论文标题
分子细丝WB 673中的恒星形成时间尺度
Star formation timescale in the molecular filament WB 673
论文作者
论文摘要
我们提出了氨发射线向星际细丝WB〜673托管密集的团块WB〜673，WB〜668，S233-IR和G173.57+2.43的观察结果。 LTE对线的分析使我们能够估算气体动力学温度（在所有团块中$ \ Lessim $ 30〜k），数量密度（$ 7-17 \ times10^3 $ 〜cm $ $^{ - 3} $）和氨基列密度（$ \ $ \ \ \ \ \ \ \ \ \ \ \ \ \ cm $ 1-1.5 \ times 10^{15} $ 〜cm $ $^cm $^cm^clump）我们发现WB 673中塌陷的特征以及S233-IR中紧凑的空间未分辨的密集团的存在。我们在团块中重建1D密度和温度分布，并使用星体化学建模估算它们的年龄。考虑到CO，CS，NH $ _3 $和N $ _2 $ H $^+$分子（加上HCN和HNC，用于WB〜673），我们发现一个化学龄为$ t _ {\ rm chem} = 1-3 \ rm chem} = 1-3 \ times 10^5 $〜yr，提供模拟和观察到的Claysed Commented Complever colliscreved colment colvered colvered classed and cland call and cllumps and clluck and cllumps and clluck and clluck and cllumps and cllumps and clumps and clumps。因此，我们将$ t _ {\ rm chem} $视为整个丝的化学年龄。在天体化学模型中，气体积累的长期低密度阶段将打破模拟和观察到的色谱柱密度之间的一致性。我们建议在细丝中发生$ \ sim 10^5 $〜yrs时刻的快速星形成。
We present observations of ammonia emission lines toward the interstellar filament WB~673 hosting the dense clumps WB~673, WB~668, S233-IR and G173.57+2.43. LTE analysis of the lines allows us to estimate gas kinetic temperature ($\lesssim$ 30~K in all the clumps), number density ($7-17\times10^3$~cm$^{-3}$), and ammonia column density ($\approx 1-1.5\times 10^{15}$~cm$^{-2}$) in the dense clumps. We find signatures of collapse in WB 673 and presence of compact spatially unresolved dense clumps in S233-IR. We reconstruct 1D density and temperature distributions in the clumps and estimate their ages using astrochemical modelling. Considering CO, CS, NH$_3$ and N$_2$H$^+$ molecules (plus HCN and HNC for WB~673), we find a chemical age of $t_{\rm chem}=1-3\times 10^5$~yrs providing the best agreement between the simulated and observed column densities in all the clumps. Therefore, we consider $t_{\rm chem}$ as the chemical age of the entire filament. A long preceding low-density stage of gas accumulation in the astrochemical model would break the agreement between the simulated and observed column densities. We suggest that rapid star formation over a $\sim 10^5$~yrs timescale take place in the filament.
