N159区的温暖稠密分子气体：12 CO J=4-3和13 CO J=3-2的NANTEN2和ASTE观测
Warm and Dense Molecular Gas in the N159 Region: 12CO J=4-3 and 13CO J=3-2 Observations with NANTEN2 and ASTE
摘要：
在大麦云云N159区进行了~（12）CO J=4-3和~（13）CO J=3-2的新观测。~（12）CO J=4-3的分布分为三个团。这些新的测量对这三个团块的分子旋转激发和线辐射传输的耦合计算中使用，随着其他过渡的12 CO以及同位素过渡的13 CO。N159 W和N159 E的温度和密度分别为~70- 80 K和~3x10^3 cm-3，N159 S的温度和密度分别为~ 30 K和~1.6x10^3 cm-3。这些结果与恒星形成活动进行了比较。N159 E团簇与在24微米处观察到的嵌入式团簇相关，并且导出的高温被解释为由于这些源的加热。N159 E团簇可能是负责一个大的HII地区的尘埃消光暗巷。N159 W星系团与嵌入星系团有关，主要集中在星系团的东部边缘。这些团簇与12 CO J=4-3峰的偏移量为20”-40”，可能是导致高温的原因。N159 W星团在12 CO J=4-3峰值位置及其西部区域没有恒星形成的迹象。我们认为N159 W峰代表一个~105M_sol的前星团核，值得进一步研究。请注意，最近的恒星形成发生在N159 W和N159 E之间，如几个星团和HII区所示，而朝向恒星的出生分子气体已经被OB星的电离和恒星风消散。N159 S团块几乎没有恒星形成的迹象，这与较低的温度和较低的密度是一致的。N159 S星团也是未来恒星形成的候选者。
英文摘要：
New 12CO J=4-3 and 13CO J=3-2 observations of the N159 region in the Large Magellanic Cloud have been made. The 12CO J=4-3 distribution is separated into three clumps. These new measurements toward the three clumps are used in coupled calculations of molecular rotational excitation and line radiation transfer, along with other transitions of the 12CO as well as the isotope transitions of 13CO. The temperatures and densities are determined to be ~70-80K and ~3x10^3 cm-3 in N159W and N159E and ~30K and ~1.6x10^3 cm-3 in N159S. These results are compared with the star formation activity. The N159E clump is associated with embedded cluster(s) as observed at 24 micron and the derived high temperature is explained as due to the heating by these sources. The N159E clump is likely responsible for a dark lane in a large HII region by the dust extinction. The N159W clump is associated with embedded clusters mainly toward the eastern edge of the clump only. These clusters show offsets of 20"-40" from the 12CO J=4-3 peak and are probably responsible for heating indicated by the derived high temperature. The N159W clump exhibits no sign of star formation toward the 12CO J=4-3 peak position and its western region. We suggest that the N159W peak represents a pre-star-cluster core of ~105M_sol which deserves further detailed studies. Note that recent star formation took place between N159W and N159E as indicated by several star clusters and HII regions, while the natal molecular gas toward the stars have already been dissipated by the ionization and stellar winds of the OB stars. The N159S clump shows little sign of star formation as is consistent with the lower temperature and somewhat lower density. The N159S clump is also a candidate for future star formation.
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