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AstroSat study of the globular cluster NGC 2298: probable evolutionary scenarios of hot HB stars: We present the far-UV (FUV) photometry of images acquired with UVIT on AstroSat to probe the horizontal branch (HB) population of the Galactic globular cluster NGC 2298. UV-optical color-magnitude diagrams (CMDs) are con...
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The dispersion of period spacing for DAV stars: Three groups of DAV star models are evolved with time-dependent element diffusion by \texttt{WDEC}. The core compositions of these models are directly from white dwarf models evolved by \texttt{MESA}, which are results of thermonuclear burning. Based on these DAV star mod...
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Surrogate forward models for population inference on compact binary mergers: Rapidly growing catalogs of compact binary mergers from advanced gravitational-wave detectors allow us to explore the astrophysics of massive stellar binaries. Merger observations can constrain the uncertain parameters that describe the unde...
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The disappearance of the helium-giant progenitor of the type Ib supernova iPTF13bvn and constraints on its companion: We report and discuss post-explosion observations of supernova iPTF13bvn. We find that the brightness of the SN at +740 days is below the level of the pre-explosion source and thus confirm that the pr...
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A characterization of ASAS-SN core-collapse supernova environments with VLT+MUSE: I. Sample selection, analysis of local environments, and correlations with light curve properties: The analysis of core-collapse supernova (CCSN) environments can provide important information on the life cycle of massive stars and co...
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The sunspot observations by Toaldo and Comparetti at November 1779: There is a low frequency of sunspot observations in some years of the 17th and 18th century. In particular, the interval 1777-1795 is one of the periods with scarce observations in the databases. In this note, we report a sunspot observation carried ou...
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Plasma sloshing in pulse-heated solar and stellar coronal loops: There is evidence that coronal heating is highly intermittent, and flares are the high energy extreme. The properties of the heat pulses are difficult to constrain. Here hydrodynamic loop modeling shows that several large amplitude oscillations (~ 20% in ...
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Measuring mean densities of delta Scuti stars with asteroseismology. Theoretical properties of large separations using TOUCAN: We aim at studying the theoretical properties of the regular spacings found in the oscillation spectra of delta Scuti stars. We performed a multi-variable analysis covering a wide range of st...
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The Non-Linear Growth of the Magnetic Rayleigh-Taylor Instability: This work examines the effect of the embedded magnetic field strength on the non-linear development of the magnetic Rayleigh-Taylor Instability (RTI) (with a field-aligned interface) in an ideal gas close to the incompressible limit in three dimensions....
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A multi-wavelength study of the young star V1118 Orionis in outburst: Abriged version for astroph: The young late-type star V1118 Orionis was in outburst from 2005 to 2006. We followed the outburst with optical and near-infrared photometry; the X-ray emission was further probed with observations taken with XMM-Newton a...
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Binarity and Accretion in AGB Stars: HST/STIS Observations of UV Flickering in Y Gem: Binarity is believed to dramatically affect the history and geometry of mass loss in AGB and post-AGB stars, but observational evidence of binarity is sorely lacking. As part of a project to search for hot binary companions to cool ...
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Spectroscopic factor of the 1+, 25Al(p,g)26Si resonance at Ex=5.68 MeV: Nuclear shell model predictions for the proton spectroscopic factor of the 1+, Ex = 5.68 MeV level in 26Si are about fifty times smaller than the value suggested by the measured (a,3He) cross section for the Ex = 5.69 MeV mirror level in 26Mg, assu...
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Multicolour photometry of pulsating stars in the Galactic Bulge fields: We present a study of photometric properties of very crowded stellar fields toward the Galactic Bulge. We performed a search for pulsating stars among thousands of variable stars from the OGLE-II survey supplementing the variability study with phot...
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Parallax of the L4.5 dwarf 2M1821$+$14 from high-precision astrometry with OSIRIS at GTC: We used the OSIRIS camera at the 10.4 m Gran Telescopio Canarias (GTC) to monitor the astrometric motion of the L4.5 dwarf 2M1821$+$14 over 17 months. The astrometric residuals of eleven epochs have a r.m.s. dispersion of 0.4 ma...
