Latest in astro-ph.sr

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Investigating dynamical properties of evolved Galactic open clustersFeb 21 2019The stellar content of Galactic open clusters is gradually depleted during their evolution as a result of internal relaxation and external interactions. The final residues of the evolution of open clusters are called open cluster remnants, barely distinguishable ... More
Deep Long Asymmetric Occultation in EPIC 204376071Feb 21 2019We have discovered a young M star of mass $0.16\,M_\odot$ and radius $0.63\,R_\odot$, likely in the Upper Sco Association, that exhibits only a single $80\%$ deep occultation of 1-day duration. The star has frequent flares and a low-amplitude rotational ... More
Limiting magnetic field for minimal deformation of a magnetised neutron starFeb 21 2019In this work we study the structure of neutron stars under the effect of a poloidal magnetic field and determine the limiting highest magnetic field intensity which still allows a satisfactory description of magnetic neutron stars in the spherical symmetry ... More
Formation and eruption of sigmoidal structure from a weak field region of NOAA 11942Feb 21 2019Using observations from Solar Dynamics Observatory, we studied an interesting example of a sigmoid formation and eruption from small-scale flux canceling regions of active region (AR) 11942. Analysis of HMI and AIA observations infer that initially the ... More
Variable stars in Palomar 13; an evaporating globular clusterFeb 21 2019We present new CCD $VI$ photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H]=-1.65, and a distance of 23.67$\pm$0.57 kpc. Light and colour near ... More
The JCMT BISTRO Survey: The Magnetic Field In The Starless Core $ρ$ Ophiuchus CFeb 20 2019We report 850~$\mu$m dust polarization observations of a low-mass ($\sim$12 $M_{\odot}$) starless core in the $\rho$ Ophiuchus cloud, Ophiuchus C, made with the POL-2 instrument on the James Clerk Maxwell Telescope (JCMT) as part of the JCMT B-fields ... More
Discovery of a directly imaged disk in scattered light around the Sco-Cen member Wray 15-788Feb 20 2019As part of our on-going survey we have carried out high-contrast imaging with VLT/SPHERE/IRDIS to obtain polarized and total intensity images of the young ($11^{+16}_{-7}$Myr old) K3IV star Wray 15-788 within the Lower Centaurus Crux subgroup of Sco-Cen. ... More
A census of $ρ$-Oph candidate members from \gaia DR2Feb 20 2019Rho-Ophiuchus (Rho-Oph), one of the nearest star forming regions, is an ideal laboratory to study the earlier stages of the stellar and protoplanetary disc evolution. We aim to find potential new members of the Rho-Oph region and identify those surrounded ... More
The Period-Luminosity Relations of Red Supergiants in M33 and M31Feb 20 2019Based on previously selected preliminary samples of Red Supergiants (RSGs) in M33 and M31, the foreground stars and luminous Asymptotic Giant Branch stars (AGBs) are further excluded, which leads to the samples of 717 RSGs in M33 and 420 RSGs in M31. ... More
Unveiling a cluster of protostellar disks around the massive protostar GGD27 MM1Feb 20 2019We used ALMA to observe the star-forming region GGD27 at 1.14 mm with an unprecedented angular resolution, 40 mas (56 au) and sensitivity (0.002 Msun). We detected a cluster of 25 continuum sources, most of which are likely tracing disks around Class ... More
The Gaia Ultra-Cool Dwarf Sample -- II: Structure at the end of the main sequenceFeb 20 2019We identify and investigate known late M, L and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultra cool dwarfs work package. We find 695 objects in the optical spectral ... More
Slingshot prominence evolution for a solar-like starFeb 20 2019Although the present-day Sun rotates too slowly to exhibit centrifugally-supported 'slingshot prominences', at some time during its past it may have formed these clouds of cool gas and ejected them into the interplanetary medium. We determine the time ... More
Stellar masses from granulation and oscillations of 23 bright red giants observed by BRITE - ConstellationFeb 20 2019Context: The study of stellar structure and evolution depends crucially on accurate stellar parameters. The photometry from space telescopes has provided superb data that allowed asteroseismic characterisation of thousands of stars. However, typical targets ... More
