Combining mid-infrared data from the Spitzer Space Telescope with cold gas and dust emission observations from the Plateau de Bure Interferometer, we characterize the infrared dark cloud IRDC 18223 - 3 at high spatial resolution. The millimeter continuum data reveal a massive ～184 solar mass gas core with a projected size of ～28,000 AU that has no associated protostellar mid-infrared counterpart. However, the detection of 4.5 μm emission at the edge of the core indicates early outflow activity, which is supported by broad CO and CS spectral line-wing emission. Moreover, systematically increasing N_2H~+(1-0) line width toward the millimeter core center can be interpreted as additional evidence for early star formation. Furthermore, the N_2H~+(1-0) line emission reveals a less massive secondary core that could be in an evolutionary stage prior to any star formation activity.
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机译：将Spitzer空间望远镜的中红外数据与Plateau de Bure干涉仪的冷气和粉尘排放观测值结合起来，我们可以在高空间分辨率下表征红外暗云IRDC 18223-3。毫米波连续体数据揭示了一个巨大的〜184太阳质量气核，预计大小为〜28,000 AU，没有相关的星状体中红外对应物。但是，在岩心边缘检测到4.5μm的发射表明有早期流出活动，这由宽广的CO和CS光谱线翼发射所支持。而且，朝着毫米核中心系统地增加N_2H〜+（1-0）线宽可以解释为早期恒星形成的附加证据。此外，N_2H〜+（1-0）线发射揭示了次要核较小，该核可能处于任何恒星形成活动之前的演化阶段。
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