Sazuna/UAT_keywords huggingface dataset:
Variability in Early Post-main-sequence Stars in Globular Cluster NGC 3201. In this paper we study stellar variability in the globular cluster NGC 3201 in the magnitude range V = 16-17, corresponding to the subgiant branch and blue stragglers region of the cluster. Our aim is to expand the sample of new type of variables with low amplitude and a short period found in previous papers. We used observations obtained at the Complejo Astronómico El Leoncito. We applied statistical tests and analyzed periodograms obtained by generalized Lomb-Scargle and phase dispersion minimization methods. We found five stars considered as variables and one as a possible variable. According to their periods (fluctuating between 0.33 and 0.57 days), amplitudes (between 0.03 and 0.87 V magnitudes), the position in the color-magnitude diagram, and the shape of their phased light curves, they do not resemble any known variable star. Because stellar variability could be produced by more than one process, we propose to complement this work with a spectroscopic analysis to confirm our results.

Keywords: Globular star clusters, Variable stars, Evolved stars
The Comprehensive Archive of Substellar and Planetary Accretion Rates. Accretion rates ( ) of young stars show a strong correlation with object mass (M); however, extension of the relation into the substellar regime is less certain. Here, we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest compilation to date of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the relation and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original 1σ scatter in the relation by ∼17%, suggesting that it makes only a small contribution to the dispersion. The CASPAR rederived values are best fit by from 10 M J to 2 M ⊙, confirming previous results. However, we argue that the brown-dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent relations for these regions and find a steepening in the brown-dwarf slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of ∼44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms.

Keywords: Brown dwarfs, Astronomy databases, Classical T Tauri stars, Pre-main sequence stars, Stellar accretion
CCD UBV and Gaia DR3 Analyses of the Open Clusters King 6 and NGC 1605. A detailed analysis of ground-based CCD UBV photometry and space-based Gaia Data Release 3 (DR3) data for the open clusters King 6 and NGC 1605 was performed. Using the PYUPMASK algorithm on Gaia astrometric data to estimate cluster membership probabilities, we have identified 112 stars in King 6 and 160 stars in NGC 1605 as the statistically most likely members of each cluster. We calculated reddening and metallicity separately using UBV two-color diagrams to estimate parameter values via independent methods. The color excess E(B - V) and photometric metallicity [Fe/H] for King 6 are 0.515 ± 0.030 mag and 0.02 ± 0.20 dex, respectively. For NGC 1605, they are 0.840 ± 0.054 mag and 0.01 ± 0.20 dex, respectively. With reddening and metallicity kept constant, we have estimated the distances and cluster ages by fitting PARSEC isochrones to color-magnitude diagrams based on the Gaia and UBV data. The photometric distances are 723 ± 34 pc for King 6 and 3054 ± 243 pc for NGC 1605. The cluster ages are 200 ± 20 Myr and 400 ± 50 Myr for King 6 and NGC 1605, respectively. The mass function slopes were found to be 1.29 ± 0.18 and 1.63 ± 0.36 for King 6 and NGC 1605, respectively. These values are in good agreement with the value of Salpeter. The relaxation times were estimated as 5.8 Myr for King 6 and 60 Myr for NGC 1605. These indicate that both clusters are dynamically relaxed since these times are less than the estimated cluster ages. A Galactic orbit analysis shows that both clusters formed outside the solar circle and are members of the young thin-disk population.

