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Evolutionary models of the optical component of the LMC X-1/Star 32
binary system: Calculations carried out to model the evolution of Star 32 under different
assumptions about the stellar wind mass-loss rate provide robust limits on the
present mass of the star. The obtained range is 31 to 35.5 Msun, which is in
very... | astro-ph_SR |
An overall view of temperature oscillations in the solar chromosphere
with ALMA: By direct measurements of the gas temperature, the Atacama Large
Millimeter/sub-millimeter Array (ALMA) has yielded a new diagnostic tool to
study the solar chromosphere. Here we present an overview of the
brightness-temperature fluctuat... | astro-ph_SR |
Millimeter imaging of MWC 758: probing the disk structure and kinematics: We investigate the structure and kinematics of the circumstellar disk around
the Herbig Ae star MWC 758 using high resolution observations of the 12CO (3-2)
and dust continuum emission at the wavelengths of 0.87 and 3.3 mm. We find that
the dust ... | astro-ph_SR |
New R Coronae Borealis and DY Persei Candidates in the SMC: We report 3 new R Coronae Borealis and 63 new DY Persei candidates in the
Small Magellanic Cloud. Our analysis, based on data published by the OGLE team,
consisted in a search for the characteristic drops in brightness that define
these classes. All candidates... | astro-ph_SR |
Measurement of the radial velocity of the Sun as a star by means of a
reflecting solar system body. The effect of the body rotation: Minor bodies of the solar system can be used to measure the spectrum of the
Sun as a star by observing sunlight reflected by their surfaces. To perform an
accurate measurement of the ra... | astro-ph_SR |
Supergranules as Probes of the Sun's Meridional Circulation: Recent analysis revealed that supergranules (convection cells seen at the
Sun's surface) are advected by the zonal flows at depths equal to the widths of
the cells themselves. Here we probe the structure of the meridional circulation
by cross-correlating maps... | astro-ph_SR |
Chemical composition of stars with massive planets: Stellar parameters of 25 planet-hosting stars and abundances of Li, C, O, Na,
Mg, Al, S, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Zn, Y, Zr, Ba, Ce, Pr, Nd, Sm and
Eu, were studied based on homogeneous high resolution spectra and uniform
techniques. The iron abundance [Fe/H... | astro-ph_SR |
SuperWASP observations of pulsating Am stars: We have studied over 1600 Am stars at a photometric precision of 1 mmag with
SuperWASP photometric data. Contrary to previous belief, we find that around
200 Am stars are pulsating delta Sct and gamma Dor stars, with low amplitudes
that have been missed in previous, less ex... | astro-ph_SR |
Towards a consistent model of the hot quadruple system HD 93206 = QZ
Carinæ: II. N-body model: HD 93206 is early-type massive stellar system, composed of components
resolved by direct imaging (Ab, Ad, B, C, D) as well as a compact sub-system
(Aa1, Aa2, Ac1, Ac2). Its geometry was already determined on the basis of
ex... | astro-ph_SR |
Collisional- and photo-excitations of Ca IV including strong 3.2 $μ$m
emission line: We report a detailed study of features of electron-impact excitation (EIE) of
Ca IV for the first time using the relativistic Breit-Pauli R-Matrix method
with a large close coupling wavefunction expansion of 54 fine structure levels
... | astro-ph_SR |
Bright Spectroscopic Binaries: II. A study of five systems with orbital
periods of P < 500 days: We present a detailed analysis of five bright spectroscopic binary systems
(HD 18665, HD 27131, HD 171852, HD 215550, HD 217427) that have orbital periods
of P < 500 days. We determined the complete set of orbital paramet... | astro-ph_SR |
Temperature and Distance Dependence of Tidal Circularization in Close
Binaries: A Catalog of Eclipsing Binaries in the Southern Hemisphere Observed
by the TESS Satellite: Tidal forces are important for understanding how close binary stars and
compact exoplanetary systems form and evolve. However, tides are difficul... | astro-ph_SR |
Oxygen abundances in G- and F-type stars from HARPS: We present a detailed and uniform study of oxygen abundance from two
different oxygen lines at 6158$\AA$ and 6300$\AA$ in a large sample of
solar-type stars. The results are used to check the behaviour of these spectral
lines as oxygen abundance indicators and to stu... | astro-ph_SR |
Connecting the Wilson depression to the magnetic field of sunspots: Context: In sunspots, the geometric height of continuum optical depth unity
is depressed compared to the quiet Sun. This so-called Wilson depression is
caused by the Lorentz force of the strong magnetic field inside the spots.
