Sazuna/UAT_keywords huggingface dataset:
High-precision Dark Halo Virial Masses from Globular Cluster Numbers: Implications for Globular Cluster Formation and Galaxy Assembly. We confirm that the number of globular clusters (GCs), NGC, is an excellent tracer of their host galaxy's halo virial mass, Mvir. The simple linear relation Mvir = 5 × 109 M⊙ × NGC fits the data perfectly from Mvir = 1010 M⊙ to Mvir = 2 × 1015 M⊙. This result is independent of galaxy morphology and extends statistically into the dwarf galaxy regime with Mvir = 108-1010 M⊙, including the extreme ultra diffuse galaxy DF44. As this correlation does not depend on GC mass, it is ideally suited for high-precision determinations of Mvir. The linearity is most simply explained by cosmological merging of a high-redshift halo seed population that hosted on average one GC per 5 × 108 M⊙ of dark matter. We show that hierarchical merging is also extremely powerful in restoring a linear correlation and erasing signatures of even a strong secular evolution of GC systems. The cosmological merging scenario also implies a strong decline of the scatter in NGC with increasing virial mass $\delta {N}_{\mathrm{GC}}/{N}_{\mathrm{GC}}\sim {M}_{\mathrm{vir}}^{-1/2}$ in contrast with the observations that show a roughly constant scatter, independent of virial mass. This discrepancy can be explained if errors in determining virial masses from kinematical tracers and gravitational lensing are on the order of a factor of 2. GCs in dwarf satellite galaxies pose a serious problem for high-redshift GC formation scenarios; the dark halo masses of dwarf galaxies hosting GCs therefore might need to be an order of magnitude larger than currently estimated.

Keywords: Galaxy stellar halos, Galaxy dark matter halos, Globular star clusters
The Featureless Transmission Spectra of Two Super-puff Planets. The Kepler mission revealed a class of planets known as "super-puffs," with masses only a few times larger than Earth's but radii larger than Neptune, giving them very low mean densities. All three of the known planets orbiting the young solar-type star Kepler 51 are super-puffs. The Kepler 51 system thereby provides an opportunity for a comparative study of the structures and atmospheres of this mysterious class of planets, which may provide clues about their formation and evolution. We observed two transits each of Kepler 51b and 51d with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope. Combining new WFC3 transit times with reanalyzed Kepler data and updated stellar parameters, we confirmed that all three planets have densities lower than 0.1 g cm-3. We measured the WFC3 transmission spectra to be featureless between 1.15 and 1.63 μm, ruling out any variations greater than 0.6 scale heights (assuming a H/He-dominated atmosphere), thus showing no significant water absorption features. We interpreted the flat spectra as the result of a high-altitude aerosol layer (pressure &lt;3 mbar) on each planet. Adding this new result to the collection of flat spectra that have been observed for other sub-Neptune planets, we find support for one of the two hypotheses introduced by Crossfield &amp; Kreidberg, that planets with cooler equilibrium temperatures have more high-altitude aerosols. We strongly disfavor their other hypothesis that the H/He mass fraction drives the appearance of large-amplitude transmission features.

Keywords: Transits, Exoplanets, Hubble Space Telescope, Exoplanet atmospheres, Exoplanet evolution, Transit timing variation method, Atmospheric composition, Exoplanet structure
KMT-2018-BLG-1292: A Super-Jovian Microlens Planet in the Galactic Plane. We report the discovery of KMT-2018-BLG-1292Lb, a super-Jovian Mplanet = 5.0 ± 1.2 MJ planet orbiting an F or G dwarf Mhost = 1.2 ± 0.3 M☉, which lies physically within ${ \mathcal O }(10\,\mathrm{pc})$ of the Galactic plane. The source star is a heavily extincted AI ∼ 5.2 luminous giant that has the lowest Galactic latitude, b = -0°28, of any planetary microlensing event. The relatively blue blended light is almost certainly either the host or its binary companion, with the first explanation being substantially more likely. This blend dominates the light at the I band and completely dominates at the R and V bands. Hence, the lens system can be probed by follow-up observations immediately, i.e., long before the lens system and the source separate due to their relative proper motion. The system is well characterized despite the low cadence, Γ = 0.15-0.20 hr-1, of observations and short viewing windows near the end of the bulge season. This suggests that optical microlensing planet searches can be extended to the Galactic plane at relatively modest cost.