Keywords: Stellar kinematics, Open star clusters, Hertzsprung Russell diagram
Characteristic Timescales for the Dayside Martian Ionosphere: Chemistry, Diffusion, and Magnetization. Different boundaries could be defined in a planetary ionosphere where the dominant process in function switches from one to the other. Identifying these boundaries and understanding their variations are hence crucial for disentangling the complexity of the ionosphere. Focusing on Mars, we perform a data-driven analysis of various boundaries and the associated time constants based on the multi-instrument measurements made by the Mars Atmosphere and Volatile Evolution mission during six campaigns that sample broadly different internal and external conditions. The boundaries we investigate include the photochemical equilibrium (PCE) boundary, the magnetic frozen boundary, the ion collision boundary, and the ion gyration boundary. Our analysis reveals systematic solar cycle and diurnal variations in that all boundaries tend to be elevated at enhanced solar activity and on the dayside and duskside of Mars. The variations with the magnetic environment are not observed for all boundaries except for the PCE boundary that exhibits an obvious elevation in strongly magnetized regions. Finally, our analysis suggests interesting species-dependent variations of different boundaries. In particularly, the PCE boundary shows the largest variability among all, with reduced boundary locations for all terminal species (NO+, HCO+, ${{\rm{O}}}_{2}^{+}$ , and H3O+) and one extra nonterminal species (CO2 +) owing to different chemical properties rendered by different ions.

Keywords: Mars, Planetary ionospheres, Solar-planetary interactions
Kepler Bonus: Light Curves of Kepler Background Sources. NASA's Kepler primary mission observed about 116 deg2 in the sky for 3.5 consecutive years to discover Earth-like exoplanets. This mission recorded pixel cutouts, known as target pixel files (TPFs), of over 200,000 targets that were selected to maximize the scientific yield. The Kepler pipeline performed aperture photometry for these primary targets to create light curves. However, hundreds of thousands of background sources were recorded in the TPFs and have never been systematically analyzed. This work uses the linearized field deblending (LFD) method, a point-spread function (PSF) photometry algorithm, to extract light curves. We use Gaia Data Release 3 as the input catalog to extract 606,900 light curves from long-cadence TPFs; 406,548 are new light curves of background sources, while the rest are Kepler's targets. These light curves have comparable quality to those computed by the Kepler pipeline, with combined differential photometric precision values &lt;100 ppm for sources G &lt; 16. The light-curve files are available as high-level science products at the Mikulski Archive for Space Telescopes. Files include PSF and aperture photometry as well as extraction metrics. Additionally, we improve the background and PSF modeling in the LFD method. The LFD method is implemented in the Python library psfmachine. We demonstrate the advantages of this new data set with two examples: deblending of contaminated false-positive Kepler objects of interest identifying the origin of the transit signal and the changes in estimated transit depth of planets using PSF photometry, which improves dilution when compared with aperture photometry. This new nearly unbiased catalog enables further studies in planet search, occurrence rates, and other time-domain studies.

Keywords: Astronomy data modeling, Astronomy databases, Exoplanets, Light curves, Astronomy data analysis, Time domain astronomy, Photometry, Time series analysis
Evidence for Low-level Dynamical Excitation in Near-resonant Exoplanet Systems. The geometries of near-resonant planetary systems offer a relatively pristine window into the initial conditions of exoplanet systems. Given that near-resonant systems have likely experienced minimal dynamical disruptions, the spin-orbit orientations of these systems inform the typical outcomes of quiescent planet formation, as well as the primordial stellar obliquity distribution. However, few measurements have been made to constrain the spin-orbit orientations of near-resonant systems. We present a Rossiter-McLaughlin measurement of the near-resonant warm Jupiter TOI-2202 b, obtained using the Carnegie Planet Finder Spectrograph on the 6.5 m Magellan Clay Telescope. This is the eighth result from the Stellar Obliquities in Long-period Exoplanet Systems survey. We derive a sky-projected 2D spin-orbit angle $\lambda ={26}_{-15}^{+12}{^\circ} $ and a 3D spin-orbit angle $\psi ={31}_{-11}^{+13}{^\circ} $ , finding that TOI-2202 b-the most massive near-resonant exoplanet with a 3D spin-orbit constraint to date-likely deviates from exact alignment with the host star's equator. Incorporating the full census of spin-orbit measurements for near-resonant systems, we demonstrate that the current set of near-resonant systems with period ratios P 2/P 1 ≲ 4 is generally consistent with a quiescent formation pathway, with some room for low-level (≲20°) protoplanetary disk misalignments or post-disk-dispersal spin-orbit excitation. Our result constitutes the first population-wide analysis of spin-orbit geometries for near-resonant planetary systems. * This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Exoplanet dynamics, Exoplanet migration, Exoplanets, Planetary alignment, Orbital resonances, Exoplanet systems, Orbital evolution, Exoplanet astronomy, Exoplanet evolution, Exoplanet formation
Hot Jupiters from Disruption of Resonant Chains in Postdisk Evolution. The formation of hot Jupiters has been a subject of interest in the field of exoplanet science. According to conventional scenarios, these gas giants are believed to form beyond the snow line and subsequently migrate inward. Although the early formation history of hot Jupiters is not well understood, they may emerge in resonant chains as a result of disk migration. Here we study the formation of hot Jupiters via the disruption of resonant chains after the gas disk disappears. We perform N-body simulations on planetary systems consisting of one gas giant and several super-Earths. The initial configuration involves all neighboring planet pairs being in a 3:2 mean motion resonance. We track the evolution of these resonant chains after the gas disk has vanished. Our results reveal that the resonant chains are prone to instability following the dispersal of the gas disk, with more than 80% of instabilities occurring within 3 million years. Only approximately 4% of resonant chains can survive the dynamical evolution. Notably, we find that resonant chains hosting hot Jupiters are more likely to be unstable compared to those hosting warm Jupiters. Our simulations indicate that 33% ± 4% hot Jupiters and 70% ± 4% warm Jupiters could possess nearby companions. Furthermore, incorporating the effects of general relativity and tidal dissipation increases the isolation of hot Jupiters, resulting in nearby companion occurrence rates of 20% ± 4% for hot Jupiters and 69% ± 6% for warm Jupiters.