However, it is not unders... | astro-ph_SR |
Low-temperature chemistry between water and hydroxyl radicals: H/D
isotopic effects: Sets of systematic laboratory experiments are presented -- combining Ultra
High Vacuum cryogenic and plasma-line deposition techniques -- that allow us to
compare H/D isotopic effects in the reaction of H2O (D2O) ice with the hydroxy... | astro-ph_SR |
LMC Blue Supergiant Stars and the Calibration of the Flux-weighted
Gravity--Luminosity Relationship: High quality spectra of 90 blue supergiant stars in the Large Magellanic
Cloud are analyzed with respect to effective temperature, gravity, metallicity,
reddening, extinction and extinction law. An average metallicity... | astro-ph_SR |
The CARMENES search for exoplanets around M dwarfs: Convective shift and
starspot constraints from chromatic radial velocities: Context. Variability caused by stellar activity represents a challenge to the
discovery and characterization of terrestrial exoplanets and complicates the
interpretation of atmospheric plane... | astro-ph_SR |
Spectroscopic Observations of Selected Planetary Nebulae from the HASH
Database: We conducted research on the classification and physical properties of 10
objects from the HASH (Hong Kong/Australian Astronomical Observatory/Strasbourg
Observatory H-alpha Planetary Nebula (PN)) database with small angular sizes (<
8\a... | astro-ph_SR |
Solar extreme events: Solar flares and CMEs have a broad range of magnitudes. This review discusses
the possibility of "extreme events," defined as those with magnitudes greater
than have been seen in the existing historical record. For most quantitative
measures, this direct information does not extend more than a cen... | astro-ph_SR |
Field Blue Stragglers and Related Mass Transfer Issues: This chapter contains my impressions and perspectives about the current state
of knowledge about field blue stragglers (FBS) stars, drawn from an extensive
literature that I searched. I conclude my review of issues that attend FBS and
mass transfer, by a brief enu... | astro-ph_SR |
The data center for the Spectrometer and Telescope for Imaging X-rays
(STIX) onboard Solar Orbiter: The Spectrometer and Telescope for Imaging X-rays (STIX) on board Solar
Orbiter observes solar X-ray emission in the range of 4 – 150 keV and
produces spectra and images of solar flares over a wide range of flare... | astro-ph_SR |
Eclipsing Binary Stars: the Royal Road to Stellar Astrophysics: Russell (1948) famously described eclipses as the "royal road" to stellar
astrophysics. From photometric and spectroscopic observations it is possible to
measure the masses and radii (to 1% or better!), and thus surface gravities and
mean densities, of sta... | astro-ph_SR |
Identifying Footpoints of Pre-eruptive and Coronal Mass Ejection Flux
Ropes with Sunspot Scars: The properties of pre-eruptive structures and coronal mass ejections (CMEs)
are characterized by those of their footpoints, the latter of which thus
attract great interest. However, how to identify the footpoints of pre-er... | astro-ph_SR |
Elemental Abundance Analysis of Single and Binary Late-B Stars Using
Sub-meter Class Telescopes: HR 342, HR 769, HR 1284, and HR 8705: We test the capabilities of 0.4 m telescopes equipped with an \'{e}chelle
spectrograph to derive fundamental parameters and elemental abundances of four
late-B type stars: HR 342, HR ... | astro-ph_SR |
The Age-Rotation-Activity Relation: From Myrs to Gyrs: Over the past 40 years, observational surveys have established the existence
of a tight relationship between a star's age, rotation period, and magnetic
activity. This age-rotation-activity relation documents the interplay between a
star's magnetic dynamo and angul... | astro-ph_SR |
Spectropolarimetric multi line analysis of stellar magnetic fields: In this paper we study the feasibility of inferring the magnetic field from
