Miracle-dz/UniFAR-FTUs huggingface dataset:
Present-day cosmic abundances - A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models

Aims. A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studi ed comprehensively. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established. Methods. High-resolution and high-S/N spectra of well-studied sharp-lined early B-type stars ar e analysed in non-LTE. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equi libria and the hydrogen Balmer lines, and they are confirmed by reproductio n of the stars’ global spectral energy distributions. Results. Effective temperatures are constrained to 1-2% and surface gravities to less than 15% uncertainty, along with accurate rotational, micro- and macroturbulence velocities. Good agreement of the resulting spectroscopic parallaxes with those from the new reduction of the Hipparcos catalogue is obtained. Absolute values for abundances of He, C, N, O, Ne, Mg, Si and Fe are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spe ctral range. Conclusions. A present-day cosmic abundance standard is established from a sample of 29 early B-type stars, indicating abundance fluctuations of less than 10% around the mean. Our results (i) resolve the long-standing discrepancy between a chemical homogeneous gas-phase ISM and a chemically inhomogeneous young stellar component out to several hundred parsec from the Sun, (ii) facilitate the amount of heavy elements locked up in the interstellar dust to be constrained precisely ‐ the results imply that carbo naceous dust is largely destroyed inside the Orion Hii region, unlike the silicates, and that graphite is only a min ority species in interstellar dust ‐, (iii) show that the mixing of CNO-burning products in the course of massive star evolution follows tightly the predicted nucl ear path, (iv) provide reliable present-day reference points for anchor ing Galactic chemical evolution models to observation, and (v) imply that the Sun has migrated outwards from the inner Galactic disk over its lifetime from a birthplace at a distance around 5-6 kpc from the Galactic Centre; a cancellation of the effects of Galactic chemical evolution and abundance gradients leads to the similarity of solar and present-day cosmic abundances in the solar neighbourhood, with a telltaling signature of the Sun’s origin left in th e C/O ratio. (ABRIDGED)
Few-body physics on a spacetime lattice in the worldline approach

We formulate the physics of two species of non-relativistic hard-core bosons with attractive or repulsive delta function interactions on a space-time lattice in the worldline approach. We show that worm algorithms can efficiently sample the worldline configurations in any fixed particle-number sector if the chemical potential is tuned carefully. Since fermions can be treated as hard-core bosons up to a permutation sign, we apply this approach to study non-relativistic fermions. The fermion permutation sign is an observable in this approach and can be used to extract energies in each particle-number sector. In one dimension, non-relativistic fermions can only permute across boundaries, and so our approach does not suffer from sign problems in many cases, unlike the auxiliary field method. Using our approach, we discover limitations of the recently proposed complex Langevin calculations in one spatial dimension for some parameter regimes. In higher dimensions, our method suffers from the usual fermion sign problem. Here we provide evidence that it may be possible to
Thermodynamics of strongly interacting fermions in two-dimensional optical lattices

We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two dimensions, by means of both flattening the trapping potential and increasing the interaction strength.
3D Smoothed Particle Hydrodynamics Models of Betelgeuse’s Bow Shock

Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse’s bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our models in light of the recent Herschel , GALEX and VLA observations. If the mass in the bow shock shell is low (~few × 10-3 M ⊙ ), as seems to be implied by the AKARI and Herschel observations, then Betelgeuse’s bow shock is very young and is unlikely to have reached a steady state. The circular, smooth bow shock shell is consistent with this conclusion. We further discuss the implications of our results, in particular, the possibility that Betelgeuse may have only recently entered the RSG phase.
Detection of the Ultraviolet Spectrum of the Hot Subdwarf Companion of 60 Cygni (B1 Ve) from a Survey of IUE Spectra of Be Stars

