Miracle-dz/UniFAR-FTUs huggingface dataset:
THE BROWN DWARF KINEMATICS PROJECT (BDKP). IV. RADIAL VELOCITIES OF 85 LATE-M AND L DWARFS WITH MagE

Radial velocity measurements are presented for 85 late M- and L-type very low-mass stars and brown dwarfs obtained with the Magellan Echellette spectrograph. Targets primarily have distances within 20 pc of the Sun, with more distant sources selected for their unusual spectral energy distributions. We achieved precisions of 2–3 km s−1, and combined these with astrometric and spectrophotometric data to calculate UVW velocities. Most are members of the thin disk of the Galaxy, and velocity dispersions indicate a mean age of 5.2 ± 0.2 Gyr for sources within 20 pc. We find signficantly different kinematic ages between late-M dwarfs (4.0 ± 0.2 Gyr) and L dwarfs (6.5 ± 0.4 Gyr) in our sample that are contrary to predictions from prior simulations. This difference appears to be driven by a dispersed population of unusually blue L dwarfs which may be more prevalent in our local volume-limited sample than in deeper magnitude-limited surveys. The L dwarfs exhibit an asymmetric U velocity distribution with a net inward flow, similar to gradients recently detected in local stellar samples. Simulations incorporating brown dwarf evolution and Galactic orbital dynamics are unable to reproduce the velocity asymmetry, suggesting non-axisymmetric perturbations or two distinct L dwarf populations. We also find the L dwarfs to have a kinematic age-activity correlation similar to more massive stars. We identify several sources with low surface gravities, and two new substellar candidate members of nearby young moving groups: the astrometric binary DENIS J08230313–4912012AB, a low-probability member of the β Pictoris Moving Group; and 2MASS J15104786–2818174, a moderate-probability member of the 30–50 Myr Argus Association.
C, S, Zn and Cu abundances in planet-harbouring stars ,

We present a detailed and uniform study of C, S, Zn and Cu abundances in a large set of planet host stars, as well as in a homogeneous comparison sample of solar-type dwarfs with no known planetary-mass companions. Carbon abundances were derived by EW measurement of two C  optical lines, while spectral syntheses were performed for S, Zn and Cu. We investigated possible differences in the behaviours of the volatiles C, S and Zn and in the refractory Cu in targets with and without known planets in order to check possible anomalies due to the presence of planets. We found that the abundance distributions in stars with exoplanets are the high (Fe/H) extensions of the trends traced by the comparison sample. All volatile elements we studied show (X/Fe) trends decreasing with (Fe/H) in the metallicity range −0.8 < (Fe/H) < 0.5, with significantly negative slopes of −0.39 ± 0.04 and −0.35 ± 0.04 for C and S, respectively. A comparison of our abundances with those available in the literature shows good agreement in most cases.
A machine learning based control of complex systems

In this work, inspired in the symbolic dynamic of chaotic systems and using machine learning techniques, a control strategy for complex systems is designed. Unlike the usual methodologies based on modeling, where the control signal is obtained from an approximation of the dynamic rule, here the strategy rest upon an approach of a function, that from the current state of the system, give the necessary perturbation to bring the system closer to a homoclinic orbit that naturally goes to the target. The proposed methodology is data-driven or can be developed in a based-model context and is illustrated with computer simulations of chaotic systems given by discrete maps, ordinary differential equations and coupled maps networks. Results shows the usefulness of the design of control techniques based on machine learning and numerical approach of homoclinic orbits.
DENSITY JUMPS NEAR THE VIRIAL RADIUS OF GALAXY CLUSTERS