polarized multi-line spectra using two methods: The pseudo line approach and
The PCA-ZDI approach. We use multi-line techniques, meaning that all the lines
of a stellar spectru... | astro-ph_SR |
HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of
WASP-6b: We report Hubble Space Telescope (HST) optical to near-infrared transmission
spectroscopy of the hot Jupiter WASP-6b, measured with the Space Telescope
Imaging Spectrograph (STIS) and Spitzer's InfraRed Array Camera (IRAC). The
resulting... | astro-ph_SR |
Binary Central Stars of Planetary Nebulae Identified With Kepler/K2: We present the identification of 34 likely binary central stars (CSs) of
planetary nebulae (PNe) from {\it Kepler/K2} data, seven of which show
eclipses. Of these, 29 are new discoveries. Two additional CSs with more
complicated variability are also p... | astro-ph_SR |
PHL 417: a zirconium-rich pulsating hot subdwarf (V366 Aquarid)
discovered in K2 data: The Kepler spacecraft observed the hot subdwarf star PHL 417 during its
extended K2 mission, and the high-precision photometric lightcurve reveals the
presence of 17 pulsation modes with periods between 38 and 105 minutes. From
fol... | astro-ph_SR |
New hydrodynamic solutions for line-driven winds of hot massive stars
using Lambert $W$-function: Hot massive stars present strong stellar winds that are driven by absorption,
scattering and re\-emission of photons by the ions of the atmosphere
(\textit{line-driven winds}). A better comprehension of this phenomenon, ... | astro-ph_SR |
V5856 Sagittarii/2016: Broad Multi-Epoch Spectral Coverage of a
Sustained High Luminosity Nova: Nova V5856 Sagittarii is unique for having remained more than nine magnitudes
above its pre-outburst brightness for more than six years. Extensive visible
and IR spectra from the time of outburst to the present epoch revea... | astro-ph_SR |
On the variation of the scaling exponent of the flare fluence with
temperature: Solar flares result in an increase of the solar irradiance at all
wavelengths. While the distribution of the flare fluence observed in coronal
emission has been widely studied and found to scale as f(E) ~ E^{-\alpha}, with
\alpha slightly... | astro-ph_SR |
Radiation Magnetohydrodynamics Simulation of Proto-Stellar Collapse:
Two-Component Molecular Outflow: We perform a three-dimensional nested-grid radiation magneto-hydrodynamics
(RMHD) simulation with self-gravity to study the early phase of the low-mass
star formation process from a rotating molecular cloud core to a... | astro-ph_SR |
Eleven Exoplanet Host Star Angular Diameters from the CHARA Array: We directly measured the angular diameters for 11 exoplanet host stars using
Georgia State University's CHARA Array interferometer and calculated their
linear radii and effective temperatures. The sample tends towards evolving or
evolved stars and inclu... | astro-ph_SR |
The Heating and Pulsations of V386 Serpentis after its 2019 Dwarf Nova
Outburst: Following the pulsation spectrum of a white dwarf through the heating and
cooling involved in a dwarf nova outburst cycle provides a unique view of the
changes to convective driving that take place on timescales of months versus
millenia... | astro-ph_SR |
Chromospheric cannonballs on the Sun: In the highly dynamic chromosphere, there exist many kinds of small-scale
activities, such as spicules, surges, and Ellerman bombs. Here, we report the
discovery of a new phenomenon in the chromosphere observed with the New Vacuum
Solar Telescope at the Fuxian Solar Observatory. In... | astro-ph_SR |
Prandtl number dependence of compressible convection: Flow statistics
and convective energy transport: (abridged) Context: The ratio of kinematic viscosity to thermal diffusivity,
the Prandtl number, is much smaller than unity in stellar convection zones.
