Latest in astro-ph.sr

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Massive, wide binaries as tracers of massive star formationFeb 13 2018Massive stars can be found in wide (hundreds to thousands AU) binaries with other massive stars. We use $N$-body simulations to show that any bound cluster should always have approximately one massive wide binary: one will probably form if none are present ... More
Asteroseismology of 16000 Kepler red giants: Global oscillation parameters, Masses, and radiiFeb 13 2018The Kepler mission has provided exquisite data to perform an ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission ... More
The consequences of a nearby supernova on the early Solar SystemFeb 12 2018If the Sun was born in a relatively compact open cluster (half-mass radius ~3pc) with ~10^3 stars, it is quite likely that a massive (>10MSun) star was nearby when it exploded in a supernova. The repercussions of a supernova can be rather profound, and ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
The chemical connection between 67P/C-G and IRAS 16293-2422Feb 08 2018The chemical evolution of a star- and planet-forming system begins in the prestellar phase and proceeds across the subsequent evolutionary phases. The chemical trail from cores to protoplanetary disks to planetary embryos can be studied by comparing distant ... More
The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopyFeb 08 2018The new CARMENES instrument comprises two high-resolution and high-stability spectrographs that are used to search for habitable planets around M dwarfs in the visible and near-infrared regime via the Doppler technique. Characterising our target sample ... More
A D'-type symbiotic binary in the planetary nebula SMP LMC 88Feb 08 2018SMP LMC 88 is one of the planetary nebulae (PN) in the Large Magellanic Cloud. We identify in its spectrum Raman scattered O VI lines at 6825 and 7083A. This unambiguously classifies the central object of the nebula as a symbiotic star (SySt). We identified ... More
Path integrals for mean-field equations in nonlinear dynamosFeb 08 2018Mean-field dynamo equations are addressed with the aid of the path-integral method. The evolution of magnetic field is treated as a three-dimensional Wiener random process, and the mean magnetic-field equations are obtained with the Wiener integral over ... More
Nitrogen isotope fractionation in protoplanetary disksFeb 08 2018Aims: The two stable isotopes of nitrogen, 14N and 15N, exhibit a range of abundance ratios both inside and outside the solar system. The elemental ratio in the solar neighborhood is 440. Recent ALMA observations showed HCN/HC15N ratios from 83 to 156 ... More
A New Tool for CME Arrival Time Prediction Using Machine Learning Algorithms: CAT-PUMAFeb 08 2018Coronal Mass Ejections (CMEs) are arguably the most violent eruptions in the Solar System. CMEs can cause severe disturbances in the interplanetary space and even affect human activities in many respects, causing damages to infrastructure and losses of ... More
Measurement process and inversions using helioseismic normal-mode couplingFeb 08 2018Normal modes are coupled by the presence of perturbations in the Sun, providing a unique and little-explored helioseismic technique with which to image the solar interior. The process of measuring coupling between normal modes is straightforward, much ... More
Decipher the Three-Dimensional Magnetic Topology of a Great Solar FlareFeb 08 2018Three-dimensional magnetic topology of solar flare plays a crucial role in understanding its explosive release of magnetic energy in the corona. However, such three-dimensional coronal magnetic field is still elusive in direct observation. Here we realistically ... More
Orbital Motion of Young Binaries in Ophiuchus and Upper Centaurus-LupusFeb 08 2018We present measurements of the orbital positions and flux ratios of 17 binary and triple systems in the Ophiuchus star forming region and the Upper Centaurus-Lupus cluster based on adaptive optics imaging at the Keck Observatory. We report the detection ... More
Longitudinal structure of the photospheric magnetic field in the Carrington systemFeb 08 2018The observations of the Sun have been performed over the years, even centuries- Whether are there active longitudes? If yes how stable are they? One of the first The Wilcox Solar Observatory data taken over three cycles N 21, N 22, N 23 have been used ... More
Discovery of a magnetic white dwarf with unusual short-period variabilityFeb 07 2018We report the discovery of a magnetic white dwarf which shows periodic variability with P=110 min, color-dependent amplitudes and a transient phase shift in the blue compared to the red lightcurve - a previously unknown type of variability for this type ... More
