A survey of deuterated ammonia in the Cepheus star-forming region L1251
A survey of deuterated ammonia in the Cepheus star-forming region L1251
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仙王座恒星形成区 L1251 氘氨调查
DOI：
10.1093/mnras/stac2084
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发表时间：
2022
影响因子：
4.8
通讯作者：
Smullen, Rachel
中科院分区：
文献类型：
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作者：
Galloway-Sprietsma, Maria;Shirley, Yancy L.;Di Francesco, James;Keown, Jared;Scibelli, Samantha;Sipilä, Olli;Smullen, Rachel
了解无星核和星前核演化过程中的化学过程是理解恒星和盘形成的初始阶段的重要一步。这项计划是对L1251恒星形成区中靠近仙王星的氢化氨o-NH2D的研究。位于基特峰的12米亚利桑那州射电天文台望远镜瞄准了22个致密核心(其中20个没有恒星或恒星前，其中两个有原恒星)，这是之前通过p-NH3(1，1)观测确定的。在检测到NH3的岩芯中有13个(59% %)检测到O-NH2DJ，灵敏度的中位数为mK。在此灵敏度下在o-NH2D中探测到的所有核心都有p-NH3柱密度>；1014 cm−2。o-NH2D柱密度的计算采用恒定激发温度(CTex)近似，同时修正了NH3源尺寸的填充分数。氚含量的中位数为0.11(包括3个σ上限)。然而，在有任何物理或进化变量的氚分数图中，没有明显的明显趋势。如果L1251中的岩心具有相似的初始化学条件，那么这个结果就是岩心物理演化速度不同的证据。
Understanding the chemical processes during starless core and prestellar core evolution is an important step in understanding the initial stages of star and disc formation. This project is a study of deuterated ammonia, o-NH2D, in the L1251 star-forming region towards Cepheus. Twenty-two dense cores (20 of which are starless or prestellar, and two of which have a protostar), previously identified by p-NH3(1,1) observations, were targeted with the 12m Arizona Radio Observatory telescope on Kitt Peak. o-NH2D Jwas detected in 13 (59 per cent) of the NH3-detected cores with a median sensitivity ofmK. All cores detected in o-NH2D at this sensitivity have p-NH3column densities >1014cm−2. The o-NH2D column densities were calculated using the constant excitation temperature (CTEX) approximation while correcting for the filling fraction of the NH3source size. The median deuterium fraction was found to be 0.11 (including 3σ upper limits). However, there are no strong, discernible trends in plots of deuterium fraction with any physical or evolutionary variables. If the cores in L1251 have similar initial chemical conditions, then this result is evidence of the cores physically evolving at different rates.