Mapping the magnetic field of flare coronal loopsFeb 20 2019Here we report on the unique observation of flaring coronal loops at the solar limb using high resolution imaging spectropolarimetry from the Swedish 1-meter Solar Telescope. The vantage position, orientation and nature of the chromospheric material that ... More
Asymmetric mid-plane gas in ALMA images of HD~100546Feb 20 2019In this paper we present new ALMA observations towards the proto-planet hosting transitional disc of Herbig Ae/Be star HD 100546. This includes resolved 1.3 mm continuum, $^{13}$CO and the first detection of C$^{18}$O in this disc, which displays azimuthal ... More
RW Tri - its Negative Superhumps and System ParametersFeb 20 2019Negative superhumps are detected in the light curves of RW Tri collected in September 1994 (Smak 1995) and November/December 1957 (Walker 1963). New system parameters, obtained using $K_2$ and $V_{2,rot}\sin i$ (from Poole et al. 2003) and $q$ (estimated ... More
Historical solar Ca II K observations at the Rome and Catania observatoriesFeb 20 2019Here we present the little explored Ca II K archives from the Rome and the Catania observatories and analyse the digitised images from these archives to derive plage areas.
A new look into putative duplicity and pulsations of the Be star $β$ CMiFeb 20 2019Bright Be star beta CMi has been identified as a non-radial pulsator on the basis of space photometry with the MOST satellite and also as a single-line spectroscopic binary with a period of 170.4 d. The purpose of this study is to re-examine both these ... More
An Infrared Census Of Dust In Nearby Galaxies With Spitzer (dustings): V. The Period-luminosity Relation For Dusty Metal-poor Agb StarsFeb 20 2019The survey for DUST In Nearby Galaxies with Spitzer (DUSTiNGS) has identified hundreds of candidate dust-producing Asymptotic Giant Branch (AGB) stars in several nearby metal-poor galaxies. We have obtained multi-epoch follow-up observations for these ... More
Studying Spectral Behavior, Accretion Processes and Photometric Behavior of Some Binary Stars in the Ultraviolet and Optical RegionsFeb 19 2019We study the evolution of the normalized flux of selected ultraviolet emission lines of three classical novae (PW Vul, V1668 Cyg and V1974 Cyg). Different phases ofthe outbursts are studied. We attribute the spectral behavior of the three systems to the ... More
Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky WayFeb 19 2019In a dynamically relaxed cluster around a massive black hole a dense stellar cusp of old stars is expected to form. Previous observations showed a relative paucity of red giant stars within the central 0.5 pc in the Galactic Center. By co-adding spectroscopic ... More
Feature Selection for Better Spectral Characterization or: How I Learned to Start Worrying and Love EnsemblesFeb 19 2019An ever-looming threat to astronomical applications of machine learning is the danger of over-fitting data, also known as the `curse of dimensionality.' This occurs when there are fewer samples than the number of independent variables. In this work, we ... More
The local and distant Universe: stellar ages and $H_0$Feb 19 2019The ages of the oldest stellar objects in our galaxy provide an independent test of the current cosmological model as they give a lower limit to the age of the Universe. Recent accurate parallaxes by the Gaia space mission, accurate measurements of the ... More
A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science ProjectFeb 19 2019Infrared excesses due to dusty disks have been observed orbiting white dwarfs with effective temperatures between 7200 K and 25000 K, suggesting that the rate of tidal disruption of minor bodies massive enough to create a coherent disk declines sharply ... More
Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1-3Feb 19 2019In the search for the building blocks of life, nitrogen-bearing molecules are of particular interest since nitrogen-containing bonds are essential for the linking of amino acids and ultimately the formation of larger biological structures. The elusive ... More
Transient Inverse-FIP Plasma Composition Evolution within a Confined Solar FlareFeb 19 2019Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of ... More
