publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2014-07-30 | The NuSTAR spectrum of Mrk 335: Extreme relativistic effects within 2 gravitational radii of the event horizon? | We present 3-50 keV NuSTAR observations of the AGN Mrk 335 in a very low flux
state. The spectrum is dominated by very strong features at the energies of the
iron line at 5-7 keV and Compton hump from 10-30 keV. The source is variable
during the observation, with the variability concentrated at low energies,
which sugg... | 1407.8223v1 |
2014-09-08 | Chemical tagging of the Ursa Major moving group: A northern selection of FGK stars | Stellar kinematic groups are kinematical coherent groups of stars which might
share a common origin.These groups spread through the Galaxy over time due to
tidal effects caused by Galactic rotation and disc heating.However, the
chemical information survives these processes. The information provided by the
analysis of c... | 1409.2348v1 |
2014-09-11 | XMM-Newton observations reveal the disappearance of the wind in 4U 1630-47 | We report on XMM-Newton observations of the black hole X-ray binary 4U
1630-47 during its 2012-2013 outburst. The first five observations monitor the
source as its luminosity increases across the high-soft state of accretion. In
the sixth observation the source has made a transition to an "anomalous" state,
characteris... | 1409.3406v2 |
2014-09-15 | The origin of the most iron-poor star | We investigate the origin of carbon-enhanced metal-poor (CEMP) stars starting
from the recently discovered $\rm [Fe/H]<-7.1$ star SMSS J031300 (Keller et al.
2014). We show that the elemental abundances observed on the surface of SMSS
J031300 can be well fit by the yields of faint, metal free, supernovae. Using
properl... | 1409.4424v2 |
2014-09-26 | VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy | Fornax is one of the most massive dwarf spheroidal galaxies in the Local
Group. The Fornax field star population is dominated by intermediate age stars
but star formation was going on over almost its entire history. It has been
proposed that Fornax experienced a minor merger event. Despite recent progress,
only the hig... | 1409.7703v1 |
2014-10-03 | Orbital occupancy and charge doping in iron-based superconductors | Iron-based superconductors (FBS) comprise several families of compounds
having the same atomic building blocks for superconductivity, but large
discrepancies among their physical properties. A longstanding goal in the field
has been to decipher the key underlying factors controlling TC and the various
doping mechanisms... | 1410.0971v1 |
2014-12-11 | The 2D Distribution of Iron Rich Ejecta in the Remnant of SN 1885 in M31 | We present Hubble Space Telescope (HST) ultraviolet Fe I and Fe II images of
the remnant of Supernova 1885 (S And) which is observed in absorption against
the bulge of the Andromeda galaxy, M31. We compare these Fe I and Fe II
absorption line images to previous HST absorption images of S And, of which the
highest quali... | 1412.3815v3 |
2014-12-31 | Strong Variability of Overlapping Iron Broad Absorption Lines in Five Radio-selected Quasars | We present the variability study of broad absorption lines (BALs) in a
uniformly radio-selected sample of 28 BAL quasars using the archival data from
the FIRST Bright Quasar Survey (FBQS) and the Sloan Digital Sky Survey (SDSS),
as well as those obtained by ourselves, covering time scales $\sim 1-10$ years
in the quasa... | 1501.00091v3 |
2015-01-02 | Determining the Mass of Kepler-78b With Nonparametric Gaussian Process Estimation | Kepler-78b is a transiting planet that is 1.2 times the radius of Earth and
orbits a young, active K dwarf every 8 hours. The mass of Kepler-78b has been
independently reported by two teams based on radial velocity measurements using
the HIRES and HARPS-N spectrographs. Due to the active nature of the host star,
a stel... | 1501.00369v2 |
2015-01-05 | Relationship between X-ray spectral index and X-ray Eddington ratio for Mrk 335 and Ark 564 | We present a comprehensive flux resolved spectral analysis of the bright
Narrow line Seyfert I AGNs, Mrk~335 and Ark~564 using observations by
XMM-Newton satellite. The mean and the flux resolved spectra are fitted by an
empirical model consisting of two Comptonization components, one for the low
energy soft excess and... | 1501.00908v1 |
2015-01-08 | Neutrino-driven supernova of a low-mass iron-core progenitor boosted by three-dimensional turbulent convection | We present the first successful simulation of a neutrino-driven supernova
explosion in three dimensions (3D), using the Prometheus-Vertex code with an
axis-free Yin-Yang grid and a sophisticated treatment of three-flavor,
energy-dependent neutrino transport. The progenitor is a nonrotating,
zero-metallicity 9.6 Msun st... | 1501.01961v2 |
2015-01-20 | Spectroscopic Abundances in the Open Cluster, NGC 6819 | High-dispersion spectra of 333 stars in the open cluster NGC 6819, obtained
using the HYDRA spectrograph on the WIYN 3.5m telescope, have been analyzed to
determine the abundances of iron and other metals from lines in the 400 A
region surrounding the Li 6708 A line. Our spectra, with signal-to-noise per
pixel (SNR) ra... | 1501.04973v1 |
2015-01-26 | A one-dimensional Chandrasekhar-mass delayed-detonation model for the broad-lined Type Ia supernova 2002bo | We present 1D non-local thermodynamic equilibrium (non-LTE) time-dependent
radiative-transfer simulations of a Chandrasekhar-mass delayed-detonation model
which synthesizes 0.51 Msun of 56Ni, and confront our results to the Type Ia
supernova (SN Ia) 2002bo over the first 100 days of its evolution. Assuming
