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  • Multiple populations in massive star clusters under the magnifying glass of photometry: theory and tools
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2020-07-07
    Santi Cassisi, Maurizio Salaris

    The existence of star-to-star light-element abundance variations in massive Galactic and extragalactic star clusters has fairly recently superseded the traditional paradigm of individual clusters hosting stars with the same age, and uniform chemical composition. Several scenarios have been put forward to explain the origin of this multiple stellar population phenomenon, but so far all have failed to

  • Nuclear star clusters
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2020-07-06
    Nadine Neumayer, Anil Seth, Torsten Böker

    We review the current knowledge about nuclear star clusters (NSCs), and the spectacularly dense and massive assemblies of stars found at the centers of most galaxies. Recent observational and theoretical works suggest that many NSC properties, including their masses, densities, and stellar populations, vary with the properties of their host galaxies. Understanding the formation, growth, and ultimate

  • Observations of galactic and extragalactic novae
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2020-07-02
    Massimo Della Valle, Luca Izzo

    The recent GAIA DR2 measurements of distances to galactic novae have allowed to re-analyse some properties of nova populations in the Milky Way and in external galaxies on new and more solid empirical bases. In some cases, we have been able to confirm results previously obtained, such as the concept of nova populations into two classes of objects, that is disk and bulge novae and their link with the

  • Cool outflows in galaxies and their implications
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2020-04-03
    Sylvain Veilleux, Roberto Maiolino, Alberto D. Bolatto, Susanne Aalto

    Neutral-atomic and molecular outflows are a common occurrence in galaxies, near and far. They operate over the full extent of their galaxy hosts, from the innermost regions of galactic nuclei to the outermost reaches of galaxy halos. They carry a substantial amount of material that would otherwise have been used to form new stars. These cool outflows may have a profound impact on the evolution of their

  • Molecular jets from low-mass young protostellar objects
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2020-03-31
    Chin-Fei Lee

    Molecular jets are seen coming from the youngest protostars in the early phase of low-mass star formation. They are detected in CO, SiO, and SO at (sub)millimeter wavelengths down to the innermost regions, where their associated protostars and accretion disks are deeply embedded and where they are launched and collimated. They are not only the fossil records of accretion history of the protostars but

  • What is a globular cluster? An observational perspective
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-11-04
    Raffaele Gratton, Angela Bragaglia, Eugenio Carretta, Valentina D’Orazi, Sara Lucatello, Antonio Sollima

    Globular clusters are large and dense agglomerate of stars. At variance with smaller clusters of stars, they exhibit signs of some chemical evolution. At least for this reason, they are intermediate between open clusters and massive objects such as nuclear clusters or compact galaxies. While some facts are well established, the increasing amount of observational data are revealing a complexity that

  • Pulsating white dwarfs: new insights
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-09-03
    Alejandro H. Córsico, Leandro G. Althaus, Marcelo M. Miller Bertolami, S. O. Kepler

    Stars are extremely important astronomical objects that constitute the pillars on which the Universe is built, and as such, their study has gained increasing interest over the years. White dwarf stars are not the exception. Indeed, these stars constitute the final evolutionary stage for more than 95% of all stars. The Galactic population of white dwarfs conveys a wealth of information about several

  • Small Solar System Bodies as granular media
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-06-25
    D. Hestroffer, P. Sánchez, L. Staron, A. Campo Bagatin, S. Eggl, W. Losert, N. Murdoch, E. Opsomer, F. Radjai, D. C. Richardson, M. Salazar, D. J. Scheeres, S. Schwartz, N. Taberlet, H. Yano

    Asteroids and other Small Solar System Bodies (SSSBs) are of high general and scientific interest in many aspects. The origin, formation, and evolution of our Solar System (and other planetary systems) can be better understood by analysing the constitution and physical properties of small bodies in the Solar System. Currently, two space missions (Hayabusa2, OSIRIS-REx) have recently arrived at their

  • The astrophysics of nanohertz gravitational waves
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-06-18
    Sarah Burke-Spolaor, Stephen R. Taylor, Maria Charisi, Timothy Dolch, Jeffrey S. Hazboun, A. Miguel Holgado, Luke Zoltan Kelley, T. Joseph W. Lazio, Dustin R. Madison, Natasha McMann, Chiara M. F. Mingarelli, Alexander Rasskazov, Xavier Siemens, Joseph J. Simon, Tristan L. Smith

