Hubble Space Telescope NICMOS Detection of a Partially Embedded, Intermediate-Mass, Pre-Main-Sequence Population in the 30 Doradus Nebula
Hubble Space Telescope NICMOS Detection of a Partially Embedded, Intermediate-Mass, Pre-Main-Sequence Population in the 30 Doradus Nebula
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哈勃太空望远镜 NICMOS 对剑鱼座星云 30 中部分嵌入、中等质量、前主序星团的探测
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发表时间：
2001
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通讯作者：
V. Kutyifa
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作者：
C. Tompkins;S. McNitt;B. Polonsky;J. Daubert;Paul J. Wang;A. Moss;W. Zareba;V. Kutyifa
我们提出了用HST/NICMOS探测到嵌入在大麦哲伦星云(LMC)剑鱼座30区周围星云细丝中的中等质量的前主序群。除了之前已知的4颗发光的I类红外“原恒星”外，NICMOS的数据还揭示了20个新的来源，它们具有类似于银河系主序前恒星的内在红外过剩。根据它们的红外亮度，这些天体可以被识别为银河系前主序恒星的LMC等价物。样本中最微弱的LMC年轻恒星物体的颜色类似于T金牛座恒星，如果放置在LMC距离处，其亮度与T金牛座恒星大致相同。我们没有发现在初始质量函数中有较低质量截止值的证据。相反，从具有∼1.5M⊙的前主序星到仍然嵌在密集结中的大质量O星的整个恒星质量光谱似乎都存在于星云细丝中。大多数年轻的恒星物体可以在中央星团R136的北部找到。这一地区很有可能演变为OB协会。这些观测提供了进一步的证据，表明剑鱼座30区域的恒星形成与银河系恒星形成非常相似，并证实了剑鱼座30区域存在顺序恒星形成，目前的恒星形成是在恒星爆发星团以北和以西的分子气体弧线上发生的。
We present the detection of an intermediate-mass, pre–main-sequence population embedded in the nebular filaments surrounding the 30 Doradus region in the Large Magellanic Cloud (LMC) using HST/NICMOS. In addition to four previously known luminous Class I infrared "protostars," the NICMOS data reveal 20 new sources with intrinsic infrared excess similar to Galactic pre–main-sequence stars. Based on their infrared brightness, these objects can be identified as the LMC equivalent of Galactic pre–main-sequence stars. The faintest LMC young stellar objects in the sample have colors similar to T Tauri stars and have about the same brightness as T Tauri stars if placed at the distance of the LMC. We find no evidence for a lower mass cutoff in the initial mass function. Instead, the whole spectrum of stellar masses from pre–main-sequence stars with ∼1.5 M⊙ to massive O stars still embedded in dense knots appears to be present in the nebular filaments. The majority of the young stellar objects can be found to the north of the central starburst cluster R136. This region is very likely evolving into an OB association. The observations provide further evidence that star formation in the 30 Doradus region is very similar to Galactic star formation and confirm the presence of sequential star formation in 30 Doradus, with present-day star formation taking place in the arc of molecular gas to the north and west of the starburst cluster.