Keywords: Gravitational microlensing
A Study of the Blue Straggler Population of the Old Open Cluster Collinder 261. Blue stragglers (BSs) are stars located in an unexpected region of the color-magnitude diagram (CMD) of a stellar population, as they appear bluer and more luminous than the stars in the turn-off region. They are ubiquitous, since they have been found among Milky Way field stars, in open and globular clusters, and also in other galaxies of the Local Group. Here we present a study on the BS population of the old and metal-rich open cluster Collinder 261, based on Gaia DR2 data and on a multi-epoch radial velocity survey conducted with Fibre Large Array Multi Element Spectrograph (FLAMES) at the Very Large Telescope (VLT). We also analyze the radial distribution of the BS population to probe the dynamical status of the cluster. BS candidates were identified first with Gaia DR2, according to their position on the CMD, proper motions, and parallaxes. Their radial distribution was compared with those of main sequence, red giant, and red clump stars, to evaluate mass segregation. Additionally, their radial velocities (and the associated uncertainties) were compared with the mean radial velocity and velocity dispersion of the cluster. When possible, close binaries and long-period binaries were also identified, based on the radial velocity variations for the different epochs. We also looked for yellow stragglers, i.e., possible evolved BSs. We found 53 BS members of Collinder 261, six of them were already identified in previous catalogs. Among the BS candidates with radial velocity measurements, we found one long-period binary, five close-binary systems, three nonvariable stars; we also identified one yellow straggler.

Keywords: Open star clusters
Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs. We perform a study of stellar flares for the 24,809 stars observed with 2 minute cadence during the first two months of the TESS mission. Flares may erode exoplanets' atmospheres and impact their habitability, but might also trigger the genesis of life around small stars. TESS provides a new sample of bright dwarf stars in our galactic neighborhood, collecting data for thousands of M dwarfs that might host habitable exoplanets. Here, we use an automated search for flares accompanied by visual inspection. Then, our public allesfitter code robustly selects the appropriate model for potentially complex flares via Bayesian evidence. We identify 1228 flaring stars, 673 of which are M dwarfs. Among 8695 flares in total, the largest superflare increased the stellar brightness by a factor of 16.1. Bolometric flare energies range from 1031.0 to 1036.9 erg, with a median of 1033.1 erg. Furthermore, we study the flare rate and energy as a function of stellar type and rotation period. We solidify past findings that fast rotating M dwarfs are the most likely to flare and that their flare amplitude is independent of the rotation period. Finally, we link our results to criteria for prebiotic chemistry, atmospheric loss through coronal mass ejections, and ozone sterilization. Four of our flaring M dwarfs host exoplanet candidates alerted on by TESS, for which we discuss how these effects can impact life. With upcoming TESS data releases, our flare analysis can be expanded to almost all bright small stars, aiding in defining criteria for exoplanet habitability.

Keywords: Extrasolar rocky planets, Exoplanets, Exoplanet atmospheres, Red dwarf flare stars, Stellar activity, Astrobiology, Stellar flares, Optical flares, Habitable zone, Habitable planets, Pre-biotic astrochemistry
ZTF18abhjrcf: The First R Coronae Borealis Star from the Zwicky Transient Facility Public Survey. R Coronae Borealis stars (RCBs) constitute a rare class of stars that are hydrogen depleted and carbon enriched, possibly from white dwarf mergers. RCBs are identified by their stochastic dimming with photometric variations of as much as eight magnitudes. Hence, the discoveries of RCBs were heavily biased to the limited regions monitored by long-term microlensing experiments. However, recent studies of galactic RCBs have shown that they exhibit distinct mid-infrared colors originating from their cool circumstellar shells. The all-sky Wide-field Infrared Survey Explorer (WISE) survey thus facilitates the identification of RCB candidates. Therefore, combining the WISE colors with large-area time-domain surveys will enable us to discover more RCBs. Here we present the results of a first attempt to identify RCBs in the public Zwicky Transient Facility (ZTF) alert stream, using the alert broker ANTARES. We identify a candidate RCB using the infrared color selection by Tisserand et al. and large light curve variations in the optical from ZTF. We then conduct subsequent observations using the FLOYDS spectrograph at the Las Cumbres Observatory and confirm ZTF18abhjrcf as a bona fide RCB. This demonstrates the potential to discover uncharted RCBs as ZTF and other time-domain surveys continue to operate.