We used archival International Ultraviolet Explorer (IUE) high-dispersion, short wavelength spectra data to search for evidence of the spectra of hot subdwarf companions of six rapidly rotating Be stars in binary systems. We searched for the signature of a hot companion through an analysis of the cross-correlation functions (CCFs) of observed and model spectra that were separated into primary and secondary components using a Doppler tomography algorithm and adopted spectroscopic orbital solutions. A positive detection of the flux from a hot companion was made for the reconstructed secondary CCF of just one target, 60 Cygni (B1 Ve). We estimate that the companion of the Be star in 60 Cygni has kK, mass ratio , and monochromatic flux ratio in the spectral region near 1525 Å. If the companions of the other target Be stars are also hot, then they must be faint and contribute less than of the UV flux (<0.6% in the case of γ Cas). We also discuss a shell episode of Pleione (28 Tau) recorded in the IUE spectran in an appendix.
Multi-temporal analysis of the cover change of the Serrano forest in central Argentina through remote sensing

The Serrano forest is the least extensive type of forest in the South American Gran Chaco with a long history of human disturbance that has altered the natural vegetation. This work aims to determine and quantify the changes in Serrano forest cover in the last 30 years based on supervised classifications in three periods (1989, 2004, 2019), with main attention to native forest cover. Supervised land cover classification was performed using Landsat 5 TM and Sentinel-2A images and a spectral indices set. This classification showed a correct differentiation of the evaluated classes, resulting in adequate maps to be used in future studies on the region. Throughout the study period, substantial changes in land use and land cover were found, estimating a 22% loss of native forest in the last 30 years. The main drivers responsible to land cover changes were urbanization, expansion of exotic trees and forest fires.
STAR CLUSTERS IN M31. IV. A COMPARATIVE ANALYSIS OF ABSORPTION LINE INDICES IN OLD M31 AND MILKY WAY CLUSTERS

We present absorption line indices measured in the integrated spectra of globular clusters both from the Galaxy and from M31. Our samples include 41 Galactic globular clusters, and more than 300 clusters in M31. The conversion of instrumental equivalent widths into the Lick system is described, and zero-point uncertainties are provided. Comparison of line indices of old M31 clusters and Galactic globular clusters suggests an absence of important differences in chemical composition between the two cluster systems. In particular, CN indices in the spectra of M31 and Galactic clusters are essentially consistent with each other, in disagreement with several previous works. We reanalyze some of the previous data, and conclude that reported CN differences between M31 and Galactic clusters were mostly due to data calibration uncertainties. Our data support the conclusion that the chemical compositions of Milky Way and M31 globular clusters are not substantially different, and that there is no need to resort to enhanced nitrogen abundances to account for the optical spectra of M31 globular clusters.
Scrambling in the black hole portrait

Recently a quantum portrait of black holes was suggested according to which a macroscopic black hole is a Bose--Einstein condensate of soft gravitons stuck at the critical point of a quantum phase transition. We explain why quantum criticality and instability are the key for an efficient generation of entanglement and consequently of the scrambling of information. By studying a simple Bose--Einstein prototype, we show that the scrambling time, which is set by the quantum break time of the system, goes as $\mathrm{log}\text{ }N$ for $N$ the number of quantum constituents or equivalently the black hole entropy.
All-optical switching of photonic entanglement

Future quantum optical networks will require the ability to route entangled photons at high speeds, with minimal loss and added in-band noise, and—most importantly—without disturbing the photons' quantum state. Here we present an all-optical switch that fulfills these requirements and characterize its performance at the single-photon level. It exhibits a 200 ps switching window, 120 : 1 contrast, 1.5 dB loss, and induces no measurable degradation in the switched photons' entangled-state fidelity (<0.002). As a proof-of-principle demonstration of its capability, we use the switch to demultiplex a single quantum channel from a dual-channel, time-division-multiplexed entangled photon stream. Furthermore, because this type of switch couples the temporal and spatial degrees of freedom, it provides an important new tool with which to encode multiple-qubit quantum states on a single photon.
RECONCILING THE GAMMA-RAY BURST RATE AND STAR FORMATION HISTORIES