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Rotational periods and evolutionary models for subgiant stars observed by CoRoT: We present rotation period measurements for subgiants observed by CoRoT. Interpreting the modulation of stellar light that is caused by star-spots on the time scale of the rotational period depends on knowing the fundamental stellar para...
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On the nature of Nova 1670 (CK Vulpeculae): a merger of a red giant with a helium white dwarf: Nova 1670 is a historical transient bearing strong similarities to a recently-recognized type of stellar eruptions known as red novae, which are thought to be powered by stellar mergers. The remnant of the transient, CK Vul...
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An Infrared Census Of Dust In Nearby Galaxies With Spitzer (DUSTiNGS): V. The Period-luminosity Relation For Dusty Metal-Poor AGB Stars: The 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 g...
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Large ion-neutral drift velocities and plasma heating in partially ionized coronal rain blobs: In this paper we present a numerical study of the dynamics of partially ionized coronal rain blobs. We use a two-fluid model to perform a high-resolution 2D simulation that takes into account the collisional interaction bet...
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Mid-infrared observations of O-type stars: spectral morphology: We present mid-infrared observations for a sample of 16 O-type stars. The data were acquired with the NASA Spitzer Space Telescope, using the IRS instrument at moderate resolution (R $\sim$ 600), covering the range $\sim 10-37$ microns. Our sample includes...
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An Incipient Debris Disk in the Chamaeleon I Cloud: The point at which a protoplanetary disk becomes a debris disk is difficult to identify. To better understand this, here we study the $\sim$40~AU separation binary T~54 in the Chamaeleon I cloud. We derive a K5 spectral type for T~54~A (which dominates the emission of...
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The LAMOST spectroscopic survey of star clusters in M31. II. Metallicities, ages and masses: We select from Paper I a sample of 306 massive star clusters observed with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) in the vicinity fields of M31 and M33 and determine their metallicities, ages a...
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HD 156324: a tidally locked magnetic triple spectroscopic binary with a disrupted magnetosphere: HD 156324 is an SB3 (B2V/B5V/B5V) system in the Sco OB4 association. The He-strong primary possesses both a strong magnetic field, and H$\alpha$ emission believed to originate in its Centrifugal Magnetosphere (CM). We ana...
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He white dwarfs with large H contamination: Convective mixing or accretion?: White dwarfs are compact objects with atmospheres containing mainly light elements, hydrogen or helium. Because of their surface high gravitational field, heavy elements diffuse downwards in a very short timescale compared to the evolutionar...
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Coronal Fourier power spectra: implications for coronal seismology and coronal heating: The dynamics of regions of the solar corona are investigated using Atmospheric Imaging Assembly (AIA) 171\AA\ and 193\AA\ data. The coronal emission from the quiet Sun, coronal loop footprints, coronal moss, and from above a sunsp...
astro-ph_SR
Observations of the forward scattering Hanle effect in the Ca i 4227 Å line: Chromospheric magnetic fields are notoriously diffcult to measure. The chromospheric lines are broad, while the fields are producing a minuscule Zeeman-effect polarization. A promising diagnostic alternative is provided by the forward-scatte...
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A Universal Law for Solar-Wind Turbulence at Electron Scales: The interplanetary magnetic fluctuation spectrum obeys a Kolmogorovian power law at scales above the proton inertial length and gyroradius which is well regarded as an inertial range. Below these scales a power law index around $-2.5$ is often measured and a...
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Evolution towards and beyond accretion-induced collapse of massive white dwarfs and formation of millisecond pulsars: Millisecond pulsars (MSPs) are generally believed to be old neutron stars (NSs), formed via type Ib/c core-collapse supernovae (SNe), which have been spun up to high rotation rates via accretion from ...
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First solar butterfly diagram from Schwabe's observations in 1825-1867: The original sunspot observations by Heinrich Samuel Schwabe of 1825-1867 were digitized and a first subset of spots was measured. In this initial project, we determined more than 14 000 sunspot positions and areas comprising about 11% of the total...
