论文标题
原始团块的进化状态托管II类甲醇果酱
The Evolutionary Status of Protostellar Clumps Hosting Class II Methanol Masers
论文作者
论文摘要
甲醇多冰淇淋调查（MMB）提供了最完整的银河大型年轻恒星物体（迈索斯），托有6.7GHz II级甲醇masers。我们使用Herschel红外银河平面调查（HI-GAL）检测到这些MASER源的性能来评估其进化状态。我们将731（73％）的MMB源与四个HI-GAL波长的紧凑发射相关联，我们得出团块性能，并定义了MySO的要求，以托管6.7GHz Maser。中位远红外（FIR）质量和光度为630m $ _ {\ odot} $和2500L $ _ {\ odot} $，用于银河中心近侧的来源，3.2亿$ $ _ {\ odot} $ _ {\ odot} $和10000l $ _ {\ odot} {\ odot} $。 $ \ sim $ 4.2L $ _ {\ odot}/$ m $ _ {\ odot} $的中值光度与质量比相似。我们确定了维持给定亮度的甲醇果酱所需的显而易见的70 $ $ m $ m光度（带有$ l_ {70} \ propto l_ {6.7}^{0.6} $）。 Maser寄主团块的质量高，而FIR仪性高于原始迈索的一般银河系。使用主成分分析，我们发现896个原始团块满足了托管甲醇maser的要求，但在MMB中缺乏检测。在这些物体中找到70 $ $ M $ M的通量密度缺陷，我们赞成这些物体在可以持续的6.7GHz Maser的年龄之上进化的情况。最后，与次级MASER物种相关的隔离确定了6.7GHz来源人群中的进化差异。
The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7GHz class II methanol masers. We characterise the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73%) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of a MYSO to host a 6.7GHz maser. The median far-infrared (FIR) mass and luminosity are 630M$_{\odot}$ and 2500L$_{\odot}$ for sources on the near side of Galactic centre and 3200M$_{\odot}$ and 10000L$_{\odot}$ for more distant sources. The median luminosity-to-mass ratio is similar for both at $\sim$4.2L$_{\odot}/$M$_{\odot}$. We identify an apparent minimum 70$μ$m luminosity required to sustain a methanol maser of a given luminosity (with $L_{70} \propto L_{6.7}^{0.6}$). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70$μ$m flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources.