Keywords: Hot Jupiters, Exoplanet systems, Exoplanets
33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble. We present new angular diameter measurements for 33 stars from the Navy Precision Optical Interferometer, reaching uncertainties on the limb-darkened diameter of 2% or less for 21 targets. We also determined the physical radius, bolometric flux, luminosity, and effective temperature for each star. Our sample is a mix of giant, subgiant, and dwarf stars, and span spectral classes from mid-A to to mid-K. We combined these 33 stars with samples from previous publications to analyze how the NPOI diameters compare to those obtained using other means, namely (V - K) color, the JMMC Stellar Diameters Catalog, and Gaia predictions.

Keywords: Fundamental parameters of stars, Optical interferometry, High angular resolution
Estimating Distances from Parallaxes. VI. A Method for Inferring Distances and Transverse Velocities from Parallaxes and Proper Motions Demonstrated on Gaia Data Release 3. The accuracy of stellar distances inferred purely from parallaxes degrades rapidly with distance. Proper motion measurements, when combined with some idea of typical velocities, provide independent information on stellar distances. Here, I build a direction- and distance-dependent model of the distribution of stellar velocities in the Galaxy, then use this together with parallaxes and proper motions to infer kinegeometric distances and transverse velocities for stars in Gaia DR3. Using noisy simulations, I assess the performance of the method and compare its accuracy to purely parallax-based (geometric) distances. Over the whole Gaia catalog, kinegeometric distances are on average 1.25 times more accurate than geometric ones. This average masks a large variation in the relative performance, however. Kinegeometric distances are considerably better than geometric ones beyond several kpc, for example. On average, kinegeometric distances can be measured to an accuracy of 19% and velocities ( $\sqrt{{v}_{\alpha * }^{2}+{v}_{\delta }^{2}}$ ) to 16 km s-1 (median absolute deviations). In Gaia DR3, kinegeometric distances are smaller than geometric ones on average for distant stars, but the pattern is more complex in the bulge and disk. With the much more accurate proper motions expected in Gaia DR5, a further improvement in the distance accuracy by a factor of (only) 1.35 on average is predicted (with kinegeometric distances still 1.25 times more accurate than geometric ones). The improvement attained from proper motions is limited by the width of the velocity prior, in a way that the improvement from better parallaxes is not limited by the width of the distance prior.