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Is it possible to detect coronal mass ejections on solar-type stars through extreme-ultraviolet spectral observations?: Stellar coronal mass ejections (CMEs) from host stars are an important factor that affects the habitability of exoplanets. Although their solar counterparts have been well observed for decades, it i...
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The Stability of the Electron Strahl against the Oblique Fast-magnetosonic/Whistler Instability in the Inner Heliosphere: We analyze the micro-kinetic stability of the electron strahl in the solar wind depending on heliocentric distance. The oblique fast-magnetosonic/whistler (FM/W) instability has emerged in the lit...
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Characteristics of transverse waves in chromospheric mottles: Using data obtained by the high temporal and spatial resolution Rapid Oscillations in the Solar Atmosphere (ROSA) instrument on the Dunn Solar Telescope, we investigate at an unprecedented level of detail transverse oscillations in chromospheric fine structu...
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Physical properties and astrometry of radio-emitting brown dwarf TVLM513-46546 revisited: We present multi-epoch astrometric observations of the M9 ultra-cool dwarf TVLM513-46546 that is placed at the brown dwarf boundary. The new observations have been performed with the European VLBI Network (EVN) at 6cm band. The ...
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The CARMENES search for exoplanets around M dwarfs: Wing asymmetries of H$α$, Na I D, and He I lines: Stellar 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 stu...
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The B Fields in OB Stars (BOB) Survey: The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a t...
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Note on the Power-2 Limb Darkening Law: Recently there has been a renewed interest in the power-2 limb darkening law for modeling exoplanet transits. This law provides a better match to the intensities generated by spherical stellar atmosphere models than other 2-parameter laws. To help facilitate a wider use of the po...
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Examining the Magnetic Field Strength and the Horizontal and Vertical Motions in an Emerging Active Region: Earlier observational studies have used the time evolution of emerging magnetic flux regions at the photosphere to infer their subsurface structures, assuming that the flux structure does not change significant...
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The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT/PISCES/Ks and LBTI/LMIRcam/L' Adaptive Optics Imaging: We present diffraction-limited \ks band and \lprime adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large B...
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Flares and rotation of M dwarfs with habitable zones accessible to TESS planet detections: We characterize the magnetic activity of M dwarfs to provide the planet community with information on the energy input from the star; in particular, in addition to the frequency of optical flares directly observed with TESS, we...
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An Interface Region Imaging Spectrograph first view on Solar Spicules: Solar spicules have eluded modelers and observers for decades. Since the discovery of the more energetic type II, spicules have become a heated topic but their contribution to the energy balance of the low solar atmosphere remains unknown. Here we g...
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Imaging from STIX visibility amplitudes: Aims: To provide the first demonstration of STIX Fourier-transform X-ray imaging using semi-calibrated (amplitude-only) visibility data acquired during the Solar Orbiter's cruise phase. Methods: We use a parametric imaging approach by which STIX visibility amplitudes are fitted ...
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Star-spot distributions and chromospheric activity on the RS CVn type eclipsing binary SV Cam: Using a time series of high-resolution spectra and high-quality multi-colour photometry, we reconstruct surface maps of the primary component of the RS CVn type rapidly rotating eclipsing binary, SV Cam (F9V + K4V). We meas...
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Can Kilonova Light curves be Standardized?: Binary neutron star mergers have been recently confirmed to be the progenitors of the optical transients kilonovae (KNe). KNe are powered by the radioactive decay of neutron-rich elements (r-process elements) which are believed to be the product of disruption of neutron stars...
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ASASSN-15jd: WZ Sge-type star with intermediate superoutburst between single and double ones: We present optical photometry of a WZ Sge-type dwarf nova (DN), ASASSN-15jd. Its light curve showed a small dip in the middle of the superoutburst in 2015 for the first time among WZ Sge-type DNe. The unusual light curve imp...
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Two-stage evolution of an extended C-class eruptive flaring activity from sigmoid active region NOAA 12734: SDO and Udaipur-CALLISTO observations: We present a multi-wavelength investigation of a C-class flaring activity that occurred in the active region NOAA 12734 on 8 March 2019. The investigation utilises data fr...