    Pulsar timing array (PTA) collaborations in North America, Australia, and Europe, have been exploiting the exquisite timing precision of millisecond pulsars over decades of observations to search for correlated timing deviations induced by gravitational waves (GWs). PTAs are sensitive to the frequency band ranging just below 1 nanohertz to a few tens of microhertz. The discovery space of this band

  • Fast radio bursts
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-05-24
    E. Petroff, J. W. T. Hessels, D. R. Lorimer

    The discovery of radio pulsars over a half century ago was a seminal moment in astronomy. It demonstrated the existence of neutron stars, gave a powerful observational tool to study them, and has allowed us to probe strong gravity, dense matter, and the interstellar medium. More recently, pulsar surveys have led to the serendipitous discovery of fast radio bursts (FRBs). While FRBs appear similar to

  • De re metallica: the cosmic chemical evolution of galaxies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-02-04
    R. Maiolino, F. Mannucci

    The evolution of the content of heavy elements in galaxies, the relative chemical abundances, their spatial distribution, and how these scale with various galactic properties, provide unique information on the galactic evolutionary processes across the cosmic epochs. In recent years major progress has been made in constraining the chemical evolution of galaxies and inferring key information relevant

  • The distribution of dark matter in galaxies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2019-02-04
    Paolo Salucci

    The distribution of the non-luminous matter in galaxies of different luminosity and Hubble type is much more than a proof of the existence of dark particles governing the structures of the Universe. Here, we will review the complex but well-ordered scenario of the properties of the dark halos also in relation with those of the baryonic components they host. Moreover, we will present a number of tight

  • Solar wind charge exchange: an astrophysical nuisance
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-12-04
    K. D. Kuntz

    Solar wind charge-exchange (SWCX) emission is present in every X-ray observation of an astrophysical object. The emission is problematic when one cannot remove the foreground by the simultaneous measurement of a nearby field. SWCX emission is a serious impediment to the study of the diffuse hot ISM, including the galactic halo, as its contribution to diagnostic emission lines is temporally variable

  • High-precision stellar abundances of the elements: methods and applications
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-10-27
    Poul Erik Nissen, Bengt Gustafsson

    Efficient spectrographs at large telescopes have made it possible to obtain high-resolution spectra of stars with high signal-to-noise ratio and advances in model atmosphere analyses have enabled estimates of high-precision differential abundances of the elements from these spectra, i.e. with errors in the range 0.01–0.03 dex for F, G, and K stars. Methods to determine such high-precision abundances

  • Molecular gas in distant galaxies from ALMA studies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-08-10
    Françoise Combes

    ALMA is now fully operational, and has been observing in early science mode since 2011. The millimetric (mm) and sub-mm domain is ideal to tackle galaxies at high redshift, since the emission peak of the dust at 100 \(\upmu \)m is shifted in the ALMA bands (0.3–1 mm) for \(z=\) 2–9, and the CO lines, stronger at the high-J levels of the ladder, are found all over the 0.3–3 mm range. Pointed surveys

  • The interstellar and circumnuclear medium of active nuclei traced by H i 21 cm absorption
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-07-17
    Raffaella Morganti, Tom Oosterloo

    This review summarises what we have learnt in the last two decades based on H i 21 cm absorption observations about the cold interstellar medium (ISM) in the central regions of active galaxies and about the interplay between this gas and the active nucleus (AGN). H i absorption is a powerful tracer on all scales, from the parsec-scales close to the central black hole to structures of many tens of kpc

  • Radio jets from young stellar objects
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-06-26
    Guillem Anglada, Luis F. Rodríguez, Carlos Carrasco-González

    Jets and outflows are ubiquitous in the process of formation of stars since outflow is intimately associated with accretion. Free–free (thermal) radio continuum emission in the centimeter domain is associated with these jets. The emission is relatively weak and compact, and sensitive radio interferometers of high angular resolution are required to detect and study it. One of the key problems in the

  • Origin and evolution of the atmospheres of early Venus, Earth and Mars
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-05-10
    Helmut Lammer, Aubrey L. Zerkle, Stefanie Gebauer, Nicola Tosi, Lena Noack, Manuel Scherf, Elke Pilat-Lohinger, Manuel Güdel, John Lee Grenfell, Mareike Godolt, Athanasia Nikolaou

