We report the discovery of a cluster of Class I protostars in GGD 27. One of these protostars is the previously known, centrally located, GGD 27-ILL, which powers a massive bipolar outflow. We show that GGD 27-ILL, which is known to be the bright infrared (IR) source, IRAS 18162-2048, and a compact radio continuum source, is also the newly discovered hard X-ray source, GGD 27-X. The observations were made with the ACIS instrument on the Chandra X-ray Observatory. The X-rays from GGD 27-X are variable when compared with 4 years earlier, with an unabsorbed 2-10 keV X-ray luminosity in this observation of 1.5-12 × 1031 erg s–1 and a plasma temperature of ≥ 107 K. The X-rays are probably associated with the underlying B0 star (rather than outflowing material), providing a rare glimpse in hard X-rays of an optically obscured massive protostar with an outflow. The X-ray luminosity and spectrum appear to be consistent with stars of its type in other star formation regions. Several other variable X-ray sources are also detected in the IR cluster that contains GGD 27-X. We also discuss another nearby cluster. In each of the clusters there is an object that is X-ray hard, highly absorbed at low energies, in a blank optical/IR/radio field, and variable in X-ray intensity by a factor of ≥ 10 on a timescale of 4 years. These latter objects may arise from more recent episodes of star formation or may be "hidden" Class III sources.
展开▼
机译：我们报告发现在GGD 27中发现了I类原恒星簇。这些原恒星之一是先前已知的位于中央的GGD 27-ILL，它为大规模的双极流出提供动力。我们显示GGD 27-ILL（它是明亮的红外（IR）源IRAS 18162-2048和紧凑型无线电连续谱源）也是最新发现的硬X射线源GGD 27-X。观测是在钱德拉X射线天文台上使用ACIS仪器进行的。与4年前相比，来自GGD 27-X的X射线是可变的，在此观察中，未吸收的2-10 keV X射线光度为1.5-12×1031 erg s-1，且等离子体温度≥107 K X射线可能与下层的B0星（而不是流出的物质）有关，从而在硬X射线中罕见地看到了光学上模糊的大质量原恒星，并带有流出。 X射线的光度和光谱似乎与其他恒星形成区域中该类型恒星一致。在包含GGD 27-X的IR群集中还检测到了其他几个可变X射线源。我们还将讨论附近的另一个集群。在每个簇中，都有一个物体是X射线坚硬的，在空白的光学/ IR /无线电场中在低能量下被高度吸收，并且在4的时间尺度上X射线强度的变化系数≥10。年份。后面这些天体可能是由于最近的恒星形成事件引起的，或者可能是“隐藏的” III类源。
展开▼
