Sazuna/UAT_keywords huggingface dataset:
Red Supergiants in M31 and M33. II. The Mass-loss Rate. Mass loss is an important activity for red supergiants (RSGs) and can influence their evolution and final fate. Previous estimations of mass-loss rates (MLRs) of RSGs exhibit significant dispersion due to differences in method and the incompleteness of samples. With the improved quality and depth of surveys including the UKIRT/WFCAM observations in the near-infrared, and LGGS and PS1 in the optical, a rather complete sample of RSGs is identified in M31 and M33 according to their brightness and colors. For about 2000 objects in either galaxy from this largest ever sample, the MLR is derived by fitting the observational optical-to-mid-infrared spectral energy distribution with the DUSTY code of a 1D dust radiative transfer model. The average MLR of RSGs is found to be around 2.0 × 10-5 M⊙ yr-1 with a gas-to-dust ratio of 100, which yields a total contribution to the interstellar dust from RSGs of about 1.1 × 10-3 M⊙ yr-1 in M31 and 6.0 × 10-4 M⊙ yr-1 in M33, a non-negligible source in comparison with evolved low-mass stars. The MLRs are divided into three types by the dust species, i.e., amorphous silicate, amorphous carbon, and optically thin, and the relations between MLR and stellar parameters, infrared flux, and colors are discussed and compared with previous works for the silicate and carbon dust groups.

Keywords: Circumstellar dust, Red supergiant stars, Stellar mass loss
Measuring the Mass and Concentration of Dark Matter Halos from the Velocity Dispersion Profile of their Stars. We use the IllustrisTNG (TNG) simulations of galaxy formation to measure the velocity dispersion profiles of dark matter and stars in Milky Way-mass, galaxy group, and cluster-scale dark matter halos. The mean profiles calculated from both tracers are similar in shape, exhibiting a large halo-to-halo scatter around the average profile. The so-called "splashback" radius demarcates the outer boundary of the halo, and manifests as a kink in the velocity dispersion profile, located on average between ∼1.0-1.5r200m, where r200m is the radius within which the density of the halo equals 200 times the background density of the universe. We find that this location may also be identified as the radius at which the (stacked) dispersion profile drops to 60% of its peak value (for line-of-sight motions in TNG halos). We further show that the scatter in the dispersion profiles may be attributed to the variations in the assembly history of the host halos. In particular, this segregates the profile into two regimes: one within ∼0.1r200m, where the scatter is set by the early assembly history of the halo; and the other beyond this radius, where the scatter is influenced more strongly by its late-time assembly. Finally, we show that a two-parameter model can be used to fit the measured velocity dispersion profiles and the fit parameters can be related directly to two fundamental halo properties: mass and concentration. We describe a simple model that allows us to express the stellar velocity dispersion profile in terms of these halo properties only.

Keywords: Cosmology, Galaxy formation
Discovery of an Edge-on Circumstellar Debris Disk around BD+45° 598: A Newly Identified Member of the β Pictoris Moving Group. We report the discovery of a circumstellar debris disk viewed nearly edge-on and associated with the young, K1 star BD+45° 598 using high-contrast imaging at 2.2 μm obtained at the W.M. Keck Observatory. We detect the disk in scattered light with a peak significance of ∼5σ over three epochs, and our best-fit model of the disk is an almost edge-on ∼70 au ring, with inclination angle ∼87°. Using the NOEMA interferometer at the Plateau de Bure Observatory operating at 1.3 mm, we find resolved continuum emission aligned with the ring structure seen in the 2.2 μm images. We estimate a fractional infrared luminosity of LIR/Ltot $\simeq \,{6}_{-1}^{+2}$ × 10-4, higher than that of the debris disk around AU Mic. Several characteristics of BD+45° 598, such as its galactic space motion, placement in a color-magnitude diagram, and strong presence of lithium, are all consistent with its membership in the β Pictoris Moving Group with an age of 23 ± 3 Myr. However, the galactic position for BD+45° 598 is slightly discrepant from previously known members of the β Pictoris Moving Group, possibly indicating an extension of members of this moving group to distances of at least 70 pc. BD+45° 598 appears to be an example from a population of young circumstellar debris systems associated with newly identified members of young moving groups that can be imaged in scattered light, key objects for mapping out the early evolution of planetary systems from ∼10-100 Myr. This target will also be ideal for northern-hemisphere, high-contrast imaging platforms to search for self-luminous, planetary mass companions residing in this system.

