The Astronomy and Astrophysics Review最新文献

{"title":"The Milky Way’s stellar disk","authors":"Hans-Walter Rix,&nbsp;Jo Bovy","doi":"10.1007/s00159-013-0061-8","DOIUrl":"https://doi.org/10.1007/s00159-013-0061-8","url":null,"abstract":"<p>A suite of vast stellar surveys mapping the Milky Way, culminating in the Gaia mission, is revolutionizing the empirical information about the distribution and properties of stars in the Galactic stellar disk. We review and lay out what analysis and modeling machinery needs to be in place to test mechanism of disk galaxy evolution and to stringently constrain the Galactic gravitational potential, using such Galactic star-by-star measurements. We stress the crucial role of stellar survey selection functions in any such modeling; and we advocate the utility of viewing the Galactic stellar disk as made up of ‘mono-abundance populations’ (MAPs), both for dynamical modeling and for constraining the Milky Way’s evolutionary processes. We review recent work on the spatial and kinematical distribution of MAPs, and point out how further study of MAPs in the Gaia era should lead to a decisively clearer picture of the Milky Way’s dark-matter distribution and formation history.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"21 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2013-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-013-0061-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4044083","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}

{"title":"Solar flares at submillimeter wavelengths","authors":"Säm Krucker,&nbsp;C. G. Giménez de Castro,&nbsp;H. S. Hudson,&nbsp;G. Trottet,&nbsp;T. S. Bastian,&nbsp;A. S. Hales,&nbsp;J. Kašparová,&nbsp;K.-L. Klein,&nbsp;M. Kretzschmar,&nbsp;T. Lüthi,&nbsp;A. Mackinnon,&nbsp;S. Pohjolainen,&nbsp;S. M. White","doi":"10.1007/s00159-013-0058-3","DOIUrl":"https://doi.org/10.1007/s00159-013-0058-3","url":null,"abstract":"<p>We discuss the implications of the first systematic observations of solar flares at submillimeter wavelengths, defined here as observing wavelengths shorter than 3?mm (frequencies higher than 0.1?THz). The events observed thus far show that this wave band requires a new understanding of high-energy processes in solar flares. Several events, including observations from two different observatories, show during the impulsive phase of the flare a spectral component with a positive (increasing) slope at the highest observable frequencies (up to 405?GHz). To emphasize the increasing spectra and the possibility that these events could be even more prominent in the THz range, we term this spectral feature a “THz component”. Here we review the data and methods, and critically assess the observational evidence for such distinct component(s). This evidence is convincing. We also review the several proposed explanations for these feature(s), which have been reported in three distinct flare phases. These data contain important clues to flare development and particle acceleration as a whole, but many of the theoretical issues remain open. We generally have lacked systematic observations in the millimeter-wave to far-infrared range that are needed to complete our picture of these events, and encourage observations with new facilities.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"21 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-013-0058-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4896897","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}

{"title":"Common envelope evolution: where we stand and how we can move forward","authors":"N. Ivanova,&nbsp;S. Justham,&nbsp;X. Chen,&nbsp;O. De Marco,&nbsp;C. L. Fryer,&nbsp;E. Gaburov,&nbsp;H. Ge,&nbsp;E. Glebbeek,&nbsp;Z. Han,&nbsp;X.-D. Li,&nbsp;G. Lu,&nbsp;T. Marsh,&nbsp;P. Podsiadlowski,&nbsp;A. Potter,&nbsp;N. Soker,&nbsp;R. Taam,&nbsp;T. M. Tauris,&nbsp;E. P. J. van den Heuvel,&nbsp;R. F. Webbink","doi":"10.1007/s00159-013-0059-2","DOIUrl":"https://doi.org/10.1007/s00159-013-0059-2","url":null,"abstract":"<p>This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"21 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2013-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-013-0059-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5038487","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}

