Annual Review of Astronomy and Astrophysics最新文献

Exoplanet Atmospheres at High Spectral Resolution 高光谱分辨率的系外行星大气

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2025-05-14 DOI: 10.1146/annurev-astro-052622-031342

Ignas A.G. Snellen

{"title":"Exoplanet Atmospheres at High Spectral Resolution","authors":"Ignas A.G. Snellen","doi":"10.1146/annurev-astro-052622-031342","DOIUrl":"https://doi.org/10.1146/annurev-astro-052622-031342","url":null,"abstract":"High-resolution spectroscopy (HRS) has grown into one of the main techniques for characterizing the atmospheres of extrasolar planets. High spectral resolving power allows for the efficient removal of telluric and host-star contamination. Combined with the large collecting area of ground-based telescopes, it enables detailed studies of atmospheric species, temperature structure, atmospheric loss, and global winds and circulation patterns. In this review, the wide range of HRS observation and data analysis techniques are described and literature results discussed. Key findings include the following: ▪ The highest irradiated planets show a rich spectrum of atomic and ionic species, just like stars. ▪ Retrieval analyses of hot Jupiters and directly imaged super-Jupiters point to solar metallicities and chemistry, but observed samples are still heterogeneous and incomplete. ▪ There appears to be a clear dichotomy between hot Jupiters with and without atmospheric inversions, depending on their equilibrium temperature. ▪ Some highly irradiated planets exhibit enormous leading and/or trailing tails of helium gas, providing unique insights into planet evolution and atmospheric escape processes. ▪ Minor isotopes of carbon and oxygen are now being detected in gas giant planets and brown dwarfs with the interesting potential to shed light on formation pathways. A list of potential pitfalls is provided for those new to the field, and synergies with the James Webb Space Telescope are discussed. HRS has a great future ahead with the advent of the extremely large telescopes, promising to bring temperate rocky exoplanets into view with their increase in HRS detection speed of up to three orders of magnitude.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"42 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Star Formation from Low to High Mass: A Comparative View 从低质量到高质量的恒星形成：比较视角

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2025-04-01 DOI: 10.1146/annurev-astro-013125-122023

H. Beuther, R. Kuiper, M. Tafalla

{"title":"Star Formation from Low to High Mass: A Comparative View","authors":"H. Beuther, R. Kuiper, M. Tafalla","doi":"10.1146/annurev-astro-013125-122023","DOIUrl":"https://doi.org/10.1146/annurev-astro-013125-122023","url":null,"abstract":"Star formation has often been studied by separating the low- and high-mass regimes with an approximate boundary at 8 M⊙. Although some of the outcomes of the star-formation process are different between the two regimes, it is less clear whether the physical processes leading to these outcomes are that different at all. Here, we systematically compare low- and high-mass star formation by reviewing the most important processes and quantities from an observational and theoretical point of view. We identify three regimes in which processes are either similar, quantitatively, or qualitatively different between low- and high-mass star formation. ▪ Similar characteristics can be identified for the turbulent gas properties and density structures of the star-forming regions. Many of the observational characteristics also do not depend that strongly on the environment. ▪ Quantitative differences can be found for outflow, infall, and accretion rates as well as mean column and volume densities. Also, the multiplicity significantly rises from low- to high-mass stars. The importance of the magnetic field for the formation processes appears still less well constrained. ▪ Qualitative differences between low- and high-mass star formation relate mainly to the radiative and ionizing feedback that occurs almost exclusively in regions forming high-mass stars. Nevertheless, accretion apparently can continue via disk structures in ionized accretion flows. Finally, we discuss to what extent a unified picture of star formation over all masses is possible and which issues need to be addressed in the future.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"21 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143775385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Star–Planet Composition Connection 恒星与行星构成的联系

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-09-13 DOI: 10.1146/annurev-astro-071221-053007