Aims: To study the statistics of convective flows and energy t... | astro-ph_SR |
The shape of sunspots and solar activity cycles: The paper presents the results of the analysis of the geometric
characteristics of sunspots for the period of 19-24 cycles of activity. The
shape of sunspots was studied on the basis of the method of normalization of
images of sunspots to study the average profile of the... | astro-ph_SR |
ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS
16342-3814: High-velocity bipolar jets and an Expanding Torus: We have mapped 12CO J=3-2 and other molecular lines from the "water-fountain"
bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ~0."35 resolution using
ALMA. We find (i) two very high... | astro-ph_SR |
The orbital periods of subdwarf B binaries produced by the first stable
Roche overflow channel: Long-orbital-period subdwarf B (sdB) stars with main-sequence companions are
believed to be the product of stable Roche Lobe overflow (RLOF), a scenario
challenged by recent observations. Here we represent the results of a... | astro-ph_SR |
On the maximum black hole mass at solar metallicity: In high metallicity environments the mass that black holes (BHs) can reach
just after core-collapse widely depends on how much mass their progenitor stars
lose via winds. On one hand new theoretical and observational insights suggest
that early-stage winds should be ... | astro-ph_SR |
Quasilinear Approach of the Whistler Heat-Flux Instability in the Solar
Wind: The hot beaming (or strahl) electrons responsible for the main electron
heat-flux in the solar wind are believed to be self-regulated by the
electromagnetic beaming instabilities, also known as the heat-flux
instabilities. Here we report th... | astro-ph_SR |
The EBLM Project I-Physical and orbital parameters, including spin-orbit
angles, of two low-mass eclipsing binaries on opposite sides of the Brown
Dwarf limit: This paper introduces a series of papers aiming to study the dozens of low
mass eclipsing binaries (EBLM), with F, G, K primaries, that have been
discovered... | astro-ph_SR |
Very Long Baseline Interferometry imaging of the advancing ejecta in the
first gamma-ray nova V407 Cyg: In 2010/3, the Large Area Telescope on board Fermi revealed a transient
gamma-ray source, positionally coincident with the optical nova in the
symbiotic binary, V407Cyg. This event marked the first discovery of gam... | astro-ph_SR |
Dissipation of magnetic fields in star-forming clouds with different
metallicities: We study dissipation process of magnetic fields in the metallicity range $0-1
Z_{\odot}$ for contracting prestellar cloud cores. By solving non-equilibrium
chemistry for important charged species including charged grains, we evaluate
... | astro-ph_SR |
The effect of the Solar wind on low-frequency observations of pulsars: We operate the six German stations of the LOw Frequency ARray as standalone
telescopes to observe more than 100 pulsars every week. To date, we have
collected almost four years of high-quality data at an unprecedented weekly
cadence. This allows us ... | astro-ph_SR |
The chemical signatures of planetary engulfment events in binary systems: Planetary engulfment events involve the chemical assimilation of a planet
into a star's external layer. This can cause a change in the chemical pattern
of the stellar atmosphere in a way that mirrors the composition of the rocky
object engulfed, ... | astro-ph_SR |
Multiwavelength observation of a large-scale flux rope eruption above
kinked mini-filament: We analyse multiwavelength observations of a western limb flare (C3.9)
occurred in AR NOAA 111465 on 30 April 2012. The high resolution images
recorded by SDO/AIA 304, 1600 \AA\ and Hinode/SOT H$\alpha$ show the activation
of ... | astro-ph_SR |
13C17O suggests gravitational instability in the HL Tau disc: We present the first detection of the 13C17O J=3-2 transition toward the HL
Tau protoplanetary disc. We find significantly more gas mass (at least a factor
of ten higher) than has been previously reported using C18O emission. This
brings the observed total d... | astro-ph_SR |
High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends
of element ratios with stellar age: A previous study of correlations between element abundance ratios, [X/Fe],
and ages of solar twin stars is extended to include Sc, Mn, Cu, and Ba. HARPS
spectra with S/N > 600 are used to derive very precise (+/... | astro-ph_SR |
Trends and Characteristics of High-Frequency Type II Bursts Detected by
CALLISTO Spectrometers: Solar radio type II bursts serve as early indicators of incoming
geo-effective space weather events such as coronal mass ejections (CMEs). In
order to investigate the origin of high-frequency type II bursts (HF type II
bur... | astro-ph_SR |
On the Variation of Fourier Parameters for Galactic and LMC Cepheids at
Optical, Near-Infrared and Mid-Infrared Wavelengths: We present a light curve analysis of fundamental-mode Galactic and Large
Magellanic Cloud (LMC) Cepheids based on the Fourier decomposition technique.
