Despite its major role in the evolution of the interstellar medium, the formation of high-mass stars (M > 10 Msol) is still poorly understood. Two types of massive star cluster precursors, the so-called Massive Dense Cores (MDCs), have been observed, which differ in their mid-infrared brightness. The origin of this difference is not established and could be the result of evolution, density, geometry differences, or a combination of these. We compare several molecular tracers of physical conditions (hot cores, shocks) observed in a sample of mid-IR weak emitting MDCs with previous results obtained in a sample of exclusively mid-IR bright MDCs. The aim is to understand the differences between these two types of object. We present single-dish observations of HDO, H2O-18, SO2 and CH3OH lines at lambda = 1.3 - 3.5 mm. We study line profiles and estimate abundances of these molecules, and use a partial correlation method to search for trends in the results. The detection rates of thermal emission lines are found to be very similar between mid-IR quiet and bright objects. The abundances of H2O, HDO (1E-13 to 1E-9 in the cold outer envelopes), SO2 and CH3OH differ from source to source but independently of their mid-IR flux. In contrast, the methanol class I maser emission, a tracer of outflow shocks, is found to be strongly anti-correlated with the 12 micron source brightnesses. The enhancement of the methanol maser emission in mid-IR quiet MDCs may indicate a more embedded nature. Since total masses are similar between the two samples, we suggest that the matter distribution is spherical around mid-IR quiet sources but flattened around mid-IR bright ones. In contrast, water emission is associated with objects containing a hot molecular core, irrespective of their mid-IR brightness. These results indicate that the mid-IR brightness of MDCs is an indicator of their evolutionary stage.
Tracing evolutionary pathways of bar-driven quenching in local Universe disc galaxies
Indian Institute of Astrophysics（印度天文物理研究所）；Pondicherry University（本地治里大学）；Leibniz-Institut für Astrophysik Potsdam（波茨坦莱布尼茨天文物理研究所）；Ludwig-Maximilians-Universitat（路德维希-马克西米利安大学）
Star-forming compact groups: Tracing the early evolutionary stages of compact group environments
Universidad de La Serena（拉塞雷纳大学）；Universidad de Talca（塔尔卡大学）；Universidad Andrés Bello（安德烈斯·贝略大学）；Universidad Técnica Federico Santa María（费德里科·圣玛丽亚技术大学）；CONICET-UNLP（阿根廷国家科学研究委员会-拉普拉塔国立大学）；Federal University of Rio de Janeiro（里约热内卢联邦大学）；Observatório Nacional（巴西国家天文台）；Universidade Federal de Santa Catarina（圣卡塔琳娜联邦大学）；NOAO（美国国家光学红外天文实验室）；Carnegie Institution for Science（卡内基科学机构）
Tracing the early Milky Way thin disc with the Gaia-ESO Survey
Institute of Theoretical Physics and Astronomy, Faculty of Physics, Vilnius University（维尔纽斯大学物理学院理论物理与天体物理研究所）；INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze（佛罗伦萨大学物理与天文学系）
Tracing the Early Milky Way with Globular Clusters: The Diagnostic Power of Neutron-Capture Elements
Istituto Nazionale di Astrofisica – Osservatorio Astrofisico di Arcetri（国家天体物理研究所-阿切特里天文台）；Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Padova（国家天体物理研究所-帕多瓦天文台）；Istituto Nazionale di Astrofisica - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（国家天体物理研究所-博洛尼亚天文与空间科学观测站）
S2D2: Small-scale Significant substructure DBSCAN Detection II. Tracing episodes and gradients of star formation activity
Universidad Internacional de Valencia (VIU)（瓦伦西亚国际大学）；Univ. Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学、法国国家科学研究中心、IPAG）；Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS（波尔多大学天体物理实验室、波尔多大学、法国国家科学研究中心）
DeepDive: Tracing the early quenching pathways of massive quiescent galaxies at $z>3$ from their star-formation histories and chemical abundances
University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间科学与技术中心）；David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto（多伦多大学戴维·A·邓普尔天文与天体物理系）；Dunlap Institute for Astronomy & Astrophysics, University of Toronto（多伦多大学邓普尔天文与天体物理研究所）；Observatories of the Carnegie Institution for Science（卡内基科学机构天文台）
Tracing the very early disruption of the Sagittarius dwarf galaxy in the distant Milky Way halo
University of Groningen（格罗宁根大学）；University of Victoria（维多利亚大学）；Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森天体物理中心）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Universidad de La Laguna（拉古纳大学）
No Blue without Red: Evolutionary Properties of Super-Early Galaxies
Scuola Normale Superiore（高等师范学院）；Dipartimento di Fisica e Astronomia ”G. Galilei”, Università di Padova（帕多瓦大学物理与天文系）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
SEAMLESS Survey: Four Faint Dwarf Galaxies Tracing Low-Mass Galaxy Evolution Across Environments
Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；Department of Physics and Astronomy, University of Tampa（坦帕大学物理与天文学系）；Department of Physics and Astronomy, Dartmouth College（达特茅斯学院物理与天文学系）；Space Telescope Science Institute（太空望远镜科学研究所）；Department of Physics, University of Surrey（萨里大学物理系）；Department of Astronomy & Astrophysics, University of Toronto（多伦多大学天文学与天体物理学系）；Dunlap Institute for Astronomy and Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理研究所）；Department of Physics, Engineering Physics and Astronomy, Queen’s University（女王大学物理、工程物理与天文学系）
Tracing grain growth in the forming prestellar core L1506C with 3D modeling of Herschel, IRAM, and CFHT observations
Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse, CNRS, CNES（天体物理学与行星学研究所以及图卢兹大学）；University of Helsinki（赫尔辛基大学）；Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale（萨克雷大学）；Observatoire de Paris, PSL, CNRS, UPMC, Univ. Paris-Diderot（巴黎天文台）
Clustered star formation at early evolutionary stages. Physical and chemical analysis of the young star-forming regions ISOSS J22478+6357 and ISOSS J23053+5953
The Road to Normalcy: Environment-Driven Evolutionary Pathways for Primordial Black Holes
University of Texas at Austin（德克萨斯大学奥斯汀分校）；Weinberg Institute for Theoretical Physics, Texas Center for Cosmology and Astroparticle Physics, University of Texas at Austin（韦恩伯格理论物理研究所，德克萨斯宇宙学与天体粒子物理中心，德克萨斯大学奥斯汀分校）；Cosmic Frontier Center, The University of Texas at Austin（宇宙前沿中心，德克萨斯大学奥斯汀分校）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；Universität Heidelberg, Zentrum fur Astronomie, Institut für Theoretische Astrophysik（海德堡大学，天文学中心，理论天体物理学研究所）；Yale University（耶鲁大学）；Black Hole Initiative, Harvard University（黑洞倡议项目，哈佛大学）
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) XVIII. Reconstructing the star formation history of early-type galaxies through the combination of their UV and H$α$ emission