{"title":"Turbulent molecular clouds","authors":"Patrick Hennebelle,&nbsp;Edith Falgarone","doi":"10.1007/s00159-012-0055-y","DOIUrl":"https://doi.org/10.1007/s00159-012-0055-y","url":null,"abstract":"<p>Stars form within molecular clouds but our understanding of this fundamental process remains hampered by the complexity of the physics that drives their evolution. We review our observational and theoretical knowledge of molecular clouds trying to confront the two approaches wherever possible. After a broad presentation of the cold interstellar medium and molecular clouds, we emphasize the dynamical processes with special focus to turbulence and its impact on cloud evolution. We then review our knowledge of the velocity, density and magnetic fields. We end by openings towards new chemistry models and the links between molecular cloud structure and star-formation rates.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0055-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4434065","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}

{"title":"Our astrochemical heritage","authors":"Paola Caselli,&nbsp;Cecilia Ceccarelli","doi":"10.1007/s00159-012-0056-x","DOIUrl":"https://doi.org/10.1007/s00159-012-0056-x","url":null,"abstract":"<p>Our Sun and planetary system were born about 4.5 billion years ago. How did this happen, and what is the nature of our heritage from these early times? This review tries to address these questions from an astrochemical point of view. On the one hand, we have some crucial information from meteorites, comets and other small bodies of the Solar System. On the other hand, we have the results of studies on the formation process of Sun-like stars in our Galaxy. These results tell us that Sun-like stars form in dense regions of molecular clouds and that three major steps are involved before the planet-formation period. They are represented by the prestellar core, protostellar envelope and protoplanetary disk phases. Simultaneously with the evolution from one phase to the other, the chemical composition gains increasing complexity.</p><p>In this review, we first present the information on the chemical composition of meteorites, comets and other small bodies of the Solar System, which is potentially linked to the first phases of the Solar System’s formation. Then we describe the observed chemical composition in the prestellar core, protostellar envelope and protoplanetary-disk phases, including the processes that lead to them. Finally, we draw together pieces from the different objects and phases to understand whether and how much we inherited chemically from the time of the Sun’s birth.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0056-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4067522","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}

{"title":"Imaging the heart of astrophysical objects with optical long-baseline interferometry","authors":"J.-P. Berger,&nbsp;F. Malbet,&nbsp;F. Baron,&nbsp;A. Chiavassa,&nbsp;G. Duvert,&nbsp;M. Elitzur,&nbsp;B. Freytag,&nbsp;F. Gueth,&nbsp;S. Hönig,&nbsp;J. Hron,&nbsp;H. Jang-Condell,&nbsp;J.-B. Le Bouquin,&nbsp;J.-L. Monin,&nbsp;J. D. Monnier,&nbsp;G. Perrin,&nbsp;B. Plez,&nbsp;T. Ratzka,&nbsp;S. Renard,&nbsp;S. Stefl,&nbsp;E. Thiébaut,&nbsp;K. R. W. Tristram,&nbsp;T. Verhoelst,&nbsp;S. Wolf,&nbsp;J. Young","doi":"10.1007/s00159-012-0053-0","DOIUrl":"https://doi.org/10.1007/s00159-012-0053-0","url":null,"abstract":"<p>The number of publications of aperture-synthesis images based on optical long-baseline interferometry measurements has recently increased due to easier access to visible and infrared interferometers. The interferometry technique has now reached a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arcsecond model-independent imaging. In writing this paper our motivation was twofold: (1) review and publicize emblematic excerpts of the impressive corpus accumulated in the field of optical interferometry image reconstruction; (2) discuss future prospects for this technique by selecting four representative astrophysical science cases in order to review the potential benefits of using optical long-baseline interferometers.</p><p>For this second goal we have simulated interferometric data from those selected astrophysical environments and used state-of-the-art codes to provide the reconstructed images that are reachable with current or soon-to-be facilities. The image-reconstruction process was “blind” in the sense that reconstructors had no knowledge of the input brightness distributions. We discuss the impact of optical interferometry in those four astrophysical fields. We show that image-reconstruction software successfully provides accurate morphological information on a variety of astrophysical topics and review the current strengths and weaknesses of such reconstructions.</p><p>We investigate how to improve image reconstruction and the quality of the image possibly by upgrading the current facilities. We finally argue that optical interferometers and their corresponding instrumentation, existing or to come, with six to ten telescopes, should be well suited to provide images of complex sceneries.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0053-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5157142","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}

