Miracle-dz/UniFAR-FTUs huggingface dataset:
The course of the Orphan Stream in the Northern Galactic hemisphere traced with Gaia DR2

The Orphan Stream is one of the most prominent tidal streams in the Galactic halo. Using data on red giants, RR Lyrae, and horizontal branch stars from Gaia and other surveys, we determine the proper motion of the Orphan Stream over a path of more than 90° on the sky. We also provide updated tracks for the sky position, distance, and radial velocity of the stream. Our tracks in these latter dimensions mostly agree with previous results. However, there are significant corrections to the earlier distance and latitude tracks as the stream approaches the Galactic disc. Stream stars selected with three-dimensional kinematics display a very tight red giant sequence. Concordantly, we find that applying a proper motion cut removes the most metal-rich stars from earlier spectroscopic samples of stream stars, though a significant dispersion remains, indicating a dwarf galaxy origin. The deceleration of the stream towards its leading end suggests a circular velocity of $\sim \! 200 \, \mbox{km}\, \mbox{s}^{-1}$ at a galactocentric radius $\sim \! 30 \, \mbox{kpc}$, consistent with other independent evidence. However, the track of the stream departs significantly from an orbit; the spatial track does not point along the same direction as the velocity vector, and it exhibits a lateral wiggle that is unlikely to match any reasonable orbit. The low metallicity and small dispersion of the stream in the various coordinates point to a progenitor with a relatively low dynamical mass $\sim \! 10^8 \, \mathrm{ M}_{\odot }$.
Circumstellar Disks and Outflows in Turbulent Molecular Cloud Cores: Possible Formation Mechanism for Misaligned Systems

We investigate the formation of circumstellar disks and outflows subsequent to the collapse of molecular cloud cores with the magnetic field and turbulence. Numerical simulations are performed by using an adaptive mesh refinement to follow the evolution up to ∼1000 years after the formation of a protostar. In the simulations, circumstellar disks are formed around the protostars; those in magnetized models are considerably smaller than those in nonmagnetized models, but their size increases with time. The models with stronger magnetic fields tend to produce smaller disks. During evolution in the magnetized models, the mass ratios of a disk to a protostar is approximately constant at ∼1%–10%. The circumstellar disks are aligned according to their angular momentum, and the outflows accelerate along the magnetic field on the 10–100 au scale; this produces a disk that is misaligned with the outflow. The outflows are classified into two types: a magnetocentrifugal wind and a spiral flow. In the latter, because of the geometry, the axis of rotation is misaligned with the magnetic field. The magnetic field has an internal structure in the cloud cores, which also causes misalignment between the outflows and the magnetic field on the scale of the cloud core. The distribution of the angular momentum vectors in a core also has a non-monotonic internal structure. This should create a time-dependent accretion of angular momenta onto the circumstellar disk. Therefore, the circumstellar disks are expected to change their orientation as well as their sizes in the long-term evolutions.
Grapesph: cosmological smoothed particle hydrodynamics simulations with the special-purpose hardware GRAPE

A combined N--body/SPH code is presented which benefits from the high speed of the special purpose hardware GRAPE (GRAvity PipE). Besides gravitational forces, GRAPE also returns the list of neighbours and can, therefore, be used to speed up the hydrodynamical part, too. After the interaction list has been passed, density, pressure forces, propagation and interpolation of particles etc. are calculated on the front end, a 50 MHz SUN SPARC 10. In order to combine SPH and GRAPE, possible limitations due to the hardware design of GRAPE are carefully analyzed and modifications compared to current SPH codes are discussed. The resulting code, GRAPESPH, is similarly flexible as TREESPH. It seems especially well suited to investigate the formation of individual objects in a large scale structure environment, like eg. galaxies or clusters. The total performance is at least half as good as treesph on a CRAY and for most applications it seems to be even better. The CPU time per time step is only slightly dependent on the clustering state. GRAPESPH, therefore, provides a very attractive alternative to the use of supercomputers in cosmology.
On the importance of progenitor asymmetry to shock revival in core-collapse supernovae