We have compiled light curve data for Gala... | astro-ph_SR |
Binary Neutron Stars in Quasi-equilibrium: Quasi-equilibrium sequences of binary neutron stars are constructed for a
variety of equations of state in general relativity. Einstein's constraint
equations in the Isenberg-Wilson-Mathews approximation are solved together with
the relativistic equations of hydrostationary eq... | astro-ph_SR |
The search of the stellar clusters in vicinity of YSOs with high and
middle masses: The results of the searching on the bases of GPS UKIDSS survey's data of
dense compact stellar clusters in the vicinity of 20 YSOs with high and middle
masses are presented. Totally we have revealed clusters in 13 areas. Around 5
obje... | astro-ph_SR |
Scattering line polarization in rotating, optically thick disks: To interpret observations of astrophysical disks it is essential to
understand the formation process of the emitted light. If the disk is optically
thick, scattering dominated and permeated by a Keplerian velocity field,
Non-Local Thermodynamic Equilibriu... | astro-ph_SR |
First ALMA Observation of a Solar Plasmoid Ejection from an X-ray Bright
Point: Eruptive phenomena such as plasmoid ejections or jets are an important
feature of solar activity with the potential for improving our understanding of
the dynamics of the solar atmosphere. Such ejections are often thought to be
signatures... | astro-ph_SR |
Nuclear constraints on non-Newtonian gravity at femtometer scale: Effects of the non-Newtonian gravity on properties of finite nuclei are
studied by consistently incorporating both the direct and exchange contribution
of the Yukawa potential in the Hartree-Fock approach using a well-tested Skyrme
force for the strong i... | astro-ph_SR |
The Periodic Spectroscopic Variability of FU Orionis: FU Orionis systems are young stars undergoing outbursts of disc accretion and
where the optical spectrum contains lines associated with both the disc
photosphere and a wind component. Previous observations of the prototype FU
Orionis have suggested that the wind lin... | astro-ph_SR |
Undetected Binary Stars Cause an Observed Mass Dependent Age Gradient in
Upper Scorpius: Young stellar associations represent a key site for the study of star
formation, but to accurately compare observations to models of stellar
evolution, the age of an association must be determined. The Upper Scorpius
region is th... | astro-ph_SR |
A novel investigation of the small-scale magnetic activity of the quiet
Sun via the Hanle effect in the Sr I 4607 Å line: One of the key research problems in stellar physics is to decipher the
small-scale magnetic activity of the quiet solar atmosphere. Recent
magneto-convection simulations that account for small-sca... | astro-ph_SR |
Some glimpses from helioseismology at the dynamics of the deep solar
interior: Helioseismology has taught us a great deal about the stratification and
kinematics of the solar interior, sufficient for us to embark upon dynamical
studies more detailed than have been possible before. The most sophisticated
studies to da... | astro-ph_SR |
Probing the shape of the mixing profile and of the thermal structure at
the convective core boundary through asteroseismology: Aims: We investigate from a theoretical perspective if space asteroseismology
can be used to distinguish between different thermal structures and shapes of
the near-core mixing profiles for d... | astro-ph_SR |
Horizontal-branch morphology and multiple stellar populations in the
anomalous globular cluster M22: M22 is an anomalous globular cluster that hosts two groups of stars with
different metallicity and s-element abundance. The star-to-star light-element
variations in both groups, with the presence of individual Na-O an... | astro-ph_SR |
Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images: A procedure is introduced to recognise sunspots automatically in solar
full-disk photosphere images obtained from Huairou Solar Observing Station,
National Astronomical Observatories of China. The images are first
pre-processed through Gaussian algorithm... | astro-ph_SR |
On Socially Distant Neighbors: Using Binaries to Constrain the Density