only homolog... | 1501.06583v2 |
2015-02-26 | Suzaku broad-band spectrum of 4U 1705-44: Probing the Reflection component in the hard state | Iron emission lines at 6.4-6.97 keV, identified with Kalpha radiative
transitions, are among the strongest discrete features in the X-ray band. These
are one of the most powerful probes to infer the properties of the plasma in
the innermost part of the accretion disk around a compact object. In this paper
we present a ... | 1502.07669v1 |
2015-02-26 | The spin rate of pre-collapse stellar cores: wave-driven angular momentum transport in massive stars | The core rotation rates of massive stars have a substantial impact on the
nature of core-collapse supernovae and their compact remnants. We demonstrate
that internal gravity waves (IGW), excited via envelope convection during a red
supergiant phase or during vigorous late time burning phases, can have a
significant imp... | 1502.07779v3 |
2015-03-09 | Gate-tuned Superconductor-Insulator transition in (Li,Fe)OHFeSe | The antiferromagnetic(AFM) insulator-superconductor transition has been
always a center of interest in the underlying physics of unconventional
superconductors. The quantum phase transition between Mott insulator with AFM
and superconductor can be induced by doping charge carriers in high-Tc cuprate
superconductors. Fo... | 1503.02457v1 |
2015-03-12 | On the alpha-element gradients of the Galactic thin disk using Cepheids | We present new homogeneous measurements of Na, Al and three alpha-elements
(Mg, Si, Ca) for 75 Galactic Cepheids. The abundances are based on high
spectral resolution (R ~ 38,000) and high signal-to-noise ratio (S/N ~ 50-300)
spectra collected with UVES at ESO VLT. The current measurements were
complemented with Cephei... | 1503.03758v1 |
2015-03-30 | Electrochemical synthesis of highly ordered nanowires with a rectangular cross-section using an in-plane nanochannel array | Rapid and reproducible assembly of aligned nanostructures on a wafer-scale is
a crucial, yet one of the most challenging tasks in the incorporation of
nanowires into integrated circuits. We present the synthesis of a periodic
nanochannel template designed for electrochemical growth of perfectly aligned,
rectangular nan... | 1503.08597v1 |
2015-04-17 | Electronic Structure and Superconductivity of FeSe-Related Superconductors | The FeSe superconductor and its related systems have attracted much attention
in the iron-based superconductors owing to their simple crystal structure and
peculiar electronic and physical properties. The bulk FeSe superconductor has a
superconducting transition temperature (Tc) of ~8 K; it can be dramatically
enhanced... | 1504.04436v2 |
2015-05-20 | Constraints on explosive silicon burning in core-collapse supernovae from measured Ni/Fe ratios | Measurements of explosive nucleosynthesis yields in core-collapse supernovae
provide tests for explosion models. We investigate constraints on explosive
conditions derivable from measured amounts of nickel and iron after radioactive
decays using nucleosynthesis networks with parameterized thermodynamic
trajectories. Th... | 1505.05323v1 |
2015-05-25 | The Carina Project. VIII. The α-element abundances | We have performed a new abundance analysis of Carina Red Giant (RG) stars
from spectroscopic data collected with UVES (high resolution) and
FLAMES/GIRAFFE (high and medium resolution) at ESO/VLT. The former sample
includes 44 RGs, while the latter consists of 65 (high) and ~800 (medium
resolution) RGs, covering a signi... | 1505.06597v2 |
2015-05-25 | Twin peak HF QPOs as a spectral imprint of dual oscillation modes of accretion tori | High frequency (millisecond) quasi-periodic oscillations (HF QPOs) are
observed in the X-ray power-density spectra of several microquasars and low
mass X-ray binaries. Two distinct QPO peaks, so-called twin peak QPOs, are
often detected simultaneously exhibiting their frequency ratio close or equal
to 3/2. Following th... | 1505.06673v1 |
2015-06-04 | Systematic NLTE study of the -2.6 < [Fe/H] < 0.2 F and G dwarfs in the solar neighbourhood. I. Stellar atmosphere parameters | We present atmospheric parameters for 51 nearby FG dwarfs uniformly
distributed over the -2.60 < [Fe/H] < +0.20 metallicity range that is suitable
for the Galactic chemical evolution research. Lines of iron, Fe I and Fe II,
were used to derive a homogeneous set of effective temperatures, surface
gravities, iron abundan... | 1506.01621v1 |
2015-07-02 | A Spectroscopic Analysis of the Galactic Globular Cluster NGC 6273 (M19) | A combined effort utilizing spectroscopy and photometry has revealed the
existence of a new globular cluster class. These "anomalous" clusters, which we
refer to as "iron-complex" clusters, are differentiated from normal clusters by
exhibiting large (>0.10 dex) intrinsic metallicity dispersions, complex
sub-giant branc... | 1507.00756v1 |
2015-08-07 | Spectrophotometry of asteroids 32 Pomona, 145 Adeona, 704 Interamnia, 779 Nina, 330825, and 2012 QG42 and laboratory study of possible analog samples | Six asteroids including two NEAs, one of which is PHA, accessible for
observation in September 2012 were investigated using a low-resolution
spectrophotometry in the range 0.35-0.90 um with the aim to study features of
their reflectance spectra. For the first time we discovered likely spectral
signs (as a maximum at 0.... | 1508.01690v1 |
2015-09-08 | Identifying the best iron-peak and $α$-capture elements for chemical tagging: The impact of the number of lines on measured scatter | The main goal of this work is to explore which elements carry the most