The progenitor stars of core-collapse supernovae (CCSNe) are asymmetrically fluctuating due to turbulent convections in the late stages of their lives. The progenitor asymmetry at the pre-supernova stage has recently caught the attention as a new ingredient to facilitate shock revival in the delayed neutrino-heating mechanism. In this paper, we investigate the importance of the progenitor asymmetries to shock revival with a semi-analytical approach. Free parameters were chosen such that the time evolution of shock radii and mass accretion rates are compatible with the results of detailed numerical simulations of CCSNe in spherical symmetry. We first estimate the amplitude of asymmetries required for the shock revival by the impulsive change of pre-shock flows in the context of neutrino heating mechanism, and then convert the amplitude to the corresponding amplitude in the pre-supernova phase by taking into account the growth of asymmetries during infall. We apply our model to various types of progenitors and find that the requisite amplitude of pre-supernova asymmetry is roughly three times larger than the prediction by current stellar evolution models unless other additional physical ingredients such as multi-dimensional fluid instabilities and turbulent convections in post-shock flows aid shock revival. We thus conclude that progenitor asymmetries can not trigger the shock revival by the impulsive way but rather play a supplementary role in reality.
Elastic Constants of D2O Ice and Variation of Intermolecular Forces on Deuteration

The elastic constants of D2O ice have been measured between 0° and −140°C. From these data and the elastic constants of H2O ice, the molecular force constants—K for change of bond length and G for change of 0⋯0⋯0 angle—have been calculated. K and G show a similar temperature dependence as the elastic constants; their absolute values enlarge on deuteration. For comparison, values of K and G calculated from infrared data are given.
Spectral properties of MXB 1658–298 in the low/hard and high/soft state

We report results from a broadband spectral analysis of the low mass X-ray binary MXB 1658-298 with the Swift/XRT and NuSTAR observations made during its 2015-2017 outburst. The source showed different spectral states and accretion rates during this outburst. The source was in low/hard state during 2015; and it was in high/soft state during the 2016 NuSTAR observations. This is the first time that a comparison of the soft and hard spectral states during an outburst is being reported in MXB 1658-298. Compared with the observation of 2015, the X-ray luminosity was about four times higher during 2016. The hard state spectrum can be well described with models consisting of a single-temperature blackbody component along with Comptonized disc emission, or three component model comprising of multi-colour disc, single-temperature blackbody and thermal Comptonization components. The soft state spectrum can be described with blackbody or disc blackbody and Comptonization component, where the neutron star surface (or boundary layer) is the dominant source for the Comptonization seed photons. We have also found a link between the spectral state of the source and the Fe K absorber. The absorption features due to highly ionized Fe were observed only in the soft state. This suggests a probable connection between accretion disc wind (or atmosphere) and spectral state (or accretion state) of MXB 1658-298.
Central Stars of Planetary Nebulae

Abstract In this brief invited review, I will attempt to summarise some of the key areas of interest in the study of central stars of planetary nebulae which (probably) will not be covered by other speakers’ proceedings. The main focus will, inevitably, be on the subject of multiplicity, with special emphasis on recent results regarding triple central star systems as well as wide binaries which avoid a common-envelope phase. Furthermore, in light of the upcoming release of Kepler’s Campaign 11 data, I will discuss a few of the prospects from that data including the unique possibility to detect merger products.
Approach for the fabrication of MgB2 superconducting tape with large in-field transport critical current density

The letter reports the fabrication of MgB2 superconducting tape using a flexible metallic substrate as well as its strong pinning force, which was verified by direct measurement of transport critical current density. The tape was prepared by depositing MgB2 film on a Hastelloy tape buffered with an yttria-stabilized-zirconia layer. The Jc of the tape exceeds 105 A/cm2 at 4.2 K and 10 T, which is considered as a common benchmark for magnet application. The Jc dependence on magnetic field remains surprisingly very small up to 10 T, suggesting that the tape has much better magnetic field characteristic than conventional Nb–Ti wires in liquid helium.
Random field Ising-like effective theory of the glass transition. II. Finite-dimensional models