Recent simulations have indicated that the dark matter halos of galaxy clusters should feature steep density jumps near the virial radius. Since the member galaxies are expected to follow similar collisionless dynamics as the dark matter, the galaxy density profile should show such a feature as well. We examine the potential of current data sets to test this prediction by selecting cluster members for a sample of 56 low-redshift ( ) galaxy clusters, constructing their projected number density profiles, and fitting them with two profiles, one with a steep density jump and one without. Additionally, we investigate the presence of a jump using a non-parametric spline approach. We find that some of these clusters show strong evidence for a model with a density jump, with the strength of the signal increasing with the inclusion of spectroscopic cluster member identification. We discuss avenues for further analysis of the density jump with future data sets, particularly with the inclusion of additional spectroscopy of cluster outskirts.
On the Disclination Lines of Nematic Liquid Crystals

Defects in liquid crystals are of great practical importance and theoretical interest. Despite tremendous efforts, predicting the location and transition of defects under various topological constraint and external field remains to be a challenge. We investigate defect patterns of nematic liquid crystals confined in three-dimensional spherical droplet and two-dimensional disk under different boundary conditions, within the Landau-de Gennes model. We implement a spectral method that numerically solves the Landau-de Gennes model with high accuracy, which allows us to study the detailed static structure of defects. We observe five types of defect structures. Among them the 1/2-disclination lines are the most stable structure at low temperature. Inspired by numerical results, we obtain the profile of disclination lines analytically. Moreover, the connection and difference between defect patterns under the Landau-de Gennes model and the Oseen-Frank model are discussed. Finally, four conjectures are made to summarize some important characteristics of defects in the Landau-de Gennes theory. This work is a continuing effort to deepen our understanding on defect patterns in nematic liquid crystals.
Spectropolarimetry of the 2012 outburst of SN 2009ip: a bi-polar explosion in a dense, disk-like CSM

We present a sequence of eight spectropolarimetric observations monitoring the geometric evolution of the late phase of the major 2012 outburst of SN 2009ip. These were acquired with the FORS2 polarimeter mounted on ESO VLT. The continuum was polarised at 0.3-0.8 per cent throughout the observations, showing that the photosphere deviated substantially from spherical symmetry by 10-15 per cent. Significant line polarisation is detected for both hydrogen and helium at high velocities. The similarity in the polarised signal between these elements indicates that they form in the same location in the ejecta. The line polarisation (p$\sim$1-1.5 per cent) at low velocities revealed the presence of a highly-aspherical hydrogen and helium rich circumstellar medium (CSM). Monte Carlo simulations of the observed polarimetry were performed in an effort to constrain the shape of the CSM. The simulations imply that the polarimetry can be understood within the framework of a disk-like CSM inclined by 14$\pm$2 degrees out of the line of sight, obscuring the photosphere only at certain epochs. The varying temporal evolution of polarisation at high and low velocities indicated that the fast-moving ejecta expanded with a preferred direction orthogonal to that of the CSM.
Star-disk interaction in classical T Tauri stars revealed using wavelet analysis

The extension of the corona of classical T Tauri stars (CTTS) is under discussion. The standard model of magnetic configuration of CTTS predicts that coronal magnetic flux tubes connect the stellar atmosphere to the inner region of the disk. However, differential rotation may disrupt these long loops. The results from Hydrodynamic modeling of X-ray flares observed in CTTS confirming the star-disk connection hypothesis are still controversial. Some authors suggest the presence of the accretion disk prevent the stellar corona to extent beyond the co-rotation radius, while others simply are not confident with the methods used to derive loop lengths. We use independent procedures to determine the length of flaring loops in stars of the Orion Nebula Cluster previously analyzed using Hydrodynamic models. Our aim is to disentangle between the two scenarios proposed. We present a different approach to determine the length of flaring loops based on the oscillatory nature of the loops after strong flares. We use wavelet tools to reveal oscillations during several flares. The subsequent analysis of such oscillations is settle on the Physics of coronal seismology. Our results likely confirm the large extension of the corona of CTTS and the hypothesis of star-disk magnetic interaction in at least three CTTS of the Orion Nebula Cluster. Analyzing oscillations in flaring events is a powerful tool to determine the physical characteristics of magnetic loops in coronae in stars other than the Sun. The results presented in this work confirm the star-disk magnetic connection in CTTS.
Extended stellar substructure surrounding the Boötes I dwarf spheroidal galaxy

