标题： 分子线在博克球状体和赫比格 Ae/be 恒星周围 显示英文标题

标题： Molecular Lines in Bok Globules and Around Herbig Ae/be Stars

摘要： 本文旨在作为在恒星形成区域更广泛的分子线调查的一部分，沿着坍缩云向年轻恒星物体演化的轨迹。我们研究了一个由七个小型暗云（博克球状体）和八个赫比格 Ae/Be 恒星组成的样本，在 HCO$^{+}$， H$^{13}$CO$^{+}$， HCN 和 H$^{13}$CN 的 J=1->0 转换中进行了研究。选择这些分子是由于简单的化学过程以及预测的反应物高丰度导致它们的形成。同位素取代物种（同位素异构体），H$^{13}$CO$^{+}$和 H$^{13}$CN 被观测到，以便尽可能确定主要物种的光学厚度。最丰富的同位素异构体几乎在所有源中都被发现（检测率 70-90%）。 那些显示出最强信号的源也搜索了$^{13}$C 同位素异构体。 H$^{13}$CO$^{+}$在一个暗云和大约三个金牛座T型星/Be星周围被发现，而 H$^{13}$CN 仅在一颗恒星周围被发现。 每当观测数据允许时，都推导出了每种分子的柱密度以及天体的物理条件。 显示英文摘要

摘要： This paper is intended as part of a more extensive molecular line survey in star forming regions along the evolutionary track of a collapsing cloud toward a young stellar object. We have studied a sample of seven small dark clouds (Bok globules) and eight Herbig Ae/Be stars in the J=1->0 transition of HCO$^{+}$, H$^{13}$CO$^{+}$, HCN and H$^{13}$CN. The choice of these molecules is determined by the simple chemistry and the predicted high abundance of the reactants leading to their formation. The isotopically substituted species (isotopomers), H$^{13}$CO$^{+}$ and H$^{13}$CN, were observed in order to determine, whenever possible, the optical thickness of the main species. The most abundant isotopomers were found in almost all the sources (detection rate 70-90\%). Those sources which exhibited the strongest signals were also searched for the $^{13}$C isotopomers. H$^{13}$CO$^{+}$ was found in one dark cloud and around three Herbig Ae/Be stars, while H$^{13}$CN around only one star. The column densities for each species and the physical conditions of the objects were derived whenever the observational data allowed it.