As in the preceding paper we aim at identifying the effective theory that describes the fluctuations of the local overlap with an equilibrium reference configuration close to a putative thermodynamic glass transition. We focus here on the case of finite-dimensional glass-forming systems, in particular supercooled liquids. The main difficulty for going beyond the mean-field treatment comes from the presence of diverging point-to-set spatial correlations. We introduce a variational low-temperature approximation scheme that allows us to account, at least in part, for the effect of these correlations. The outcome is an effective theory for the overlap fluctuations in terms of a random-field + random-bond Ising model with additional, power-law decaying, pair and multi-body interactions generated by the point-to-set correlations. This theory is much more tractable than the original problem. We check the robustness of the approximation scheme by applying it to a fully connected model already studied in the companion paper. We discuss the physical implications of this mapping for glass-forming liquids and the possibility it offers to determine the presence or not of a finite-temperature thermodynamic glass transition.
Electric-field-induced phase switching in the lead free piezoelectric potassium sodium bismuth titanate

High-energy synchrotron radiation has been used to demonstrate an electric-field-induced phase transformation in the ceramic xK1/2Bi1/2TiO3–(1−x)Na1/2Bi1/2TiO3, x=0.2. Application of an electric field ≥2 kV mm−1 leads to a transformation from single phase rhombohedral to a mixture of tetragonal and rhombohedral phases. The texturing of the tetragonal phase increases with field strength. The electric-field-induced transformation suggests an excursion into the morphotropic phase boundary in this system. The compositions x=0.1 and 0.3 reveal rhombohedral and tetragonal symmetry, respectively, both before and after the application of an electric field.
The Galactic 26Al Problem and the Close Binary Type Ib/c Supernova Solution?

The origin of the long-lived (1.07 Myr mean life) radioactive 26Al, which has been observed in the Galactic interstellar medium from its 1.809 MeV decay gamma-ray line emission, has been a persistent problem for over 20 years. Wolf-Rayet (W-R) winds were thought to be the most promising source, but their calculated 26Al yields are not consistent with recent analyses of the 1.809 MeV emission from the nearest W-R star and nearby OB associations. The expected 26Al yield from the W-R star exceeds, by as much as a factor of 3, that set by the 2 σ upper limit on the 1.809 MeV emission, while the W-R yields in the OB associations are only about of that required by the 1.809 MeV emission. We suggest that a solution to these problems may lie in 26Al from a previously ignored source: explosive nucleosynthesis in the core-collapse Type Ib/c supernovae (SNe Ib/c) of W-R stars that have lost most of their mass to close binary companions. Recent nucleosynthetic calculations of SNe Ib/c suggest that their 26Al yields depend very strongly on the final pre-SN mass of the W-R star and that those with final masses around 6-8 M☉ are expected to produce as much as 10-2 M☉ of 26Al per SN. Such binary SNe Ib/c make up only a small fraction of the current SNe Ib/c and only about 1% of all Galactic core-collapse SNe. But they appear to be such prolific sources that the bulk of the present 26Al in the Galaxy may come from just a few hundred close binary SNe Ib/c, and the intense 1.809 MeV emission from nearby OB associations may come from just one or two such SNe. More extensive SN Ib/c calculations of the 26Al yields versus pre-SN mass are clearly needed to test this possibility.
Dust-driven viscous ring-instability in protoplanetary disks

