The 10 most-cited articles in Astronomische Nachrichten, 2016

Abstract In the last decade, X‐ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X‐ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low‐mass X‐ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract Fast time variability is the most prominent characteristic of accreting systems and the presence of quasi periodic oscillations (QPOs) is a constant in all accreting systems, from cataclysmic variables to AGNs, passing through black hole and neutron star X‐ray binaries and through the enigmatic ultra‐luminous X‐ray sources. In this paper, I will briefly review the current knowledge of QPOs in black hole X‐ray binaries, mainly focussing on their observed properties, but also mentioning the most important models that have been proposed to explain the origin of QPOs over the last decades. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract A time series is a sample of observations of well‐defined data points obtained through repeated measurements over a certain time range. The analysis of such data samples has become increasingly important not only in natural science but also in many other fields of research. Peranso offers a complete set of powerful light curve and period analysis functions to work with large astronomical data sets. Substantial attention has been given to ease‐of‐use and data accuracy, making it one of the most productive time series analysis software available. In this paper, we give an introduction to Peranso and its functionality. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract The Apache Point Observatory Galactic Evolution Experiment (APOGEE) of Sloan Digital Sky Survey III (SDSS‐III) has produced a large catalog of high resolution (R = 22 500), high quality (S/N > 100), infrared (H ‐band) spectra for stars throughout all stellar populations of the Milky Way, including in regions veiled by significant dust opacity. APOGEE's half million spectra collected on > 163 000 unique stars, with time series information via repeat visits to each star, are being applied to numerous problems in stellar populations, Galactic astronomy, and stellar astro‐physics. From among the early results of the APOGEE project – which span from measurements of Galactic dynamics, to multi‐element chemical maps of the disk and bulge, new views of the interstellar medium, explorations of stellar companions, the chemistry of star clusters, and the discovery of rare stellar species – I highlight a few results that demonstrate APOGEE's unique ability to sample and characterize the Galactic disk and bulge. Plans are now under way for an even more ambitious successor to APOGEE: the…

Abstract We present the current status of the PLATO space mission, which is currently in its design phase. A brief overview of its capabilities is given, after introducing the core science goals of the mission. We also present the amount of observing time offered to the community as Guest Observer program. This will allow a wealth of complementary science in many areas of astro‐physics, ranging from stellar to extragalactic science and covering variability phenomena with time scales from a few seconds to years.

Abstract The 4‐m aperture Daniel K. Inouye Solar Telescope (DKIST) formerly known as the Advanced Technology Solar Telescope (ATST) is currently under construction on Haleakalā (Maui, Hawai'i) projected to start operations in 2019. At the time of completion, DKIST will be the largest ground‐based solar telescope providing unprecedented resolution and photon collecting power. The DKIST will be equipped with a set of first‐light facility‐class instruments offering unique imaging, spectroscopic and spectropolarimetric observing opportunities covering the visible to infrared wavelength range. This first‐light instrumentation suite will include: a Visible Broadband Imager (VBI) for high‐spatial and ‐temporal resolution imaging of the solar atmosphere; a Visible Spectro‐Polarimeter (ViSP) for sensitive and accurate multi‐line spectropolarimetry; a Fabry‐Pérot based Visible Tunable Filter (VTF) for high‐spatial resolution spectropolarimetry; a fiber‐fed Diffraction‐Limited Near Infra‐Red Spectro‐Polarimeter (DL‐NIRSP) for two‐dimensional high‐spatial resolution spectropolarimetry…

Abstract We review results from our monitoring observations of several lensed quasars performed in the optical, UV, and X‐ray bands. Modeling of the multi‐wavelength light curves provides constraints on the extent of the optical, UV, and X‐ray emission regions. One of the important results of our analysis is that the optical sizes as inferred from the microlensing analysis are significantly larger than those predicted by the theoretical‐thin‐disk estimate. In a few cases we also constrain the slope of the size‐wavelength relation. Our size constraints of the soft and hard X‐ray emission regions of quasars indicate that in some objects of our sample the hard X‐ray emission region is more compact than the soft and in others the soft emission region is smaller. This difference may be the result of the relative strengths of the disk‐reflected (harder and extended) versus corona‐direct (softer and compact) components in the quasars of our sample. Finally, we present the analysis of several strong microlensing events where we detect an evolution of the relativistic Fe line profile as the…

Abstract Compact steep spectrum (CSS) and GHz‐peaked spectrum (GPS) radio sources represent a large fraction of the extragalactic objects in flux density‐limited samples. They are compact, powerful radio sources whose synchrotron peak frequency ranges between a few hundred MHz to several GHz. CSS and GPS radio sources are currently interpreted as objects in which the radio emission is in an early evolutionary stage. In this contribution I review the radio properties and the physical characteristics of this class of radio sources, and the interplay between their radio emission and the ambient medium of the host galaxy. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star‐formation by pressure‐triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet‐driven feedback on galaxy scales that are applicable to compact radio sources. The simulations show that the efficiency of feedback and the relative importance of negative and positive feedback depend strongly on interstellar medium properties, especially the column depth and spatial distribution of clouds. Negative feedback is most effective if clouds are distributed spherically and individual clouds have small column depths, while positive feedback is most effective if clouds are predominantly in a disc‐like configuration. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract Coronal mass ejections (CMEs), caused by large‐scale eruptions of the coronal magnetic field, often are accompanied by a more localized energy release in the form of flares, as a result of dissipative magnetic‐field reconfiguration. Morphology and evolution of such flares, also denoted as dynamical flares are often explained as a consequence of reconnection of the arcade magnetic field, taking place below the erupting magnetic flux rope. A close relationship of the CME acceleration and the flare energy release is evidenced by various statistical correlations between parameters describing CMEs and flares, as well as by the synchronization of the CME acceleration phase with the impulsive phase of the associated flare. Such behavior implies that there must be a feedback relation between the dynamics of the CME and the flare‐associated reconnection process. From the theoretical standpoint, magnetic reconnection affects the CME dynamics in several ways. First, it reduces the tension of the overlying arcade magnetic field and increases the magnetic pressure below the flux rope,…