    We review the origin and evolution of the atmospheres of Earth, Venus and Mars from the time when their accreting bodies were released from the protoplanetary disk a few million years after the origin of the Sun. If the accreting planetary cores reached masses \(\ge 0.5 M_\mathrm{Earth}\) before the gas in the disk disappeared, primordial atmospheres consisting mainly of H\(_2\) form around the young

  • Mass loss of stars on the asymptotic giant branch
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2018-01-09
    Susanne Höfner, Hans Olofsson

    As low- and intermediate-mass stars reach the asymptotic giant branch (AGB), they have developed into intriguing and complex objects that are major players in the cosmic gas/dust cycle. At this stage, their appearance and evolution are strongly affected by a range of dynamical processes. Large-scale convective flows bring newly-formed chemical elements to the stellar surface and, together with pulsations

  • The Main Belt Comets and ice in the Solar System
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2017-11-14
    Colin Snodgrass, Jessica Agarwal, Michael Combi, Alan Fitzsimmons, Aurelie Guilbert-Lepoutre, Henry H. Hsieh, Man-To Hui, Emmanuel Jehin, Michael S. P. Kelley, Matthew M. Knight, Cyrielle Opitom, Roberto Orosei, Miguel de Val-Borro, Bin Yang

    We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling

  • Radio observations of active galactic nuclei with mm-VLBI
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2017-11-06
    B. Boccardi, T. P. Krichbaum, E. Ros, J. A. Zensus

    Over the past few decades, our knowledge of jets produced by active galactic nuclei (AGN) has greatly progressed thanks to the development of very-long-baseline interferometry (VLBI). Nevertheless, the crucial mechanisms involved in the formation of the plasma flow, as well as those driving its exceptional radiative output up to TeV energies, remain to be clarified. Most likely, these physical processes

  • Major achievements of the Rosetta mission in connection with the origin of the solar system
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2017-10-24
    M. A. Barucci, M. Fulchignoni

    Comets have been studied from a long time and are believed to preserve pristine materials, so they are fundamental to understand the origin of the solar system and life. Starting in the early 1990s, ESA decided to have a more risky and fantastic mission to a comet. As Planetary Cornerstone mission of the ESA Horizon 2000 program, the Rosetta mission was selected with the aim of realizing two asteroid

  • Active galactic nuclei: what’s in a name?
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2017-08-23
    P. Padovani, D. M. Alexander, R. J. Assef, B. De Marco, P. Giommi, R. C. Hickox, G. T. Richards, V. Smolčić, E. Hatziminaoglou, V. Mainieri, M. Salvato

    Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different “flavours” in the literature that now comprise a complex

  • Giant star seismology
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2017-06-15
    S. Hekker, J. Christensen-Dalsgaard

    Abstract The internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales. Long near-uninterrupted high-precision photometric timeseries observations from dedicated space missions such as CoRoT and Kepler have provided seismic inferences of the global and internal properties of a large number of evolved stars, including red giants. These inferences

  • Mars: a small terrestrial planet
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-11-16
    N. Mangold, D. Baratoux, O. Witasse, T. Encrenaz, C. Sotin

    Abstract Mars is characterized by geological landforms familiar to terrestrial geologists. It has a tenuous atmosphere that evolved differently from that of Earth and Venus and a differentiated inner structure. Our knowledge of the structure and evolution of Mars has strongly improved thanks to a huge amount of data of various types (visible and infrared imagery, altimetry, radar, chemistry, etc) acquired

  • The realm of the galaxy protoclusters
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-11-11
    Roderik A. Overzier

    The study of galaxy protoclusters is beginning to fill in unknown details of the important phase of the assembly of clusters and cluster galaxies. This review describes the current status of this field and highlights promising recent findings related to galaxy formation in the densest regions of the early universe. We discuss the main search techniques and the characteristic properties of protoclusters

  • The faint radio sky: radio astronomy becomes mainstream
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-09-29
    Paolo Padovani

    Radio astronomy has changed. For years it studied relatively rare sources, which emit mostly non-thermal radiation across the entire electromagnetic spectrum, i.e. radio quasars and radio galaxies. Now, it is reaching such faint flux densities that it detects mainly star-forming galaxies and the more common radio-quiet active galactic nuclei. These sources make up the bulk of the extragalactic sky

  • Time delay cosmography
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-07-21
    Tommaso Treu; Philip J. Marshall

    Gravitational time delays, observed in strong lens systems where the variable background source is multiply imaged by a massive galaxy in the foreground, provide direct measurements of cosmological distance that are very complementary to other cosmographic probes. The success of the technique depends on the availability and size of a suitable sample of lensed quasars or supernovae, precise measurements