Johanna K. Teske

{"title":"The Star–Planet Composition Connection","authors":"Johanna K. Teske","doi":"10.1146/annurev-astro-071221-053007","DOIUrl":"https://doi.org/10.1146/annurev-astro-071221-053007","url":null,"abstract":"The mantra “know thy star, know thy planet” has proven to be very important for many aspects of exoplanet science. Here I review how stellar abundances inform our understanding of planet composition and, thus, formation and evolution. In particular, I discuss how: ▪ The strongest star–planet connection is still the giant planet–metallicity correlation, the strength of which may indicate a break point between the formation of planets versus brown dwarfs. ▪ We do not have very good constraints on the lower metallicity limit for planet formation, although new statistics from TESS are helping, and it appears that, at low [Fe/H], α elements can substitute for iron as seeds for planet formation. ▪ The depletion of refractory versus volatile elements in stellar photospheres (particularly the Sun) was initially suggested as a sign of small planet formation but is challenging to interpret, and small differences in binary star compositions can be attributed mostly to processes other than planet formation. ▪ We can and should go beyond comparisons of the carbon-to-oxygen ratio in giant planets and their host stars, incorporating other volatile and refractory species to better constrain planet formation pathways. ▪ There appears to be a positive correlation between small planet bulk density and host star metallicity, but exactly how closely small planet refractory compositions match those of their host stars—and their true diversity—is still uncertain.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"63 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142231550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Solar Flare Spectroscopy 太阳耀斑光谱学

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-09-13 DOI: 10.1146/annurev-astro-052920-010547

Lyndsay Fletcher

{"title":"Solar Flare Spectroscopy","authors":"Lyndsay Fletcher","doi":"10.1146/annurev-astro-052920-010547","DOIUrl":"https://doi.org/10.1146/annurev-astro-052920-010547","url":null,"abstract":"This review covers the techniques, observations, and inferences of solar flare spectroscopy. It is not a spectroscopist's view of solar flares but rather a solar flare physicist's view of spectroscopy. Spectroscopy is carried out across the electromagnetic spectrum, but this review emphasizes the optical to soft X-ray part of the spectrum and discusses results from spectroscopy applied to the preflare, impulsive, and gradual phases, as well as a few highlights from modeling. ▪ The main spectroscopic signatures of the preflare phase are line broadening in optically thin ultraviolet to soft X-ray lines and small Doppler shifts in active region filaments that are becoming unstable. ▪ In the impulsive phase, fast upflows of heated plasma into the corona and slow downflows of cooler chromospheric plasma take place at the sites of strong chromospheric energy deposition. ▪ Radiation-hydrodynamic modeling of optically thick spectral lines gives a picture of an impulsive-phase chromosphere with a dense, heated layer deep in the atmosphere and an overlying, downward moving condensation that is partially optically thin. ▪ Gradual-phase observations show us the heated coronal plasma cooling and draining but also provide evidence for ongoing slow energy input and slow upflows in other locations. ▪ Interesting hints of non-Maxwellian and nonequilibrium plasmas have been found, along with possible evidence of plasma turbulence from line broadening.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142231553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Tale of Many H0 许多 H0 的故事

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-07-23 DOI: 10.1146/annurev-astro-052622-033813

Licia Verde, Nils Schöneberg, Héctor Gil-Marín

{"title":"A Tale of Many H0","authors":"Licia Verde, Nils Schöneberg, Héctor Gil-Marín","doi":"10.1146/annurev-astro-052622-033813","DOIUrl":"https://doi.org/10.1146/annurev-astro-052622-033813","url":null,"abstract":"▪The Hubble parameter, H0, is not an univocally defined quantity: It relates redshifts to distances in the near Universe, but it is also a key parameter of the ΛCDM standard cosmological model. As such, H0 affects several physical processes at different cosmic epochs and multiple observables. We have counted more than a dozen H0s that are expected to agree if (a) there are no significant systematics in the data and their interpretation and (b) the adopted cosmological model is correct.▪With few exceptions (proverbially confirming the rule), these determinations do not agree at high statistical significance; their values cluster around two camps: the low (68 km s1 Mpc1) and high (73 km s1 Mpc1) camps. It appears to be a matter of anchors. The shape of the Universe expansion history agrees with the model; it is the normalizations that disagree.▪Beyond systematics in the data/analysis, if the model is incorrect, there are only two viable ways to “fix” it: by changing the early time (z ≳ 1,100) physics and, thus, the early time normalization or by a global modification, possibly touching the model's fundamental assumptions (e.g., homogeneity, isotropy, gravity). None of these three options has the consensus of the community.▪The research community has been actively looking for deviations from ΛCDM for two decades; the one we might have found makes us wish we could put the genie back in the bottle.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"43 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141755178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Theory and Observation of Winds from Star-Forming Galaxies 恒星形成星系风的理论与观测