information about the birth origin of stars and as such that are best suited
for chemical tagging. We explored different techniques to minimize the effect
of outlier value lines in the abundances by using Ni abundances derived for
1111 FGK type star... | 1509.02419v1 |
2015-09-08 | Metallicity of Ca2Cu6P5 with Single and Double Copper-Pnictide Layers | We report thermodynamic and transport properties, and also theoretical
calculations, for Cu-based compound Ca2Cu6P5 and compare with CaCu(2-x)P2. Both
materials have layers of edge-sharing copper pnictide tetrahedral CuP4, similar
to Fe-As and Fe-Se layers (with FeAs4, FeSe4) in the iron-based
superconductors. Despite ... | 1509.02508v1 |
2015-09-14 | Cool Core Clusters from Cosmological Simulations | We present results obtained from a set of cosmological hydrodynamic
simulations of galaxy clusters, aimed at comparing predictions with
observational data on the diversity between cool-core (CC) and non-cool-core
(NCC) clusters. Our simulations include the effects of stellar and AGN feedback
and are based on an improve... | 1509.04247v2 |
2015-09-29 | Enrichment of r-process elements in dwarf spheroidal galaxies in chemo-dynamical evolution model | The rapid neutron-capture process (r-process) is a major process to
synthesize elements heavier than iron, but the astrophysical site(s) of
r-process is not identified yet. Neutron star mergers (NSMs) are suggested to
be a major r-process site from nucleosynthesis studies. Previous chemical
evolution studies however re... | 1509.08934v1 |
2015-10-07 | Nanoanalytical TEM studies and micromagnetic modelling of Nd-Fe-B magnets | We have analysed the influence of the microstructural features, such as
intergranular grain boundary (GB) phases and misalignment of the hard magnetic
grains, on the optimization of magnetization reversal processes in order to
improve the coercive field of Nd-Fe-B magnets. The microstructural model of the
grains and in... | 1510.01958v2 |
2015-10-23 | GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC3 | The Scutum complex in the inner disk of the Galaxy has a number of young star
clusters dominated by red supergiants that are heavily obscured by dust
extinction and observable only at infrared wavelengths. These clusters are
important tracers of the recent star formation and chemical enrichment history
in the inner Gal... | 1510.06870v1 |
2015-10-27 | Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies | A comprehensive abundance analysis providing rare insight into the chemical
history of lead stars is still lacking. We present results from high resolution
(R ~ 50000), spectral analyses of three CH stars, HD 26, HD 198269, HD 224959,
and, a carbon star with a dusty envelope, HD 100764. Previous studies on these
object... | 1510.07814v1 |
2015-11-11 | Polarization of Magnetic Dipole Emission and Spinning Dust Emission from Magnetic Nanoparticles | Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is an
important Galactic foreground in the microwave frequencies, and its
polarization level may pose great challenges for achieving reliable
measurements of cosmic microwave background (CMB) B-mode signal. To obtain
theoretical constraints on the ... | 1511.03691v1 |
2015-12-25 | Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconducting FeTe$_{1-x}$Se$_x$ | It has recently been demonstrated that dynamical magnetic correlations
measured by neutron scattering in iron chalcogenides can be described with
models of short-range correlations characterized by particular {choices of
four-spin plaquettes, where the appropriate choice changes as the} parent
material is doped towards... | 1512.08036v2 |
2015-12-26 | CALET: a high energy astroparticle physics experiment on the ISS | CALET (CALorimetric Electron Telescope) is a high energy astroparticle
physics experiment planned for a long exposure mission aboard the International
Space Station (ISS) by the Japanese Aerospace Exploration Agency, in
collaboration with the Italian Space Agency (ASI) and NASA. The main science
goal is high precision ... | 1512.08059v1 |
2016-01-17 | COSMIC-LAB: Unexpected Results from High-resolution Spectra of AGB Stars in Globular Clusters | This thesis is aimed at clarifying one of the least studied phases of stellar
evolution: the asymptotic giant branch (AGB). Recent results obtained for
Galactic globular clusters (GCs) suggest that the AGB stage may contain crucial
information about the evolutionary history of exotic stars (Beccari et al.
2006) and mul... | 1601.04346v1 |
2016-01-21 | High resolution spectroscopic analysis of seven giants in the bulge globular cluster NGC 6723 | Globular clusters associated with the Galactic bulge are important tracers of
stellar populations in the inner Galaxy. High resolution analysis of stars in
these clusters allows us to characterize them in terms of kinematics,
metallicity, and individual abundances, and to compare these fingerprints with
those character... | 1601.05736v1 |
2016-02-02 | The initial abundance and distribution of 92Nb in the Solar System | Niobium-92 is an extinct proton-rich nuclide, which decays to 92Zr with a
half-life of 37 Ma. This radionuclide potentially offers a unique opportunity
to determine the timescales of early Solar System processes and the site(s) of
nucleosynthesis for p-nuclei, once its initial abundance and distribution in
the Solar Sy... | 1602.00966v1 |
2016-03-02 | Optimal Auctions for Negatively Correlated Items | We consider the problem of designing revenue-optimal auctions for selling two
items and bidders' valuations are independent among bidders but negatively
correlated among items.