  • Radio AGN in the local universe: unification, triggering and evolution
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-06-03
    Clive Tadhunter

    Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (\(L_{1.4\,\mathrm{GHz}} > 10^{24}\) W \(\hbox {Hz}^{-1}\)) are a key sub-class of the overall AGN population. Recently their study has benefitted dramatically from the availability of high-quality data covering the X-ray to far-IR

  • Accurate abundance analysis of late-type stars: advances in atomic physics
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-05-31
    Paul S. Barklem

    The measurement of stellar properties such as chemical compositions, masses and ages, through stellar spectra, is a fundamental problem in astrophysics. Progress in the understanding, calculation and measurement of atomic properties and processes relevant to the high-accuracy analysis of F-, G-, and K-type stellar spectra is reviewed, with particular emphasis on abundance analysis. This includes fundamental

  • Complex organics in space from Solar System to distant galaxies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-02-29
    Sun Kwok

    Recent observational and experimental evidence for the presence of complex organics in space is reviewed. Remote astronomical observations have detected \(\sim \)200 gas-phased molecules through their rotational and vibrational transitions. Many classes of organic molecules are represented in this list, including some precursors to biological molecules. A number of unidentified spectral phenomena observed

  • Accretion disks in luminous young stellar objects
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-01-11
    M. T. Beltrán; W. J. de Wit

    An observational review is provided of the properties of accretion disks around young stars. It concerns the primordial disks of intermediate- and high-mass young stellar objects in embedded and optically revealed phases. The properties were derived from spatially resolved observations and, therefore, predominantly obtained with interferometric means, either in the radio/(sub)millimeter or in the optical/infrared

  • GG Tau: the ringworld and beyond
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2016-01-11
    Anne Dutrey; Emmanuel Di Folco; Tracy Beck; Stéphane Guilloteau

    In binary stellar systems, exoplanet searches have revealed planetary mass companions orbiting both in circumstellar and in circumbinary orbits. Modelling studies suggest increased dynamical complexity around the young stars that form such systems. Circumstellar and circumbinary disks likely exhibit different physical conditions for planet formation, which also depends on the stellar separation. Although

  • Magnetic fields in spiral galaxies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-12-29
    Rainer Beck

    Radio synchrotron emission, its polarization and Faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20–30 \(\upmu \)G) and in central starburst regions (50–100 \(\upmu \)G). Such fields are dynamically important;

  • Spectroradiometry with space telescopes
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-12-21
    Anuschka Pauluhn; Martin C. E. Huber; Peter L. Smith; Luis Colina

    Radiometry, i.e. measuring the power of electromagnetic radiation—hitherto often referred to as “photometry”—is of fundamental importance in astronomy. We provide an overview of how to achieve a valid laboratory calibration of space telescopes and discuss ways to reliably extend this calibration to the spectroscopic telescope’s performance in space. A lot of effort has been, and still is going into

  • The extragalactic gamma-ray sky in the Fermi era
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-12-19
    Francesco Massaro; David J. Thompson; Elizabeth C. Ferrara

    The Universe is largely transparent to \(\gamma \)-rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After 7 years of operation, the Fermi Gamma-ray Space Telescope has produced a wealth of information about the high-energy sky. This review focuses on extragalactic \(\gamma \)-ray sources: what has been learned about the sources

  • Extragalactic HI surveys
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-12-09
    Riccardo Giovanelli; Martha P. Haynes

    We review the results of HI line surveys of extragalactic sources in the local Universe. In the last two decades major efforts have been made in establishing on firm statistical grounds the properties of the HI source population, the two most prominent being the HI Parkes All Sky Survey and the Arecibo Legacy Fast ALFA survey. We review the choices of technical parameters in the design and optimization

  • The legacy of Venus Express: highlights from the first European planetary mission to Venus
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-11-20
    Pierre Drossart; Franck Montmessin

    The ESA/Venus Express mission spent more than 8 years in orbit around Venus to extensively study its atmosphere, ionosphere and plasma environment and unveil new aspects of its surface. Extensive reviews of the work of Venus Express are underway, to cover in-depth studies of the new face of Venus revealed by Venus Express and ground-based concurrent observations. This paper intends to give a summarized

  • Spontaneous magnetic reconnection
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-10-31
    R. A. Treumann; W. Baumjohann