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-07-23 DOI: 10.1146/annurev-astro-041224-011924

Todd A. Thompson, Timothy M. Heckman

{"title":"Theory and Observation of Winds from Star-Forming Galaxies","authors":"Todd A. Thompson, Timothy M. Heckman","doi":"10.1146/annurev-astro-041224-011924","DOIUrl":"https://doi.org/10.1146/annurev-astro-041224-011924","url":null,"abstract":"Galactic winds shape the stellar, gas, and metal content of galaxies. To quantify their impact, we must understand their physics. We review potential wind-driving mechanisms and observed wind properties, with a focus on the warm ionized and hot X-ray-emitting gas. Energy and momentum injection by supernovae (SNe), cosmic rays, radiation pressure, and magnetic fields are considered in the light of observations:▪Emission and absorption line measurements of cool/warm gas provide our best physical diagnostics of galactic outflows.▪The critical unsolved problem is how to accelerate cool gas to the high velocities observed. Although conclusive evidence for no one mechanism exists, the momentum, energy, and mass-loading budgets observed compare well with theory.▪A model in which star formation provides a force ∼L/c, where L is the bolometric luminosity, and cool gas is pushed out of the galaxy's gravitational potential, compares well with available data. The wind power is ∼0.1 of that provided by SNe.▪The very hot X-ray-emitting phase may be a (or the) prime mover. Momentum and energy exchange between the hot and cooler phases is critical to the gas dynamics.▪Gaps in our observational knowledge include the hot gas kinematics and the size and structure of the outflows probed with UV absorption lines.Simulations are needed to more fully understand mixing, cloud–radiation, cloud–cosmic ray, andcloud–hot wind interactions, the collective effects of star clusters, and both distributed andclustered SNe. Observational works should seek secondary correlations in the wind data thatprovide evidence for specific mechanisms and compare spectroscopy with the column density–velocity results from theory.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"13 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141755177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Molecular Gas and the Star-Formation Process on Cloud Scales in Nearby Galaxies 近邻星系云尺度上的分子气体和恒星形成过程

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-07-03 DOI: 10.1146/annurev-astro-071221-052651

E. Schinnerer, A.K. Leroy

{"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":"https://doi.org/10.1146/annurev-astro-071221-052651","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: ▪ 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. ","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Character of M Dwarfs M 矮人的特性

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-07-01 DOI: 10.1146/annurev-astro-052722-102740

Todd J. Henry, Wei-Chun Jao

{"title":"The Character of M Dwarfs","authors":"Todd J. Henry, Wei-Chun Jao","doi":"10.1146/annurev-astro-052722-102740","DOIUrl":"https://doi.org/10.1146/annurev-astro-052722-102740","url":null,"abstract":"M dwarfs dominate the stellar population, accounting for three of every four stars, the nearest of which is Proxima Centauri, the closest destination beyond our Solar System. These cool stars span large ranges in luminosities (one ten-thousandth to 6% L⊙) and temperatures (2,100–3,900 K) and have spectra dominated by absorption bands of titanium oxide (TiO) and, for the latest spectral types, vanadium oxide (VO). They have masses that span 0.075 to 0.61 M⊙, a factor of eight, which is comparable with a spread in masses for dwarf types mid-B through K. Unlike these more massive stars, in the age of the Universe no M dwarfs have evolved in any significant way. M dwarf systems are multiple roughly one-quarter of the time, with the closest binaries found in orbits that have been circularized via tides for orbital periods of about one week. Unlike any other type of main sequence star, there is a gap in the distribution of M dwarfs near masses of 0.35 M⊙ that pinpoints the separation of partially and fully convective stars, yet both types of M dwarfs are often active, showing both Hα in emission and flares. Many planets are found orbiting M dwarfs, and most of them are terrestrial or neptunian in size, rather than jovian, yet much more work remains to be done to characterize the exoplanet population. Overall, the Solar Neighborhood is dominated by M dwarfs that are likely orbited by many small, as yet unseen, planets—some of which may harbor life very near to that in our Solar System. ▪ M dwarfs account for three of every four stars. ▪ M dwarf counts increase all the way to the end of the main sequence. ▪ M dwarfs are partially radiative at high masses and fully convective at low masses. ","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141489490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Three-Dimensional Non–Local Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars 晚型恒星的三维非局部热力学平衡丰度分析