Keywords: Parallax, Bayesian statistics, Stellar motion, Distance indicators, Astrometry, Proper motions, Stellar distance, Catalogs
The Wagging Plasma Tail of Comet C/2020 S3 (Erasmus). Long-period comet C/2020 S3 (Erasmus) reached perihelion at 0.398 au on UT 2020 December 12.67, making it a bright, near-Sun object. Images taken between 2020 mid-November and December using the HI-1 camera and COR2 coronagraph on board STEREO-A, as well as the LASCO/C3 coronagraph on board SoHO, show significant variations in the plasma tail position angles. To analyze these variations, a simple technique was developed to calculate the aberration angles. These angles are defined as the angle between the Sun-comet line and the tail axis, measured in the orbital plane. The aberration angles were found to range from 1.°2 to 46.°8, with an average (median) value of approximately 20.°3 (16.°3). By considering the aberration angles, the solar wind radial velocities during the observations were inferred to range from 73.9 to 573.5 km s-1, with a mean (median) value of approximately 205.5 km s-1 (182.3 km s-1). Throughout the observations, two periods were identified where the tails showed forward tilting, which cannot be explained by aberration alone. In one case, this anomalous position angle was sustained for at least 11 days and is possibly due to corotating interaction regions. In the other case, the tail exhibited dramatic excursions from 180° to 150° back to 210° over a limited period of around 34 hr. This behavior is tentatively explained as a consequence of the interaction with a halo coronal mass ejection that was launched from NOAA Active Region 12786 and arrived at comet C/2020 S3 during the time when the tail displayed its wagging behavior.

Keywords: Comet tails, Solar wind
Three Warm Jupiters around Solar-analog Stars Detected with TESS. We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every ~13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m  p  = ${9.3}_{-0.2}^{+0.2}\,{M}_{\mathrm{jup}}$ and a radius of r  p  = ${0.93}_{-0.2}^{+0.2}\,{R}_{\mathrm{jup}}$ . With a mean density of $\rho ={14.4}_{-1.0}^{+0.9}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ , TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of ~8.3 days and an eccentricity of e = ${0.32}_{-0.02}^{+0.02}$ . TOI-2416 b is more massive than Jupiter with m  p  = ${3.0}_{-0.09}^{+0.10}\,{M}_{\mathrm{jup}}$ , however is significantly smaller with a radius of r  p  = ${0.88}_{-0.02}^{+0.02},{R}_{\mathrm{jup}}$ , leading to a high mean density of $\rho ={5.4}_{-0.3}^{+0.3}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ . TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every ~7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m  p = ${0.64}_{-0.04}^{+0.04}\,{M}_{\mathrm{jup}}$ , and is consistent with an inflated radius of r  p = ${1.00}_{-0.03}^{+0.02}\,{R}_{\mathrm{jup}}$ , leading to a low mean density of $\rho ={0.79}_{-0.08}^{+0.08}\,{\rm{g}}\,{\mathrm{cm}}^{-3}$ . The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of ${860}_{-10}^{+10}$ K, ${1080}_{-10}^{+10}$ K, and ${1100}_{-20}^{+20}$ K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters. *Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere under MPG programmes 0104.A-9007(A) and 0106.A-9014(A).

Keywords: Radial velocity, Exoplanet detection methods, Exoplanet systems
Pore Accessibility in Amorphous Solid Water. The porous nature of amorphous solid water (ASW) can significantly effect the chemical evolution of any planetary or astrophysical surface it forms on due to its ability to trap and retain volatiles. The amount of volatiles that can enter an ASW grain or mantle is limited by how interconnected the pores are to each other and to the exterior surface. Previous laboratory studies examined the interconnectivity of ASW pores in thin ASW films relevant to ice mantles on interstellar grains. Here, we investigate to what extent the interconnectivity of pores and subsequent gas absorption properties of ASW change as one moves toward thicker samples (up to ~1019 H2O cm-2 or ~4 μm) more representative of icy material found in the outer solar system. We find that for all film thicknesses studied, the internal pores are accessible from the sample's surface, and the amount of gas needed to fill the pores increases linearly with the ASW column density. This linear relation supports that the interconnectivity to the surface will persist in ices that are much thicker than those we were able to study, suggesting that the amount of contaminant gas trapped within ASW can significantly alter the chemical evolution of a variety of ASW-rich surfaces in the outer solar system.