While there are numerous indications that gamma-ray bursts (GRBs) arise from the deaths of massive stars, the GRB rate does not follow the global cosmic star formation rate and, within their hosts, GRBs are more concentrated in regions of very high star formation. We explain both puzzles here. Using the publicly available VESPA database of the Sloan Digital Sky Survey (SDSS) Data Release 7 spectra, we explore a multi-parameter space in galaxy properties such as stellar mass, metallicity, and dust to find the subset of galaxies that reproduces the GRB rate recently obtained by Wanderman & Piran. We find that only galaxies with present stellar masses below <1010 M☉ and low metallicity reproduce the observed GRB rate. This is consistent with direct observations of GRB hosts and provides an independent confirmation of the nature of GRB hosts. Because of the significantly larger sample of SDSS galaxies, we compute their correlation function and show that they are anti-biased with respect to dark matter: they are in filaments and voids. Using recent observations of massive stars in local dwarfs we show how the fact that GRB host galaxies are dwarfs can explain the observation that GRBs are more concentrated in regions of high star formation than are supernovae. Finally, we explain these results using new theoretical advances in the field of star formation.
Hole and electron contributions to the transport properties of Ba ( Fe 1 − x Ru x ) 2 As 2 single crystals

We report a systematic study of structural and transport properties in single crystals of $\text{Ba}{({\text{Fe}}_{1\ensuremath{-}x}{\text{Ru}}_{x})}_{2}{\text{As}}_{2}$ for $x$ ranging from 0 to 0.5. The isovalent substitution of Fe by Ru leads to an increase in the $a$ parameter and a decrease in the $c$ parameter, resulting in a strong increase in the As-Fe-As angle and a decrease in the As height above the Fe planes. On Ru substitution, the magnetic order is progressively suppressed and superconductivity emerges for $x\ensuremath{\ge}0.15$ with an optimal ${T}_{c}\ensuremath{\simeq}20\text{ }\text{K}$ at $x=0.35$ and coexistence of magnetism and superconductivity between these two Ru contents. Moreover, the Hall coefficient ${R}_{H}$, which is always negative and decreases with temperature in ${\text{BaFe}}_{2}{\text{As}}_{2}$, is found to increase here with decreasing $T$ and even changes sign for $x\ensuremath{\ge}0.20$. For ${x}_{\text{Ru}}=0.35$, photoemission studies have shown that the number of holes and electrons are similar with ${n}_{e}={n}_{h}\ensuremath{\simeq}0.11$ carriers/Fe, that is twice larger than found in ${\text{BaFe}}_{2}{\text{As}}_{2}$ [V. Brouet, F. Rullier-Albenque, M. Marsi, B. Mansart, J. Faure, L. Perfetti, A. Taleb-Ibrahimi, P. Le F\`evre, F. Bertran, A. Forget, and D. Colson, arXiv:1002.4952 (unpublished)]. Using this estimate, we find that the transport properties of $\text{Ba}{({\text{Fe}}_{0.65}{\text{Ru}}_{0.35})}_{2}{\text{As}}_{2}$ can be accounted for by the conventional multiband description for a compensated semimetal. In particular, our results show that the mobility of holes is strongly enhanced on Ru addition and overcomes that of electrons at low temperature when ${x}_{\text{Ru}}\ensuremath{\ge}0.15$.
Spectroscopic Pulsational Frequency and Mode Determination of the γ Doradus Star HD 189631

Abstract We present improvement and confirmation of identified frequencies and pulsation modes for the γ Doradus star HD 189631. This work improves upon previous studies by incorporating a significant number of additional spectra and precise determination of frequencies. Four frequencies were identified for this star: 1.6774 ± 0.0002 d−1, 1.4174 ± 0.0002 d−1, 0.0714 ± 0.0002 d−1, and 1.8228 ± 0.0002 d−1 which were identified with the modes (l,m) = (1, +1), (1, +1), (2, −2), and (1, +1) respectively. These findings are in agreement with the most recent literature. The prevalence of (l,m) = (1, +1) modes in γ Doradus stars is starting to become apparent and we discuss this result.
DETECTION OF PLASMA FLUCTUATIONS IN WHITE-LIGHT IMAGES OF THE OUTER SOLAR CORONA: INVESTIGATION OF THE SPATIAL AND TEMPORAL EVOLUTION