We present deep stellar photometry of the Bootes I dwarf spheroidal galaxy in g and i band filters, taken with the Dark Energy Camera at Cerro Tololo in Chile. Our analysis reveals a large, extended region of stellar substructure surrounding the dwarf, as well as a distinct over-density encroaching on its tidal radius. A radial profile of the Bootes I stellar distribution shows a break radius indicating the presence of extra-tidal stars. These observations strongly suggest that Bootes I is experiencing tidal disruption, although not as extreme as that exhibited by the Hercules dwarf spheroidal. Combined with revised velocity dispersion measurements from the literature, we see evidence suggesting the need to review previous theoretical models of the Bootes I dwarf spheroidal galaxy.
Compton thick absorber in type 1 quasar 3C 345 revealed by Suzaku and Swift/BAT

The archival data of 3C 345, a type 1 quasar at $z = 0.5928$, obtained with Suzaku and Swift/BAT are analysed. Though previous studies of this source applied only a simple broken power law model, a heavily obscuring material is found to be required by considering Akaike information criteria. The application of the numerical torus model by Murphy & Yaqoob (2009) surprisingly reveals the existence of Compton thick type 2 nucleus with the line-of-sight hydrogen column density of the torus of $N_{\rm H} = 10^{24.5}$ cm$^{-2}$ and the inclination angle of $\theta_{\rm inc} = 90^{\circ}$. However, this model fails to account for the Eddington ratio obtained with the optical observations by Gu et al. (2001) and Shen et al. (2011), or requires the existence of a supermassive black hole binary, which was suggested by Lobanov & Roland (2005), thus this model is likely to be inappropriate for 3C 345. A partial covering ionized absorber model which accounts for absorption in "hard excess" type 1 AGNs is also applied, and finds a Compton thick absorber with the column density of $N_{\rm H} \simeq 10^{25}$ cm$^{-2}$, the ionization parameter of $\log \xi \gtrsim 2$, and the covering fraction of $75\% \lesssim f_{c} \lesssim 85\%$. Since this model obtains a black hole mass of $\log ( M_{\rm BH} / M_{\odot} ) = 9.8$, which is consistent with the optical observation by Gu et al. (2001), this model is likely to be the best-fitting model of this source. The results suggest that 3C 345 is the most distant and most obscured hard excess AGN at this time.
A new gauge for gravitational perturbations of Kerr spacetimes II: The linear stability of Schwarzschild revisited

We present a new proof of linear stability of the Schwarzschild solution to gravitational perturbations. Our approach employs the system of linearised gravity in the new geometric gauge of [2], specialised to the | a | = 0 case. The proof fundamentally relies on the novel structure of the transport equations in the system. Indeed, while exploiting the well-known decoupling of two gauge invariant linearised quantities into spin ± 2 Teukolsky equations, we make enhanced use of the red-shifted transport equations and their stabilising properties to control the gauge dependent part of the system. As a result, an initial-data gauge normalisation suﬃces to establish both orbital and asymptotic stability for all the linearised quantities in the system. The absence of future gauge normalisations is a novel element in the linear stability analysis of black hole spacetimes in geometric gauges governed by transport equations. In particular, our approach simpliﬁes the proof of [5], which requires a future normalised (double-null) gauge to establish asymptotic stability for the full system.
Branes and polytopes

We investigate the hierarchies of half-supersymmetric branes in maximal supergravity theories. By studying the action of the Weyl group of the U-duality group of maximal supergravities we discover a set of universal algebraic rules describing the number of independent 1/2-BPS p-branes, rank by rank, in any dimension. We show that these relations describe the symmetries of certain families of uniform polytopes. This induces a correspondence between half-supersymmetric branes and vertices of opportune uniform polytopes. We show that half-supersymmetric 0-, 1- and 2-branes are in correspondence with the vertices of the k21, 2k1 and 1k2 families of uniform polytopes, respectively, while 3-branes correspond to the vertices of the rectified version of the 2k1 family. For 4-branes and higher rank solutions we find a general behavior. The interpretation of half-supersymmetric solutions as vertices of uniform polytopes reveals some intriguing aspects. One of the most relevant is a triality relation between 0-, 1- and 2-branes.
Event Tables for Efficient Experience Replay

