Annual Review of Astronomy and Astrophysics最新文献_第9页

Atomic and Ionized Microstructures in the Diffuse Interstellar Medium 漫射星际介质中的原子和电离微观结构

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/annurev-astro-081817-051810

S. Stanimirović, E. Zweibel

{"title":"Atomic and Ionized Microstructures in the Diffuse Interstellar Medium","authors":"S. Stanimirović, E. Zweibel","doi":"10.1146/annurev-astro-081817-051810","DOIUrl":"https://doi.org/10.1146/annurev-astro-081817-051810","url":null,"abstract":"It has been known for half a century that the interstellar medium (ISM) of our Galaxy is structured on scales as small as a few hundred kilometers, more than 10 orders of magnitude smaller than typical ISM structures and energy input scales. In this review we focus on neutral and ionized structures on spatial scales of a few to ∼104 AU, which appear to be highly overpressured, as these have the most important role in the dynamics and energy balance of interstellar gas: the tiny scale atomic structures (TSASs) and extreme scattering events (ESEs) as the most overpressured example of the tiny scale ionized structures (TSISs). We review observational results and highlight key physical processes at AU scales. We present evidence for and against microstructures as part of a universal turbulent cascade and as discrete structures, and we review their association with supernova remnants, the Local Bubble, and bright stars. We suggest a number of observational and theoretical programs that could clarify the nature of AU structures. TSAS and TSIS probe spatial scales in the range of what is expected for turbulent dissipation scales and are therefore of key importance for constraining exotic and not-well-understood physical processes that have implications for many areas of astrophysics. The emerging picture is one in which a magnetized, turbulent cascade, driven hard by a local energy source and acting jointly with phenomena such as thermal instability, is the source of these microstructures.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":" ","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/annurev-astro-081817-051810","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41929711","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: 19

Introduction 介绍

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/annurev-aa-56-071318-100001

S. Faber, E. V. van Dishoeck

引用次数: 0

Extreme Adaptive Optics 极端自适应光学

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/ANNUREV-ASTRO-081817-052000

O. Guyon

{"title":"Extreme Adaptive Optics","authors":"O. Guyon","doi":"10.1146/ANNUREV-ASTRO-081817-052000","DOIUrl":"https://doi.org/10.1146/ANNUREV-ASTRO-081817-052000","url":null,"abstract":"Over the last two decades, several thousand exoplanets have been identified, and their study has become a high scientific priority. Direct imaging of nearby exoplanets and the circumstellar disks in which they form and evolve is challenging due to the high contrast ratio and small angular separation relative to the central star. Exoplanets are typically within 1 arcsec of, and between 4 and 10 orders of magnitude fainter than, the stars they orbit. To meet these challenges, ground-based telescopes must be equipped with extreme adaptive optics (ExAO) systems optimized to acquire high-contrast images of the immediate surrounding of nearby bright stars. Current ExAO systems have the sensitivity to image thermal emission from young massive planets in near-IR, while future systems deployed on Giant Segmented Mirror Telescopes will image starlight reflected by lower-mass rocky planets. Thanks to rapid progress in optical coronagraphy, wavefront control, and data analysis techniques, direct imaging and spectroscopic characterization of habitable exoplanets will be within reach of the next generation of large ground-based telescopes.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/ANNUREV-ASTRO-081817-052000","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41390503","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: 72

Multiconjugate Adaptive Optics for Astronomy 用于天文学的多共轭自适应光学

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/ANNUREV-ASTRO-091916-055320

F. Rigaut, B. Neichel

{"title":"Multiconjugate Adaptive Optics for Astronomy","authors":"F. Rigaut, B. Neichel","doi":"10.1146/ANNUREV-ASTRO-091916-055320","DOIUrl":"https://doi.org/10.1146/ANNUREV-ASTRO-091916-055320","url":null,"abstract":"Since the year 2000, adaptive optics (AO) has seen the emergence of a variety of new concepts addressing particular science needs; multiconjugate adaptive optics (MCAO) is one of them. By correcting the atmospheric turbulence in 3D using several wavefront sensors and a tomographic phase reconstruction approach, MCAO aims to provide uniform diffraction limited images in the near-infrared over fields of view larger than 1 arcmin2, i.e., 10 to 20 times larger in area than classical single conjugated AO. In this review, we give a brief reminder of the AO principles and limitations, and then focus on aspects particular to MCAO, such as tomography and specific MCAO error sources. We present examples and results from past or current systems: MAD (Multiconjugate Adaptive Optics Demonstrator) and GeMS (Gemini MCAO System) for nighttime astronomy and the AO system, at Big Bear for solar astronomy. We examine MCAO performance (Strehl ratio up to 40% in H band and full width at half maximum down to 52 mas in the case of MCAO), with a particular focus on photometric and astrometric accuracy, and conclude with considerations on the future of MCAO in the Extremely Large Telescope and post–HST era.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":" ","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/ANNUREV-ASTRO-091916-055320","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45068330","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: 42

Rubble Pile Asteroids 碎石堆小行星

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/annurev-astro-081817-052013

K. Walsh

引用次数: 99

Cosmology Paradigm Changes 宇宙学范式的改变

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-09-14 DOI: 10.1146/ANNUREV-ASTRO-081817-051748

J. Einasto

引用次数: 0

Dynamical Evolution of the Early Solar System 早期太阳系的动力演化

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-07-17 DOI: 10.1146/annurev-astro-081817-052028