This work focuses on the first results from the identification and characterization of periodic plasma density fluctuations in the outer corona, observed in STEREO-A COR1 white-light image time series. A two-dimensional reconstruction of the spatial distribution and temporal evolution of the coronal fluctuation power has been performed over the whole plane of the sky, from 1.4 to 4.0 R☉. The adopted diagnostic tool is based on wavelet transforms. This technique, with respect to the standard Fourier analysis, has the advantage of localizing non-persistent fluctuating features and exploring variations of the relating wavelet power in both space and time. The map of the variance of the coronal brightness clearly outlines intermittent spatially coherent fluctuating features, localized along, or adjacent to, the strongest magnetic field lines. In most cases, they do not correspond to the visible coronal structures in the brightness maps. The results obtained provide a scenario in which the solar corona shows quasi-periodic, non-stationary density variations characterized by a wide range of temporal and spatial scales and strongly confined by the magnetic field topology. In addition, structures fluctuating with larger power are larger in size and evolve more slowly. The characteristic periodicities of the fluctuations are comparable to their lifetimes. This suggests that plasma fluctuations lasting only one or two wave periods and initially characterized by a single dominant periodicity either rapidly decay into a turbulent mixed flow via nonlinear interactions with other plasma modes, or they are damped by thermal conduction. The periodic non-stationary coronal fluctuations outlined by the closed field lines at low and mid latitudes might be associated with the existence of slow standing magneto-acoustic waves excited by the convective supergranular motion. The fluctuating ray-like structures observed along open field lines appear to be linked either to the intermittent nature of the processes underlying the generation of magnetic reconnection in the polar regions or to the oscillatory transverse displacements of the coronal ray itself.
VUV-Vis optical characterization of Tetraphenyl-butadiene films on glass and specular reflector substrates from room to liquid Argon temperature

The use of efficient wavelength-shifters from the vacuum-ultraviolet to the photo-sensor's range of sensitivity is a key feature in detectors for Dark Matter search and neutrino physics based on liquid argon scintillation detection. Thin film of Tetraphenyl-butadiene (TPB) deposited onto the surface delimiting the active volume of the detector and/or onto the photosensor optical window is the most common solution in current and planned experiments. Detector design and response can be evaluated and correctly simulated only when the properties of the optical system in use (TPB film + substrate) are fully understood. Characterization of the optical system requires specific, sometimes sophisticated optical methodologies. In this paper the main features of TPB coatings on different, commonly used substrates is reported, as a result of two independent campaigns of measurements at the specialized optical metrology labs of ENEA and University of Tor Vergata. Measured features include TPB emission spectra with lineshape and relative intensity variation recorded as a function of the film thickness and for the first time down to LAr temperature, as well as optical reflectance and transmittance spectra of the TPB coated substrates in the wavelength range of the TPB emission.
Implications upon theory discrimination of an accurate measurement of the time rate of change of the gravitational “constant” G and other cosmological parameters

A substantial improvement in the accuracy of ˙ G tests (The dot denotes the time derivative.) would make it realistic to speak in terms of a measurement of ˙G , rather than merely a smaller upper bound on | ˙G|. We show that the accuracy Δ | ˙G/G|≈︁ 10‐14 yr‐1 may be sufficient, given the accuracy of other cosmological parameters, to observe effects predicted by higher dimensions theories and, hence, to discriminate among different models. The ˙G design goal for the SEE (Satellite Energy Exchange) mission is Δ (˙G/G) ≈︁ 10‐14 yr‐1.
Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations

Binary populations in young star clusters show multiplicit y fractions both lower and up to twice as high as those observed in the Galactic field. We follow the evolution of a population of bin ary stars in dense and loose star clusters starting with an in variant initial binary population and a formal multiplicity fracti on of unity, and demonstrate that these models can explain the observed binary properties in Taurus, ρ Ophiuchus, Chamaeleon, Orion, IC 348, Upper Scorpius A, Praesepe, and the Pleiades. The model needs to consider solely different birth densities for these regions. The evolved theore tical orbital-parameter distributions are highly probable parent distributions for the observed ones. We con strain the birth conditions (stellar mass, Mecl, and half-mass radius, rh) for the derived progenitors of the star clusters and the over all present-day binary fractions allowed by the present model. The results compare very well with properties of molecular cloud clumps on the verge of star formation. Combining these with previously and independently obtained constraints on the birth densities of globular clusters, we identify a weak stellar mass ‐ half- mass radius correlation for cluster-forming cloud clumps, rh/pc∝ (Mecl/M⊙) 0.13±0.04 . The ability of the model to reproduce the binary properties in all the investigated young objects, covering present-da y densities from 1− 10 stars pc −3 (Taurus) to 2× 10 4 stars pc −3 (Orion), suggests that environment-dependent dynamical evolution plays an important role in shaping the present-day properti es of binary populations in star clusters, and that the initial binary pr operties may not vary dramatically between different environments.
Ranking the Importance of Nuclear Reactions for Activation and Transmutation Events

Abstract Pathways-reduced analysis is one of the techniques used by the FISPACT-II nuclear activation and transmutation software to study the sensitivity of the computed inventories to uncertainties in reaction cross sections. Although deciding which pathways are most important is very helpful in for example determining which nuclear data would benefit from further refinement, pathways-reduced analysis need not necessarily define the most critical reaction, since one reaction may contribute to several different pathways. This work examines three different techniques for ranking reactions in their order of importance in determining the final inventory, comparing the pathways-based metric (PBM), the direct method, and a method based on the Pearson correlation coefficient. Reasons why the PBM is to be preferred are presented.
$|V_{ub}|$ determination in lattice QCD

The 2012 PDG reports a tension at the level of $3 \sigma$ between two exclusive determinations of $|V_{ub}|$. They are obtained by combining the experimental branching ratios of $B \to \tau \nu$ and $B \to \pi l \nu$ (respectively) with a theoretical computation of the hadronic matrix elements $\fB$ and the $B \to \pi$ form factor $f_+(q^2)$. To understand the tension, improved precision and a careful analysis of the systematics involved are necessary. We report the results of the ALPHA collaboration for $\fB$ from the lattice with 2 flavors of $O(a)$ improved Wilson fermions. We employ HQET, including $1/m_b$ corrections, with pion masses ranging down to $\approx$ 190 MeV. Renormalization and matching were performed non-perturbatively, and three lattice spacings reaching $a^{-1}\approx 4.1$ GeV are used in the continuum extrapolation. We also present progress towards a computation of $f_+(q^2)$, to directly compare two independent exclusive determinations of $|V_{ub}|$ with each other and with inclusive determinations. Additionally, we report on preliminary results for $\fBq{s}$, needed for the analysis of $B_s \to \mu^+\mu^-$. }
Surface acoustic wave modes in two-dimensional shallow void inclusion phononic crystals on GaAs

Surface acoustic waves in two-dimensional phononic crystals consisting of a square array of shallow, two to three micron deep cylindrical void inclusions are studied computationally via the finite element method. For the [110] propagation direction on a (001) GaAs half-space, the conventional Rayleigh wave modes, the layered substrate-associated Sezawa and Lamb modes, the high frequency longitudinal surface waves and bulk waves exhibit hybridization and modal interaction. The longitudinal, vertical shear and horizontal shear bulk wave dispersions are observed to be significant thresholds for surface acoustic waves on a shallow phononic crystal. This results in dramatic changes in the attenuation and surface boundedness properties that enable supersonic modes with diminished attenuation in otherwise largely bulk wave-radiative dispersion branch continua of modes.