Experience replay (ER) is a crucial component of many deep reinforcement learning (RL) systems. However, uniform sampling from an ER buffer can lead to slow convergence and unstable asymptotic behaviors. This paper introduces Stratified Sampling from Event Tables (SSET), which partitions an ER buffer into Event Tables, each capturing important subsequences of optimal behavior. We prove a theoretical advantage over the traditional monolithic buffer approach and combine SSET with an existing prioritized sampling strategy to further improve learning speed and stability. Empirical results in challenging MiniGrid domains, benchmark RL environments, and a high-fidelity car racing simulator demonstrate the advantages and versatility of SSET over existing ER buffer sampling approaches.
Carbon Footprints on Inter-Domain Paths: Uncovering CO2 Tracks on Global Networks

In the years after signing the Paris agreement, corporations have been experiencing increasing pressure to monitor and reduce their carbon footprint. Nevertheless, the information and communication technology sector lacks an effective tool for monitoring and optimizing the carbon footprint of data transmissions over the public Internet. In this work, we propose a carbon-footprint transparency system based on a path-aware Internet architecture that enables endpoints to monitor the carbon footprint of their inter-domain communications, and optimize it through carbon-aware path selection. Furthermore, we show by means of simulations that in a realistic inter-domain topology, 85% of trafﬁc sources could reduce the carbon footprint of their outbound inter-domain trafﬁc by at least 50% through carbon-aware path selection.
No-audio speaking status detection in crowded settings via visual pose-based filtering and wearable acceleration

—Recognizing who is speaking in a crowded scene is a key challenge towards the understanding of the social interactions going on within. Detecting speaking status from body movement alone opens the door for the analysis of social scenes in which personal audio is not obtainable. Video and wearable sensors make it possible recognize speaking in an unobtrusive, privacy-preserving way. When considering the video modality, in action recognition problems, a bounding box is traditionally used to localize and segment out the target subject, to then recognize the action taking place within it. However, cross-contamination, occlusion, and the articulated nature of the human body, make this approach challenging in a crowded scene. Here, we leverage articulated body poses for subject localization and in the subsequent speech detection stage. We show that the selection of local features around pose keypoints has a positive effect on generalization performance while also signiﬁcantly reducing the number of local features considered, making for a more efﬁcient method. Using two in-the-wild datasets with different viewpoints of subjects, we investigate the role of cross-contamination in this effect. We additionally make use of acceleration measured through wearable sensors for the same task, and present a multimodal approach combining both methods.
Korg: A Modern 1D LTE Spectral Synthesis Package

We present Korg, a new package for 1D LTE spectral synthesis of FGK stars, which computes theoretical spectra from the near-ultraviolet to the near-infrared, and implements both plane-parallel and spherical radiative transfer. We outline the inputs and internals of Korg, and compare synthetic spectra from Korg, Moog, Turbospectrum, and SME. The disagreements between Korg and the other codes are no larger than those between the other codes, although disagreement between codes is substantial. We examine the case of a C2 band in detail, finding that uncertainties on physical inputs to spectral synthesis account for a significant fraction of the disagreement. Korg is 1–100 times faster than other codes in typical use, compatible with automatic differentiation libraries, and easily extensible, making it ideal for statistical inference and parameter estimation applied to large data sets. Documentation and installation instructions are available at https://ajwheeler.github. io/Korg.jl/stable/.
Shocks or photoionization: direct temperature measurements of the low-ionization gas in quiescent galaxies

