Exploring the timescale for high-mass star formation through deuterium fractionation ratios

我们研究了大质量团块中高质量无星核心相的时间标度。我们用Nobeama射电天文台45米望远镜观测到了HNC和HN13C向包括红外暗云(IRDC)和高质量原恒星物体(HMPO)在内的大质量星团的谱线。我们发现，大质量核的DNC/HNC比小质量核的低。这表明高质量无星相的时间尺度比低质量无星相的时间尺度短。通过与模型计算的比较，我们发现高质量无星相的时间尺度比104年要短几倍。

We have investigated the timescale of high-mass starless core phase from the deuterium fractionation rations in massive clumps. We have observed the HNC and HN13C lines toward the massive clumps, including infrared dark clouds (IRDCs) and high-mass protostellar objects (HMPOs), with the Nobeyama Radio Observatory 45 m telescope. We have found that the DNC/HNC ratio of the massive clumps is lower than that of the low-mass cores. This suggests that the timescale of high-mass starless phase is shorter than that of low-mass starless phase. By comparing with the model calculations, we have found that the timescale of high-mass starless phase is shorter than several times 104 yr.