发表机构
Niels Bohr Institute, University of Copenhagen; Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES; Physikalisch-Meteorologisches Observatorium Davos und Weltstrahlungszentrum (PMOD/WRC); Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP), Universität Bern; National Radio Astronomy Observatory; Max-Planck-Institut für Radioastronomie; Institut de Planétologie et d’Astrophysique de Grenoble, Univ. Grenoble Alpes, CNRS, IPAG; Korea Astronomy and Space Science Institute; Institute of Astronomy, Department of Physics, National Tsinghua University（哥本哈根大学尼尔斯·玻尔研究所; 图卢兹大学天体物理学与行星学研究所以及法国国家科学研究中心、法国国家空间研究中心; 达沃斯物理气象观测站与世界辐射中心; 伯尔尼大学化学、生物化学和药学系; 美国国家射电天文台; 马克斯·普朗克射电天文研究所; 格勒诺布尔行星学与天体物理学研究所，格勒诺布尔阿尔卑斯大学，法国国家科学研究中心; 韩国天文学与空间科学研究所; 国立清华大学物理系天文学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过COMPASS巡天数据发现低质量原恒星中I类甲醇脉泽普遍存在，且与激波化学示踪物乙醛空间相关，表明其优先出现在年轻嵌入源中。
AI 中文摘要
碰撞泵浦的CH3OH脉泽，称为“I类”脉泽，通常示踪恒星形成区域中的激波界面，但它们在低质量原恒星中的发生率仍缺乏量化。我们利用COMPASS ALMA大型计划的数据，确定了在302.9 GHz处新探测到的I类CH3OH脉泽在低质量原恒星中的出现率、空间起源和激发机制，并检验其泵浦环境是否表现出激波驱动的复杂化学特征。COMPASS提供了11个源在279.0至311.7 GHz范围内的无偏线巡天，典型角分辨率为0.3"-0.5"。对302.9 GHz CH3OH激发中偏离LTE的旋转图分析可靠地揭示了11个源中有7个存在脉泽现象，峰值亮温从几K到约10^3 K。最亮的探测朝向HOPS 108，可能与该源附近中等质量原恒星HOPS 370的强大外流有关。排除此情况后，在10个低质量原恒星中探测到6个脉泽（60%）。所有这6个源都是与致密环境物质相互作用的Class 0源，而未探测到的源包括3个Class I源和1个孤立的Class 0核，这表明脉泽偏好早期演化阶段和富含气体的外流-环境介质相互作用环境。脉泽发射在空间上与沿外流腔壁和弓形激波的热CH3OH重合，但更致密且呈结节状。在所巡天的复杂有机分子中，只有CH3CHO紧密示踪了302.9 GHz脉泽的激波形态，且仅围绕HOPS 108。这些结果表明，低质量原恒星系统中的I类CH3OH脉泽比以前认为的更普遍，并且优先出现在更年轻、更深的嵌入源中。需要更灵敏的CH3CHO观测来检验在低质量范围内是否也存在与激波驱动化学类似的关联。
英文摘要
CH3OH masers that are collisionally pumped, referred to as `class I', commonly trace shock interfaces in star-forming regions, but their incidence in low-mass protostars remains poorly quantified. We use data from the COMPASS ALMA Large Program to establish the occurrence, spatial origin, and excitation of a newly detected class I CH3OH maser at 302.9 GHz towards low-mass protostars and to test whether its pumping environments exhibit signatures of shock-driven complex chemistry. COMPASS provides unbiased line surveys of 11 sources between 279.0 and 311.7 GHz at typical angular resolutions of 0.3"-0.5". Rotation diagram analysis of departures from LTE in the 302.9 GHz CH3OH excitation robustly reveals masing in seven of 11 sources, with peak brightness temperatures from a few to ~10^3 K. The brightest detection is towards HOPS 108 and is likely associated with the powerful outflow from the nearby intermediate-mass protostar HOPS 370. Excluding this case, the maser is detected in six of ten low-mass protostars (60%). All six are Class 0 sources interacting with dense ambient material, whereas the non-detections comprise three Class I sources and one isolated Class 0 core, indicating a preference for early evolutionary stages and gas-rich environments for outflow-ambient medium interactions. The maser emission is spatially coincident with thermal CH3OH along outflow cavity walls and bow shocks, but is more compact and knot-like. Among the surveyed COMs, only CH3CHO closely traces the shocked morphology of the 302.9 GHz maser, and only around HOPS 108. These results show that class I CH3OH masers in low-mass protostellar systems are more prevalent than previously recognised and preferentially occur in younger, more embedded sources. More sensitive CH3CHO observations are needed to test whether a similar relationship with shock-driven chemistry also applies in the low-mass regime.
CommentsAccepted for publication in Astronomy and Astrophysics