On the iron ionization balance of cool starsFeb 18 2019High-resolution spectroscopic studies of solar-type stars have revealed higher iron abundances derived from singly ionized species compared to neutral, violating the ionization equilibrium under the assumption of local thermodynamic equilibrium. In this ... More
Asteroseismic masses, ages, and core properties of $γ$ Doradus stars using gravito-inertial dipole modes and spectroscopyFeb 18 2019Feb 20 2019The asteroseismic modelling of period spacing patterns from gravito-inertial modes in stars with a convective core is a high-dimensional problem. We utilise the measured period spacing pattern of prograde dipole gravity modes (acquiring $\Pi_0$), in combination ... More
Asteroseismic masses, ages, and core properties of $γ$ Doradus stars using gravito-inertial dipole modes and spectroscopyFeb 18 2019The asteroseismic modelling of period spacing patterns from gravito-inertial modes in stars with a convective core is a high-dimensional problem. We utilise the measured period spacing pattern of prograde dipole gravity modes (acquiring $\Pi_0$), in combination ... More
A highly variable methanol maser in G111.256-0.770Feb 18 2019G111.256-0.770 is a high-mass young stellar object associated with a weak 6.7 GHz methanol maser showing strong variability. We present results of a multi-epoch monitoring program of the target, conducted with the Torun 32 m telescope for more than a ... More
A New Analysis Procedure for Detecting Periodicities within Complex Solar Coronal ArcadesFeb 18 2019We study intensity variations, as measured by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), in a solar coronal arcade using a newly developed analysis procedure that employs spatio-temporal auto-correlations. We ... More
Selected new results on pulsating variable starsFeb 18 2019Recent progress in the studies of pulsating variable stars is summarized from an observational point of view. A number of unexpected phenomena have been revealed in the case of pulsators in the classical instability strip. These discoveries -- lacking ... More
Full inversion of solar relativistic electron events measured by the Helios spacecraftFeb 18 2019Up to present, the largest data set of SEP events in the inner heliosphere are the observations by the two Helios spacecraft. We re-visit a sample of 15 solar relativistic electron events measured by the Helios mission with the goal of better characterising ... More
Full inversion of solar relativistic electron events measured by the Helios spacecraftFeb 18 2019Feb 19 2019Up to present, the largest data set of SEP events in the inner heliosphere are the observations by the two Helios spacecraft. We re-visit a sample of 15 solar relativistic electron events measured by the Helios mission with the goal of better characterising ... More
States of the $^{12}$C Nucleus in the Toroidal ConfigurationFeb 18 2019The $^{12}$C nucleus with $N$=6 and $Z$=6 is a doubly-magic closed-shell nucleus in a toroidal potential and Wheeler's triangular resonating group model of $^{12}$C as three clusters of alpha particles will naturally generate a toroidal density if the ... More
Diagnostic potential of the Ca II 8542A line for solar filamentsFeb 18 2019In this study we explore the diagnostic potential of the chromospheric Ca II line at 8542A for studying the magnetic and dynamic properties of solar filaments. We have acquired high spatial resolution spectropolarimetric observations in the Ca II 8542A ... More
Contrasting turbulence in stably stratified flows and thermal convectionFeb 18 2019In this paper, the properties of stably stratified turbulence (SST) and turbulent thermal convection are contrasted. A key difference between these flows is the sign of the kinetic energy feed by buoyancy, $\mathcal{F}_B$. For SST, $\mathcal{F}_B < 0$ ... More
Model-free inverse method for transit imaging of stellar surfaces: Using transit surveys to map stellar spot coverageFeb 18 2019Context. We present a model-free method for mapping surface brightness variations. Aims. We aim to develop a method that is not dependent on either stellar atmosphere models or limb-darkening equation. This method is optimized for exoplanet transit surveys ... More
Rotational Desorption of Ice Mantles and Complex Molecules from Suprathermally Rotating Dust Grains around Young Stellar ObjectsFeb 18 2019Complex organic molecules (COMs) are increasingly observed in the environs of young stellar objects (YSOs), including hot cores/corinos around high-mass/low-mass protostars and protoplanetary disks. It is widely believed that COMs are first formed in ... More
