Sazuna/UAT_keywords huggingface dataset:
Kinematic-chemical Analysis and Time Tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red-giant Branch Stars. We investigate the kinematic-chemical distribution of red-giant branch stars from the LAMOST survey crossed matched with Gaia DR2 proper motions, and present time tagging for the well-known ridge structures (diagonal distributions for V  R  in the R, V  ϕ  plane) in the range of Galactocentric distance R = 8 to 15 kpc. We detect six ridge structures, including five ridges apparent in the radial velocity distribution and three ridges apparent in the vertical velocity, the sensitive time of which to the perturbations are from young population (0-3 Gyr) to old population (9-14 Gyr). Based on an analysis of the evolution of angular momentum distribution, we find that four ridges are relatively stationary, while another is evolving with time, which is confirmed by the difference analysis at different populations and supporting that there might be two kinds of dynamical origins. Furthermore, ridge features are also vividly present in the chemical properties ([Fe/H], [α/Fe]). The comparison between the north and south hemispheres of the Galaxy does show some differences and the ridge features are asymmetrical. Moreover, we find that diagonal ridge structures may affect the shape of the rotation curve, which is manifested as fluctuations and undulations on top of a smooth profile. Finally we speculate that the bar dynamics should be not enough to explain all ridge properties including the break feature in the V  Z -L  Z  plane.

Keywords: Milky Way disk, Milky Way formation
The Solar System Notification Alert Processing System (SNAPS): Design, Architecture, and First Data Release (SNAPShot1). We present here the design, architecture, and first data release for the Solar System Notification Alert Processing System (SNAPS). SNAPS is a solar system broker that ingests alert data from all-sky surveys. At present, we ingest data from the Zwicky Transient Facility (ZTF) public survey, and we will ingest data from the forthcoming Legacy Survey of Space and Time (LSST) when it comes online. SNAPS is an official LSST downstream broker. In this paper we present the SNAPS design goals and requirements. We describe the details of our automatic pipeline processing in which the physical properties of asteroids are derived. We present SNAPShot1, our first data release, which contains 5,458,459 observations of 31,693 asteroids observed by ZTF from 2018 July to 2020 May. By comparing a number of derived properties for this ensemble to previously published results for overlapping objects we show that our automatic processing is highly reliable. We present a short list of science results, among many that will be enabled by our SNAPS catalog: (1) we demonstrate that there are no known asteroids with very short periods and high amplitudes, which clearly indicates that in general asteroids in the size range 0.3-20 km are strengthless; (2) we find no difference in the period distributions of Jupiter Trojan asteroids, implying that the L4 and L5 clouds have different shape distributions; and (3) we highlight several individual asteroids of interest. Finally, we describe future work for SNAPS and our ability to operate at LSST scale.

Keywords: Small Solar System bodies, Sky surveys, Asteroids, Catalogs
On the Application of Bayesian Leave-one-out Cross-validation to Exoplanet Atmospheric Analysis. Over the last decade exoplanetary transmission spectra have yielded an unprecedented understanding about the physical and chemical nature of planets outside our solar system. Physical and chemical knowledge is mainly extracted via fitting competing models to spectroscopic data, based on some goodness-of-fit metric. However, current employed metrics shed little light on how exactly a given model is failing at the individual data point level and where it could be improved. As the quality of our data and complexity of our models increases, there is a need to better understand which observations are driving our model interpretations. Here we present the application of Bayesian leave-one-out cross-validation to assess the performance of exoplanet atmospheric models and compute the expected log pointwise predictive density (elpdLOO). elpdLOO estimates the out-of-sample predictive accuracy of an atmospheric model at data-point resolution, providing interpretable model criticism. We introduce and demonstrate this method on synthetic Hubble Space Telescope transmission spectra of a hot Jupiter. We apply elpdLOO to interpret current observations of HAT-P-41 b and assess the reliability of recent inferences of H- in its atmosphere. We find that previous detections of H- are dependent solely on a single data point. This new metric for exoplanetary retrievals complements and expands our repertoire of tools to better understand the limits of our models and data. elpdLOO provides the means to interrogate models at the single-data-point level, which will help in robustly interpreting the imminent wealth of spectroscopic information coming from JWST.