    The present review concerns the relevance of collisionless reconnection in the astrophysical context. Emphasis is put on recent developments in theory obtained from collisionless numerical simulations in two and three dimensions. It is stressed that magnetic reconnection is a universal process of particular importance under collisionless conditions, when both collisional and anomalous dissipation are

  • Radio emission from supernova remnants
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-09-16
    Gloria Dubner; Elsa Giacani

    The explosion of a supernova releases almost instantaneously about 10\(^{51}\) ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic

  • High-mass X-ray binaries in the Milky Way
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-08-05
    Roland Walter; Alexander A. Lutovinov; Enrico Bozzo; Sergey S. Tsygankov

    High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, whose number has increased by almost a factor of three. INTEGRAL played a crucial role in the

  • Cosmic X-ray surveys of distant active galaxies
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2015-01-30
    W. N. Brandt; D. M. Alexander

    We review results from cosmic X-ray surveys of active galactic nuclei (AGNs) over the past \(\approx 15\) years that have dramatically improved our understanding of growing supermassive black holes in the distant universe. First, we discuss the utility of such surveys for AGN investigations and the capabilities of the missions making these surveys, emphasizing Chandra, XMM-Newton, and NuSTAR. Second

  • On the origin of the faint-end of the red sequence in high-density environments
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-18
    Alessandro Boselli; Giuseppe Gavazzi

    With the advent of the new generation wide-field cameras it became possible to survey in an unbiased mode galaxies spanning a variety of local densities, from the core of rich clusters, to compact and loose groups, down to filaments and voids. The sensitivity reached by these instruments allowed to extend the observation to dwarf galaxies, the most “fragile” objects in the universe. At the same time

  • Atmospheres of brown dwarfs
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-16
    Christiane Helling; Sarah Casewell

    Brown dwarfs are the coolest class of stellar objects known to date. Our present perception is that brown dwarfs follow the principles of star formation, and that brown dwarfs share many characteristics with planets. Being the darkest and lowest mass stars known makes brown dwarfs also the coolest stars known. This has profound implication for their spectral fingerprints. Brown dwarfs cover a range

  • The magnetic field in the solar atmosphere
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-16
    Thomas Wiegelmann; Julia K. Thalmann; Sami K. Solanki

    This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In

  • Nonthermal particles and photons in starburst regions and superbubbles
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-14
    Andrei M. Bykov

    Starforming factories in galaxies produce compact clusters and loose associations of young massive stars. Fast radiation-driven winds and supernovae input their huge kinetic power into the interstellar medium in the form of highly supersonic and superalfvenic outflows. Apart from gas heating, collisionless relaxation of fast plasma outflows results in fluctuating magnetic fields and energetic particles

  • What characterizes planetary space weather?
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-12
    Jean Lilensten; Andrew J. Coates; Véronique Dehant; Thierry Dudok de Wit; Richard B. Horne; François Leblanc; Janet Luhmann; Emma Woodfield; Mathieu Barthélemy

    Space weather has become a mature discipline for the Earth space environment. With increasing efforts in space exploration, it is becoming more and more necessary to understand the space environments of bodies other than Earth. This is the background for an emerging aspect of the space weather discipline: planetary space weather. In this article, we explore what characterizes planetary space weather

  • Atmospheric and adaptive optics
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-11-01
    Paul Hickson

    Atmospheric optics is the study of optical effects induced by the atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable growth in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate

  • Giant magnetospheres in our solar system: Jupiter and Saturn compared
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-09-30
    Norbert Krupp

    We review the current knowledge about the two biggest magnetospheres in our solar system based on the significant progress made with data from the Cassini spacecraft in orbit around Saturn since 2004, and based on the last mission to Jupiter by the Galileo spacecraft between 1995 and 2003. In addition we take into account new observations of the Hubble Space Telescope and other telescopes as well as

  • An optical view of BL Lacertae objects
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-09-27
    Renato Falomo; Elena Pian; Aldo Treves

    BL Lac objects are active nuclei, hosted in massive elliptical galaxies, the emission of which is dominated by a relativistic jet closely aligned with the line of sight. This implies the existence of a parent population of sources with a misaligned jet that have been identified with low-power radiogalaxies. The spectrum of BL Lacs, dominated by non-thermal emission over the whole electromagnetic range

  • X-ray reverberation around accreting black holes
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-08-08
    P. Uttley; E. M. Cackett; A. C. Fabian; E. Kara; D. R. Wilkins