The ionization mechanism of the low-ionization gas in quiescent red sequence galaxies has been a long-standing puzzle. Direct temperature measurements would put strong constraints on this issue. We carefully selected a sample of quiescent red sequence galaxies from SDSS. We bin them into three bins with different [N II]/H{\alpha} and [N II]/[O II] ratios, and we measure the temperature-sensitive [O III] {\lambda}4363, [N II] {\lambda}5755, [S II] {\lambda}{\lambda}4068,4076, and [O II] {\lambda}{\lambda}7320,7330 lines in the stacked spectra. The [S II] doublet ratios indicate the line-emitting gas is in the low density regime (~10-100 cm$^{-3}$). We found the temperatures in the S+ zones to be around 8000K, the temperatures in the O+ zones to be around $1.1-1.5\times10^4$K, and the temperatures in the N+ zones to be around $1-1.4\times10^4$K. The [O III] {\lambda}4363 line is not robustly detected. We found that the extinction corrections derived from Balmer decrements would yield unphysical relationships between the temperatures of the S+ zones and O+ zones, indicating that the extinction is significantly overestimated by the measured Balmer decrements. We compared these line ratios with model predictions for three ionization mechanisms: photoionization by hot evolved stars, shocks, and turbulent mixing layers. For both the photoionization and shock models, the hot temperatures inferred from [S II] and [N II] coronal-to-strong line ratios require metallicities to be significantly subsolar. However, the [N II]/[O II] line ratios require them to be supersolar. None of the models could simultaneously explain all of the observed line ratios, neither could their combinations do.
Reasoning on Property Graphs with Graph Generating Dependencies

Graph Generating Dependencies (GGDs) informally express constraints between two (possibly di ﬀ erent) graph patterns which enforce relationships on both graph’s data (via property value constraints) and its structure (via topological constraints). Graph Generating Dependencies (GGDs) can express tuple- and equality-generating dependencies on property graphs, both of which ﬁnd broad application in graph data management. In this paper, we discuss the reasoning behind GGDs. We propose algorithms to solve the satisﬁability , implication , and validation problems for GGDs and analyze their complexity. To demonstrate the practical use of GGDs, we propose an algorithm which ﬁnds inconsistencies in data through validation of GGDs. Our experiments show that even though the validation of GGDs has high computational complexity, GGDs can be used to ﬁnd data inconsistencies in a feasible execution time on both synthetic and real-world data.
Follow-up Imaging of Disk Candidates from the Disk Detective Citizen Science Project: New Discoveries and False Positives in WISE Circumstellar Disk Surveys

The Disk Detective citizen science project aims to find new stars with excess 22 μm emission from circumstellar dust in the AllWISE data release from the Wide-field Infrared Survey Explorer. We evaluated 261 Disk Detective objects of interest with imaging with the Robo-AO adaptive optics instrument on the 1.5 m telescope at Palomar Observatory and with RetroCam on the 2.5 m du Pont Telescope at Las Campanas Observatory to search for background objects at 0. ″15–12″ separations from each target. Our analysis of these data leads us to reject 7% of targets. Combining this result with statistics from our online image classification efforts implies that at most 7.9% ± 0.2% of AllWISE-selected infrared excesses are good disk candidates. Applying our false-positive rates to other surveys, we find that the infrared excess searches of McDonald et al. and Marton et al. all have false-positive rates >70%. Moreover, we find that all 13 disk candidates in Theissen & West with W4 signal-to-noise ratio >3 are false positives. We present 244 disk candidates that have survived vetting by follow-up imaging. Of these, 213 are newly identified disk systems. Twelve of these are candidate members of comoving pairs based on Gaia astrometry, supporting the hypothesis that warm dust is associated with binary systems. We also note the discovery of 22 μm excess around two known members of the Scorpius–Centaurus association, and we identify known disk host WISEA J164540.79-310226.6 as a likely Sco-Cen member. Thirty of these disk candidates are closer than ∼125 pc (including 26 debris disks), making them good targets for both direct-imaging exoplanet searches.