Keywords: Circumstellar disks
Properties of Highly Rotationally Excited H<SUB>2</SUB> in Photodissociation Regions. Molecular hydrogen (H2) is the dominant molecular species in the vast majority of interstellar environments and it plays a crucial role as a radiative coolant. In photodissociation regions (PDRs), it is one of the primary emitters in the near- to mid-infrared, which is due to lines originating from highly excited levels. The sparseness of H2 collisional data for rotational levels J ≥ 9, particularly for H2-H2 collisions, has limited nonlocal thermal equilibrium (NLTE) studies in ultraviolet-irradiated regions. Utilizing new calculations for para- and ortho-H2 high rotational collisional rate coefficients colliding with H2 (up to the maximum value for v = 0: J = 31), existing data for H2-H and H2-He collisions, and approximate scaling relations for missing collisional data, we investigate the excitation properties of H2 in a range of astrophysical environments, with the focus on PDRs (including benchmark PDR models and the Orion Bar). In these NLTE models, H2 emission is illustrated and shown as a diagnostic for physical conditions, such as temperature and density. Furthermore, we demonstrated the effect of updates in the collisional rates on the modeling results of H2 excitation. The resulting data sets of H2 collisional data should find wide application to other molecular environments.

Keywords: Interstellar molecules, Photodissociation regions, Astronomy databases, Interstellar medium
Likely Detection of GeV Gamma-Ray Emission from the Composite Supernova Remnant COMP G327.1+1.1 with Fermi-LAT. We report the likely GeV γ-ray emission from the composite supernova remnant (SNR) COMP G327.1+1.1 by analyzing ∼12.2 yr of the Fermi Large Area Telescope (Fermi-LAT) Pass 8 data. We found the features of its spectrum and luminosity are well consistent with those of the observed COMP SNRs in the Milky Way. Moreover, the position of the source matches those in radio and TeV energy bands; we propose that the γ-ray source is likely to be a GeV counterpart of COMP G327.1+1.1. Considering the case of the association from COMP G327.1+1.1 and the γ-ray source, we interpreted its broadband spectral energy distribution (SED) by using three simple stationary models including one-zone and two-zone leptonic models and a one-zone leptohadronic model. We found that the simple two-zone model dominated by leptons can better explain its SED. More high-energy data are expected to firmly confirm the association between the γ-ray source and COMP G327.1+1.1 in the future.

Keywords: Supernova remnants, Gamma-ray astronomy, Non-thermal radiation sources, Diffuse nebulae
Mrk 1239: a Type-2 Counterpart of Narrow-line Seyfert-1?. We present new spectrophotometric and spectropolarimetric observations of Mrk 1239, one of the 8 prototypes that defines type-1 narrow-line Seyfert galaxies (NLS1s). Unlike the other typical NLS1s though, a high degree of polarization (P ∼ 5.6%) and red optical-IR (g-W4 = 12.35) colors suggest that Mrk 1239 is more similar to type-2 active galactic nuclei like NGC 1068. Detailed analysis of spectral energy distribution in the UV-optical-IR yields two components from the nucleus: a direct and transmitted component that is heavily obscured (EB-V ≈ 1.6), and another indirect and scattered one with mild extinction (EB-V ∼ 0.5). Such a two-light-paths scenario is also found in previous reports based on the X-ray data. Comparison of emission lines and the detection of He I*λ10830 BAL at [-3000, -1000] km s-1 indicates that the obscuring clouds are at physical scale between the sublimation radius and that of the narrow emission line regions. The potential existence of powerful outflows is found as both the obscurer and scatterer are outflowing. Similar to many other type-2s, jet-like structure in the radio band is found in Mrk 1239, perpendicular to the polarization angle, suggesting polar scattering. We argue that Mrk 1239 is very probably a type-2 counterpart of NLS1s. The identification of 1 out of 8 prototype NLS1s as a type-2 counterpart implies that there can be a substantial amount of analogs of Mrk 1239 misidentified as type-1s in the optical band. Properties of these misidentified objects are going to be explored in our future works.

