发表机构
European Southern Observatory; Max-Planck-Institut für Extraterrestrische Physik; University of Helsinki; Institute for Advanced Study, Kyushu University; Kyushu University; Max-Planck-Institut für Radioastronomie; Kyushu Sangyo University; National Astronomical Observatory of Japan（欧洲南方天文台; 马克斯·普朗克地外物理研究所; 赫尔辛基大学; 九州大学高等研究院; 九州大学; 马克斯·普朗克射电天文研究所; 九州产业大学; 日本国立天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过分析ALMA数据，评估南冕座151的演化阶段，发现其为极年轻原恒星，是研究恒星形成初期演化的新实验室。
AI 中文摘要
背景：前恒星核是恒星与行星系统的诞生地，但它们寿命很短，因为致密核演化、坍缩及原恒星种子形成的初始阶段十分迅速。为构建近邻太阳的真实前恒星核目录，我们利用APEX观测在Herschel观测的致密核中识别动力学演化的核，其中南冕座151因中心峰状结构、中心500-1000 au区域密度高于1e7cm-3、高氘化水平（N2D+/N2H+~0.5）而突出，这些特征表明它处于演化的前恒星阶段。目标：南冕座151看似是演化的前恒星核，但部分探测谱线存在宽翼、Herschel暂测到70微米辐射，这对其前恒星阶段构成部分挑战，我们旨在评估其演化阶段。方法：我们分析新的ALMA数据，包括连续谱发射及多种示踪线（含典型外流示踪线），分辨率约150-200 au，用于追踪包层。结果：我们揭示存在由SiO、CO和H2CO发射示踪的致密年轻外流，投影动力学年龄约500年；连续谱发射追踪到大小约1000 au、质量0.33M_sun（假设尘埃温度Tdust=20 K）的包层结构。结论：南冕座151是一颗极年轻的原恒星，可能是近邻太阳中已知最年轻的原恒星之一，因此成为研究恒星形成初期化学与动力学演化的新实验室。
英文摘要
Context. Prestellar cores are the birthplace of stars and planetary systems, but they are short-lived objects, since the initial stages of dense core evolution, collapse, and the formation of a protostellar seed are fast. In an effort to build a catalogue of bona-fide prestellar cores in the Solar neighbourhood, we used APEX observations to identify dynamically evolved cores among dense cores observed with Herschel. One of them, Corona Australis 151, stood out because of its centrally peaked structure, with densities above 1e7cm-3 in the central 500-1000 au, and high deuteration levels (N2D+/N2H+~0.5), suggestive of an evolved, prestellar stage. Aims. Corona Australis 151 appears to be an evolved prestellar core, but the presence of broad wings in some of the detected lines and a tentative 70micron detection with Herschel partially challenges its prestellar stage. We intend to assess its evolutionary stage. Methods. We analyse new ALMA data of the continuum emission and of several line tracers (including typical outflow tracers) at a resolution of~150-200au, tracing the envelope. Results. We unveil the presence of a compact and young outflow (projected dynamical age:~500yr), traced by SiO, CO, and H2CO emission. The continuum emission traces an envelope structure of size~1000 au and mass 0.33M_sun(assuming Tdust=20 K). Conclusions. Corona Australis 151 is an extremely young protostar, possibly one of the youngest known in the Solar neighbourhood, and hence a new laboratory to study the chemical and dynamical evolution at the dawn of star formation.
CommentsAccepted for publication in A&A Letters