In this paper, we obtain the closed-form optimal auction for this setting, by
directly addressing the two difficulties above. In particular, ... | 1603.00562v3 |
2016-03-04 | The thermal instability of the warm absorber in NGC 3783 | We model the observed X-ray spectral continuum shape, ionic column densities,
and absorption measure distribution (AMD) of the warm absorber in the Seyfert
galaxy NGC 3783. We assume a photo-ionized medium with a uniform total
(gas+radiation) pressure. The irradiation causes the wind to be radiation
pressure compressed... | 1603.01448v1 |
2016-03-11 | Nonlinear and time-resolved optical study of the 112-type iron-based superconductor parent Ca$_{1-x}$La$_{x}$FeAs$_{2}$ across its structural phase transition | The newly discovered 112-type ferropnictide superconductors contain chains of
As atoms that break the tetragonal symmetry between the $a$ and $b$ axes. This
feature eliminates the need for uniaxial strain that is usually required to
stabilize large single domains in the electronic nematic state that exists in
the vicin... | 1603.03785v1 |
2016-04-09 | Reduced radiative conductivity of high and low spin FeO6 octahedra in the Earth's lower mantle | The ability of Earths mantle to conduct heat by radiation is determined by
optical properties of mantle phases. Optical properties of mantle minerals at
high pressure are accessible through diamond anvil cell experiments, but
because of the extensive thermal radiation at T above 1000 K such studies are
limited to lower... | 1604.02613v1 |
2016-04-11 | Chemical abundances and kinematics of barium stars | In this paper we present an homogeneous analysis of photospheric abundances
based on high-resolution spectroscopy of a sample of 182 barium stars and
candidates. We determined atmospheric parameters, spectroscopic distances,
stellar masses, ages, luminosities and scale height, radial velocities,
abundances of the Na, A... | 1604.03031v1 |
2016-04-14 | Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456 | High resolution soft X-ray spectroscopy of the prototype accretion disk wind
quasar, PDS 456, is presented. Here, the XMM-Newton RGS spectra are analyzed
from the large 2013-2014 XMM-Newton campaign, consisting of 5 observations of
approximately 100 ks in length. During the last observation (hereafter OBS. E),
the quas... | 1604.04196v1 |
2016-04-22 | Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations | We report Raman light scattering in the phase separated superconducting
single crystal Rb0.77Fe1.61Se2 with Tc = 32 K. The spectra have been measured
in a wide temperature range 3K -500K. The observed phonon lines from the
majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN= 525 K
demonstrate modes... | 1604.06825v1 |
2016-05-10 | Cosmic-ray energy spectrum and composition up to the ankle - the case for a second Galactic component | We have carried out a detailed study to understand the observed energy
spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our
study shows that a single Galactic component with subsequent energy cut-offs in
the individual spectra of different elements, optimised to explain the observed
spectra below ... | 1605.03111v2 |
2016-05-11 | Broadband observations of the X-ray burster 4U 1705-44 with BeppoSAX | 4U 1705-44 is one of the most-studied type I X-ray burster and Atoll sources.
This source represents a perfect candidate to test different models proposed to
self-consistently track the physical changes occurring between different
spectral states because it shows clear spectral state transitions. The
broadband coverage... | 1605.03366v1 |
2016-05-12 | The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk | We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state
based on four observations with NuSTAR. Despite the basic similarity of the
observed spectra, there is clear spectral variability between epochs. To
investigate this variability, we construct a model incorporating both the
standard disk-corona... | 1605.03966v1 |
2016-06-02 | A search for X-ray reprocessing echoes in the power spectral density functions of AGN | We present the results of a detailed study of the X-ray power spectra density
(PSD) functions of twelve X-ray bright AGN, using almost all the archival
XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger
than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a
physical scen... | 1606.00844v1 |
2016-06-09 | Ternary borides Nb$_7$Fe$_3$B$_8$ and Ta$_7$Fe$_3$B$_8$ with Kagome-type iron framework | Two new ternary borides $TM$$_7$Fe$_3$B$_8$ ($TM$ = Nb, Ta) were synthesized
by high-temperature thermal treatment of samples obtained by arc-melting. This
new type of structure with space group $P$6/$mmm$, comprises $TM$ slabs
containing isolated planar hexagonal [B$_6$] rings and iron centered $TM$
columns in a Kagom... | 1606.03123v1 |
2016-08-02 | Atomic-scale observation and manipulation of plaquette antiferromagnetic order in iron-based superconductor | The symmetry requirement and the origin of magnetic orders coexisting with
superconductivity have been strongly debated issues of iron-based
superconductors (FeSCs). Observation of C$_4$-symmetric antiferromagnetism in
violation of the inter-band nesting condition of spin-density waves in
superconducting ground state w... | 1608.00884v3 |
2016-08-19 | Optical properties of $A$Fe$_\mathbf{2}$As$_\mathbf{2}$ ($A=\,$Ca, Sr, and Ba) single crystals | The detailed optical properties have been determined for the iron-based
materials $A$Fe$_2$As$_2$, where $A=\,$Ca, Sr, and Ba, for light polarized in
the iron-arsenic ($a-b$) planes over a wide frequency range, above and below
the magnetic and structural transitions at $T_N =$ 172, 195, and 138 K,
respectively. The rea... | 1608.05709v3 |
2016-09-16 | A deep X-ray view of the bare AGN Ark 120. II. Evidence for Fe K emission transients | We report on the results from a large observational campaign on the bare
