We present a statistical comparison of the mass ratio distribution of companions, as observed in different multiplicity surveys, to the most recent estimate of the single object mass function (Bochanski et al. 2010). The main goal of our analysis is to test whether or not the observed companion mass ratio distribution (CMRD) as a function of primary star mass and star formation environment is consistent with having been drawn from the field star IMF. We consider samples of companions for M dwarfs, solar type and intermediate mass stars, both in the field as well as clusters or associations, and compare them with populations of binaries generated by random pairing from the assumed IMF for a fixed primary mass. With regard to the field we can reject the hypothesis that the CMRD was drawn from the IMF for different primary mass ranges: the observed CMRDs show a larger number of equal-mass systems than predicted by the IMF. This is in agreement with fragmentation theories of binary formation. For the open clusters α Persei and the Pleiades we also reject the IMF random- pairing hypothesis. Concerning young star-forming regions, currently we can rule out a connection between the CMRD and the field IMF in Taurus but not in Chamaeleon I. Larger and different samples are needed to better constrain the result as a function of the environment. We also consider other companion mass functions (CMF) and we compare them with observations. Moreover the CMRD both in the field and clusters or associations appears to be independent of separation in the range covered by the observations. Combining therefore the CMRDs of M and G primaries in the field and intermediate mass primary binaries in Sco OB2 for mass ratios, q = M2/M1, from 0.2 to 1, we find that the best chi-square fit follows a power law dN/dq \propto q^β, with β = -0.50 \pm 0.29, consistent with previous results.
The Tarantula Massive Binary Monitoring VI: Characterisation of hidden companions in 51 single-lined O-type binaries, a flat mass-ratio distribution, and black-hole binary candidates
Close Binary Companions to APOGEE DR16 Stars: 20,000 Binary-star Systems Across the Color-Magnitude Diagram
当代天体物理学中的许多问题--从理解黑洞的形成到解开星系的化学演化--都依赖于关于双星的知识。这反过来又取决于发现和描述大量不同类型恒星在不同化学和动力学环境中的双星伴星。目前的恒星光谱巡天观测到数十万至数百万颗恒星，（通常）只有很少的观测时期，这允许发现双星，但使轨道特征具有挑战性。我们使用一个自定义的蒙特卡罗采样器（The Monte Carlo sampler），通过径向速度，在稀疏，嘈杂和采样差的多历元数据的制度，执行发现和表征的二进制系统。我们使用它来生成开普勒参数的后验样本，用于APOGEE Data Release 16中发布的232，531个源。我们的最终星表包含19，635个高置信度的近双星系统（P <几年，a <几个AU），这些系统显示了颜色-星等图中双星出现率和位置之间的有趣关系。我们在高质量（黑洞候选者），低质量（亚恒星候选者）和非常接近的分离（质量转移候选者）中发现了显着的微弱同伴。我们还使用后验抽样（玩具）层次推理来测量长周期双星偏心率分布。我们发布了232，531颗星的整个母样本的全套后验样本。这组采样不涉及启发式的“发现”阈值，因此可以用于无数的统计目的，包括关于双星种群和亚阈值搜索的分层推断。
Protostellar Outflows Shed Light on the Dominant Close Companion Star Formation Pathways
University of Illinois（伊利诺伊大学）；National Radio Astronomy Observatory（国家射电天文台）；Yale University（耶鲁大学）；NSF-Simons AI Institute for the Sky (SkAI)（NSF-Simons天空人工智能研究所）；Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)（天体物理跨学科探索与研究中心）；NRC Herzberg Astronomy and Astrophysics（NRC赫茨伯格天文学与天体物理学研究所）；University of Victoria（维多利亚大学）；Space Science Institute（太空科学研究所）；University of Virginia（弗吉尼亚大学）
Red supergiant stars in binary systems II. Confirmation of B-type companions of red supergiants in the Small Magellanic Cloud using Hubble ultra-violet spectroscopy