Search for variable stars in the northern sky:Analysis of photometric time series for 3598 starsFeb 18 2019As extensive ground-based observations and characterisation of different variable stars are of the utmost importance in preparing optimal input catalogues for space missions, our aim was to search for new variable stars in selected fields of the northern ... More
Hydrodynamical simulations and similarity relations for eruptive mass loss from massive starsFeb 17 2019Motivated by the eruptive mass loss inferred from Luminous Blue Variable (LBV) stars, we present 1D hydrodynamical simulations of the response from sudden energy injection into the interior of a very massive ($100 \, M_\odot$) star. For a fiducial case ... More
Synthetic Emissions of the Fe XXI 1354 Å Line from Flare Loops Experiencing Fundamental Fast Sausage OscillationsFeb 16 2019Inspired by recent IRIS observations, we forward model the response of the Fe XXI 1354 \AA\ line to fundamental, standing, linear fast sausage modes (FSMs) in flare loops. Starting with the fluid parameters for an FSM in a straight tube with equilibrium ... More
Ejection History of the IRAS 04166+2706 Molecular JetFeb 16 2019The high-velocity molecular jet driven by Class 0 protostar IRAS 04166+2706 exhibits a unique saw-tooth velocity pattern. It consists of a series of well-aligned symmetric knots with similar averaged speeds, whose speeds at peaks of emission decreases ... More
$^{60}$Fe in core-collapse supernovae and prospects for X-ray and $γ$-ray detection in supernova remnantsFeb 15 2019We investigate $^{60}$Fe in massive stars and core-collapse supernovae focussing on uncertainties that influence its production in 15, 20 and 25 $M_\odot$ stars at solar metallicity. We find that the $^{60}$Fe yield is a monotonic increasing function ... More
The Mass Evolution of Protostellar Disks and Envelopes in the Perseus Molecular CloudFeb 15 2019In the standard picture for low-mass star formation, a dense molecular cloud undergoes gravitational collapse to form a protostellar system consisting of a new central star, a circumstellar disk, and a surrounding envelope of remaining material. The mass ... More
Magnetic topologies of young suns: The weak-line T Tauri stars TWA 6 and TWA 8AFeb 15 2019Feb 19 2019We present a spectropolarimetric study of two weak-line T Tauri stars (wTTSs), TWA 6 and TWA 8A, as part of the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets) program. Both stars display significant Zeeman signatures ... More
Magnetic topologies of young suns: The weak-line T Tauri stars TWA 6 and TWA 8AFeb 15 2019We present a spectropolarimetric study of two weak-line T Tauri stars (wTTSs), TWA 6 and TWA 8A, as part of the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets) program. Both stars display significant Zeeman signatures ... More
The eye of Gaia on globular clusters kinematics: internal rotationFeb 15 2019We derived the three-dimensional velocities of individual stars in a sample of 62 Galactic globular clusters using proper motions from the second data release of the Gaia mission together with the most comprehensive set of line-of-sight velocities with ... More
The variation of the magnetic field of the Ap star HD~50169 over its 29 year rotation periodFeb 15 2019Context. The Ap stars that rotate extremely slowly, with periods of decades to centuries, represent one of the keys to the understanding of the processes leading to the differentiation of stellar rotation. Aims. We characterise the variations of the magnetic ... More
Evidence for Electron Landau Damping in Space Plasma TurbulenceFeb 15 2019How turbulent energy is dissipated in weakly collisional space and astrophysical plasmas is a major open question. Here, we present the application of a field-particle correlation technique to directly measure the transfer of energy between the turbulent ... More
Ruprecht 147 DANCe I. Members, empirical isochrone, luminosity and mass distributionsFeb 15 2019Context. Ruprecht 147 is the oldest (2.5 Gyr) open cluster in the solar vicinity (< 300 pc), making it an important target for stellar evolution studies and exoplanet searches. Aims. Derive a census of members and the luminosity, mass, and spatial distributions ... More