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-06-17 DOI: 10.1146/annurev-astro-052722-103557

Karin Lind, Anish M. Amarsi

{"title":"Three-Dimensional Non–Local Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars","authors":"Karin Lind, Anish M. Amarsi","doi":"10.1146/annurev-astro-052722-103557","DOIUrl":"https://doi.org/10.1146/annurev-astro-052722-103557","url":null,"abstract":"The chemical compositions of stars encode the history of the universe and are thus fundamental for advancing our knowledge of astrophysics and cosmology. However, measurements of elemental abundances ratios, and our interpretations of them, strongly depend on the physical assumptions that dictate the generation of synthetic stellar spectra. Three-dimensional radiation-hydrodynamic (3D RHD) box-in-a-star simulations of stellar atmospheres offer a more realistic representation of surface convection occurring in late-type stars than do traditional one-dimensional (1D) hydrostatic models. As evident from a multitude of observational tests, the coupling of 3D RHD models with line formation in nonlocal thermodynamic equilibrium (non-LTE) today provides a solid foundation for abundance analysis for many elements. This review describes the ongoing and transformational work to advance the state of the art and replace 1D LTE spectrum synthesis with its 3D non-LTE counterpart. In summary: ▪ 3D and non-LTE effects are intricately coupled, and consistent modeling thereof is necessary for high-precision abundances; such modeling is currently feasible for individual elements in large surveys. Mean 3D (〈3D〉) models are not adequate as substitutes. ▪ The solar abundance debate is presently dominated by choices and systematic uncertainties that are not specific to 3D non-LTE modeling. ▪ 3D non-LTE abundance corrections have a profound impact on our understanding of FGK-type stars, exoplanets, and the nucleosynthetic origins of the elements. ","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141530256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An Observational View of Structure in Protostellar Systems 原恒星系统结构的观测视角

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2024-05-09 DOI: 10.1146/annurev-astro-052920-103752

John J. Tobin, Patrick D. Sheehan

{"title":"An Observational View of Structure in Protostellar Systems","authors":"John J. Tobin, Patrick D. Sheehan","doi":"10.1146/annurev-astro-052920-103752","DOIUrl":"https://doi.org/10.1146/annurev-astro-052920-103752","url":null,"abstract":"The envelopes and disks that surround protostars reflect the initial conditions of star and planet formation and govern the assembly of stellar masses. Characterizing these structures requires observations that span the near-IR to centimeter wavelengths. Consequently, the past two decades have seen progress driven by numerous advances in observational facilities across this spectrum, including the Spitzer Space Telescope, Herschel Space Observatory, the Atacama Large Millimeter/submillimeter Array, and a host of other ground-based interferometers and single-dish radio telescopes. ▪ Nearly all protostars have well-formed circumstellar disks that are likely to be rotationally supported; the ability to detect a disk around a protostar is more a question of spatial resolution rather than whether or not a disk is present. ▪ The disks around protostars have inherently higher millimeter/submillimeter luminosities as compared to disks around more-evolved pre-main-sequence stars, though there may be systematic variations between star-forming regions. ▪ The envelopes around protostars are inherently asymmetric, and streamers emphasize that mass flow through the envelopes to the disks may not be homogeneous. ▪ The current mass distribution of protostars may be impacted by selection bias given that it is skewed toward solar-mass protostars, which is inconsistent with the stellar initial mass function. ","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"11 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0