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A multi-wavelength analysis of BL Her stars: Models versus Observations: We present new theoretical period--luminosity (PL) and period--radius (PR) relations at multiple wavelengths (Johnson--Cousins--Glass and {\sl Gaia} passbands) for a fine grid of BL~Herculis models computed using {\sc mesa-rsp}. The non-linear mod...
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Uncovering a 260 pc wide, 35 Myr old filamentary relic of star formation: Several recent studies have shown that the Vela OB2 region hosts a complex constellation of sub-populations with ages in the range 10 to 50 Myr. Such populations might represent the best example of the outcome of clustered star formation in Giant...
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The timing behaviour of radio pulsars: The purpose of this review paper is to summarise the pulsar timing method, to provide an overview of recent research into the spin-down of pulsars over decadal timescales and to highlight the science that can be achieved using high-precision timing of millisecond pulsars.
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The Luminous Blue Variable RMC127 as seen with ALMA and ATCA: We present ALMA and ATCA observations of the luminous blue variable \rmc. The radio maps show for the first time the core of the nebula and evidence that the nebula is strongly asymmetric with a Z-pattern shape. Hints of this morphology are also visible in t...
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Dynamic kink instability and transverse motions of solar spicules: Hydrodynamic jets are unstable to the kink instability (m=1 mode in cylindrical geometry) owing to the centripetal force, which increases the transverse displacement of the jet. When the jet moves along a magnetic field, then the Lorentz force tries to ...
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Photospheric magnetic structure of coronal holes: In this study, we investigate in detail the photospheric magnetic structure of 98 coronal holes using line-of-sight magnetograms of SDO/HMI, and for a subset of 42 coronal holes using HINODE/SOT G-band filtergrams. We divided the magnetic field maps into magnetic elemen...
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Spatially resolving the inhomogeneous structure of the dynamical atmosphere of Betelgeuse with VLTI/AMBER: We present spatially resolved high-spectral resolution K-band observations of the red supergiant Betelgeuse (alpha Ori) using AMBER at the Very Large Telescope Interferometer (VLTI). Betelgeuse was observed betw...
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The intermediate neutron capture process. V. The i-process in AGB stars with overshoot: The intermediate neutron capture process (i-process) can develop during proton ingestion events (PIE), potentially during the early stages of low-mass low-metallicity asymptotic giant branch (AGB) stars. We examine the impact of o...
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A new class of Roche lobe-filling hot subdwarf binaries: We present the discovery of the second binary with a Roche lobe-filling hot subdwarf transferring mass to a white dwarf (WD) companion. This 56 minute binary was discovered using data from the Zwicky Transient Facility. Spectroscopic observations reveal an He-sdO...
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IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales: The XXIXth IAU General Assembly in Honolulu adopted IAU 2015 Resolution B2 on recommended zero points for the absolute and apparent bolometric magnitude scales. The resolution was proposed by the IAU Inter-Div...
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Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data: Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H$_2^{18}$O transitions were carried out towards the h...
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Using stellar rotation to identify tidally stripped members of the Praesepe open cluster: As an open cluster orbits the Milky Way, gravitational fields distort it, stripping stars from the core and forming tidal tails. Recent work has identified tidal tails of the Praesepe cluster; we explore rotation periods as a wa...
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Forward Modelling of Standing Kink Modes in Coronal Loops I. Synthetic Views: Kink magnetohydrodynamic (MHD) waves are frequently observed in various magnetic structures of the solar atmosphere. They may contribute significantly to coronal heating and could be used as a tool to diagnose the solar plasma. In this stud...
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High Fidelity Imaging of the Inner AU Mic Debris Disk: Evidence of Differential Wind Sculpting?: We present new high fidelity optical coronagraphic imagery of the inner $\sim$50 au of AU Mic's edge-on debris disk using the BAR5 occulter of the Hubble Space Telescope Imaging Spectrograph (HST/STIS) obtained on 26-27 J...