Keywords: R Coronae Borealis variable stars, Astrostatistics techniques, Sky surveys, Time series analysis
ALMA Observations of the Extraordinary Carina Pillars: HH 901/902. We present Atacama Large Millimeter/Submillimeter Array 1.3 mm continuum and C18O(2-1), N2D+(3-2), 13CS(5-4), and 12CO(2-1) line sensitive and high angular resolution (∼0"3) observations of the famous Carina pillars and protostellar objects HH 901/902. Our observations reveal for the first time, the bipolar CO outflows and the dusty disks (plus envelopes) that are energizing the extended and irradiated Herbig-Haro (HH) objects far from the pillars. We find that the masses of the disks+envelopes are about 0.1 M⊙ and that the bipolar outflows are between 10-3 and 10-4 M⊙, which suggests that they could be low- or maybe intermediate-mass protostars. Moreover, we suggest that these young low-mass stars are likely embedded Class 0/I protostars with high-accretion rates. We also show the kinematics of the gas in the pillars together with their respective gas masses (0.1-0.2 M⊙). We estimate that the pillars will be photoevaporated in 104 to 105 yr by the massive and luminous stars located in the Trumpler 14 cluster. Finally, given the short photoevaporated timescales and that the protostars in these pillars are still very embedded, we suggest that the disks inside of the pillars will be quickly affected by the radiation of the massive stars, forming proplyds, like those observed in Orion.

Keywords: Proplyds, Stellar jets, Aperture synthesis, Interstellar molecules
Population-level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels. The orbital eccentricities of directly imaged exoplanets and brown dwarf companions provide clues about their formation and dynamical histories. We combine new high-contrast imaging observations of substellar companions obtained primarily with Keck/NIRC2 together with astrometry from the literature to test for differences in the population-level eccentricity distributions of 27 long-period giant planets and brown dwarf companions between 5 and 100 au using hierarchical Bayesian modeling. Orbit fits are performed in a uniform manner for companions with short orbital arcs; this typically results in broad constraints for individual eccentricity distributions, but together as an ensemble, these systems provide valuable insight into their collective underlying orbital patterns. The shape of the eccentricity distribution function for our full sample of substellar companions is approximately flat from e = 0-1. When subdivided by companion mass and mass ratio, the underlying distributions for giant planets and brown dwarfs show significant differences. Low mass ratio companions preferentially have low eccentricities, similar to the orbital properties of warm Jupiters found with radial velocities and transits. We interpret this as evidence for in situ formation on largely undisturbed orbits within massive extended disks. Brown dwarf companions exhibit a broad peak at e ≈ 0.6-0.9 with evidence for a dependence on orbital period. This closely resembles the orbital properties and period-eccentricity trends of wide (1-200 au) stellar binaries, suggesting that brown dwarfs in this separation range predominantly form in a similar fashion. We also report evidence that the "eccentricity dichotomy" observed at small separations extends to planets on wide orbits: the mean eccentricity for the multi-planet system HR 8799 is lower than for systems with single planets. In the future, larger samples and continued astrometric orbit monitoring will help establish whether these eccentricity distributions correlate with other parameters such as stellar host mass, multiplicity, and age.