of Objects in the Galactic Center: Stars often reside in binary configurations. The nuclear star cluster
surrounding the supermassive black hole (SMBH) in the Galactic Center (GC) is
expected to include a binary population. In this dense environme... | astro-ph_SR |
Study of the Blazhko type RRc stars in the Stripe 82 region using SDSS
and ZTF: RR Lyrae stars are pulsating stars, many of which also show a long-term
variation called the Blazhko effect which is a modulation of amplitude and
phase of the lightcurve. In this work, we searched for the incidence rate of
the Blazhko ef... | astro-ph_SR |
Direct formation of millisecond pulsars from rotationally delayed
accretion-induced collapse of massive white dwarfs: Millisecond pulsars (MSPs) are believed to be old neutron stars, formed via
Type Ib/c core-collapse supernovae, which have subsequently been spun up to
high rotation rates via accretion from a compani... | astro-ph_SR |
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 ... | astro-ph_SR |
Angular Expansion of Nova Shells: Nova shells can provide us with important information on their distance,
their interactions with the circumstellar and interstellar media, and the
evolution in morphology of the ejecta. We have obtained narrow-band images of a
sample of five nova shells, namely DQHer, FHSer, TAur, V476... | astro-ph_SR |
Accretion Kinematics in the T Tauri Binary TWA 3A: Evidence for
Preferential Accretion onto the TWA 3A Primary: We present time-series, high-resolution optical spectroscopy of the eccentric
T Tauri binary TWA 3A. Our analysis focuses on variability in the strength and
structure of the accretion tracing emission lines... | astro-ph_SR |
Properties of quasi-periodic pulsations in solar flares from a single
active region: We investigate the properties of a set of solar flares originating from a
single active region (AR) that exhibit QPPs, and look for signs of the QPP
periods relating to AR properties. The AR studied, best known as NOAA 12192,
was unu... | astro-ph_SR |
Detailed optical spectroscopy of the B[e] star MWC 17: Based on the data of multiple high-resolution R=60 000 observations obtained
at the 6-meter telescope BTA in combination with the NES spectrograph, we
studied the features of the optical spectrum of the star MWC 17 with the B[e]
phenomenon. In the wavelength interv... | astro-ph_SR |
Mass and orbit constraints of the gamma-ray binary LS 5039: We present the results of space-based photometric and ground-based
spectroscopic observing campaigns on the gamma-ray binary LS 5039. The new
orbital and physical parameters of the system are similar to former results,
except we found a lower eccentricity. Our... | astro-ph_SR |
Embedded protostellar disks around (sub-)solar stars. II. Disk masses,
sizes, densities, temperatures and the planet formation perspective: We present basic properties of protostellar disks in the embedded phase of
star formation (EPSF), which is difficult to probe observationally using
available observational facili... | astro-ph_SR |
Calculating energy storage due to topological changes in emerging active
region NOAA AR 11112: The Minimum Current Corona (MCC) model provides a way to estimate stored
coronal energy using the number of field lines connecting regions of positive
and negative photospheric flux. This information is quantified by the ne... | astro-ph_SR |
Modelling the occurrence of grand minima in sun-like stars using a
dynamo model: In this work, we have studied the variability and frequency of occurrence of
the grand minima using kinematic dynamo models of one solar mass star with
different rotation rates and depths of convection zones. We specify the
large-scale f... | astro-ph_SR |
A Search for Strongly Mg-enhanced Stars from the Sloan Digital Sky
Survey: Strongly Mg-enhanced stars with [Mg/Fe] $>$ 1.0 show peculiar abundance
patterns and hence are of great interest for our understanding of stellar
formation and chemical evolution of the Galaxy. A systematical search for
strongly Mg-enhanced st... | astro-ph_SR |
Helium abundances and the helium isotope anomaly of sdB stars: Helium abundances and atmospheric parameters have been determined from high
resolution spectra for a new sample of 46 bright hot subdwarf B (sdB) stars.