Seyfert galaxy Ark 120, jointly carried out in 2014 with XMM-Newton, Chandra,
and NuSTAR. The fortunate line of sight to this source, devoid of any
significant absorbing material, provides an incomparably clean view to the
nuclear regions of an ac... | 1609.05210v1 |
2016-10-14 | Elemental partitioning and isotopic fractionation of Zn between metal and silicate and geochemical estimation of the S content of the Earth's core | Zinc metal-silicate fractionation provides experimental access to the
conditions of core formation and Zn has been used to estimate the S contents of
the Earth's core and of the bulk Earth, assuming that they share similar
volatility and that Zn was not partitioned into the Earth's core. We have
conducted a suite of pa... | 1610.04463v1 |
2016-10-20 | The Broadband Spectral Variability of Holmberg IX X-1 | We present results from four new broadband X-ray observations of the extreme
ultraluminous X-ray source Holmberg IX X-1 ($L_{\rm{X}} > 10^{40}$ erg/s),
performed by $Suzaku$ and $NuSTAR$ in coordination. Combined with the archival
data, we now have broadband observations of this remarkable source from six
separate epoc... | 1610.06611v2 |
2016-10-21 | Two Groups of Red Giants with Distinct Chemical Abundances in the Bulge Globular Cluster NGC 6553 Through the Eyes of APOGEE | Multiple populations revealed in globular clusters (GCs) are important
windows to the formation and evolution of these stellar systems. The metal-rich
GCs in the Galactic bulge are an indispensable part of this picture, but the
high optical extinction in this region has prevented extensive research. In
this work, we us... | 1610.06763v1 |
2016-10-24 | Observations of the X-ray pulsar LMC X-4 with NuSTAR: limit on the magnetic field and tomography of the system in the fluorescent iron line | We present results of the spectral and timing analysis of the X-ray pulsar
LMC X-4 with the NuSTAR observatory in the broad energy range 3-79 keV. Along
with the detailed analysis of the averaged source spectrum, the high-precision
pulse phased-resolved spectra were obtained for the first time. It has been
shown that t... | 1610.08092v1 |
2016-10-27 | IC 3639 - A new bona fide Compton thick AGN unveiled by NuSTAR | We analyse high-quality NuSTAR observations of the local (z = 0.011) Seyfert
2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku
and Chandra data. This provides the first broadband X-ray spectral analysis of
the source, spanning nearly two decades in energy (0.5-30 keV). Previous X-ray
observat... | 1610.08997v1 |
2016-11-04 | Chemical trends in the Galactic Halo with APOGEE data | The galaxy formation process in the $\Lambda$-Cold Dark Matter scenario can
be constrained from the analysis of stars in the Milky Way's halo system. We
examine the variation of chemical abundances in distant halo stars observed by
the Apache Point Galactic Evolution Experiment (APOGEE), as a function of
distance from ... | 1611.01249v1 |
2016-11-11 | Competing instabilities, orbital ordering and splitting of band degeneracies from a parquet renormalization group analysis of a 4-pocket model for iron-based superconductors: application to FeSe | We report the results of a parquet renormalization group (RG) study of
competing instabilities in the full 2D four pocket, three orbital low-energy
model for iron-based superconductors. We derive and analyze the RG flow of the
couplings, which describe all symmetry-allowed interactions between low-energy
fermions. Desp... | 1611.03912v1 |
2016-11-17 | A Chemical Composition Survey of the Iron-Complex Globular Cluster NGC 6273 (M 19) | Recent observations have shown that a growing number of the most massive
Galactic globular clusters contain multiple populations of stars with different
[Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been
recognized as a member of this "iron-complex" cluster class, and we provide
here a chemi... | 1611.05830v1 |
2017-01-04 | A re-analysis of the NuSTAR and XMM-Newton broad-band spectrum of Ser~X-1 | Context: Ser X-1 is a well studied LMXB which clearly shows a broad iron
line. Recently, Miller et al. (2103) have presented broad-band, high quality
NuSTAR data of SerX-1.Using relativistically smeared self-consistent reflection
models, they find a value of R_in close to 1.0 R_ISCO (corresponding to 6 R_g),
and a low ... | 1701.01069v1 |
2017-01-22 | Determination of robust metallicities for metal-rich red giant branch stars | The study of the Milky Way relies on our ability to interpret the light from
stars correctly. This calls for a reinvestigation of how reliably we can
determine, e.g., iron abundances in such stars and how well they reproduce
those of dwarf stars. Here we explore robust ways to determine the iron content
of metal-rich g... | 1701.06132v1 |
2017-03-05 | Reliable estimation of prediction uncertainty for physico-chemical property models | The predictions of parameteric property models and their uncertainties are
sensitive to systematic errors such as inconsistent reference data, parametric
model assumptions, or inadequate computational methods. Here, we discuss the
calibration of property models in the light of bootstrapping, a sampling method
akin to B... | 1703.01685v2 |
2017-08-03 | Observations of the Ultraviolet-Bright Star Y453 in the Globular Cluster M4 (NGC 6121) | We present a spectral analysis of the UV-bright star Y453 in M4. Model fits
to the star's optical spectrum yield T_eff ~ 56,000 K. Fits to the star's FUV
spectrum, obtained with the Cosmic Origins Spectrograph (COS) on board the
Hubble Space Telescope, reveal it to be considerably hotter, with T_eff ~
72,000 K. We adop... | 1708.01315v1 |
2017-09-04 | Iron Snow in the Martian Core? | The decline of Mars' global magnetic field some 3.8-4.1 billion years ago is
thought to reflect the demise of the dynamo that operated in its liquid core.