Keywords: Exoplanet atmospheric composition , Exoplanets, Transmission spectroscopy, Exoplanet astronomy, Exoplanet atmospheres
Detecting Exomoons from Radial Velocity Measurements of Self-luminous Planets: Application to Observations of HR 7672 B and Future Prospects. The detection of satellites around extrasolar planets, so called exomoons, remains a largely unexplored territory. In this work, we study the potential of detecting these elusive objects from radial velocity monitoring of self-luminous, directly imaged planets. This technique is now possible thanks to the development of dedicated instruments combining the power of high-resolution spectroscopy and high-contrast imaging. First, we demonstrate a sensitivity to satellites with a mass ratio of 1%-4% at separations similar to the Galilean moons from observations of a brown-dwarf companion (HR 7672 B; K mag = 13; 0.″7 separation) with the Keck Planet Imager and Characterizer (R ~ 35,000 in the K band) at the W. M. Keck Observatory. Current instrumentation is therefore already sensitive to large unresolved satellites that could be forming from gravitational instability akin to binary star formation. Using end-to-end simulations, we then estimate that future instruments such as the Multi-Object Diffraction-limited High-resolution Infrared Spectrograph, planned for the Thirty Meter Telescope, should be sensitive to satellites with mass ratios of ~10-4. Such small moons would likely form in a circumplanetary disk similar to the Jovian satellites in the solar system. Looking for the Rossiter-McLaughlin effect could also be an interesting pathway to detecting the smallest moons on short orbital periods. Future exomoon discoveries will allow precise mass measurements of the substellar companions that they orbit and provide key insight into the formation of exoplanets. They would also help constrain the population of habitable Earth-sized moons orbiting gas giants in the habitable zone of their stars.

Keywords: Radial velocity, Exoplanet detection methods, Natural satellites (Extrasolar), Direct imaging
The Breakthrough Listen Search for Intelligent Life: A Laser Search Pipeline for the Automated Planet Finder. The Search for Extraterrestrial Intelligence has traditionally been conducted at radio wavelengths, but optical searches are well-motivated and increasingly feasible due to the growing availability of high-resolution spectroscopy. We present a data analysis pipeline to search Automated Planet Finder (APF) spectroscopic observations from the Levy Spectrometer for intense, persistent, narrow-bandwidth optical lasers. We describe the processing of the spectra, the laser search algorithm, and the results of our laser search on 1983 spectra of 388 stars as part of the Breakthrough Listen search for technosignatures. We utilize an empirical spectra-matching algorithm called SpecMatch-Emp to produce residuals between each target spectrum and a set of best-matching catalog spectra, which provides the basis for a more sensitive search than previously possible. We verify that SpecMatch-Emp performs well on APF-Levy spectra by calibrating the stellar properties derived by the algorithm against the SpecMatch-Emp library and against Gaia catalog values. We leverage our unique observing strategy, which produces multiple spectra of each target per night of observing, to increase our detection sensitivity by programmatically rejecting events that do not persist between observations. With our laser search algorithm, we achieve a sensitivity equivalent to the ability to detect an 84 kW laser at the median distance of a star in our data set (78.5 ly). We present the methodology and vetting of our laser search, finding no convincing candidates consistent with potential laser emission in our target sample.