Keywords: Active galactic nuclei, Broad-absorption line quasar
Detection of Al II in the Ultraviolet Spectra of Metal-poor Stars: An Empirical LTE Test of NLTE Aluminum Abundance Calculations. We report the detection of an Al II line at 2669.155 Å in 11 metal-poor stars, using ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive Al abundances from this line using a standard abundance analysis, assuming local thermodynamic equilibrium (LTE). The mean [Al/Fe] ratio is -0.06 ± 0.04 (σ = 0.22) for these 11 stars spanning - 3.9 &lt; [Fe/H] &lt; -1.3, or [Al/Fe] = -0.10 ± 0.04 (σ = 0.18) for 9 stars spanning -3.0 &lt; [Fe/H] &lt; -1.3 if two carbon-enhanced stars are excluded. We use these abundances to perform an empirical test of non-LTE (NLTE) abundance corrections predicted for resonance lines of Al I, including the commonly used optical Al I line at 3961 Å. The Al II line is formed in LTE, and the abundance derived from this line matches that derived from high-excitation Al I lines predicted to have minimal NLTE corrections. The differences between the abundance derived from the Al II line and the LTE abundance derived from Al I resonance lines are +0.4 to +0.9 dex, which match the predicted NLTE corrections for the Al I resonance lines. We conclude that the NLTE abundance calculations are approximately correct and should be applied to LTE abundances derived from Al I lines. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. The data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes. Other data have been obtained from the European Southern Observatory Science Archive Facility. This research has also made use of the Keck Observatory Archive, which is operated by the W.M. Keck Observatory and the NASA Exoplanet Science Institute, under contract with NASA. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin, and the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Ultraviolet astronomy, Stellar abundances, Stellar atmospheres, Nucleosynthesis
Long-term Coherent Timing of the Accreting Millisecond Pulsar IGR J17062-6143. We report on a coherent timing analysis of the 163 Hz accreting millisecond X-ray pulsar IGR J17062-6143. Using data collected with the Neutron Star Interior Composition Explorer and XMM-Newton, we investigated the pulsar evolution over a time span of four years. We obtained a unique phase-coherent timing solution for the stellar spin, finding the source to be spinning up at a rate of (3.77 ± 0.09) × 10-15 Hz s-1. We further find that the 0.4-6 keV pulse fraction varies gradually between 0.5% and 2.5% following a sinusoidal oscillation with a 1210 ± 40 day period. Finally, we supplemented this analysis with an archival Rossi X-ray Timing Explorer observation and obtained a phase-coherent model for the binary orbit spanning 12 yr, yielding an orbital period-derivative measurement of (8.4 ± 2.0) × 10-12 s s-1. This large orbital period derivative is inconsistent with a binary evolution that is dominated by gravitational wave emission and is suggestive of highly nonconservative mass transfer in the binary system.

Keywords: Low-mass x-ray binary stars, Millisecond pulsars
Exploring Mutual Information between IRIS Spectral Lines. I. Correlations between Spectral Lines during Solar Flares and within the Quiet Sun.. Spectral lines allow us to probe the thermodynamics of the solar atmosphere, but the shape of a single spectral line may be similar for different thermodynamic solutions. Multiline analyses are therefore crucial, but computationally cumbersome. We investigate correlations between several chromospheric and transition region lines to restrain the thermodynamic solutions of the solar atmosphere during flares. We used machine-learning methods to capture the statistical dependencies between six spectral lines sourced from 21 large solar flares observed by NASA's Interface Region Imaging Spectrograph. The techniques are based on an information-theoretic quantity called mutual information (MI), which captures both linear and nonlinear correlations between spectral lines. The MI is estimated using both a categorical and numeric method, and performed separately for a collection of quiet Sun and flaring observations. Both approaches return consistent results, indicating weak correlations between spectral lines under quiet Sun conditions, and substantially enhanced correlations under flaring conditions, with some line-pairs such as Mg II and C II having a normalized MI score as high as 0.5. We find that certain spectral lines couple more readily than others, indicating a coherence in the solar atmosphere over many scale heights during flares, and that all line-pairs are correlated to the GOES derivative, indicating a positive relationship between correlation strength and energy input. Our methods provide a highly stable and flexible framework for quantifying dependencies between the physical quantities of the solar atmosphere, allowing us to obtain a three-dimensional picture of its state.