Unlocking CO Depletion in Protoplanetary Disks I. The Warm Molecular LayerFeb 07 2018CO is commonly used as a tracer of the total gas mass in both the interstellar medium and in protoplanetary disks. Recently there has been much debate about the utility of CO as a mass tracer in disks. Observations of CO in protoplanetary disks reveal ... More
New variable Stars from the Photographic Archive: Semi-automated Discoveries, Attempts of Automatic Classification, and the New Field 104 HerFeb 07 2018Using 172 plates taken with the 40-cm astrograph of the Sternberg Astronomical Institute (Lomonosov Moscow University) in 1976-1994 and digitized with the resolution of 2400 dpi, we discovered and studied 275 new variable stars. We present the list of ... More
The Chemical Homogeneity of Sun-like Stars in the Solar NeighborhoodFeb 07 2018The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large intrinsic variation ... More
Cracking the Conundrum of F-Supergiant CoronaeFeb 07 2018Chandra X-ray and HST far-ultraviolet (FUV) observations of three early-F supergiants have shed new light on a previous puzzle involving a prominent member of the class: Alpha Persei (HD20902: F5Ib). The warm supergiant is a moderately strong, hard coronal ... More
Rotation of the photospheric magnetic field through solar cycles 21, 22, 23Feb 07 2018Rotation of the large scale solar magnetic field has a great importance for the understanding of solar dynamic, for the search of longitidinal structure and for the study of solar-terrestrial relations. 30-year long observations taken at the Wilcox Solar ... More
Latitudinal structure and dynamic of the photospheric magnetic fieldFeb 07 2018Analysis of the structure and dynamics of the magnetic field of the Sun is fundamental for understanding of the origin of solar activity and variability as well as for the study of solar-terrestrial relations. Observations of the large scale magnetic ... More
On the formation of neutron stars via accretion-induced collapse in binariesFeb 07 2018Although most neutron stars are believed to form in core-collapse supernovae, some fraction of them may form in less well-known sites. We investigate evolutionary pathways leading to neutron stars formed through the collapse of oxygen-neon white dwarf ... More
On the formation of neutron stars via accretion-induced collapse in binariesFeb 07 2018Feb 08 2018Although most neutron stars are believed to form in core-collapse supernovae, some fraction of them may form in less well-known sites. We investigate evolutionary pathways leading to neutron stars formed through the collapse of oxygen-neon white dwarf ... More
Intermittency spectra of current helicity in solar active regionsFeb 07 2018We intend to analyse the intermittency spectra of current helicity in solar active regions. We made a pixel-by-pixel comparison of current helicity maps derived from three different instruments, namely by Helioseismic and Magnetc Imager on board the Solar ... More
A focus on L dwarfs with trigonometric parallaxesFeb 07 2018We report new parallax measurements for ten L and early T type dwarfs, five of which have no previous published values, using observations over 3 years at the robotic Liverpool Telescope. The resulting parallaxes and proper motions have median errors ... More
Variability of Disk Emission in Pre-Main Sequence and Related Stars IV. Investigating the Structural Changes in the Inner Disk Region of MWC 480Feb 07 2018We present five epochs of near IR observations of the protoplanetary disk around MWC 480 (HD31648) obtained with the SpeX spectrograph on NASA's Infrared Telescope Facility (IRTF) between 2007 and 2013, inclusive. Using the measured line fluxes in the ... More
An unexpected detection of bifurcated blue straggler sequences in the young globular cluster NGC 2173Feb 07 2018Bifurcated patterns of blue straggler stars in their color--magnitude diagrams have atracted significant attention. This type of special (but rare) pattern of two distinct blue straggler sequences is commonly interpreted as evidence of cluster core-collapse-driven ... More
Optical Photometric Variable Stars towards the Galactic \hii region NGC 2282Feb 07 2018We report here CCD $I$-band time-series photometry of a young (2$-$5 Myr) cluster NGC 2282 to identify and understand the variability of pre-main-sequence (PMS) stars. The $I$-band photometry, down to $\sim$ 20.5 mag, enables us to probe the variability ... More
Evolution of Magnetic Rayleigh-Taylor Instability into the Outer Solar Corona and Low Inter Planetary SpaceFeb 07 2018We analyze the observations from Solar TErrestrial RElations Observatory (STEREO)-A\&B/COR-1 of an eruptive prominence in the intermediate corona on 7 June 2011 at 08:45 UT, which consists of magnetic Rayleigh-Taylor (MRT) unstable plasma segments. Its ... More
