We report subarcsecond images of the high-mass star forming region Onsala 1 (ON 1) made with the Submillimeter Array (SMA) at 0.85 mm and the Very Large Array at 1.3 cm and 3.6 cm. ON~1 is one of the smallest ultracompact HII regions in the Galaxy and exhibits various star formation signposts. With our VLA and SMA observations, two new cm-wave sources and five sub-mm dust sources, respectively, within a field of ~3" (corresponding to a linear scale of 0.05 pc) are identified, indicating the multiplicity at the center of the ON 1 region. The dust and gas masses of these sub-mm sources are in the range of 0.8 to 6.4 M_sun. Among the five sub-mm dust sources, SMA2, with a dust and gas mass of 2.6 M_sun, demonstrates several star formation signatures, and hence likely represents an intermediate-mass (or even high-mass) star forming core. Due to the low star formation efficiency of ~10%, we suggest that star formation in the ON 1 region will continue. For example, SMA4 and SMA5 are not associated with any star formation signatures and likely mark star formation cores at very early evolutionary stages.
OPTIMus-Survey of massive star-forming regions at OPTical, Infrared, and Millimeter wavelengths
Institute of Astronomy, Russian Academy of Sciences（俄罗斯科学院天文研究所）；Special Astrophysical Observatory, Russian Academy of Sciences（俄罗斯科学院特殊天文台）；Sternberg Astronomical Institute, Lomonosov Moscow State University（莫斯科国立大学斯恩伯格天文研究所）
本文研究了含有多个致密团簇的粘性分子云中的致密气体分布。细丝的中心由密集的团块WB 673给出。这些团块是高质量和中等质量的恒星形成区域。我们使用Onsala空间天文台20 m望远镜在96 GHz处观察到了朝向WB 673的CS（2-1）、13 CO（1 -0）、C18 O（1-0）和甲醇谱线。我们发现CS（2-1）的发射在团间介质，所以团是物理连接，整个云确实是一个灯丝。其总质量为$10^4$ M $_{\odot}$，根据13 CO（1-0）数据，质量与长度比为360 M $_{\odot}$ pc $^{-1}$。致密气体的质量与长度比为来自CS（2-1）数据的$3.4-34$ M $_{\odot}$ pc $^{-1}$。灯丝的PV曲线呈V形。我们用甲醇谱线估计了分子气体的物理条件。灯丝在天空中延伸壳层之间的位置表明，它可能是一个很好的例子来测试通过超声波对星际气体的多次压缩形成灯丝的理论模型。
Complex organic molecules and cosmic ray ionisation rate towards the massive protostar Cepheus A HW2
Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Chalmers University of Technology（查尔姆斯理工大学）；University of Duisburg-Essen（杜伊斯堡-埃森大学）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；Universität Heidelberg（海德堡大学）；University of Virginia（弗吉尼亚大学）
研究宇宙射线对复杂有机分子形成的影响，通过高灵敏度光谱观测Cepheus A HW2，发现电离率增强，验证了宇宙射线在高质星形成环境中的作用。
