}\mathrm{CO}(2{-}1)$ Line Ratio from 100 Molecular Clouds in the Large Magellanic Cloud
University of Alberta(阿尔伯塔大学);The Ohio State University(俄亥俄州立大学);Center for Cosmology and Astroparticle Physics (CCAPP)(宇宙学与天体粒子物理中心);University of Virginia(弗吉尼亚大学);National Radio Astronomy Observatory(美国国家射电天文台)
ALMA Observations of DEM L241/LMC P3 in the Large Magellanic Cloud: Evidence for the Formation of Cool Molecular Jets Driven by a Microquasar
Nagoya University(名古屋大学);Gifu University(岐阜大学);Institute for Advanced Study, Gifu University(岐阜大学高等研究院);National Astronomical Observatory of Japan, National Institutes of Natural Sciences(日本国立天文台,国立自然科学研究所);Institute for Advanced Research, Nagoya University(名古屋大学高等研究院);Western Sydney University(西悉尼大学)
Unveiling star formation at sub-solar metallicity with ALMA2040
INAF-Osservatorio Astrofisico di Arcetri(意大利国家天体物理研究所阿切尔西天文台);Univ. Grenoble Alpes, CNRS, IPAG(格勒诺布尔阿尔卑斯大学,法国国家科学研究中心,天体物理学与行星学研究所);University of Hertfordshire, Centre for Astrophysics Research(赫特福德大学天体物理学研究中心);Niels Bohr Institute, University of Copenhagen(哥本哈根大学尼尔斯·玻尔研究所);Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS(波尔多大学天体物理学实验室,法国国家科学研究中心);Centro de Astrobiología (CAB), CSIC-INTA(西班牙国家航空航天技术研究所与高等科学研究委员会天体生物学中心);Institut de Ciències de l’Espai (ICE-CSIC)(空间科学学院(西班牙高等科学研究委员会));Institute of Astrophysics, University of Cologne(科隆大学天体物理研究所);Max Planck Institute for Astronomy(马克斯·普朗克天文学研究所)
A High Resolution View of Three Massive Young Stellar Objects in the Magellanic Clouds
National Astronomical Observatory of Japan(日本国立天文台);Institute of Science Tokyo(东京科学大学);Niigata University(新潟大学);Shanghai Jiao Tong University(上海交通大学);RIKEN Pioneering Research Institute(理化学研究所先锋研究本部);Institut de Ciències de l’Espai (ICE-CSIC)(空间科学研究所在(加泰罗尼亚高等科学研究院))
MAGellanic Outflow and chemistry Survey (MAGOS): Hot cores in the LMC
Institute of Science and Technology, Niigata University(新潟大学科学技术研究院);Institute of Science Tokyo(东京科学研究所);School of Physics and Astronomy, Shanghai Jiao Tong University(上海交通大学物理与天文学院);State Key Laboratory of Dark Matter Physics(暗物质物理全国重点实验室);Key Laboratory for Particle Astrophysics and Cosmology (MOE)(粒子天体物理与宇宙学教育部重点实验室);Shanghai Key Laboratory for Particle Physics and Cosmology(上海粒子物理与宇宙学重点实验室);RIKEN Pioneering Research Institute(理化学研究所前沿研究中心)
A wide-field, multi-line survey of CO in the Magellanic Clouds at parsec-scale resolution: characterising the molecular gas content with a 50-m single-dish submillimeter telescope
ICE-CSIC/ICREA/IEEC(西班牙高等科学研究理事会/加泰罗尼亚高级研究院/加泰罗尼亚天体物理研究所);MPIfR(马克斯·普朗克射电天文研究所);Observatoire astronomique de Strasbourg(斯特拉斯堡天文台);CEA/Saclay(法国原子能委员会萨克雷中心);United Arab Emirates University(阿联酋大学);U. Chile(智利大学);Kagawa University(香川大学)
First Results from the $Herschel$ and ALMA Spectroscopic Surveys of the SMC: The Relationship Between [CII]-bright Gas and CO-bright Gas at Low Metallicity
A multi-scale molecular and atomic gas view on the HII region N113 in the Large Magellanic Cloud:Evidence for high-mass star formation triggered by supersonically-colliding HI flows
National Astronomical Observatory of Japan, National Institutes of Natural Sciences(日本国立天文台,国立自然科学研究院);Faculty of Engineering, Gifu University(岐阜大学工学部);Department of Physics, Nagoya University(名古屋大学物理学系);Faculty of Education, Kagawa University(香川大学教育学部);Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University(九州大学理学行星地球科学系);Department of Physics, Graduate School of Science, Osaka Metropolitan University(大阪公立大学理学院物理学系);Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center(NASA戈达德太空飞行中心系外行星与恒星天体物理实验室);Department of Astronomy, University of Maryland, College Park(马里兰大学帕克分校天文学系);Center for Research and Exploration in Space Science and Technology, NASA Goddard Space Flight Center(NASA戈达德太空飞行中心空间科学与技术研究探索中心)
ALMA view on the nature of the compact VLA continuum sources in the massive young stellar object G25.65+1.05
P.N. Lebedev Physical Institute of RAS(俄罗斯科学院列别杰夫物理研究所);Kotel'nikov Institute of Radio Engineering and Electronics of RAS(俄罗斯科学院科捷利尼科夫无线电电子学研究所);Xinjiang Astronomical Observatory, Chinese Academy of Sciences(中国科学院新疆天文台);Ural Federal University(乌拉尔联邦大学);Institute of Astronomy and Astrophysics, Academia Sinica(中央研究院天文及天文物理学研究所)