Keywords: Solar flares, Solar flare spectra, Neural networks
Analysis of Solar Diameter Measurements Made at the Basilica of San Petronio during and after the Maunder Minimum. A series of measurements of the solar diameter taken in the meridian line of the Basilica of San Petronio (Bologna, Italy) between 1655 and 1736 has been analyzed. This series is of interest because the measurement period includes the Maunder Minimum (1645-1715; hereafter MM) when solar activity was abnormally low. Some authors have suggested an increase of the solar diameter during the MM. Trying to detect these changes, statistical analyses comparing measurements taken in San Petronio during the MM (1655-1715) and other ones taken in a subsequent period (1716-1736) have been performed. Mann-Whitney U tests and Student's t-tests indicate that there is no statistically significant difference in the medians and averages of the solar diameter in both periods. In fact, we have found differences around 0"6 in the medians and the averages, which are below the mean accuracy of the instrument. Therefore, we conclude that there is no difference between the solar diameter value measured during the MM (1655-1715) and that for the subsequent period 1716-1736. This implies that there has not been an increase in the solar diameter of several arcseconds during the MM as has been speculated by some authors.

Keywords: Maunder minimum, Astronomy databases, Solar radius
Temperature and Distance Dependence of Tidal Circularization in Close Binaries: A Catalog of Eclipsing Binaries in the Southern Hemisphere Observed by the TESS Satellite. Tidal forces are important for understanding how close binary stars and compact exoplanetary systems form and evolve. However, tides are difficult to model, and significant uncertainties exist about the strength of tides. Here, we investigate tidal circularization in close binaries using a large sample of well-characterized eclipsing systems. We searched TESS photometry from the southern hemisphere for eclipsing binaries. We derive best-fit orbital and stellar parameters by jointly modeling light curves and spectral energy distributions. To determine the eccentricity distribution of eclipsing binaries over a wide range of stellar temperatures (3000-50,000 K) and orbital separations a/R1 (2-300), we combine our newly obtained TESS sample with eclipsing binaries observed from the ground and by the Kepler mission. We find a clear dependency of stellar temperature and orbital separation in the eccentricities of close binaries. We compare our observations with predictions of the equilibrium and dynamical tides. We find that while cool binaries agree with the predictions of the equilibrium tide, a large fraction of binaries with temperatures between 6250 K and 10,000 K and orbital separations between a/R1 ∼ 4 and 10 are found on circular orbits, contrary to the predictions of the dynamical tide. This suggests that some binaries with radiative envelopes may be tidally circularized significantly more efficiently than usually assumed. Our findings on orbital circularization have important implications also in the context of hot Jupiters, where tides have been invoked to explain the observed difference in the spin-orbit alignment between hot and cool host stars.

Keywords: Binary stars, Close binary stars, Light curves, Tides, Detached binary stars, Eclipsing binary stars, Tidal interaction
A Deep Chandra X-Ray Observatory Study of the Millisecond Pulsar Population in the Globular Cluster Terzan 5. We present an analysis of 745.8 ks of archival Chandra X-Ray Observatory Advanced CCD Imaging Spectrometer data accumulated between 2000 and 2016 of the millisecond pulsar (MSP) population in the rich Galactic globular cluster Terzan 5. Eight of the 38 MSPs with precise positions are found to have plausible X-ray source matches. Despite the deep exposure, the remaining MSPs are either marginally detected or have no obvious X-ray counterparts, which can be attributed to the typically soft thermal spectra of rotation-powered MSPs, which are strongly attenuated by the high intervening absorbing column (∼1022 cm-2) toward the cluster, and in some instances to severe source crowding/blending. For the "redback" MSP binaries PSR J1748-2446P and PSR J1748-2446ad and the "black widow" binary system PSR J1748-2446O, we find clear evidence for large-amplitude X-ray variability at the orbital period consistent with an intrabinary shock origin. The third redback MSP in the cluster, PSR J1748-2446A, shows order-of-magnitude variations in flux on timescales of years, possibly due to state transitions or intense flaring episodes from a magnetically active secondary star.