Keywords: Ice formation, Solid matter physics, Ice physics, Laboratory astrophysics, Astrochemistry, Surface ices, Ice porosity
Dominance of Bursty over Steady Heating of the 4-8 MK Coronal Plasma in a Solar Active Region: Quantification Using Maps of Minimum, Maximum, and Average Brightness. A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating's bursty and steady components in ARs, applying it to Fe XVIII (hot 94) emission of an AR observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The maximum-, minimum-, and average-brightness values for each pixel, over a 24 hr period, yield a maximum-brightness map, a minimum-brightness map, and an average-brightness map of the AR. Running sets of such three maps come from repeating this process for each time step of running windows of 20, 16, 12, 8, 5, 3, 1, and 0.5 hr. From each running window's set of three maps, we obtain the AR's three corresponding luminosity light curves. We find (1) the time-averaged ratio of minimum-brightness-map luminosity to average-brightness-map luminosity increases as the time window decreases, and the time-averaged ratio of maximum-brightness-map luminosity to average-brightness-map luminosity decreases as the window decreases; (2) for the 24 hr window, the minimum-brightness map's luminosity is 5% of the average-brightness map's luminosity, indicating that at most 5% of the AR's hot 94 luminosity is from heating that is steady for 24 hr; (3) this upper limit on the fraction of the hot 94 luminosity from steady heating increases to 33% for the 30 minute running window. This requires that the heating of the 4-8 MK plasma in this AR is mostly in bursts lasting less than 30 minutes: at most a third of the heating is steady for 30 minutes.

Keywords: Active solar corona, Solar coronal loops, Solar coronal heating, Solar corona
Is There a Dynamic Difference between Stealthy and Standard Coronal Mass Ejections?. Stealthy coronal mass ejections (CMEs), lacking low coronal signatures, may result in significant geomagnetic storms. However, the mechanism of stealthy CMEs is still highly debated. In this work, we investigate whether there are differences between stealthy and standard CMEs in terms of their dynamic behaviors. Seven stealthy and eight standard CMEs with low speeds are selected. We calculate two-dimensional speed distributions of CMEs based on the cross-correlation method, rather than the unidimensional speed, and further obtain more accurate distributions and evolution of CME mechanical energies. Then we derive the CME driving powers and correlate them with CME parameters (total mass, average speed, and acceleration) for standard and stealthy CMEs. Besides, we study the forces that drive CMEs, namely, the Lorentz force, gravitational force, and drag force due to the ambient solar wind near the Sun. The results reveal that both standard and stealthy CMEs are propelled by the combined action of those forces in the inner corona. The drag force and gravitational force are comparable with the Lorentz force. However, the impact of the drag and Lorentz forces on the global evolution of stealthy CMEs is significantly weaker than that on standard CMEs.

Keywords: Solar coronal mass ejections, Solar corona
Measuring the Dust Masses of Protoplanetary Disks in Lupus with ALMA: Evidence That Disks Can Be Optically Thick at 3 mm. Accurate disk mass measurements are necessary to constrain disk evolution and the timescale of planet formation, but such measurements are difficult to make and are very dependent on assumptions. Here, we look at the assumption that the disk is optically thin at radio wavelengths and the effect of this assumption on measurements of disk dust mass. We model the optical to radio spectral energy distributions of 41 protoplanetary disks located in the young (~1-3 Myr old) Lupus star-forming region, including 0.89 1.33 and 3 mm flux densities when available. We measure disk dust masses that are ~1.5-6 times higher than when using the commonly adopted disk dust mass equation under the assumption of optically thin emission in the (sub)millimeter range. The cause of this discrepancy is that most disks are optically thick at millimeter wavelengths, even up to 3 mm, demonstrating that observations at longer wavelengths are needed to trace the fully optically thin emission of disks.

Keywords: T Tauri stars, Protoplanetary disks, Neural networks