The dynamo was probably powered by planetary cooling and so its termination is
intimately tied to the thermochemical evolution and present-day physical state
of the ... | 1709.01100v1 |
2017-09-24 | Fe I in the β Pictoris circumstellar gas disk I. Physical properties of the neutral iron gas | The young planetary system {\beta} Pictoris is surrounded by a circumstellar
disk of dust and gas. Because both dust and gas have a lifetime shorter than
the system age, they need to be replenished continuously. The gas composition
is partly known, but its location and its origin are still a puzzle. The gas
source coul... | 1709.08170v1 |
2017-09-26 | Near L-Edge Single and Multiple Photoionization of Singly Charged Iron Ions | Absolute cross sections for m-fold photoionization (m=1,...,6) of Fe+ by a
single photon were measured employing the photon-ion merged-beams setup PIPE at
the PETRA III synchrotron light source, operated by DESY in Hamburg, Germany.
Photon energies were in the range 680-920 eV which covers the photoionization
resonance... | 1709.09092v1 |
2017-10-10 | High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age | HARPS-N spectra with S/N > 250 and MARCS model atmospheres were used to
derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten
stars from the Kepler LEGACY sample (including the binary pair 16 Cyg A and B)
selected to have metallicities in the range -0.15 < [Fe/H] < +0.15 and ages
between 1 and... | 1710.03544v1 |
2017-10-23 | The velocity ellipsoid in the Galactic disc using Gaia DR1 | The stellar velocity ellipsoid of the solar neighbour is re-examined using
intermediate-old mono-abundances stellar groups with high quality chemistry
data together with parallaxes and proper motions from Gaia DR1. We find the
average velocity dispersion values for the three space velocity components for
the thin and t... | 1710.08479v1 |
2017-11-06 | K2-141 b: A 5-M$_\oplus$ super-Earth transiting a K7 V star every 6.7 hours | We report on the discovery of K2-141 b (EPIC 246393474 b), an
ultra-short-period super-Earth on a 6.7-hour orbit transiting an active K7 V
star based on data from K2 campaign 12. We confirmed the planet's existence and
measured its mass with a series of follow-up observations: seeing-limited
MuSCAT imaging, NESSI high-... | 1711.02097v2 |
2017-12-15 | Interior Structures and Tidal Heating in the TRAPPIST-1 Planets | With seven planets, the TRAPPIST-1 system has the largest number of
exoplanets discovered in a single system so far. The system is of
astrobiological interest, because three of its planets orbit in the habitable
zone of the ultracool M dwarf. Assuming the planets are composed of
non-compressible iron, rock, and H$_2$O,... | 1712.05641v2 |
2018-01-16 | The origin of ICM enrichment in the outskirts of present-day galaxy clusters from cosmological hydrodynamical simulations | The uniformity of the intra-cluster medium (ICM) enrichment level in the
outskirts of nearby galaxy clusters suggests that chemical elements were
deposited and widely spread into the intergalactic medium before the cluster
formation. This observational evidence is supported by numerical findings from
cosmological hydro... | 1801.05425v2 |
2018-03-07 | Extracting a less model dependent cosmic ray composition from $X_\mathrm{max}$ distributions | At higher energies the uncertainty in the estimated cosmic ray mass
composition, extracted from the observed distributions of the depth of shower
maximum $X_\text{max}$, is dominated by uncertainties in the hadronic
interaction models. Thus, the estimated composition depends strongly on the
particular model used for it... | 1803.02520v1 |
2018-03-23 | Neutron-induced reactions in nuclear astrophysics | The quest for the origin of the chemical elements, which we find in our body,
in our planet (Earth), in our star (Sun), or in our galaxy (Milky Way) could
only be resolved with a thorough understanding of the nuclear physics
properties of stable and unstable atomic nuclei. While the elements until iron
are either creat... | 1803.08678v1 |
2018-03-26 | Distinct pressure evolution of coupled nematic and magnetic order in FeSe | FeSe, despite being the structurally simplest compound in the family of
iron-based superconductors, shows an astoundingly rich interplay of physical
phenomena including nematicity and pressure-induced magnetism. Here, we present
a microscopic study of these two phenomena by high-energy x-ray diffraction and
time-domain... | 1803.09449v1 |
2018-04-01 | The 1.5 Ms Observing Campaign on IRAS 13224-3809: X-ray Spectral Analysis I | We present a detailed spectral analysis of the recent 1.5\,Ms XMM-Newton
observing campaign on the narrow line Seyfert 1 galaxy IRAS~13224$-$3809, taken
simultaneously with 500\,ks of NuSTAR data. The X-ray lightcurve shows three
flux peaks, registering at about 100 times the minimum flux seen during the