Keywords: Globular star clusters, X-ray astronomy, X-ray binary stars, Millisecond pulsars, Pulsars, X-ray identification, Astronomical methods, X-ray sources, Binary pulsars
I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility. We present a novel method to detect variable astrophysical objects and transient phenomena using anomalous excess scatter in repeated measurements from public catalogs of Gaia DR2 and Zwicky Transient Facility (ZTF) DR3 photometry. We first provide a generalized, all-sky proxy for variability using only Gaia DR2 photometry, calibrated to white dwarf stars. To ensure more robust candidate detection, we further employ a method combining Gaia with ZTF photometry and alerts. To demonstrate its efficacy, we apply this latter technique to a sample of roughly 12,100 white dwarfs within 200 pc centered on the ZZ Ceti instability strip, where hydrogen-atmosphere white dwarfs are known to pulsate. By inspecting the top 1% of the samples ranked by these methods, we demonstrate that both the Gaia-only and ZTF-informed techniques are highly effective at identifying known and new variable white dwarfs, which we verify using follow-up, high-speed photometry. We confirm variability in all 33 out of 33 (100%) observed white dwarfs within our top 1% highest-ranked candidates, both inside and outside the ZZ Ceti instability strip. In addition to dozens of new pulsating white dwarfs, we also identify five white dwarfs highly likely to show transiting planetary debris; if confirmed, these systems would more than triple the number of white dwarfs known to host transiting debris.

Keywords: Transits, Stellar pulsations, White dwarf stars, Cataclysmic variable stars, ZZ Ceti stars, Variable stars, Planetesimals, Transient detection, Circumstellar dust
The Dusty Heart of NGC 4151 Revealed by λ ∼ 1-40 μm Reverberation Mapping and Variability: A Challenge to Current Clumpy Torus Models. We probe the dusty environment of the archetypical Type 1 active galactic nucleus (AGN) in NGC 4151 with comprehensive IR reverberation mapping over several decades, in the J (∼1.22 μm), H (∼1.63 μm), K (∼2.19 μm), L (∼3.45 μm), and N bands (∼10.6 μm), plus multiple measurements at 20-40 μm. At 1-4 μm, the hot dust reverberation signals come from two distinct dust populations at separate radii (∼0.033 pc and ∼0.076 pc), with temperatures of ∼1500-2500 K and ∼900-1000 K, consistent with the expected properties of sublimating graphite and silicate dust grains. The domination of the torus infrared output by carbon and silicate grains near their sublimation temperatures and radii may account for the general similarity of AGN near-IR spectral energy distributions. The torus inner edge defined by the hottest dust remains at roughly the same radius independent of the AGN optical luminosity over ∼25 yr. The emission by hot dust warmed directly by the optical/UV AGN output has increased gradually by ∼4% yr-1, indicating a possibly growing torus. A third dust component at ∼700 K does not seem to participate directly in the IR reverberation behavior, and its emission may originate deep in the circumnuclear torus. We find a reverberation signal at ∼10 μm with an inferred radius for the warm dust of ∼2.2-3.1 pc. The lack of variability at 20-40 μm indicates that the far-IR emission comes from even more extended regions. The torus properties revealed by dust reverberation analysis are inconsistent with predictions from pure clumpy torus models. Instead, the longer-wavelength emission possibly originates in a flared torus or the polar wind.

Keywords: Interstellar dust, Reverberation mapping, Galaxy nuclei, Seyfert galaxies, Dust continuum emission, Active galactic nuclei, Extragalactic astronomy
Photometric Variability as a Proxy for Magnetic Activity and Its Dependence on Metallicity. Understanding how the magnetic activity of low-mass stars depends on their fundamental parameters is an important goal of stellar astrophysics. Previous studies have shown that activity levels are largely determined by the stellar Rossby number, defined as the rotation period divided by the convective turnover time. However, we currently have little information on the role played by chemical composition. In this work, we investigate how metallicity affects magnetic activity, using photometric variability as an activity proxy. Similarly to other proxies, we demonstrate that the amplitude of photometric variability is well parameterized by the Rossby number, although in a more complex way. We also show that variability amplitude and metallicity are generally positively correlated. This trend can be understood in terms of the effect of metallicity on stellar structure, and hence the convective turnover time (or, equivalently, the Rossby number). Lastly, we demonstrate that the metallicity dependence of photometric variability results in a rotation-period detection bias, whereby the periods of metal-rich stars are more easily recovered for stars of a given mass.

Keywords: Stellar rotation, Metallicity, Low mass stars, Stellar activity