Magnetohydrodynamic Turbulence in the Plasmoid-Mediated RegimeFeb 06 2018Magnetohydrodynamic turbulence and magnetic reconnection are ubiquitous in astrophysical environments. In most situations, these processes do not occur in isolation, but interact with each other. This renders a comprehensive theory of these processes ... More
Near-infrared study of new embedded clusters in the Carina complexFeb 06 2018We analyse the nature of a sample of stellar overdensities that we found projected on the Carina complex. This study is based on 2MASS photometry and involves the photometry decontamination of field stars, elaboration of intrinsic colour-magnitude diagrams ... More
CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observationsFeb 06 2018CARMENES is a spectrograph for radial velocity surveys of M dwarfs with the aim of detecting Earth-mass planets orbiting in the habitable zones of their host stars. To ensure an optimal use of the CARMENES Guaranteed Time Observations, in this paper we ... More
The shape of convective core overshooting from gravity-mode period spacingsFeb 06 2018The evolution of stars born with a convective core is highly dependent on the efficiency and extent of near core mixing processes, which effectively increases both the core mass and main-sequence lifetime. We investigate to what extent gravity-mode period ... More
From cool to hot F-stars: the influence of two ionization regions in the acoustic oscillationsFeb 06 2018Feb 07 2018The high-precision data available from the Kepler satellite allows us to venture in the study of the complex outer convective envelopes of solar-type stars. We use a seismic diagnostic, specialized for investigating the outer layers of solar-type stars, ... More
The Coronal Monsoon: Thermal Nonequilibrium Revealed by Periodic Coronal RainFeb 06 2018We report on the discovery of periodic coronal rain in an off-limb sequence of {\it Solar Dynamics Observatory}/Atmospheric Imaging Assembly images. The showers are co-spatial and in phase with periodic (6.6~hr) intensity pulsations of coronal loops of ... More
On-Orbit Performance of the Helioseismic and Magnetic Imager Instrument onboard the Solar Dynamics ObservatoryFeb 05 2018The Helioseismic and Magnetic Imager (HMI) instrument is a major component of NASA's Solar Dynamics Observatory (SDO) spacecraft. Since beginning normal science operations on 1 May 2010, HMI has operated with remarkable continuity, e.g. during the more ... More
The Maveric Survey: a Red Straggler Binary with an Invisible Companion in the Galactic Globular Cluster M10Feb 05 2018We present the discovery and characterization of a radio-bright binary in the Galactic globular cluster M10. First identified in deep radio continuum data from the Karl G. Jansky Very Large Array, M10-VLA1 has a flux density of $27\pm4$ $\mu$Jy at 7.4 ... More
The empirical Gaia G-band extinction coefficientFeb 05 2018The first Gaia data release unlocked the access to the photometric information of 1.1 billion sources in the $G$-band. Yet, given the high level of degeneracy between extinction and spectral energy distribution for large passbands such as the Gaia $G$-band, ... More
PISCO: The Pmas/ppak Integral-field Supernova hosts COmpilationFeb 05 2018We present the Pmas/ppak Integral-field Supernova hosts COmpilation (PISCO) which comprises Integral Field Spectroscopy (IFS) of 232 supernova (SN) host galaxies, that hosted 272 SNe, observed over several semesters with the 3.5m telescope at the Calar ... More
Discovery of distant RR Lyrae stars in the Milky Way using DECamFeb 05 2018We report the discovery of distant RR Lyrae stars, including the most distant known in the Milky Way, using data taken in the $g-$band with the Dark Energy Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We detect a total of ... More
ATLAS Probe: Breakthrough Science of Galaxy Evolution, Cosmology, Milky Way, and the Solar SystemFeb 05 2018ATLAS (Astrophysics Telescope for Large Area Spectroscopy) Probe is a concept for a NASA probe-class space mission, the spectroscopic follow-up to WFIRST, multiplexing its scientific return by obtaining deep 1 to 4 micron slit spectroscopy for ~90% of ... More
Non-Radial Pulsations in Post-Outburst NovaeFeb 05 2018After an optical peak, a classical or recurrent nova settles into a brief (days to years) period of quasi-stable thermonuclear burning in a compact configuration nearly at the white dwarf (WD) radius. During this time, the underlying WD becomes visible ... More
Solar type III radio burst time characteristics at LOFAR frequencies and the implications for electron beam transportFeb 05 2018Solar type III radio bursts contain a wealth of information about the dynamics of electron beams in the solar corona and the inner heliosphere; currently unobtainable through other means. However, the motion of different regions of an electron beam (front, ... More
