{"title":"近邻星系云尺度上的分子气体和恒星形成过程","authors":"E. Schinnerer, A.K. Leroy","doi":"10.1146/annurev-astro-071221-052651","DOIUrl":null,"url":null,"abstract":"Observations that resolve nearby galaxies into individual regions across multiple phases of the gas–star formation feedback “matter cycle” have provided a sharp new view of molecular clouds, star-formation efficiencies, timescales for region evolution, and stellar feedback. We synthesize these results, covering aspects relevant to the interpretation of observables, and conclude the following: <jats:list list-type=\"bullet\"> <jats:list-item> <jats:label>▪</jats:label> The observed cloud-scale molecular gas surface density, line width, and internal pressure all reflect the large-scale galactic environment while also appearing mostly consistent with properties of a turbulent medium strongly affected by self-gravity. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> Cloud-scale data allow for statistical inference of both evolutionary and physical timescales. These suggest a period of cloud collapse on the order of the free-fall or turbulent crossing time (∼10–30 Myr) followed by forming massive stars and subsequent rapid (≲5 Myr) gas clearing after the onset of star formation. The star-formation efficiency per free-fall time is well determined over thousands of individual regions at ε<jats:sub>ff</jats:sub> ≈ 0.5<jats:sub>−0.3</jats:sub> <jats:sup>+0.7</jats:sup>%. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> The role of stellar feedback is now measured using multiple observational approaches. The net yield is constrained by the requirement to support the vertical weight of the galaxy disk. Meanwhile, the short gas-clearing timescales suggest a large role for presupernova feedback in cloud disruption. This leaves the supernovae free to exert a large influence on the larger galaxy, including stirring turbulence, launching galactic-scale winds, and carving superbubbles. </jats:list-item> </jats:list>","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":26.3000,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Molecular Gas and the Star-Formation Process on Cloud Scales in Nearby Galaxies\",\"authors\":\"E. Schinnerer, A.K. Leroy\",\"doi\":\"10.1146/annurev-astro-071221-052651\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Observations that resolve nearby galaxies into individual regions across multiple phases of the gas–star formation feedback “matter cycle” have provided a sharp new view of molecular clouds, star-formation efficiencies, timescales for region evolution, and stellar feedback. We synthesize these results, covering aspects relevant to the interpretation of observables, and conclude the following: <jats:list list-type=\\\"bullet\\\"> <jats:list-item> <jats:label>▪</jats:label> The observed cloud-scale molecular gas surface density, line width, and internal pressure all reflect the large-scale galactic environment while also appearing mostly consistent with properties of a turbulent medium strongly affected by self-gravity. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> Cloud-scale data allow for statistical inference of both evolutionary and physical timescales. These suggest a period of cloud collapse on the order of the free-fall or turbulent crossing time (∼10–30 Myr) followed by forming massive stars and subsequent rapid (≲5 Myr) gas clearing after the onset of star formation. The star-formation efficiency per free-fall time is well determined over thousands of individual regions at ε<jats:sub>ff</jats:sub> ≈ 0.5<jats:sub>−0.3</jats:sub> <jats:sup>+0.7</jats:sup>%. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> The role of stellar feedback is now measured using multiple observational approaches. The net yield is constrained by the requirement to support the vertical weight of the galaxy disk. Meanwhile, the short gas-clearing timescales suggest a large role for presupernova feedback in cloud disruption. This leaves the supernovae free to exert a large influence on the larger galaxy, including stirring turbulence, launching galactic-scale winds, and carving superbubbles. </jats:list-item> </jats:list>\",\"PeriodicalId\":8138,\"journal\":{\"name\":\"Annual Review of Astronomy and Astrophysics\",\"volume\":\"31 1\",\"pages\":\"\"},\"PeriodicalIF\":26.3000,\"publicationDate\":\"2024-07-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Annual Review of Astronomy and Astrophysics\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1146/annurev-astro-071221-052651\",\"RegionNum\":1,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annual Review of Astronomy and Astrophysics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1146/annurev-astro-071221-052651","RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Molecular Gas and the Star-Formation Process on Cloud Scales in Nearby Galaxies
Observations that resolve nearby galaxies into individual regions across multiple phases of the gas–star formation feedback “matter cycle” have provided a sharp new view of molecular clouds, star-formation efficiencies, timescales for region evolution, and stellar feedback. We synthesize these results, covering aspects relevant to the interpretation of observables, and conclude the following: ▪ The observed cloud-scale molecular gas surface density, line width, and internal pressure all reflect the large-scale galactic environment while also appearing mostly consistent with properties of a turbulent medium strongly affected by self-gravity. ▪ Cloud-scale data allow for statistical inference of both evolutionary and physical timescales. These suggest a period of cloud collapse on the order of the free-fall or turbulent crossing time (∼10–30 Myr) followed by forming massive stars and subsequent rapid (≲5 Myr) gas clearing after the onset of star formation. The star-formation efficiency per free-fall time is well determined over thousands of individual regions at εff ≈ 0.5−0.3+0.7%. ▪ The role of stellar feedback is now measured using multiple observational approaches. The net yield is constrained by the requirement to support the vertical weight of the galaxy disk. Meanwhile, the short gas-clearing timescales suggest a large role for presupernova feedback in cloud disruption. This leaves the supernovae free to exert a large influence on the larger galaxy, including stirring turbulence, launching galactic-scale winds, and carving superbubbles.
期刊介绍:
The Annual Review of Astronomy and Astrophysics is covers significant developments in the field of astronomy and astrophysics including:The Sun,Solar system and extrasolar planets,Stars,Interstellar medium,Galaxy and galaxies,Active galactic nuclei,Cosmology,Instrumentation and techniques,
History of the development of new areas of research.