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arXiv 2005.04629astro-ph.GA
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太空生命种子SOLIS。IX。$\rm SO_2$和SO向L1157低质量原恒星激波区的化学分离

Seeds of Life in Space SOLIS. IX. Chemical segregation of $\rm SO_2$ and SO toward the low-mass protostellar shocked region of L1157

S. Feng, C. Codella, C. Ceccarelli, P. Caselli, A. Lopez-Sepulcre, R. Neri, F. Fontani, L. Podio, B. Lefloch, H. B. Liu, R. Bachiller, S. Viti

摘要:

我们目前的观测SO和$\rm SO_2$线的冲击区域沿L1157化学丰富的流出,采取的背景下,生命的种子在空间IRAM-NORTHED扩展毫米阵列大计划,并支持的数据,从亚毫米阵列和IRAM-30米望远镜在1.1- 3.6毫米波长。我们首次同时分析了蓝移波瓣中所有最亮的激波,即B 0、B1和B2。我们发现了以下内容。(1)SO和$\rm SO_2$可以追踪不同的气体,假设大(尺度)速度梯度分析表明$\rm SO_2$的体积密度($\rm 10^5\text{--}10^6\,cm^{-3}$)比SO中发射的气体的体积密度高一个数量级。(2)调查0.1 pc尺度的视野,我们注意到一个试探性的梯度沿旋进射流的路径。更具体地说,从B 0-B1电击到较老的B2电击,$\rm χ({SO/SO_2})$减少。(3)在500- 1400 au的线性分辨率下,检测到两个发射分子之间的试探性空间位移,SO峰更接近(相对于$\rm SO_2$)最近的射流撞击B1腔壁的位置。我们的天体化学模拟表明,SO和$\rm SO_2$丰度的演变时间尺度小于约1000年。此外,由于激波的发生,模拟需要高丰度($2\times10^{-6}$)的$\rm H_2S/H$和S/H注入气相中,因此仅预冷冻OCS不足以再现我们的新观测结果。

英文摘要:

We present observations of SO and $\rm SO_2$ lines toward the shocked regions along the L1157 chemically rich outflow, taken in the context of the Seeds Of Life In Space IRAM-NOrthern Extended Millimeter Array Large Program, and supported by data from Submillimeter Array and IRAM-30 m telescope at 1.1--3.6 mm wavelengths. We simultaneously analyze, for the first time, all of the brightest shocks in the blueshifted lobe, namely, B0, B1, and B2. We found the following. (1) SO and $\rm SO_2$ may trace different gas, given that the large(-scale) velocity gradient analysis indicates for $\rm SO_2$ a volume density ($\rm 10^5\text{--}10^6\,cm^{-3}$) denser than that of the gas emitting in SO by a factor up to an order of magnitude. (2) Investigating the 0.1 pc scale field of view, we note a tentative gradient along the path of the precessing jet. More specifically, $\rm χ({SO/SO_2})$ decreases from the B0-B1 shocks to the older B2. (3) At a linear resolution of 500--1400 au, a tentative spatial displacement between the two emitting molecules is detected, with the SO peak closer (with respect to $\rm SO_2$) to the position where the recent jet is impinging on the B1 cavity wall. Our astrochemical modeling shows that the SO and $\rm SO_2$ abundances evolve on timescales less than about 1000 years. Furthermore, the modeling requires high abundances ($2\times10^{-6}$) of both $\rm H_2S/H$ and S/H injected in the gas phase due to the shock occurrence, so pre-frozen OCS only is not enough to reproduce our new observations.

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