Instability, finite amplitude pulsation and mass-loss in models of massive OB-type starsFeb 05 2018Variability and mass-loss are common phenomena in massive OB-type stars. It is argued that they are caused by violent strange mode instabilities identified in corresponding stellar models. We present a systematic linear stability analysis with respect ... More
Plasma evolution within an erupting coronal cavityFeb 05 2018Coronal cavities have previously been observed associated with long-lived quiescent filaments and are thought to correspond to the associated magnetic flux rope. Although the standard flare model predicts a coronal cavity corresponding to the erupting ... More
Frequency identification and asteroseismic analysis of the red giant KIC 9145955: fundamental parameters and helium core sizeFeb 05 2018We have analyzed 18 quarters of long-cadence data of KIC 9145955 provided by \emph{Kepler}, and extracted 61 oscillation frequencies from these high precision photometric data. The oscillation frequencies include 7 $l = 0$ modes, 44 $l = 1$ modes, 7 $l ... More
Scale Selection in the Stratified Convection of the Solar PhotosphereFeb 05 2018In this paper we examine the role of stratification in setting the scale for turbulent anelastic convection. Motivated by the range of scales observed in convection at the solar photosphere, we perform local numerical simulations of convection for a range ... More
Testing Asteroseismic Radii of Dwarfs and Subgiants with Kepler and GaiaFeb 04 2018We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed ... More
The Distance and the near-IR extinction of the Monoceros Supernova RemnantFeb 04 2018Supernova remnants (SNRs) embody the information of the influence on dust properties by the supernova explosion. Based on the color indexes from the 2MASS photometric survey and the stellar parameters from the SDSS$-$DR12$/$APOGEE and LAMOST$-$DR2$/$LEGUE ... More
Magnetic field topology of the cool, active, short-period binary system $σ^2$ Coronae BorealisFeb 03 2018The goal of this work is to study the cool, active binary star $\sigma^2$ CrB, focussing on its magnetic field. We used Stokes $IV$ data from the twin spectropolarimeters Narval at the TBL and ESPaDOnS at the CFHT. The least-squares deconvolution multi-line ... More
Is molecular cloud turbulence driven by external supernova explosions?Feb 03 2018We present high-resolution ($\sim$ 0.1 pc), hydrodynamical and magneto-hydrodynamical simulations to investigate whether the observed level of molecular cloud (MC) turbulence can be generated and maintained by external supernova (SN) explosions. The MCs ... More
DECam Survey for Low-Mass Stars and Substellar Objects in the UCL and LCC Subgroups of the Sco-Cen OB Association (SCOCENSUS)Feb 02 2018Using images taken with the Dark Energy Camera (DECam), the first extensive survey of low mass and substellar objects is made in the 15-20 Myr Upper Centaurus Lupus (UCL) and Lower Centaurus Crux (LCC) subgroups of the Scorpius Centaurus OB Association ... More
Seeds of Life in Space (SOLIS). III. Zooming into the methanol peak of the pre-stellar core L1544Feb 02 2018Towards the pre-stellar core L1544, the methanol (CH$_3$OH) emission forms an asymmetric ring around the core centre, where CH$_3$OH is mostly in solid form, with a clear peak 4000~au to the north-east of the dust continuum peak. As part of the NOEMA ... More
Image Quality in High-resolution and High-cadence Solar ImagingFeb 02 2018Broad-band imaging and even imaging with a moderate bandpass (about 1 nm) provides a "photon-rich" environment, where frame selection ("lucky imaging") becomes a helpful tool in image restoration allowing us to perform a cost-benefit analysis on how to ... More
A high-resolution study of levels in the astrophysically important nucleus $^{26}$Mg and resulting updated level assignmentsFeb 02 2018The $^{22}$Ne($\alpha,n$)$^{25}$Mg reaction is an important source of neutrons for the s-process. Due to the difficulty in directly measuring the cross section of this reaction and the competing $^{22}$Ne($\alpha,\gamma$)$^{26}$Mg reaction, indirect methods ... More
Helioseismology: Observations and Space MissionsFeb 02 2018The great success of Helioseismology resides in the remarkable progress achieved in the understanding of the structure and dynamics of the solar interior. This success mainly relies on the ability to conceive, implement, and operate specific instrumentation ... More
Stellar dynamics: rotation, convection, and magnetic fieldsFeb 02 2018Stars are changing entities in a constant evolution during their lives. At non-secular time scales (from seconds to years) the effect of dynamical processes such as convection, rotation, and magnetic fields can modify the stellar oscillations. Convection ... More