The helium abundances have been measured with high accuracy. We confirm the
correlation of helium abunda... | astro-ph_SR |
On the optically-thick winds of Wolf-Rayet stars: (abridged) The strong winds of Wolf-Rayet (WR) stars are important for the
mechanical and chemical feedback of the most massive stars and determine
whether they end their lives as neutron stars or black holes. In this work we
investigate theoretically the mass-loss prop... | astro-ph_SR |
MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri: We present a study of white light flares from the active M5.5 dwarf Proxima
Centauri using the Canadian microsatellite MOST. Using 37.6 days of monitoring
data from 2014 and 2015, we have detected 66 individual flare events, the
largest number of wh... | astro-ph_SR |
The formation of long-period eccentric binaries with a helium white
dwarf: The recent discovery of long-period eccentric binaries hosting a He-WD or a
sdB star has been challenging binary-star modelling. Based on accurate
determinations of the stellar and orbital parameters for IP Eri, a K0 + He-WD
system, we propose... | astro-ph_SR |
Reconnaissance of the HR 8799 Exosolar System II: Astrometry and Orbital
Motion: We present an analysis of the orbital motion of the four sub-stellar objects
orbiting HR8799. Our study relies on the published astrometric history of this
system augmented with an epoch obtained with the Project 1640 coronagraph +
Integ... | astro-ph_SR |
Sub-Chandrasekhar White Dwarf Mergers as the Progenitors of Type Ia
Supernovae: Type Ia supernovae are generally thought to be due to the thermonuclear
explosions of carbon-oxygen white dwarfs with masses near the Chandrasekhar
mass. This scenario, however, has two long-standing problems. First, the
explosions do not... | astro-ph_SR |
AGB and post-AGB objects in the outer Galaxy: We present the results of our search for low- and intermediate mass evolved
stars in the outer Galaxy using AllWISE catalogue photometry. We show that the
[3.4]-[12] versus [4.6]-[22] colour-colour diagram is most suitable for
separating C-rich/O-rich AGB and post- AGB star... | astro-ph_SR |
New mass-loss rates of B supergiants from global wind models: Massive stars lose a significant fraction of mass during their evolution.
However, the corresponding mass-loss rates are rather uncertain. To improve
this, we calculated global line-driven wind models for Galactic B supergiants.