The core and stellar mass functions in massive collapsing filamentsFeb 15 2019The connection between the pre-stellar core mass function (CMF) and the stellar initial mass function (IMF) lies at the heart of all star formation theories. In this paper, we study the earliest phases of star formation with a series of high-resolution ... More
Limits on Mode Coherence Due to a Non-static Convection ZoneFeb 14 2019The standard theory of pulsations deals with the frequencies and growth rates of infinitesimal perturbations in a stellar model. Modes which are calculated to be linearly driven should increase their amplitudes exponentially with time; the fact that nearly ... More
Asteroseismology of main-sequence F stars with \textit{Kepler}: overcoming short mode lifetimesFeb 14 2019Asteroseismology is a powerful way of determining stellar parameters and properties of stars like the Sun. However, main-sequence F-type stars exhibit short mode lifetimes relative to their oscillation frequency, resulting in overlapping radial and quadrupole ... More
Visual Orbits of Spectroscopic Binaries with the CHARA Array. I. HD 224355Feb 14 2019We present the visual orbit of the double-lined spectroscopic binary HD 224355 from interferometric observations with the CHARA Array, as well as an updated spectroscopic analysis using echelle spectra from the Apache Point Observatory 3.5m telescope. ... More
A panchromatic view of the bulge globular cluster NGC 6569Feb 14 2019We used high-resolution optical HST/WFC3 and multi-conjugate adaptive optics assisted GEMINI GeMS/GSAOI observations in the near-infrared to investigate the physical properties of the globular cluster NGC 6569 in the Galactic bulge. We have obtained the ... More
A Code to Make Your Own Synthetic ObservaTIonS (MYOSOTIS)Feb 14 2019We introduce our new code MYOSOTIS (Make Your Own Synthetic ObservaTIonS) which is designed to produce synthetic observations from simulated clusters. The code can synthesise observations from both ground- and spaced-based observatories, for a range of ... More
Near-infrared spectroscopy of the massive stellar population of W51: evidence for multi-seeded star formationFeb 14 2019The interplay between the formation of stars, stellar feedback and cloud properties strongly influences the star formation history of giant molecular clouds. The formation of massive stars leads to a variety of stellar clusters, ranging from low stellar ... More
Carbon star wind models at solar and sub-solar metallicities: a comparative study. I. Mass loss and the properties of dust-driven windsFeb 14 2019The atmospheres and winds of C-type AGB stars are modeled with the 1D spherically symmetric radiation-hydrodynamical code DARWIN. To explore the metallicity-dependence of mass loss we calculate model grids at three different chemical abundances. Since ... More
A VLT/FLAMES survey for massive binaries in Westerlund 1: VI. Properties of X-ray bright massive cluster membersFeb 14 2019Despite the first detection of X-rays from massive stars occurring four decades ago, the physical dependence of the emission mechanism(s) on the underlying stellar and binary properties of the emitters remains uncertain. The young massive cluster Westerlund ... More
The central 1000 AU of a pre-stellar core revealed with ALMA. I. 1.3 mm continuum observationsFeb 14 2019Stars like our Sun form in self-gravitating dense and cold structures within interstellar clouds, called pre-stellar cores. Although much is known about the physical structure of dense clouds just before and soon after the switch-on of a protostar, the ... More
Solar cycle activity: an early prediction for cycle #25Feb 14 2019Solar activity forecasting is an important topic for numerous scientific and technological areas, such as space mission operations, electric power transmission lines, power transformation stations and earth geophysical and climatic impact. Nevertheless, ... More
Experimental nuclear astrophysics in ItalyFeb 14 2019Feb 15 2019Nuclear astrophysics, the union of nuclear physics and astronomy, went through an impressive expansion during the last twenty years. This could be achieved thanks to milestone improvements in astronomical observations, cross section measurements, powerful ... More
Experimental nuclear astrophysics in ItalyFeb 14 2019Nuclear astrophysics, the union of nuclear physics and astronomy, went through an impressive expansion during the last twenty years. This could be achieved thanks to milestone improvements in astronomical observations, cross section measurements, powerful ... More
