Massive stars and their stellar winds are important for a number of feedback processes. The mass lost in the stellar wind can help determine the end-point of the star as a NS or a BH. However, the impact of mass-loss on the post-Main Sequence evolutionary stage of massive stars is not well understood. Westerlund 1 is an ideal astrophysical laboratory in which to study massive stars and their winds in great detail over a large range of different evolutionary phases. Aims: We aim to study the radio emission from Westerlund 1, in order to measure radio fluxes from the population of massive stars, and determine mass-loss rates and spectral indices where possible. Methods: Observations were carried out in 2015 and 2016 with the Australia telescope compact array (ATCA) at 5.5 and 9 GHz using multiple configurations, with maximum baselines ranging from 750m to 6km. Results: 30 stars were detected in the radio from the fully concatenated dataset, 10 of which were WRs (predominantly late type WN stars), 5 YHGs, 4 RSGs, 1 LBV star, the sgB[e] star W9, and several O and B supergiants. New source detections in the radio were found for 5 WR stars, and 5 OB supergiants. These detections have led to evidence for 3 new OB supergiant binary candidates, inferred from derived spectral index limits. Conclusions: Spectral indices and index limits were determined for massive stars in Westerlund 1. For cluster members found to have partially optically thick emission, mass-loss rates were calculated. Under the approximation of a thermally emitting stellar wind and a steady mass-loss rate, clumping ratios were then estimated for 8 WRs. Diffuse radio emission was detected throughout the cluster. Detections of knots of radio emission with no known stellar counterparts indicate the highly clumped structure of this intra-cluster medium, likely shaped by a dense cluster wind.
EWOCS-VIII: Internal kinematics and expansion of Westerlund 1 from VVVX proper motions
Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Universidad de Concepción（康塞普西翁大学）；European Southern Observatory（欧洲南方天文台）；Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Palermo（意大利国家天体物理研究所（INAF）- 巴勒莫天文台）；Universidad de Santiago de Chile（智利圣地亚哥大学）；Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS)（天体物理学与空间探索跨学科研究中心）；Keele University（基尔大学）；Universidade de Lisboa（里斯本大学）
Meerkat measurement of the radio emission from massive stars in the Galactic plane I. Wolf-Rayet stars
Space Sciences, Technologies and Astrophysics Research (STAR) Institute, University of Liège（列日大学空间科学、技术与天体物理研究（STAR）研究所）；Instituto Argentino de Radioastronomia (CONICET（阿根廷射电天文研究所）；CICPBA（印度空间科学与技术学院）；UNLP)；Indian Institute of Space Science and Technology
Discovery of over a thousand variable stars in Terzan 5 and Liller 1 with JWST
Massachusetts Institute of Technology（麻省理工学院）；Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（麻省理工学院卡弗里天体物理学与空间研究研究所）；Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究院）；Dipartimento di Fisica e Astronomia “Augusto Righi”, Università di Bologna（博洛尼塔大学物理与天文学系）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna (OAS)（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森天体物理中心）