On the origin of phosphorus nitride in star-forming regionsFeb 02 2018We present multi-transition observations of PN towards a sample of nine massive dense cores in different evolutionary stages. Using transitions with different excitation conditions, we have found for the first time that the excitation temperatures of ... More
K2 photometry and HERMES spectroscopy of the blue supergiant rho Leo: rotational wind modulation and low-frequency wavesFeb 02 2018We present an 80-d long uninterrupted high-cadence K2 light curve of the B1Iab supergiant rho Leo (HD 91316), deduced with the method of halo photometry. This light curve reveals a dominant frequency of $f_{\rmrot}=0.0373$d$^{-1}$ and its harmonics. This ... More
A Statistical Study of Massive Cluster-Forming ClumpsFeb 02 2018We report results of the observations of 15 regions in several molecular lines for a statistical study of massive cluster-forming clumps. We identified 24 clumps based on the C18O (J=1-0) data obtained by the NRO 45 m telescope, and found that 16 of them ... More
A Solar cycle correlation of coronal element abundances in Sun-as-a-star observationsFeb 02 2018The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, ... More
The UV Emission of Stars in LAMOST Survey I. CatalogsFeb 02 2018We present the ultraviolet magnitudes for over three million stars in the LAMOST survey, in which 2,202,116 stars are detected by $GALEX$. For 889,235 undetected stars, we develop a method to estimate their upper limit magnitudes. The distribution of ... More
High-Speed Photometry of Gaia14aae: An Eclipsing AM CVn That Challenges Formation ModelsFeb 01 2018AM CVn-type systems are ultra-compact, hydrogen-deficient accreting binaries with degenerate or semi-degenerate donors. The evolutionary history of these systems can be explored by constraining the properties of their donor stars. We present high-speed ... More
2MASS J13243553+6358281 is an Early T-Type Planetary-Mass Object in the AB Doradus Moving GroupFeb 01 2018We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2MASS J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. ... More
Precision Orbit of $δ$ Delphini and Prospects for Astrometric Detection of ExoplanetsFeb 01 2018Combining visual and spectroscopic orbits of binary stars leads to a determination of the full 3D orbit, individual masses, and distance to the system. We present a full analysis of the evolved binary system $\delta$ Delphini using astrometric data from ... More
ALMA's Polarized View of 10 Protostars in the Perseus Molecular CloudFeb 01 2018We present 870 $\mu$m ALMA dust polarization observations of 10 young Class 0/I protostars in the Perseus Molecular Cloud. At $\sim$ 0.35$"$ (80 au) resolution, all of our sources show some degree of polarization, with most (9/10) showing significantly ... More
Hidden Planetary Friends: On the Stability Of 2-Planet Systems in the Presence of a Distant, Inclined CompanionFeb 01 2018Recent observational campaigns have shown that multi-planet systems seem to be abundant in our Galaxy. Moreover, it seems that these systems might have distant companions, either planets, brown-dwarfs or other stellar objects. These companions might be ... More
The effects of diffusion in hot subdwarf progenitors from the common envelope channelFeb 01 2018Diffusion of elements in the atmosphere and envelope of a star can drastically alter its surface composition, leading to extreme chemical peculiarities. We consider the case of hot subdwarfs, where surface helium abundances range from practically zero ... More
Discovery of New Dipper Stars with K2: A Window into the Inner Disk Region of T Tauri StarsFeb 01 2018In recent years a new class of Young Stellar Object has been defined, referred to as dippers, where large transient drops in flux are observed. These dips are too large to be attributed to stellar variability, last from hours to days and can reduce the ... More
Survey of astrophysical conditions in neutrino-driven supernova ejecta nucleosynthesisFeb 01 2018Core-collapse supernovae produce elements between Fe and Ag depending on the properties of the ejected matter. Despite the fast progress in supernova simulations in the last decades, there are still uncertainties in the astrophysical conditions. In this ... More
Polarimetry and Spectroscopy of the `Oxygen Flaring' DQ Herculis-like nova: V5668 Sagittarii (2015)Feb 01 2018Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells ... More
Powerful Solar Flares of September 2017: Correspondence Between Parameters of Microwave Bursts and Proton Fluxes near EarthFeb 01 2018In this note, we consider radio characteristics of three proton flares that caused discrete enhancements of solar energetic particles (SEPs) near Earth. The analysis confirmed that the flux density and frequency spectrum of microwave bursts, although ... More