Plasma flows in the cool loop systemsFeb 14 2019We study the dynamics of low-lying cool loop systems for three datasets as observed by the Interface Region Imaging Spectrograph (IRIS). Radiances, Doppler shifts and line widths are investigated in and around observed cool loop systems using various ... More
Non-thermal emission from the interaction of magnetized exoplanets with the wind of their host starFeb 13 2019We study the non-thermal emission from the interaction between magnetized Jupiter-like exoplanets and the wind from their host star. The supersonic motion of planets through the wind forms a bow shock that accelerates electrons which produces non-thermal ... More
A class of partly burnt runaway stellar remnants from peculiar thermonuclear supernovaeFeb 13 2019We report the discovery of three stars that, along with the prototype LP 40-365, form a distinct class of chemically peculiar runaway stars that are the survivors of thermonuclear explosions. Spectroscopy of the four confirmed LP 40-365 stars finds ONe-dominated ... More
The Evolution of Magnetic Rayleigh-Taylor Unstable Plumes and Hybrid KH-RT Instability into A Loop-like Eruptive ProminenceFeb 13 2019MRT unstable plumes are observed in a loop-like eruptive prominence using SDO/AIA observations. The small-scale cavities are developed within the prominence, where perturbations trigger dark plumes (P1 \& P2) propagating with the speed of 35-46 km s$^{-1} ... More
CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite linesFeb 13 2019CHIANTI contains a large quantity of atomic data for the analysis of astrophysical spectra. Programs are available in IDL and Python to perform calculation of the expected emergent spectrum from these sources. The database includes atomic energy levels, ... More
Spectral analysis of the barium central star of the planetary nebula Hen 2-39Feb 13 2019Barium stars are peculiar red giants characterized by an overabundance of s-process elements along with an enrichment in carbon. These stars are discovered in binaries with white dwarf companions. The more recently formed of these stars are still surrounded ... More
The Role of a Tiny Brightening in a Huge Geo-effective Solar Eruption Leading to the St Patrick's Day StormFeb 13 2019The largest magnetic storm in solar cycle 24 was caused by a fast coronal mass ejection (CME) that was related to a small C9.1 flare that occurred on 15 March 2015 in solar active region (AR) NOAA 12297. The purpose of this study is to understand the ... More
HADES RV Programme with HARPS-N at TNG. X. The non-saturated regime of the stellar activity-rotation relationship for M-DwarfsFeb 13 2019Aims. We aim to extend the relationship between X-ray luminosity (Lx) and rotation period (Prot) found for main-sequence FGK stars and test whether it also holds for early-M dwarfs, especially in the non-saturated regime (Lx {\alpha} P_{rot}^{-2}) which ... More
Diagnosing the Clumpy Protoplanetary Disk of the UXor Type Young Star GM CepheiFeb 13 2019UX Orionis stars (UXors) are Herbig Ae/Be or T Tauri stars exhibiting sporadic occultation of stellar light by circumstellar dust. GM\,Cephei is such a UXor in the young ($\sim4$~Myr) open cluster Trumpler\,37, showing prominent infrared excess, emission-line ... More
Self-similar expansion model of cylindrical flux ropes combined with Alfven wave current systemFeb 13 2019Magnetic flux ropes in space are generally connected to some regions electromagnetically. We consider the whole closed current system of the expanding flux ropes including the electric current associated with them. By combining the theories regarding ... More
Compositional differences between the component stars of eclipsing close binary systems showing chemical peculiaritiesFeb 13 2019A spectroscopic study was carried out on the surface chemical abundances of CNO and several heavier elements in the primary and secondary components of 5 eclipsing close binaries around A-type (AR Aur, beta Aur, YZ Cas, WW Aur, and RR Lyn), in order to ... More
Minimalist shear-driven large scale dynamoFeb 13 2019We show that non-axisymmetric, non-helical perturbations in an unstratified shear flow produce a shear-plane averaged electromotive force (EMF) rigorously proportional to a spatially dependent kinetic helicity. This new "shear-driven $\alpha$-effect" ... More