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Revealing the structure of the outer disks of Be stars: Context. The structure of the inner parts of Be star disks (20 stellar radii) is well explained by the viscous decretion disk (VDD) model, which is able to reproduce the observable properties of most of the objects studied so far. The outer parts, on the ther hand...
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Discovery of A Binary System in IRAM 04191+1522: We present high angular resolution observations of the Class 0 protostar IRAM04191+1522, using the Submillimeter Array (SMA). The SMA 1.3 mm continuum images reveal within IRAM04191+1522 two distinct sources with an angular separation of 7.8\,$\pm$\,0.2$"$. The two conti...
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Doppler Probe of Accretion onto a T Tauri star: The YY Ori stars are T Tauri stars with prominent time-variable redshifted absorption components that flank certain emission lines. One of the brightest in this class is S CrA, a visual double star. We have obtained a series of high-resolution spectra of the two component...
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Stability of thermal modes in cool prominence plasmas: Context: Magnetohydrodynamic thermal modes may play an important role in the formation, plasma condensation, and evolution of solar prominences. Unstable thermal modes due to unbalance between radiative losses and heating can lead to rapid plasma cooling and conden...
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Extended atmospheres of AGB stars: modeling and measurement: Encoded in the time- and wavelength dependent properties of pulsating AGB stars are the underlying fundamental parameters of mass, composition and evolutionary state. However, the standard technique of placing stars on a HR diagram, even with the aid of pulsa...
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The binary nature of the Galactic Centre X-ray source CXOGC J174536.1-285638: X-ray and near-IR surveys of the central 2x0.8 degrees of the Galactic Centre have revealed a population of X-ray bright massive stars. However, the nature of the emission, originating in a wind collision zone or via accretion onto a compac...
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New Double Periodic Variable Stars in the ASAS-SN Catalog: We report the discovery of 3 new Double Periodic Variables based on the analysis of ASAS-SN light curves: GSD J11630570-510306, V593 Sco and TYC 6939-678-1. These systems have orbital periods between 10 and 20 days and long cycles between 300 and 600 days.
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Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: II. Comparison with Observation, Clump Properties, and Scaling to Physical Units: Ambipolar diffusion is important in redistributing magnetic flux and in damping Alfven waves in molecular clouds. The importance of ambipolar diffusion on a l...
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Annihilation of Magnetic Islands at the Top of Solar Flare Loops: The dynamics of magnetic reconnection in the solar current sheet (CS) is studied by high-resolution 2.5-dimensional MHD simulation. With the commence of magnetic reconnection, a number of magnetic islands are formed intermittently and move quickly upward...
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First evidence of non-Gaussian solar flare EUV spectral line profiles and accelerated non-thermal ion motion: The properties of solar flare plasma can be determined from the observation of optically thin lines. The emitting ion distribution determines the shape of the line, with an isothermal Maxwellian ion distribut...
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Three-dimensional kinetic-MHD model of the global heliosphere with the heliopause-surface fitting: This paper provides a detailed description of the latest version of our model of the solar wind (SW) interaction with the local interstellar medium (LISM). This model has already been applied to the analysis of Lyman-al...
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Correlation between the solar magnetic field strength and the millimeter brightness temperature: Images of the Sun at millimeter wavelengths obtained by ALMA show a significant correspondence with the magnetograms. In this paper, we investigate this correspondence by comparing ALMA full-disk solar image taken at 1.2 ...
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Exploring wind-driving dust species in cool luminous giants III. Wind models for M-type AGB stars: dynamic and photometric properties: Stellar winds observed in asymptotic giant branch (AGB) stars are usually attributed to a combination of stellar pulsations and radiation pressure on dust. Shock waves triggered by pu...
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Mass and Angular Momentum Transport in a Gravitationally Unstable Protoplanetary Disk with Improved 3D Radiative Hydrodynamics: During early phases of a protoplanetary disks's life, gravitational instabilities can produce significant mass transport, can dramatically alter disk structure, can mix and shock-process gas...