HST spectrum and timing of the ultra-compact X-ray binary candidate 47 Tuc X9Feb 01 2018To confirm the nature of the donor star in the ultra-compact X-ray binary candidate 47 Tuc X9, we obtained optical spectra (3,000$-$10,000 {\AA}) with the Hubble Space Telescope / Space Telescope Imaging Spectrograph. We find no strong emission or absorption ... More
Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours. II. The role of convection accross the H-R diagramJan 31 2018We studied the influence of convection on the spectral energy distributions, photometric magnitudes, and colour indices of different types of stars across the H-R diagram. The 3D hydrodynamical CO5BOLD, averaged <3D>, and 1D hydrostatic LHD model atmospheres ... More
Kepler K2 observations of the transitional millisecond pulsar PSR J1023+0038Jan 31 2018For 80 days in 2017, the Kepler Space Telescope continuously observed the transitional millisecond pulsar system PSR J1023$+$0038 in its accreting state. We present analyses of the 59-second cadence data, focusing on investigations of the orbital light ... More
Asteroseismology of ZZ Ceti stars with full evolutionary white dwarf models. II. The impact of AGB thermal pulses on the asteroseismic inferences of ZZ Ceti starsJan 31 2018The thermally pulsing phase on the asymptotic giant branch (TP-AGB) is the last nuclear burning phase experienced by most of low and intermediate mass stars. During this phase, the outer chemical stratification above the C/O core of the emerging white ... More
Uncertainties in the heliosheath ion temperaturesJan 31 2018The Voyager plasma observations show that the physics of the heliosheath is rather complex, and especially that the temperature derived from observation differs from expectations. To explain this fact the temperature in the heliosheath should be based ... More
Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569Jan 31 2018Photometric and spectroscopic analyses have shown that the Galactic bulge cluster Terzan 5 hosts several populations with different metallicities and ages that manifest as a double red horizontal branch (HB). A recent investigation of the massive bulge ... More
Magnetic fields at the onset of high-mass star formationJan 31 2018Context: The importance of magnetic fields at the onset of star formation related to the early fragmentation and collapse processes is largely unexplored today. Aims: We want to understand the magnetic field properties at the earliest evolutionary stages ... More
The CARMENES search for exoplanets around M dwarfs: Wing asymmetries of H$α$, Na I D, and He I linesJan 31 2018Stellar activity is ubiquitously encountered in M dwarfs and often characterised by the H$\alpha$ line. In the most active M dwarfs, H$\alpha$ is found in emission, sometimes with a complex line profile. Previous studies have reported extended wings and ... More
Rotational broadening and conservation of angular momentum in post-extreme horizontal branch starsJan 31 2018We show that the recent realization that isolated post-extreme horizontal branch (post-EHB) stars are generally characterized by rotational broadening with values of $V_{\rm rot} \sin i$ between 25 and 30 km~s$^{-1}$ can be explained as a natural consequence ... More
Chemical abundances of primary stars in the Sirius-like binary systemsJan 31 2018Study of primary stars lying in Sirius-like systems with various masses of WD companions and orbital separations is one of the key aspects to understand the origin and nature of Barium (Ba) stars. In this paper, based on high resolution and high S/N spectra, ... More
K2 spots rotation in the helium star HD144941Jan 30 2018HD144941 is an evolved early-type metal-poor low-mass star with a hydrogen-poor surface. It is frequently associated with other intermediate helium-rich subdwarfs and extreme helium stars. Previous photometric studies have failed to detect any variability. ... More
Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence modelJan 30 2018We present a concept study of a solar wind forecasting method for Earth, based on persistence modeling from STEREO in-situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs) extracted ... More
Formation of interstellar methanol ice prior to the heavy CO freeze-out stageJan 30 2018The formation of methanol (CH3OH) on icy grain mantles during the star formation cycle is mainly associated with the CO freeze-out stage. Yet there are reasons to believe that CH3OH also can form at an earlier period of interstellar ice evolution in CO-poor ... More
Large Starspot Groups on HAT-P-11 in Activity Cycle 1Jan 30 2018HAT-P-11 is a planet-hosting K4V star in the Kepler field, with an activity cycle that bear similarities to the Sun's. The chromospheric activity of HAT-P-11 indicates that a new activity cycle is beginning. We report ground-based observations with holographic ... More