D. Nesvorný

{"title":"Dynamical Evolution of the Early Solar System","authors":"D. Nesvorný","doi":"10.1146/annurev-astro-081817-052028","DOIUrl":"https://doi.org/10.1146/annurev-astro-081817-052028","url":null,"abstract":"Several properties of the Solar System, including the wide radial spacing of the giant planets, can be explained if planets radially migrated by exchanging orbital energy and momentum with outer disk planetesimals. Neptune's planetesimal-driven migration, in particular, has a strong advocate in the dynamical structure of the Kuiper belt. A dynamical instability is thought to have occurred during the early stages with Jupiter having close encounters with a Neptune-class planet. As a result of the encounters, Jupiter acquired its current orbital eccentricity and jumped inward by a fraction of an astronomical unit, as required for the survival of the terrestrial planets and from asteroid belt constraints. Planetary encounters also contributed to capture of Jupiter Trojans and irregular satellites of the giant planets. Here we discuss the dynamical evolution of the early Solar System with an eye to determining how models of planetary migration/instability can be constrained from its present architecture. Specifically, we review arguments suggesting that the Solar System may have originally contained a third ice giant on a resonant orbit between Saturn and Uranus. This hypothesized planet was presumably ejected into interstellar space during the instability. The Kuiper belt kernel and other dynamical structures in the trans-Neptunian region may provide evidence for the ejected planet. We favor the early version of the instability where Neptune migrated into the outer planetesimal disk within a few tens of millions of years after the dispersal of the protosolar nebula. If so, the planetary migration/instability was not the cause of the Late Heavy Bombardment. Mercury's orbit may have been excited during the instability.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":" ","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/annurev-astro-081817-052028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42542366","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: 156

Obscured Active Galactic Nuclei 暗活动星系核

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-06-12 DOI: 10.1146/annurev-astro-081817-051803

R. Hickox, D. Alexander

引用次数: 199

Chemodynamical History of the Galactic Bulge 星系凸起的化学动力学史

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-05-03 DOI: 10.1146/annurev-astro-081817-051826

B. Barbuy, C. Chiappini, Ortwin Gerhard

{"title":"Chemodynamical History of the Galactic Bulge","authors":"B. Barbuy, C. Chiappini, Ortwin Gerhard","doi":"10.1146/annurev-astro-081817-051826","DOIUrl":"https://doi.org/10.1146/annurev-astro-081817-051826","url":null,"abstract":"The Galactic Bulge can uniquely be studied from large samples of individual stars and is therefore of prime importance for understanding the stellar population structure of bulges in general. Here the observational evidence on the kinematics, chemical composition, and ages of Bulge stellar populations based on photometric and spectroscopic data is reviewed. The bulk of Bulge stars are old and span a metallicity range of −1.5≲[Fe/H]≲+0.5. Stellar populations and chemical properties suggest a star-formation timescale below ∼2 Gyr. The overall Bulge is barred and follows cylindrical rotation, and the more metal-rich stars trace a box/peanut (B/P) structure. Dyna-mical models demonstrate the different spatial and orbital distributions of metal-rich and metal-poor stars. We discuss current Bulge-formation scenarios based on dynamical, chemical, chemodynamical, and cosmological models. Despite impressive progress, we do not yet have a successful fully self-consistent chemodynamical Bulge model in the cosmological framework, and we will also need a more extensive chrono-chemical-kinematic 3D map of stars to better constrain such models.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":" ","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/annurev-astro-081817-051826","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44612390","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: 102

The Connection Between Galaxies and Their Dark Matter Halos 星系与其暗物质晕之间的联系

IF 33.3 1区物理与天体物理

Annual Review of Astronomy and Astrophysics Pub Date : 2018-04-09 DOI: 10.1146/annurev-astro-081817-051756

R. Wechsler, J. Tinker

{"title":"The Connection Between Galaxies and Their Dark Matter Halos","authors":"R. Wechsler, J. Tinker","doi":"10.1146/annurev-astro-081817-051756","DOIUrl":"https://doi.org/10.1146/annurev-astro-081817-051756","url":null,"abstract":"In our modern understanding of galaxy formation, every galaxy forms within a dark matter halo. The formation and growth of galaxies over time is connected to the growth of the halos in which they form. The advent of large galaxy surveys as well as high-resolution cosmological simulations has provided a new window into the statistical relationship between galaxies and halos and its evolution. Here, we define this galaxy–halo connection as the multivariate distribution of galaxy and halo properties that can be derived from observations and simulations. This galaxy–halo connection provides a key test of physical galaxy-formation models; it also plays an essential role in constraints of cosmological models using galaxy surveys and in elucidating the properties of dark matter using galaxies. We review techniques for inferring the galaxy–halo connection and the insights that have arisen from these approaches. Some things we have learned are that galaxy-formation efficiency is a strong function of halo mass; at its peak in halos around a pivot halo mass of 1012M⊙, less than 20% of the available baryons have turned into stars by the present day; the intrinsic scatter in galaxy stellar mass is small, less than 0.2 dex at a given halo mass above this pivot mass; below this pivot mass galaxy stellar mass is a strong function of halo mass; the majority of stars over cosmic time were formed in a narrow region around this pivot mass. We also highlight key open questions about how galaxies and halos are connected, including understanding the correlations with secondary properties and the connection of these properties to galaxy clustering.","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":" ","pages":""},"PeriodicalIF":33.3,"publicationDate":"2018-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1146/annurev-astro-081817-051756","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47912049","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: 364