Keywords: High resolution spectroscopy, Technosignatures, Stellar classification, Astrobiology, Search for extraterrestrial intelligence, Stellar spectral lines
Hiding Dust around ϵ Eridani. With a Jupiter-like exoplanet and a debris disk with both asteroid and Kuiper Belt analogs, ϵ Eridani has a fascinating resemblance to our expectations for a young solar system. We present a deep Hubble Space Telescope/Space Telescope Imaging Spectrograph coronographic data set using eight orbit visits and the point-spread function calibrator δ Eridani. While we were unable to detect the debris disk, we place stringent constraints on the scattered light surface brightness of $\sim 4\,\mu \mathrm{Jy}\,{\mathrm{arcsec}}^{-2}.$ We combine this scattered light detection limit with a reanalysis of archival near- and mid-infrared observations and a dynamical model of the full planetary system to refine our model of the ϵ Eridani debris disk components. Radiative transfer modeling suggests an asteroid belt analog inside of 3 au, an intermediate disk component in the 6-37 au region, and a Kuiper Belt analog colocated with the narrow belt observed in the millimeter (69 au). Modeling also suggests a large minimum grain size requiring either very porous grains or a suppression of small grain production, and a radially stratified particle size distribution. The inner disk regions require a steep power-law slope (s -3.8 where s is the grain size) weighted toward smaller grains and the outer disk prefers a shallower slope (s -3.4) with a minimum particle size of &gt;2 μm. These conclusions will be enhanced by upcoming coronagraphic observations of the system with the James Webb Space Telescope, which will pinpoint the radial location of the dust belts and further diagnose the dust particle properties.

Keywords: Coronagraphic imaging, Circumstellar dust, Debris disks
Discovery of 20 UV-emitting SNRs in M31 with UVIT. We present the first catalog of supernova remnants (SNRs) in M31 that exhibit diffuse ultraviolet (UV) emission. UV images of M31 were obtained by the Ultraviolet Imaging Telescope (UVIT) on the AstroSat satellite, and the list of SNRs was obtained from X-ray, optical, and radio catalogs of SNRs in M31. We used the UVIT images to find SNRs with diffuse emission, omitting those too contaminated with stellar emission. A total of 20 SNRs in M31 were detected with diffuse UV emission. Fluxes in the UVIT F148W, F169M, F172M, N219M, and N279N filters are measured for these SNRs. The luminosities are compared to those computed from the spectra of seven known UV-emitting SNRs in the Milky Way, the Large Magellanic Cloud, and the Small Magellanic Cloud. We find similar spectral shapes between the known and the M31 UV-emitting SNRs. The spectral shapes and the diffuse nature of the emission are good evidence that the UV emissions are dominated by line emissions, like known SNRs, and the UV is associated with the SNRs. Models are applied to the six SNRs with X-ray spectra. The main difference is that the two X-ray/UV SNRs are Type Ia and the four X-ray/non-UV SNRs are core-collapse or unknown type. A comparison of M31 SNRs in different wave bands shows that most are detected optically, similar to the case for other nearby galaxies. A total of 19 of the 20 UV-emitting SNRs are detected optically, expected because both UV and optical are from forbidden and recombination lines from shock-ionized gas.

Keywords: Supernova remnants, Ultraviolet astronomy, Andromeda Galaxy
Intensity Interferometry Observations of the Hα Envelope of γCas with MéO and a Portable Telescope. We report on observations of the extended environment of the bright Be star γ-Cas performed using intensity interferometry measurements within its Hα emission line. These observations were performed using a modified version of the I2C intensity interferometry instrument installed onto the 1.54 m MéO optical metrology telescope and a portable 1 m telescope (T1M). In order to better constrain the extent of the H α envelope, observations were performed for two different positions of the T1M telescope, corresponding to an intermediate and long baselines in which the extended region was partially and fully resolved. We find that the observed data are consistent with past interferometric observations of γ-Cas. These observations demonstrate the capability to equip optical telescopes of different optical designs with intensity interferometry capabilities and illustrate the potential to scale a similar system onto many additional telescopes.