{"title":"Clusters of galaxies: observational properties of the diffuse radio emission","authors":"Luigina Feretti,&nbsp;Gabriele Giovannini,&nbsp;Federica Govoni,&nbsp;Matteo Murgia","doi":"10.1007/s00159-012-0054-z","DOIUrl":"https://doi.org/10.1007/s00159-012-0054-z","url":null,"abstract":"<p>Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures. The luminous matter of clusters consists of galaxies and of an embedding intracluster medium (ICM), which has been heated to temperatures of tens of millions degrees, and thus is detected through its thermal emission in the soft X-ray regime. Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission.</p><p>The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution.</p><p>We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0054-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5058498","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}

{"title":"Circumstellar disks and planets","authors":"S. Wolf,&nbsp;F. Malbet,&nbsp;R. Alexander,&nbsp;J.-P. Berger,&nbsp;M. Creech-Eakman,&nbsp;G. Duchêne,&nbsp;A. Dutrey,&nbsp;C. Mordasini,&nbsp;E. Pantin,&nbsp;F. Pont,&nbsp;J.-U. Pott,&nbsp;E. Tatulli,&nbsp;L. Testi","doi":"10.1007/s00159-012-0052-1","DOIUrl":"https://doi.org/10.1007/s00159-012-0052-1","url":null,"abstract":"<p>We present a review of the interplay between the evolution of circumstellar disks and the formation of planets, both from the perspective of theoretical models and dedicated observations. Based on this, we identify and discuss fundamental questions concerning the formation and evolution of circumstellar disks and planets which can be addressed in the near future with optical and infrared long-baseline interferometers. Furthermore, the importance of complementary observations with long-baseline (sub)millimeter interferometers and high-sensitivity infrared observations is outlined.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0052-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5119565","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}

{"title":"Interferometric observations of rapidly rotating stars","authors":"Gerard T. van Belle","doi":"10.1007/s00159-012-0051-2","DOIUrl":"https://doi.org/10.1007/s00159-012-0051-2","url":null,"abstract":"<p>Optical interferometry provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Through <i>direct observation</i> of rotationally distorted photospheres at sub-milliarcsecond scales, we are now able to characterize latitude dependencies of stellar radius, temperature structure, and even energy transport. These detailed new views of stars are leading to revised thinking in a broad array of associated topics, such as spectroscopy, stellar evolution, and exoplanet detection. As newly advanced techniques and instrumentation mature, this topic in astronomy is poised to greatly expand in depth and influence.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0051-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4576556","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}

{"title":"Multiple populations in globular clusters","authors":"Raffaele G. Gratton,&nbsp;Eugenio Carretta,&nbsp;Angela Bragaglia","doi":"10.1007/s00159-012-0050-3","DOIUrl":"https://doi.org/10.1007/s00159-012-0050-3","url":null,"abstract":"<p>Recent progress in studies of globular clusters has shown that they are not simple stellar populations, but rather are made up of multiple generations. Evidence stems both from photometry and spectroscopy. A new paradigm is arising for the formation of massive star clusters, which includes several episodes of star formation. While this provides an explanation for several features of globular clusters, including the second-parameter problem, it also opens new perspectives on the relation between globular clusters and the halo of our Galaxy, and by extension on all populations with a high specific frequency of globular clusters, such as, e.g., giant elliptical galaxies. We review progress in this area, focussing on the most recent studies. Several points remain to become properly understood, in particular those concerning the nature of the polluters producing the abundance pattern in the clusters and the typical timescale, the range of cluster masses where this phenomenon is active, and the relation between globular clusters and other satellites of our Galaxy.</p>","PeriodicalId":785,"journal":{"name":"The Astronomy and Astrophysics Review","volume":"20 1","pages":""},"PeriodicalIF":25.8,"publicationDate":"2012-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s00159-012-0050-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5077411","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}