campaign, and ... | 1804.00349v1 |
2018-04-08 | A high-density relativistic reflection origin for the soft and hard X-ray excess emission from Mrk 1044 | We present the first results from a detailed spectral-timing analysis of a
long ($\sim$130 ks) XMM-Newton observation and quasi-simultaneous NuSTAR and
Swift observations of the highly-accreting narrow-line Seyfert 1 galaxy Mrk
1044. The broadband (0.3$-$50 keV) spectrum reveals the presence of a strong
soft X-ray exce... | 1804.02703v2 |
2018-04-19 | The Peculiar Atmospheric Chemistry of KELT-9b | The atmospheric temperatures of the ultra-hot Jupiter KELT-9b straddle the
transition between gas giants and stars, and therefore between two
traditionally distinct regimes of atmospheric chemistry. Previous theoretical
studies assume the atmosphere of KELT-9b to be in chemical equilibrium. Despite
the high ultraviolet... | 1804.07137v3 |
2018-04-23 | Metal Pollution of Low-Mass Population III Stars through Accretion of Interstellar Objects like `Oumuamua | We calculate accretion mass of interstellar objects (ISOs) like `Oumuamua
onto low-mass population III stars (Pop.~III survivors), and estimate surface
pollution of Pop.~III survivors. An ISO number density estimated from the
discovery of `Oumuamua is so high ($\sim 0.2$~au$^{-3}$) that Pop.~III
survivors have chances ... | 1804.08200v2 |
2018-05-02 | Electronic phase separation in iron selenide (Li, Fe)OHFeSe superconductor system | The phenomenon of phase separation into antiferromagnetic (AFM) and
superconducting (SC) or normal-state regions has great implication for the
origin of high-temperature (high-Tc) superconductivity. However, the occurrence
of an intrinsic antiferromagnetism above the Tc of (Li, Fe)OHFeSe
superconductor is questioned. H... | 1805.00688v1 |
2018-05-02 | On a new and homogeneous metallicity scale for Galactic classical Cepheids - I. Physical parameters | We gathered more than 1130 high-resolution optical spectra for more than 250
Galactic classical Cepheids. The spectra were collected with different optical
spectrographs: UVES at VLT, HARPS at 3.6m, FEROS at 2.2m MPG/ESO, and STELLA.
To improve the effective temperature estimates, we present more than 150 new
line dept... | 1805.00727v1 |
2018-05-09 | Near-infrared spectral evolution of the Type Ia supernova 2014J in the nebular phase: implications for the progenitor system | As the closest Type Ia supernova in decades, SN 2014J provides a unique
opportunity for detailed investigation into observational signatures of the
progenitor system and explosion mechanism in addition to burning product
distribution. We present a late-time near-infrared spectral series from
Gemini-N at $307-466$ days ... | 1805.03556v2 |
2018-05-18 | Consistent Iron Abundances Derived from Neutral and Singly-Ionized Iron Lines in Ultraviolet and Optical Spectra of Six Warm Metal-Poor Stars | Neutral Fe lines in metal-poor stars yield conflicting abundances depending
on whether and how deviations from local thermodynamic equilibrium (LTE) are
considered. We have collected new high resolution and high signal-to-noise
ultraviolet (UV) spectra of three warm dwarf stars with [Fe/H] = -2.9 with the
Space Telesco... | 1805.07390v1 |
2018-05-30 | A Recommendation Algorithm to Predict Giant Exoplanet Host Stars Using Stellar Elemental Abundances | The presence of certain elements within a star, and by extension its planet,
strongly impacts the formation and evolution of the planetary system. The
positive correlation between a host star's iron-content and the presence of an
orbiting giant exoplanet has been confirmed; however, the importance of other
elements in ... | 1805.12144v2 |
2018-06-12 | Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo | Understanding the evolution of carbon and iron in the Milky Way's halo is of
importance because these two elements play crucial roles constraining star
formation, Galactic assembly, and chemical evolution in the early Universe.
Here, we explore the spatial distributions of carbonicity, [C/Fe], and
metallicity, [Fe/H], ... | 1806.04738v1 |
2018-06-26 | Modeling dust emission in PN IC 418 | We investigated the infrared (IR) dust emission from PN IC 418, using a
detailed model controlled by a previous determination of the stellar properties
and the characteristics of the photoionized nebula, keeping as free parameters
the dust types, amounts and distributions relative to the distance of the
central star. T... | 1806.10248v2 |
2018-11-02 | NuSTAR and XMM-Newton broad-band spectrum of SAX J1808.4-3658 during its latest outburst in 2015 | The first discovered accreting millisecond pulsar, SAX J1808.4-3658, went
into X-ray outburst in April 2015. We triggered a 100 ks XMM-Newton ToO, taken
at the peak of the outburst, and a 55 ks NuSTAR ToO, performed four days apart.