Wideband polarized radio emission from the newly revived radio magnetar XTE J1810$-$197Feb 13 2019The anomalous X-ray pulsar XTE J1810$-$197 was the first magnetar found to emit pulsed radio emission. After spending almost a decade in a quiescent, radio-silent state, the magnetar was reported to have undergone a radio outburst in early 2018 December. ... More
Hydrodynamic and Magnetohydrodynamic Simulations of Wire TurbulenceFeb 12 2019We report on simulations of laboratory experiments in which magnetized supersonic flows are driven through a wire mesh. The goal of the study was to investigate the ability of such a configuration to generate supersonic, MHD turbulence. We first report ... More
Magnetic Properties and Flow Angle of the Inverse Evershed Flow at Its Downflow PointsFeb 12 2019We determined the direction and strength of the photospheric and lower chromospheric magnetic field in the umbra and penumbra of a sunspot from inversions of spectropolarimetric observations of photospheric lines at 617\,nm and 1565\,nm, and the chromospheric ... More
The survivability of planetary systems in young and dense star clustersFeb 12 2019We perform a simulation using the Astrophysical Multipurpose Software Environment of the Orion Trapezium star cluster in which the evolution of the stars and the dynamics of planetary systems are taken into account. The initial conditions are selected ... More
Spatial segregation of dust grains in transition disks. SPHERE observations of 2MASS J16083070-3828268 and RXJ1852.3-3700Feb 12 2019Context. The mechanisms governing the opening of cavities in transition disks are not fully understood. Several processes have been proposed but their occurrence rate is still unknown. Aims. We present spatially resolved observations of two transition ... More
External photoevaporation of protoplanetary discs in Cygnus OB2: linking discs to star formation dynamical historyFeb 12 2019Feb 19 2019Many stars form in regions of enhanced stellar density, wherein the influence of stellar neighbours can have a strong influence on a protoplanetary disc (PPD) population. In particular, far ultraviolet (FUV) flux from massive stars drives thermal winds ... More
External photoevaporation of protoplanetary discs in Cygnus OB2: linking discs to star formation dynamical historyFeb 12 2019Many stars form in regions of enhanced stellar density, wherein the influence of stellar neighbours can have a strong influence on a protoplanetary disc (PPD) population. In particular, far ultraviolet (FUV) flux from massive stars drives thermal winds ... More
Can supernova kicks trigger EMRIs in the Galactic Centre?Feb 12 2019One of the most promising gravitational wave (GW) sources detectable by the forthcoming LISA observatory are the so-called extreme-mass ratio inspirals (EMRIs), i.e. GW-driven inspirals of stellar-mass compact objects onto supermassive black holes (SMBHs). ... More
Observations of tides and circularization in red-giant binaries from Kepler photometryFeb 12 2019Binary stars are places of complex stellar interactions. While all binaries are in principle converging towards a state of circularization, many eccentric systems are found even in advanced stellar phases. In this work we discuss the sample of binaries ... More
A study of full space motions of outer Galactic disk A and F stars in two deep pencil-beamsFeb 12 2019A and F stars can be used as probes of outer Galactic disk kinematics: here we extend the work of Harris et al. (2018) by crossmatching their A/F sample with Gaia DR2 to bring in proper motions. These are combined with the already measured radial velocities ... More
Deterministic and stochastic properties of self-similar Rayleigh-Taylor mixing induced by space-varying accelerationFeb 12 2019Rayleigh-Taylor interfacial mixing has critical importance in a broad range of processes in nature and technology. In most instances Rayleigh-Taylor dynamics is induced by variable acceleration, whereas the bulk of existing studies is focused on the cases ... More
Heavy metal rules. I. Exoplanet incidence and metallicityFeb 12 2019Discovery of only handful of exoplanets required to establish a correlation between giant planet occurrence and metallicity of their host stars. More than 20 years have already passed from that discovery, however, many questions are still under lively ... More