Our models predict radial win... | astro-ph_SR |
A helium-flash-induced mixing event can explain the lithium abundances
of red clump stars: Observations demonstrate that the surface abundance of $^7{\rm Li}$ in
low-mass stars changes dramatically between the tip of the red giant branch and
the red clump. This naturally suggests an association with the helium core
f... | astro-ph_SR |
Externally heated protostellar cores in the Ophiuchus star-forming
region: We present APEX 218 GHz observations of molecular emission in a complete
sample of embedded protostars in the Ophiuchus star-forming region. To study
the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$
rotational temper... | astro-ph_SR |
$f$-mode interaction with models of sunspot : near-field scattering and
multi-frequency effects: We use numerical simulations to investigate the interaction of an $f$-mode
wave packet with small and large models of a sunspot in a stratified
atmosphere. While a loose cluster model has been largely studied before, we
f... | astro-ph_SR |
What is the relationship between photospheric flow fields and solar
flares?: We estimated photospheric velocities by separately applying the Fourier Local
Correlation Tracking (FLCT) and Differential Affine Velocity Estimator (DAVE)
methods to 2708 co-registered pairs of SOHO/MDI magnetograms, with nominal
96-minute ... | astro-ph_SR |
The Origin of Sequential Chromospheric Brightenings: Sequential chromospheric brightenings (SCBs) are often observed in the
immediate vicinity of erupting flares and are associated with coronal mass
ejections. Since their initial discovery in 2005, there have been several
subsequent investigations of SCBs. These studie... | astro-ph_SR |
The origin of the planetary nebula M 1-16. A morphokinematic and
chemical analysis: We investigated the origin of the Planetary Nebula (PN) M 1-16 using
narrow-band optical imaging, and high- and low-resolution optical spectra to
perform a detailed morpho-kinematic and chemical studies. M 1-16 is revealed to
be a mul... | astro-ph_SR |
Simultaneous Multiwavelength Observations of Magnetic Activity in
Ultracool Dwarfs. IV. The Active, Young Binary NLTT 33370 AB (=2MASS
J13142039+1320011): We present multi-epoch simultaneous radio, optical, H{\alpha}, UV, and X-ray
observations of the active, young, low-mass binary NLTT 33370 AB (blended
spectral t... | astro-ph_SR |
Bayesian Asteroseismology of 23 Solar-Like Kepler Targets: We study 23 previously published Kepler targets to perform a consistent
grid-based Bayesian asteroseismic analysis and compare our results to those
obtained via the Asteroseismic Modelling Portal (AMP). We find differences in
the derived stellar parameters of m... | astro-ph_SR |
X-ray Irradiation of the LkCa 15 Protoplanetary Disk: LkCa 15 in the Taurus star-forming region has recently gained attention as
the first accreting T Tauri star likely to host a young protoplanet. High
spatial resolution infrared observations have detected the suspected
protoplanet within a dust-depleted inner gap of ... | astro-ph_SR |
Impact of Type II Spicules in the Corona: Simulations and Synthetic
Observables: The role of type II spicules in the corona has been a much debated topic in
recent years. This paper aims to shed light on the impact of type II spicules
in the corona using novel 2.5D radiative MHD simulations including ion-neutral
inte... | astro-ph_SR |
Coronal temperature profiles obtained from kinetic models and from
coronal brightness measurements obtained during solar eclipses: Coronal density, temperature and heat flux distributions for the equatorial
and polar corona have been deduced by Lemaire [2012] from Saito's model of
averaged coronal white light (WL) br... | astro-ph_SR |
Cannibals in the thick disk II -- Radial-velocity monitoring of the
young alpha-rich stars: Determining ages of stars for reconstructing the history of the Milky Way
remains one of the most difficult tasks in astrophysics. This involves knowing
when it is possible to relate the stellar mass with its age and when it i... | astro-ph_SR |
UVMag: stellar formation, evolution, structure and environment with
space UV and visible spectropolarimetry: Important insights into the formation, structure, evolution and environment
of all types of stars can be obtained through the measurement of their winds
and possible magnetospheres. However, this has hardly be... | astro-ph_SR |
The hybrid CONe WD + He star scenario for the progenitors of type Ia
supernovae: The hybrid CONe white dwarfs (WDs) have been suggested to be possible
progenitors of type Ia supernovae (SNe Ia). In this article, we systematically
studied the hybrid CONe WD + He star scenario for the progenitors of SNe Ia, in
which a ... | astro-ph_SR |
Case AD, AR, and AS binary evolution and their possible connections with
W UMa binaries: Close detached binaries were theoretically predicted to evolve into contact
by three subtypes of case A binary evolution: case AD, AR, and AS, which
correspond to the formation of contact during dynamic-, thermal-, and
nuclear-ti... | astro-ph_SR |
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