Protoplanetary disks often appear as multiple concentric rings in dust continuum emission maps and scattered light images. These features are often associated with possible young planets in these disks. Many non-planetary explanations have also been suggested, including snow lines, dead zones and secular gravitational instabilities in the dust. In this paper we suggest another potential origin. The presence of copious amounts of dust tends to strongly reduce the conductivity of the gas, thereby inhibiting the magneto-rotational instability, and thus reducing the turbulence in the disk. From viscous disk theory it is known that a disk tends to increase its surface density in regions where the viscosity (i.e. turbulence) is low. Local maxima in the gas pressure tend to attract dust through radial drift, increasing the dust content even more. We investigate mathematically if this could potentially lead to a feedback loop in which a perturbation in the dust surface density could perturb the gas surface density, leading to increased dust drift and thus amplification of the dust perturbation and, as a consequence, the gas perturbation. We find that this is indeed possible, even for moderately small dust grain sizes, which drift less efficiently, but which are more likely to affect the gas ionization degree. We speculate that this instability could be triggered by the small dust population initially, and when the local pressure maxima are strong enough, the larger dust grains get trapped and lead to the familiar ring-like shapes. We also discuss the many uncertainties and limitations of this model.
A nonlinear theory for fibre-reinforced magneto-elastic rods

We derive a model for the finite motion of a fibre-reinforced magneto-elastic rod. The reinforcing particles are assumed weakly and uniformly magnetized, rigid and firmly embedded into the elastomeric matrix. We deduce closed-form expressions of the quasi-static motion of the rod in terms of the external magnetic field and of the body forces. The dependences of the motion on the shape of the inclusions, their orientation, their anisotropic magnetic properties and the Young modulus of the matrix are analysed and discussed. Two case studies are presented, in which the rod is used as an actuator suspended in a cantilever configuration. This work can foster new applications in the field of soft-actuators.
Updated Masses for the TRAPPIST-1 Planets

The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30\% to nearly 100\%, with the mass of the outermost, $P=18.8\,{\rm d}$, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding $e<0.02$ for inner six known members of the system), and we derive masses of $0.79\pm 0.27 \,M_{\oplus}$, $1.63\pm 0.63\,M_{\oplus}$, $0.33\pm 0.15\,M_{\oplus}$, $0.24^{+0.56}_{-0.24}\,M_{\oplus}$, $0.36\pm 0.12\,M_{\oplus}$, $0.566\pm 0.038\,M_{\oplus}$, and $0.086\pm 0.084\,M_{\oplus}$ for planets b, c, d, e, f, g, and h, respectively.
Optical fluxes in coupled PT-symmetric photonic structures

In this work we first examine transverse and longitudinal fluxes in a $\cal PT$-symmetric photonic dimer using a coupled-mode theory. Several surprising understandings are obtained from this perspective: The longitudinal flux shows that the $\cal PT$ transition in a dimer can be regarded as a classical effect, despite its analogy to $\cal PT$-symmetric quantum mechanics. The longitudinal flux also indicates that the so-called giant amplification in the $\cal PT$-symmetric phase is a sub-exponential behavior and does not outperform a single gain waveguide. The transverse flux, on the other hand, reveals that the apparent power oscillations between the gain and loss waveguides in the $\cal PT$-symmetric phase can be deceiving in certain cases, where the transverse power transfer is in fact unidirectional. We also show that this power transfer cannot be arbitrarily fast even when the exceptional point is approached. Finally, we go beyond the coupled-mode theory by using the paraxial wave equation and also extend our discussions to a $\cal PT$ diamond and a one-dimensional periodic lattice.
Origin of the wide-orbit circumbinary giant planet HD 106906 - A dynamical scenario and its impact on the disk