Keywords: Be stars, Interferometers, Emission line stars, High angular resolution
A Reinforcement Learning-Based Follow-up Framework. Classification and characterization of variable and transient phenomena are critical for astrophysics and cosmology. Given the volume of nightly data produced by ongoing and future surveys such as LSST, it is critical to develop automatic tools that assist in observation decision-making, maximizing scientific output without resource wastage. We propose a reinforcement learning-based recommendation system for real-time astronomical observation of sources. We assess whether it is worth making further observations and recommend the best instrument from a preexisting candidate set of instruments. Current possible choices include single-band, multiband, and spectroscopic observations, although it is generalizable to any other kind of instrumentation. We rely on a reward metric to make recommendations, which incorporates the gain in a classification sense and the cost incurred for the queried observations. This metric is flexible and easily adaptable to different application scenarios. We run 24 simulations in an offline setting with preexisting observations from Gaia DR2 and SDSS DR14. We propose four comparison strategies, including the baseline strategy, which recommends based on the most similar past cases to the current case. Our strategy surpasses all other strategies in regard to reward. We reach an accuracy of 0.932, comparable to using the accuracy reached using all possible resources (0.948) but with half the number of photometric observations and 1000 times fewer spectroscopic resources. The baseline strategy lacks the complexity to achieve competitive results with our proposed strategy. Our framework is meant to aid continuous online observation decision-making and can be extended to incorporate multiple environmental and observation conditions.

Keywords: Astrostatistics tools, Neural networks, Astronomy data analysis, Computational methods, Variable stars
ELM of ELM-WD: An Extremely-low-mass Hot Star Discovered in LAMOST Survey. The extremely-low-mass white dwarfs (ELM WDs) and pre-ELM WDs are helium-core white dwarfs with mass &lt;~ 0.3M ⊙. Evolution simulations show that a lower mass limit for ELM WDs exists at ≈0.14M ⊙ and no ELM WD is proposed by observation to be less massive than that. Here we report the discovery of a binary system, LAMOST J224040.77-020732.8 (J2240 in short), which consists of a very low-mass hot star and a compact companion. Multiepoch spectroscopy shows an orbital period P orb = 0.219658 ± 0.000002 days and a radial-velocity semiamplitude K1 = 318.5 ± 3.3 km s-1, which gives the mass function of 0.74M ⊙, indicating the companion is a compact star. The F-type low-resolution spectra illustrate no emission features, and the temperature (~7400 K) is consistent with that from spectral energy distribution fitting and multicolor light-curve solution. The optical light curves, in ZTF g, r, and i bands and the Catalina V band, show ellipsoidal variability with amplitudes of ~30%, suggesting that the visible component is heavily tidally distorted. Combining the distance from Gaia survey, the ZTF light curves are modeled with Wilson-Devinney code and the result shows that the mass of the visible component is $M1={0.085}_{-0.024}^{+0.036}{M}_{\odot }$ , and the mass of the invisible component is $M2={0.98}_{-0.09}^{+0.16}{M}_{\odot }$ . The radius of the visible component is $R1={0.29}_{-0.03}^{+0.04}{R}_{\odot }$ . The inclination angle is approximately between 60° and 90°. The observations indicate the system is most likely a pre-ELM WD + WD/NS binary, and the mass of pre-ELM is possibly lower than the 0.14M ⊙ theoretical limit.

Keywords: Close binary stars, White dwarf stars
TOI-5205b: A Short-period Jovian Planet Transiting a Mid-M Dwarf. We present the discovery of TOI-5205b, a transiting Jovian planet orbiting a solar metallicity M4V star, which was discovered using Transiting Exoplanet Survey Satellite photometry and then confirmed using a combination of precise radial velocities, ground-based photometry, spectra, and speckle imaging. TOI-5205b has one of the highest mass ratios for M-dwarf planets, with a mass ratio of almost 0.3%, as it orbits a host star that is just 0.392 ± 0.015 M ⊙. Its planetary radius is 1.03 ± 0.03 R J, while the mass is 1.08 ± 0.06 M J. Additionally, the large size of the planet orbiting a small star results in a transit depth of ~7%, making it one of the deepest transits of a confirmed exoplanet orbiting a main-sequence star. The large transit depth makes TOI-5205b a compelling target to probe its atmospheric properties, as a means of tracing the potential formation pathways. While there have been radial-velocity-only discoveries of giant planets around mid-M dwarfs, this is the first transiting Jupiter with a mass measurement discovered around such a low-mass host star. The high mass of TOI-5205b stretches conventional theories of planet formation and disk scaling relations that cannot easily recreate the conditions required to form such planets.