    Luminous accreting stellar mass and supermassive black holes produce power–law continuum X-ray emission from a compact central corona. Reverberation time lags occur due to light travel time delays between changes in the direct coronal emission and corresponding variations in its reflection from the accretion flow. Reverberation is detectable using light curves made in different X-ray energy bands,

  • Star formation sustained by gas accretion
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2014-07-16
    Jorge Sánchez Almeida; Bruce G. Elmegreen; Casiana Muñoz-Tuñón; Debra Meloy Elmegreen

    Numerical simulations predict that metal-poor gas accretion from the cosmic web fuels the formation of disk galaxies. This paper discusses how cosmic gas accretion controls star formation, and summarizes the physical properties expected for the cosmic gas accreted by galaxies. The paper also collects observational evidence for gas accretion sustaining star formation. It reviews evidence inferred from

  • On the chronology of lunar origin and evolution
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-11-12
    Johannes Geiss; Angelo Pio Rossi

    An origin of the Moon by a Giant Impact is presently the most widely accepted theory of lunar origin. It is consistent with the major lunar observations: its exceptionally large size relative to the host planet, the high angular momentum of the Earth–Moon system, the extreme depletion of volatile elements, and the delayed accretion, quickly followed by the formation of a global crust and mantle. According

  • The origin of galactic cosmic rays
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-11-05
    Pasquale Blasi

    One century ago Viktor Hess carried out several balloon flights that led him to conclude that the penetrating radiation responsible for the discharge of electroscopes was of extraterrestrial origin. One century from the discovery of this phenomenon seems to be a good time to stop and think about what we have understood about Cosmic Rays. The aim of this review is to illustrate the ideas that have been

  • Classical Be stars
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-10-31
    Thomas Rivinius; Alex C. Carciofi; Christophe Martayan

    In the past decade, a consensus has emerged regarding the nature of classical Be stars: They are very rapidly rotating main sequence B stars, which, through a still unknown, but increasingly constrained process, form an outwardly diffusing gaseous, dust-free Keplerian disk. In this work, first the definition of Be stars is contrasted to similar classes, and common observables obtained for Be stars

  • Dark energy and fundamental physics
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-10-30
    P. Binétruy

    The acceleration of the expansion of the Universe which has been identified in recent years has deep connections with some of the most central issues in fundamental physics. At present, the most plausible explanation is some form of vacuum energy. The puzzle of vacuum energy is a central question which lies at the interface between quantum theory and general relativity. Solving it will presumably require

  • Spectroscopy of planetary atmospheres in our Galaxy
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-10-26
    Giovanna Tinetti; Thérèse Encrenaz; Athena Coustenis

    About 20 years after the discovery of the first extrasolar planet, the number of planets known has grown by three orders of magnitude, and continues to increase at neck breaking pace. For most of these planets we have little information, except for the fact that they exist and possess an address in our Galaxy. For about one third of them, we know how much they weigh, their size and their orbital parameters

  • The near-Earth objects and their potential threat to our planet
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-09-28
    D. Perna; M. A. Barucci; M. Fulchignoni

    The near-Earth object (NEO) population includes both asteroids (NEAs) and comet nuclei (NECs) whose orbits have perihelion distances q<1.3 AU and which can approach or cross that of the Earth. A NEA is defined as a “potentially hazardous asteroid” (PHA) for Earth when its minimum orbit intersection distance (MOID) comes inside 0.05 AU and it has an absolute magnitude H<22 mag (i.e. mean diameter > 140 m)

  • Solar magnetic fields as revealed by Stokes polarimetry
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-09-21
    J. O. Stenflo

    Observational astrophysics started when spectroscopy could be applied to astronomy. Similarly, observational work on stellar magnetic fields became possible with the application of spectro-polarimetry. In recent decades there have been dramatic advances in the observational tools for spectro-polarimetry. The four Stokes parameters that provide a complete representation of partially polarized light

  • Gamma-ray binaries and related systems
    Astron. Astrophys. Rev. (IF 16.0) Pub Date : 2013-08-31
    Guillaume Dubus

    After initial claims and a long hiatus, it is now established that several binary stars emit high- (0.1–100 GeV) and very high-energy (>100 GeV) gamma rays. A new class has emerged called “gamma-ray binaries”, since most of their radiated power is emitted beyond 1 MeV. Accreting X-ray binaries, novae and a colliding wind binary (η Car) have also been detected—“related systems” that confirm the ubiquity

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