Towards a better classification of unclear eruptive variables: the cases of V2492 Cyg, V350 Cep, and ASASSN-15qiJan 30 2018Eruptive variables are young stars that show episodic variations of brightness: EXors/FUors variations are commonly associated with enhanced accretion outbursts occurring at intermittent cadence of months/years (EXors) and decades/centuries (FUors). Variations ... More
Period variations of Algol-type eclipsing binaries AD And, TW Cas and IV CasJan 30 2018We present new analysis of O-C diagrams variations of three Algol-type eclipsing binary stars AD And, TW Cas and IV Cas. We have used all published minima times (including visual and photographic) as well as new determined ones from our and SuperWasp ... More
Embedded ClustersJan 30 2018The past decade has seen an increase of star formation studies made at the molecular cloud scale, motivated mostly by the deployment of a wealth of sensitive infrared telescopes and instruments. Embedded clusters, long recognised as the basic units of ... More
SY Mus - search for physical parametersJan 30 2018This is a preliminary analysis of the orbital parameters of the well known eclipsing symbiotic binary, SY Muscae. It is a system composed of a white dwarf (WD) and a red giant (RG), located in the southern sky. With the use of photometric data in the ... More
Extreme value theory applied to the millennial sunspot number seriesJan 29 2018In this work, we use two decadal sunspot number series reconstructed from cosmogenic radionuclide data (14C in tree trunks, SN-14C and 10Be in polar ice, SN-10Be) and the Extreme Value Theory to study variability of solar activity during the last 9 millennia. ... More
Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg BJan 29 2018Time-resolved observations of brown dwarfs' rotational modulations provide powerful insights into the properties of condensate clouds in ultra-cool atmospheres. Multi-wavelength light curves reveal cloud vertical structures, condensate particle sizes, ... More
SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of StarsJan 29 2018The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their ... More
HD 4915: A Maunder Minimum CandidateJan 29 2018We study the magnetic activity cycle of HD 4915 using the \ion{Ca}{2} H \& K emission line strengths measured by Keck I/HIRES spectrograph. The star has been observed as a part of California Planet Search Program from 2006 to present. We note decreasing ... More
Production of sunspots and their effects on the corona and solar wind: Insights from a new 3D flux-transport dynamo modelJan 29 2018We present a three-dimensional numerical model for the generation and evolution of the magnetic field in the solar convection zone, in which sunspots are produced and contribute to the cyclic reversal of the large-scale magnetic field. We then assess ... More
The Solar Electron and Proton Telescope aboard STEREO -- understanding proton spectraJan 29 2018The Solar Electron and Proton Telescope (SEPT) aboard the Solar Terrestrial Relations Observatory (STEREO) is designed to provide the three-dimensional distribution of energetic electrons and protons with good energy and time resolution. Each SEPT instrument ... More
Numerical Studies of the Kelvin-Hemholtz Instability in the Coronal JetJan 29 2018The Kelvin-Hemholtz (K-H) instability in the corona EUV jet is studied via 2.5 MHD numerical simulations. The jet results from magnetic reconnection due to the interation of the new emerging magnetic field and the pre-existing magnetic field in the corona. ... More
C/O vs Mg/Si ratios in solar type stars: The HARPS sampleJan 29 2018Aims. We present a detailed study of the Mg/Si and C/O ratios and their importance in determining the mineralogy of planetary companions. Methods. Using 499 solar-like stars from the HARPS sample, we determine C/O and Mg/Si elemental abundance ratios ... More
Interstellar neutral helium in the heliosphere from IBEX observations. V. Observations in IBEX-Lo ESA steps 1, 2, & 3Jan 29 2018Direct-sampling observations of interstellar neutral (ISN) He by Interstellar Boundary Explorer (IBEX) provide valuable insight into the physical state of and processes operating in the interstellar medium ahead of the heliosphere. The ISN He atom signals ... More
Effective temperatures of red giants in the APOKASC catalogue and the mixing length calibration in stellar modelsJan 29 2018Red giants in the updated APOGEE-Kepler catalogue, with estimates of mass, chemical composition, surface gravity and effective temperature, have recently challenged stellar models computed under the standard assumption of solar calibrated mixing length. ... More