We report here the results of a detailed spectral analysis of both the
XMM-Newton and N... | 1811.00940v1 |
2018-11-09 | The chemical composition of planet building blocks as predicted by stellar population synthesis | Future space missions will improve considerably our understanding of the
formation and history of planetary systems. Currently, observations show that
the presence of planetary companions is closely linked to the metallicity and
the chemical abundances of the host stars. We aim to build an integrated tool
to predict th... | 1811.04096v1 |
2018-11-22 | Effect of PEG binder on gas sensitivity of ferric oxide films synthesized by spin coating and doctor blade methods | Ferric oxide (Fe2O3) thin films were fabricated on amorphous nonconductive
and FTO conductive glass substrates starting from iron acetate nanoparticles by
the doctor blade and the spin coating techniques. Thin films of Fe2O3 with and
without the PEG binder were investigated. Films were subsequently annealed at
500 0C i... | 1811.09614v1 |
2019-02-04 | Quantum-critical scale invariance in a transition metal alloy | Quantum-mechanical fluctuations between competing phases at $T=0$ induce
exotic finite-temperature collective excitations that are not described by the
standard Landau Fermi liquid framework. These excitations exhibit anomalous
temperature dependences, or non-Fermi liquid behavior, in the transport and
thermodynamic pr... | 1902.01034v3 |
2019-02-13 | Spectral analysis of the barium central star of the planetary nebula Hen 2-39 | Barium stars are peculiar red giants characterized by an overabundance of
s-process elements along with an enrichment in carbon. These stars are
discovered in binaries with white dwarf companions. The more recently formed of
these stars are still surrounded by a planetary nebula. Precise abundance
determinations of the... | 1902.04897v1 |
2019-03-01 | Signature of Dispersing 1D Majorana Channels in an Iron-based Superconductor | The possible realization of Majorana fermions as quasiparticle excitations in
condensed matter physics has created much excitement. Most recent studies have
focused on Majorana bound states which can serve as topological qubits. More
generally, akin to elementary particles, Majorana fermions can propagate and
display l... | 1903.00515v4 |
2019-08-05 | Spectral and orbital survey of medium-sized meteoroids | We investigate the spectra, material properties, and orbital distribution of
millimeter- to decimeter-sized meteoroids. Our study aims to distinguish the
characteristics of populations of differently sized meteoroids and reveal the
heterogeneity of identified meteoroid streams. We verify the surprisingly large
ratio of... | 1908.01565v2 |
2019-08-08 | High-$T_c$ Iron-phosphide Superconductivity Enhanced by Reemergent Antiferromagnetic Spin Fluctuations in (Sr$_4$Sc$_2$O$_6$)Fe$_2$(As$_{1-x}$P$_{x}$)$_2$ probed by NMR | We report a systematic NMR study on
[Sr$_4$Sc$_2$O$_6$]Fe$_2$(As$_{1-x}$P$_x$)$_2$, for which the local lattice
parameters of the iron-pnictogen (Fe$Pn$) layer are similar to those of the
series LaFe(As$_{1-x'}$P$_{x'}$)O, which exhibit two segregated
antiferromagnetic (AFM) order phases, AFM1 at $x'$=0-0.2 and AFM2 at... | 1908.02980v1 |
2019-08-09 | Abundances of alpha-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis | The atmospheric parameters and abundances of Mg, Si, Ca, and Ti have been
determined for 20 stars using the Gaia DR2 parallaxes, high-resolution spectra,
and the non-local thermodynamic equilibrium (non-LTE) line formation modeling.
A sample of stars with homogeneous data on the abundances of alpha-process
elements has... | 1908.03370v1 |
2019-09-16 | An evolving broad iron line from the first Galactic ultraluminous X-ray pulsar Swift J0243.6+6124 | We present a spectral study of the ultraluminous Be/X-ray transient pulsar
Swift J0243.6+6124 using Neutron Star Interior Composition Explorer (NICER)
observations during the system's 2017--2018 giant outburst. The 1.2--10~keV
energy spectrum of the source can be approximated with an absorbed cut-off
power law model. W... | 1909.07338v1 |
2019-11-06 | The Impact of Starbursts on Element Abundance Ratios | We investigate the impact of bursts in star formation on the predictions of
one-zone chemical evolution models, adopting oxygen (O), iron (Fe), and
strontium (Sr), as representative $\alpha$, iron-peak, and s-process elements,
respectively. To this end, we develop the Versatile Integrator for Chemical
Evolution (VICE),... | 1911.02598v1 |
2019-11-14 | Stellar population astrophysics (SPA) with the TNG. Revisiting the metallicity of Praesepe (M44) | Open clusters exquisitely track the Galactic disc chemical properties and its
time evolution; a substantial number of studies and large spectroscopic surveys
focus mostly on the chemical content of relatively old clusters (age $\gtrsim$
1 Gyr). Interestingly, the less studied young counterpart populating the solar
surr... | 1911.06337v2 |
2020-01-15 | Utilizing Essential Symmetry Breaking in Auxiliary-Field Quantum Monte Carlo: Application to the Spin Gaps of the C$_{36}$ Fullerene and an Iron Porphyrin Model Complex | We present three distinct examples where phaseless auxiliary-field Quantum
Monte Carlo (ph-AFQMC) can be reliably performed with a single-determinant
trial wavefunction with essential symmetry breaking. We first utilized
essential time-reversal symmetry breaking with ph-AFQMC to compute the
triplet-singlet energy gap i... | 2001.05109v2 |
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