Keywords: M dwarf stars, Radial velocity, Transits, Extrasolar gaseous giant planets
TOI-4562b: A Highly Eccentric Temperate Jupiter Analog Orbiting a Young Field Star. We report the discovery of TOI-4562b (TIC-349576261), a Jovian planet orbiting a young F7V-type star, younger than the Praesepe/Hyades clusters (&lt;700 Myr). This planet stands out because of its unusually long orbital period for transiting planets with known masses (P orb = 225.11781 ${}_{-0.00022}^{+0.00025}$ days) and because it has a substantial eccentricity (e = 0.76 ${}_{-0.02}^{+0.02}$ ). The location of TOI-4562 near the southern continuous viewing zone of TESS allowed observations throughout 25 sectors, enabling an unambiguous period measurement from TESS alone. Alongside the four available TESS transits, we performed follow-up photometry using the South African Astronomical Observatory node of the Las Cumbres Observatory and spectroscopy with the CHIRON spectrograph on the 1.5 m SMARTS telescope. We measure a radius of ${1.118}_{+0.013}^{-0.014}$ R J and a mass of 2.30 ${}_{-0.47}^{+0.48}$ M J for TOI-4562b. The radius of the planet is consistent with contraction models describing the early evolution of the size of giant planets. We detect tentative transit timing variations at the ~20 minutes level from five transit events, favoring the presence of a companion that could explain the dynamical history of this system if confirmed by future follow-up observations. With its current orbital configuration, tidal timescales are too long for TOI-4562b to become a hot Jupiter via high-eccentricity migration though it is not excluded that interactions with the possible companion could modify TOI-4562b's eccentricity and trigger circularization. The characterization of more such young systems is essential to set constraints on models describing giant-planet evolution.

Keywords: Exoplanet migration, Exoplanets, Elliptical orbits, Stellar activity, Young stellar objects, Transit timing variation method, Extrasolar gaseous giant planets
Disintegration of Long-period Comet C/2021 A1 (Leonard). We present imaging observations of the disintegrating long-period comet C/2021 A1 (Leonard). High-resolution observations with the Hubble Space Telescope show no evidence for surviving fragments, and place a 3σ upper limit on their possible radius of ~60 m (albedo 0.1 assumed). In contrast, wide-field observations from the Swan Hill Observatory, Australia, show an extensive debris cloud, the cross section and estimated mass of which are consistent with complete disintegration of the nucleus near 2021 mid-December (at about 0.8 au). Two methods give the pre-disruption radius of the nucleus, r  n  = 0.6 ± 0.2 km. Tidal, collisional, sublimation, and pressure-confined explosion models provide implausible explanations of the disintegration. However, rotational instability driven by outgassing torques has a very short timescale (~0.1 yr) given the orbit and size of the nucleus of C/2021 A1, and offers the most plausible mechanism for the disruption. Initial rotational breakup is accelerated by the exposure and strong sublimation of previously buried volatiles, leading to catastrophic destruction of the nucleus.

Keywords: Comet nuclei, Comets, Comet volatiles , Long period comets
Identification of Galaxy Shreds in Large Photometric Catalogs Using Convolutional Neural Networks. Contamination from galaxy fragments, identified as sources, is a major issue in large photometric galaxy catalogs. In this paper, we prove that this problem can be easily addressed with computer vision techniques. We use image cutouts to train a convolutional neural network (CNN) to identify cataloged sources that are in reality just star-formation regions and/or shreds of larger galaxies. The CNN reaches an accuracy ~98% on our testing data sets. We apply this CNN to galaxy catalogs from three among the largest surveys available today: the Sloan Digital Sky Survey, the DESI Legacy Imaging Surveys, and the Panoramic Survey Telescope and Rapid Response System Survey. We find that, even when strict selection criteria are used, all catalogs still show a ~5% level of contamination from galaxy shreds. Our CNN gives a simple yet effective solution to clean galaxy catalogs from these contaminants.

Keywords: Sky surveys, Convolutional neural networks, Astronomical techniques, Galaxy evolution, Catalogs