METHANOL MASER EMISSION FROM GALACTIC CENTER SOURCES WITH EXCESS 4.5 μm EMISSION
METHANOL MASER EMISSION FROM GALACTIC CENTER SOURCES WITH EXCESS 4.5 μm EMISSION
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DOI：
10.1088/0004-637x/733/1/42
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发表时间：
2011-03
期刊：
影响因子：
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通讯作者：
E. Chambers;F. Yusef-Zadeh;D. Roberts
中科院分区：
文献类型：
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作者：
E. Chambers;F. Yusef-Zadeh;D. Roberts
我们研究了在银河系中心附近具有增强的4.5μm辐射(“绿色”源)的原恒星天体样本中正在形成的恒星的特征。为了了解银河系中心区域的恒星形成与银盘形成的比较，我们使用扩展的甚大阵列观测了辐射激发的II类6.7 GHz CH3OH脉泽和碰撞激发的I类44 GHz CH3OH脉泽，这两种脉泽都是高质量恒星形成的示踪物，指向34个银河系中心和前景的“绿色”源。我们发现，33%±15%的银河系中心源与6.7 GHz脉泽重合，44%±17%的前景源与6.7 GHz脉泽重合。对于44 GHz脉泽，银河中心绿源和前景绿源的相关率分别为27%±13%和25%±13%。基于这些CH3OH脉泽的探测率，以及绿源与其他恒星形成示踪物，如24μm辐射和红外暗云(IRDC)的相关性，我们发现银河中心的绿源与其前景的绿源没有显著差异。这表明，一旦恒星形成过程开始，银河系中心区和银盘之间的环境差异对其观测特征几乎没有影响。然而，我们确实发现了一些证据，可能支持最近在银河系中心区域形成恒星的事件。
We present a study of signatures of on-going star formation in a sample of protostellar objects with enhanced 4.5 μm emission (“green” sources) near the Galactic center. To understand how star formation in the Galactic center region compares to that of the Galactic disk, we used the Expanded Very Large Array to observe radiatively excited Class II 6.7 GHz CH3OH masers and collisionally excited Class I 44 GHz CH3OH masers, both tracers of high-mass star formation, toward a sample of 34 Galactic center and foreground “green” sources. We find that 33% ± 15% of Galactic center sources are coincident with 6.7 GHz masers, and that 44% ± 17% of foreground sources are coincident with 6.7 GHz masers. For 44 GHz masers, we find correlation rates of 27% ± 13% and 25% ± 13% for Galactic center green sources and foreground green sources, respectively. Based on these CH3OH maser detection rates, as well as correlations of green sources with other tracers of star formation, such as 24 μm emission and infrared dark clouds (IRDCs), we find no significant difference between the green sources in the Galactic center and those foreground to it. This suggests that once the star formation process has begun, the environmental differences between the Galactic center region and the Galactic disk have little effect on its observational signatures. We do find, however, some evidence that may support a recent episode of star formation in the Galactic center region.