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Origin of Quasi-Periodic Pulsation at the Base of Kink Unstable Jet: We study a blowout jet that occurs at the west limb of the Sun on August 29$^{th}$, 2014 using high-resolution imaging/spectroscopic observations provided by SDO/AIA and IRIS. An inverse $\gamma$-shape flux-rope appears before the jet{--} morphologica...
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Evolution and Consequences of Interacting CMEs of 2012 November 9-10 using STEREO/SECCHI and In Situ Observations: Understanding of the kinematic evolution of Coronal Mass Ejections (CMEs) in the heliosphere is important to estimate their arrival time at the Earth. It is found that kinematics of CMEs can change when ...
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The Mass Budget of Planet Forming Discs: Isolating the Epoch of Planetesimal Formation: The high rate of planet detection among solar-type stars argues that planet formation is common. It is also generally assumed that planets form in protoplanetary discs like those observed in nearby star forming regions. On what ti...
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Horizontal flow fields observed in Hinode G-band images III. The decay of a satellite sunspot and the role of magnetic flux removal in flaring: The flare-prolific active region NOAA 10930 offered both a developing delta-spot and a decaying satellite sunspot of opposite polarity. The objective of this study is to char...
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Asteroseismic sensitivity to internal rotation along the red-giant branch: Transport of angular momentum in stellar interiors is currently not well understood. Asteroseismology can provide us with estimates of internal rotation of stars and thereby advances our understanding of angular momentum transport. We can meas...
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New Horizons Solar Wind Around Pluto (SWAP) Observations of the Solar Wind From 11-33 AU: The Solar Wind Around Pluto (SWAP) instrument on NASA's New Horizon Pluto mission has collected solar wind observations en route from Earth to Pluto, and these observations continue beyond Pluto. Few missions have explored the s...
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Ionization: a possible explanation for the difference of mean disk sizes in star-forming regions: Surveys of protoplanetary disks in star-forming regions of similar age revealed significant variations in average disk mass between some regions. For instance, disks in the Orion Nebular Cluster (ONC) and Corona Australi...
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Stellar disk destruction by dynamical interactions in the Orion Trapezium star cluster: We compare the observed size distribution of circum stellar disks in the Orion Trapezium cluster with the results of $N$-body simulations in which we incorporated an heuristic prescription for the evolution of these disks. In our ...
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Direct diagnostics of forming massive stars: stellar pulsation and periodic variability of maser sources: The 6.7 GHz methanol maser emission, a tracer of forming massive stars, sometimes shows enigmatic periodic flux variations over several 10-100 days. In this Letter, we propose that this periodic variations could ...
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Modelling depletion by re-accretion of gas from a dusty disc in post-AGB stars: Many disc-type post-asymptotic giant branch (post-AGB) stars are chemically peculiar, showing underabundances of refractory elements in their photospheres that correlate with condensation temperature. The aim of this paper is to investiga...
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A solar blowout jet caused by the eruption of a magnetic flux rope: We investigate the three-dimensional (3D) magnetic structure of a blowout jet originated in the west edge of NOAA Active Region (AR) 11513 on 02 July 2012 by means of recently developed forced field extrapolation (FFE) model. The results show that the ...
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Investigating the IBEX Ribbon Structure a Solar Cycle Apart: A Ribbon of enhanced energetic neutral atom (ENA) emissions was discovered by the Interstellar Boundary Explorer (IBEX) in 2009, redefining our understanding of the heliosphere boundaries and the physical processes occurring at the interstellar interface. The...
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Photometric search for variable stars in young open cluster Berkeley 59: We present time-series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04 m telescope at ARIES, Nainital, we have identified 42 variables in a field of 13'x13' around the cluster. The probable members of th...
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An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations: We report ground based, low frequency heliograph (80 MHz), spectral (85-35 MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the `hal...
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On the incidence of episodic accretion in Class I YSOs from VVV: Episodic accretion is one of the competing models to explain the observed luminosity spread in young stellar clusters. These short-lived high accretion events could also have a strong impact on planet formation. Observations of high-amplitude variability ...