A giant planet has been recently resolved at a projected distance of 730 au from the tight pair of young ($\sim$ 13 Myr) intermediate-mass stars HD 106906AB in the Lower Centaurus Crux (LCC) group. The stars are surrounded by a debris disk which displays a ring-like morphology and strong asymmetries at multiple scales. We aim at studying the likelihood of a scenario where the planet formed closer to the stars in the disk, underwent inward disk-induced migration, and got scattered away by the binary star before being stabilized by a close encounter (fly-by). We performed semi-analytical calculations and numerical simulations (Swift_HJS package) to model the interactions between the planet and the two stars. We accounted for the migration as a simple force. We studied the LCC kinematics to set constraints on the local density of stars, and therefore on the fly-by likelihood. We performed N-body simulations to determine the effects of the planet trajectories (ejection and secular effects) onto the disk morphology. The combination of the migration and mean-motion resonances with the binary star (often 1:6) can eject the planet. Nonetheless, we estimate that the fly-by hypothesis decreases the scenario probability to less than $10^{-7}$ for a derived local density of stars of 0.11 stars/pc$^{3}$. We show that the concomitant effect of the planet and stars trajectories induce spiral-features in the disk which may correspond to the observed asymmetries. Moreover, the present disk shape suggests that the planet is on an eccentric orbit. The scenario we explored is a natural hypothesis if the planet formed within a disk. Conversely, its low probability of occurrence and the fact that HD 106906 b shares some characteristics with other systems in Sco-Cen (e.g. HIP 78530, in terms of mass ratio and separation) may indicate an alternative formation pathway for those objects.
Fundamental Physics with the Hubble Frontier Fields: Constraining Dark Matter Models with the Abundance of Extremely Faint and Distant Galaxies

We show that the measured abundance of ultra-faint lensed galaxies at z ≈ 6 in the Hubble Frontier Fields (HFF) provides stringent constraints on the parameter space of (i) dark matter models based on keV sterile neutrinos; (ii) “fuzzy” wavelike dark matter models, based on Bose–Einstein condensates of ultra-light particles. For the case of sterile neutrinos, we consider two production mechanisms: resonant production through mixing with active neutrinos and the decay of scalar particles. For the former model, we derive constraints for the combination of sterile neutrino mass m ν and mixing parameter sin 2 ( 2 θ ) which provide the tightest lower bounds on the mixing angle (and hence on the lepton asymmetry) derived so far by methods independent of baryonic physics. For the latter we compute the allowed combinations of the scalar mass, its coupling to the Higgs field, and the Yukawa coupling of scalar to sterile neutrinos. We compare our results to independent existing astrophysical bounds on sterile neutrinos in the same mass range. For the case of “fuzzy” dark matter, we show that the observed number density ≈ 1 / Mpc 3 of high-redshift galaxies in the HFF sets a lower limit m ψ ≥ 8 · 10 − 22 eV (at the 3-σ confidence level) on the particle mass, a result that strongly disfavors wavelike bosonic dark matter as a viable model for structure formation. We discuss the impact on our results of uncertainties due to systematics in the selection of highly magnified, faint galaxies at high redshift.
Phase-Transition Theory of Instabilities. II. Fourth-Harmonic Bifurcations and Lambda-Transitions

We use a free-energy minimization approach to describe the secular and dynamical instabilities as well as the bifurcations along equilibrium sequences of rotating, self-gravitating fluid systems. Our approach is fully nonlinear and stems from the Ginzburg-Landau theory of phase transitions. In this paper, we examine fourth-harmonic axisymmetric disturbances in Maclaurin spheroids and fourth-harmonic nonaxisymmetric disturbances in Jacobi ellipsoids. These two cases are very similar in the framework of phase transitions. Irrespective of whether a nonlinear first-order phase transition occurs between the critical point and the higher turning point or an apparent second-order phase transition occurs beyond the higher turning point, the result is fission (i.e. ``spontaneous breaking'' of the topology) of the original object on a secular time scale: the Maclaurin spheroid becomes a uniformly rotating axisymmetric torus and the Jacobi ellipsoid becomes a binary. The presence of viscosity is crucial since angular momentum needs to be redistributed for uniform rotation to be maintained. The phase transitions of the dynamical systems are briefly discussed in relation to previous numerical simulations of the formation and evolution of protostellar systems.