Low state transitions in the nova-like cataclysmic variable HS 0506+7725Feb 12 2019The twelve-year light curve of the nova-like cataclysmic variable HS 0506+7725 between 2006 April and 2018 November is presented. This shows that the star spends most of the time in a normal state at magnitude ~14.7, but multiple excursions to a fainter ... More
Exploring circumstellar effects on the lithium and calcium abundances in massive Galactic O-rich AGB starsFeb 12 2019We previously explored the circumstellar effects on the Rb and Zr abundances in massive Galactic O-rich AGB stars. Here we are interested in the role of the extended atmosphere in the case of Li and Ca. Li is an important indicator of HBB while the total ... More
Apsidal Motion and Absolute Parameters of 21 Early-type Small Magellanic Cloud Eccentric Eclipsing BinariesFeb 12 2019We present the apsidal motion and light-curve analyses of 21 eccentric eclipsing binaries located in the Small Magellanic Cloud. Most of these systems have never been studied before, hence their orbital and physical properties as well as the apsidal motion ... More
Imbalanced kinetic Alfvén wave turbulence: from weak turbulence theory to nonlinear diffusion models for the strong regimeFeb 12 2019A two-field Hamiltonian gyrofluid model for kinetic Alfv\'en waves retaining ion finite Larmor radius corrections, parallel magnetic field fluctuations and electron inertia, is used to study turbulent cascades from the MHD to the sub-ion scales. Special ... More
Constraining transport of angular momentum in stars: Combining asteroseismic observations of core helium burning stars and white dwarfsFeb 12 2019Transport of angular momentum has been a challenging topic within the stellar evolution community, even more since the recent asteroseismic surveys. All published studies on rotation using asteroseismic observations show a discrepancy between the observed ... More
Mending the structural surface effect of 1D stellar structure models with non-solar metallicities based on interpolated 3D envelopesFeb 12 20191D stellar evolution codes employ rudimentary treatments of turbulent convection. For stars with convective envelopes, this leads to systematic errors in the predicted oscillation frequencies needed for asteroseismology. One way of mending these structural ... More
A Critical Assessment of Turbulence Models for 1D Core-Collapse Supernova SimulationsFeb 12 2019It has recently been proposed that global or local turbulence models can be used to simulate core-collapse supernova explosions in spherical symmetry (1D) more consistently than with traditional approaches for parameterised 1D models. However, a closer ... More
Solar Ultraviolet Bursts in a Coordinated Observation of IRIS, Hinode and SDOFeb 12 2019Solar ultraviolet (UV) bursts are small-scale compact brightenings in transition region images. The spectral profiles of transition region lines in these bursts are significantly enhanced and broadened, often with chromospheric absorption lines such as ... More
HARPS-N Solar Radial-Velocity Variations Are Dominated By Large, Bright Magnetic RegionsFeb 11 2019State of the art radial-velocity (RV) exoplanet searches are currently limited by RV signals arising from stellar magnetic activity. We analyze solar observations acquired over a 3-year period during the decline of Carrington Cycle 24 to test models of ... More
Antisolar differential rotation of slowly rotating cool starsFeb 11 2019It is well-known that rotating stellar convection transports angular momentum equatorward while a thermal energy flows poleward producing warm poles. The characteristic equatorial acceleration of the solar rotation law is a consequence of these phenomena. ... More
Multicolor study of V1009 Per, a close binary system at the beginning of the overcontact phase, and of CRTS J031642.2+332639, a new binary system in the same fieldFeb 11 2019The first multicolor observations, and light curve solutions, of the eclipsing binary systems V1009~Per and CRTS~J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact binaries. V1009~Per ... More
Magnetic Field of the Eclipsing M Dwarf Binary YY GemFeb 11 2019YY Gem is a short-period eclipsing binary system containing two nearly identical, rapidly rotating, very active early-M dwarfs. This binary represents an important benchmark system for calibrating empirical relations between fundamental properties of ... More