Keywords: Exoplanet formation, Brown dwarfs, Extrasolar gaseous giant planets
Analytic Marginalization of Absorption Line Continua. Absorption line spectroscopy is a powerful way of measuring properties of stars and the interstellar medium. Absorption spectra are often analyzed manually, an approach that limits reproducibility and which cannot practically be applied to modern data sets consisting of thousands or even millions of spectra. Simultaneous probabilistic modeling of absorption features and continuum shape is a promising approach for automating this analysis. Existing implementations of this approach use numerical methods such as Markov Chain Monte Carlo to marginalize over the continuum parameters. When continua are parameterized as linear functions such as polynomials or splines, it is possible to reduce continuum parameter marginalization to an integral over a multivariate normal distribution, which has a known closed form. Analytic marginalization makes it possible to combine optimization for absorption line parameters with marginalization of nuisance continuum parameters. We compare the accuracy to within which absorption line parameters can be recovered using different continuum placement methods and find that marginalization with an informative prior on continuum parameters is a clear improvement over other continuum placement methods over a broad range of signal-to-noise ratios. We implement analytic marginalization over linear continuum parameters in the open-source package amlc.

Keywords: Interstellar line absorption, Astrostatistics techniques, Spectroscopy
Morphological Star-Galaxy Separation. We discuss the statistical foundations of morphological star-galaxy separation. We show that many of the star-galaxy separation metrics in common use today (e.g., by Sloan Digital Sky Survey or SExtractor) are closely related both to each other, and to the model odds ratio derived in a Bayesian framework by Sebok. While the scaling of these algorithms with the noise properties of the sources varies, these differences do not strongly differentiate their performance. We construct a model of the performance of a star-galaxy separator in a realistic survey to understand the impact of observational signal-to-noise ratio (S/N) (or equivalently, 5σ limiting depth) and seeing on classification performance. The model quantitatively demonstrates that, assuming realistic densities and angular sizes of stars and galaxies, 10% worse seeing can be compensated for by approximately 0.4 mag deeper data to achieve the same star-galaxy classification performance. We discuss how to probabilistically combine multiple measurements, either of the same type (e.g., subsequent exposures), or differing types (e.g., multiple bandpasses), or differing methodologies (e.g., morphological and color-based classification). These methods are increasingly important for observations at faint magnitudes, where the rapidly rising number density of small galaxies makes star-galaxy classification a challenging problem. However, because of the significant role that the S/N plays in resolving small galaxies, surveys with large-aperture telescopes, such as LSST, will continue to see improving star-galaxy separation as they push to these fainter magnitudes.

Keywords: Observational astronomy, CCD observation, Astronomical methods
Low-activity Main-belt Comet 133P/Elst-Pizarro: New Constraints on Its Albedo, Temperature, and Active Mechanism from a Thermophysical Perspective. 133P/Elst-Pizarro is the first recognized main-belt comet, but we still know little about its nucleus. First we use mid-infrared data of Spitzer MIPS, Spitzer IRS, and the Wide-field Infrared Survey Explorer to estimate its effective diameter, ${D}_{\mathrm{eff}}={3.9}_{-0.3}^{+0.4}$ km, geometric albedo, ${p}_{{\rm{v}}}=0.074\pm 0.013$ , and mean Bond albedo ${A}_{\mathrm{eff},{\rm{B}}}=0.024\pm 0.004$ . The albedo is used to compute 133P's temperature distribution, which shows significant seasonal variation, especially polar regions, ranging from ∼40 to ∼200 K. Based on current activity observations, the maximum water gas production rate is estimated to be $\sim 1.4\times {10}^{23}\,{{\rm{s}}}^{-1}$ , being far weaker than $\sim {10}^{26}\,{{\rm{s}}}^{-1}$ of JFC 67P at a similar heliocentric distance of ∼2.7 au, indicating a thick dust mantle on the surface to lower down the gas production rate. The diameter of the sublimation area may be &lt;∼200 m according to our model prediction. We thus propose that 133P's activity is more likely to be caused by sublimation of a regional near-surface ice patch rather than a homogeneous buried ice layer. Such a small near-surface ice patch might be exposed by one impact event, before which 133P may be an extinct comet (or ice-rich asteroid) with an ice layer buried below ∼40 m depth. The proposed ice patch may be located somewhere within latitude -50 ∼ 50° by comparing theoretical variation of sublimation temperature to the constraints from observations. The timescale to form such a thick dust mantle is estimated to be &gt;100 Myr, indicating that 133P may be more likely to be a relatively old planetesimals or a member of an old family than a recently formed fragment of some young family.