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Amplitude of solar gravity modes generated by penetrative plumes: The detection of gravity modes is expected to give us unprecedented insights into the inner dynamics of the Sun. Within this framework, predicting their amplitudes is essential to guide future observational strategies and seismic studies. In this work, w...
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Low-Resolution Spectroscopy of the Recurrent Nova T Pyxidis at its Early Stage of 2011 Outburst: We present our observational results of the recurrent nova T Pyxidis at its early stage of 2011 outburst, using a low-resolution spectrograph ($R\approx400$) attached to a 28cm telescope. Total nights of our observation a...
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The Solar Minimum Eclipse of 2019 July 2. III. Inferring the Coronal $T_e$ with a Radiative Differential Emission Measure Inversion: Differential Emission Measure (DEM) inversion methods use the brightness of a set of emission lines to infer the line-of-sight (LOS) distribution of the electron temperature ($T_e$) in ...
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Gas phase SiO in the circumstellar environment of the recurrent nova T Coronae Borealis: We report the discovery of the diatomic molecule SiO in the gas phase in the environment of the recurrent nova T Coronae Borealis. While some of the SiO is photospheric, a substantial portion must arise in the wind from the red g...
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Cycling Dynamo in a Young Sun: Grand Minima and Equatorward Propagation: We assess the global-scale dynamo action achieved in a simulation of a sun-like star rotating at three times the solar rate. The 3-D MHD Anelastic Spherical Harmonic code, using slope-limited diffusion, is employed to capture convection and dynamo...
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HIFISTARS Herschel/HIFI observations of VY Canis Majoris. Molecular-line inventory of the envelope around the largest known star: To gain insight into the physical conditions and kinematics of the warm (100-1000 K) gas around the red hyper-giant VY CMa, we performed sensitive high spectral resolution observations of ...
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Photometric light curve solutions of three ultra-short period eclipsing binaries: We present the results of our study of the eclipsing binary systems CSS J112237.1+395219, LINEAR 1286561 and LINEAR 2602707 based on new CCD $B$, $V$, $R_c$ and $I_c$ complete light curves. The ultra-short period nature of the stars \ci...
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Discovery of deep eclipses in the cataclysmic variable ZTF17aaaeefu (2MASS J00594349+6454419): I performed photometric observations of the cataclysmic variable candidate ZTF17aaaeefu and discovered very deep eclipses. The observations were obtained over 8 nights covering 7 months. The eclipse profile is similar to th...
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Chemistry in a forming protoplanetary disk: main accretion phase: We investigate the chemistry in a radiation-hydrodynamics model of star-forming core which evolves from a cold ($\sim 10$ K) prestellar core to the main accretion phase in $\sim 10^5$ yr. A rotationally-supported gravitationally unstable disk is formed a...
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A $ΔR\sim 9.5$ mag Super Flare of An Ultracool Star Detected by $\text{SVOM/GWAC}$ System: In this paper, we report the detection and follow-ups of a super stellar flare GWAC\,181229A with an amplitude of $\Delta R\sim$9.5 mag on a M9 type star by $\text{SVOM/GWAC}$ and the dedicated follow-up telescopes. The estimat...
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A Very Small and Super Strong Zebra Pattern Burst at the Beginning of a Solar Flare: Microwave emission with spectral zebra pattern structures (ZPs) is observed frequently in solar flares and the Crab pulsar. The previous observations show that ZP is only a structure overlapped on the underlying broadband continuum w...
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The Frequency and Mass-Ratio Distribution of Binaries in Clusters I: Description of the method and application to M67: We present a new method for probabilistic generative modelling of stellar colour-magnitude diagrams (CMDs) to infer the frequency of binary stars and their mass-ratio distribution. The method invokes...
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Signatures of ubiquitous magnetic reconnection in the lower solar atmosphere: Ellerman Bomb-like brightenings of the hydrogen Balmer line wings in the quiet Sun (QSEBs) are a signature of the fundamental process of magnetic reconnection at the smallest observable scale in the solar lower atmosphere. We analyze high s...
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