Keywords: Asteroid belt, Comets, Small Solar System bodies
Cosmicflows-3: Two Distance-Velocity Calculators. Tools are provided at the Extragalactic Distance Database website which provide relationships between the distances and velocities of galaxies based on smoothed versions of the velocity fields derived by the Cosmicflows program.

Keywords: Observational cosmology, Galaxy distances, Astronomy data visualization, Large-scale structure of the universe
Keck Observations Confirm a Super-Jupiter Planet Orbiting M Dwarf OGLE-2005-BLG-071L. We present adaptive optics imaging from the NIRC2 instrument on the Keck II telescope that resolves the exoplanet host (and lens) star as it separates from the brighter source star. These observations yield the K-band brightness of the lens and planetary host star, as well as the lens-source relative proper motion, ${{\boldsymbol{\mu }}}_{\mathrm{rel},{\rm{H}}}$ , in the heliocentric reference frame. The ${{\boldsymbol{\mu }}}_{\mathrm{rel},{\rm{H}}}$ measurement allows for the determination of the microlensing parallax vector, ${{\boldsymbol{\pi }}}_{E}$ , which had only a single component determined by the microlensing light curve. The combined measurements of ${{\boldsymbol{\mu }}}_{\mathrm{rel},{\rm{H}}}$ and KL provide the masses of the host star, ${M}_{\mathrm{host}}=0.426\pm 0.037{M}_{\odot }$ , and planet, mp = 3.27 ± 0.32MJupiter with a projected separation of 3.4 ± 0.5 au. This confirms the tentative conclusion of a previous paper that this super-Jupiter mass planet, OGLE-2005-BLG-071Lb, orbits an M dwarf. Such planets are predicted to be rare by the core accretion theory and have been difficult to find with other methods, but there are two such planets with firm mass measurements from microlensing, and an additional 11 planetary microlens events with host mass estimates $\lt 0.5{M}_{\odot }$ and planet mass estimates &gt;2 Jupiter masses that could be confirmed by high angular follow-up observations. We also point out that OGLE-2005-BLG-071L has separated far enough from its host star that it should be possible to measure the host-star metallicity with spectra from a high angular resolution telescope such as Keck, the Very Large Telescope, the Hubble Space Telescope, or the James Webb Space Telescope.

Keywords: M dwarf stars, Extrasolar gaseous giant planets, Exoplanets
Lower AGN Abundance in Galaxy Clusters at z &lt; 0.5. Most galaxies in clusters have supermassive black holes (SMBHs) at their center, and a fraction of those SMBHs show strong activity. These active galactic nuclei (AGNs) are an important probe of environmental dependence of galaxy evolution, intracluster medium, and cluster-scale feedback. We investigated AGN fraction in one of the largest samples of X-ray selected clusters from the ROSAT and their immediate surrounding field regions below z &lt; 0.5. We found a lower average AGN fraction in clusters (2.37 ± 0.39)% than for the fields (5.12 ± 0.16)%. The lower AGN fractions in clusters were measured, after dividing the clusters into five redshift intervals between 0.0 and 0.5, in each redshift interval, and we found an increase in the fraction for both cluster and field galaxies with redshift below z &lt; 0.5, which clearly indicates an environment and redshift dependence. We further divided the clusters into low-mass and high-mass objects using a mass cut at log10(M500/M⊙) = 13.5, finding comparable AGN fractions for both classifications, while a significantly higher AGN fraction in field. We also measured increasing AGN fractions with cluster-centric distance for all redshift bins, further confirming the environmental dependence of AGN activities. In addition, we did not find an obvious trend between AGN fraction and Sloan Digital Sky Survey Mr absolute magnitudes among different redshift bins. We conclude that the lower AGN fraction in clusters relative to fields indicate that factors, such as inefficient galaxy mergers and ram pressure stripping, cause a deficit of cold gas available in high-density regions to fuel the central SMBH. Clusters and fields in the present universe have lost more gas relative to their high-redshift counterparts resulting in a lower AGN fraction observed today.

Keywords: Galaxy clusters, Quasars, Infrared astronomy, Active galactic nuclei, Galaxies