Sazuna/UAT_keywords huggingface dataset:
A Two-Component Probability Distribution Function Describes the Mid-IR Emission from the Disks of Star-forming Galaxies. High-resolution JWST-MIRI images of nearby spiral galaxies reveal emission with complex substructures that trace dust heated both by massive young stars and the diffuse interstellar radiation field. We present high angular (0.″85) and physical resolution (20-80 pc) measurements of the probability distribution function (PDF) of mid-infrared (mid-IR) emission (7.7-21 μm) from 19 nearby star-forming galaxies from the PHANGS-JWST Cycle 1 Treasury. The PDFs of mid-IR emission from the disks of all 19 galaxies consistently show two distinct components: an approximately lognormal distribution at lower intensities and a high-intensity power law component. These two components only emerge once individual star-forming regions are resolved. Comparing with locations of H II regions identified from Very Large Telescope/MUSE Hα mapping, we infer that the power-law component arises from star-forming regions and thus primarily traces dust heated by young stars. In the continuum-dominated 21 μm band, the power law is more prominent and contains roughly half of the total flux. At 7.7-11.3 μm, the power law is suppressed by the destruction of small grains (including PAHs) close to H II regions, while the lognormal component tracing the dust column in diffuse regions appears more prominent. The width and shape of the lognormal diffuse emission PDFs in galactic disks remain consistent across our sample, implying a lognormal gas column density N(H) ≈ 1021 cm-2 shaped by supersonic turbulence with typical (isothermal) turbulent Mach numbers ≈5-15. Finally, we describe how the PDFs of galactic disks are assembled from dusty H II regions and diffuse gas and discuss how the measured PDF parameters correlate with global properties such as star formation rate and gas surface density.

Keywords: Dust physics, Stellar feedback, Infrared astronomy, Interstellar medium, Extragalactic astronomy, H II regions
Free-floating or Wide-orbit? Keck Adaptive-optics Observations of Free-floating Planet Candidates Detected with Gravitational Microlensing. Recent detections of extremely short-timescale microlensing events imply the existence of a large population of Earth- to Neptune-mass planets that appear to have no host stars. However, it is currently unknown whether these objects are truly free-floating planets or whether they are in wide orbits around a distant host star. Here, we present an analysis of high-resolution imaging observations of five free-floating planet candidates collected with the Keck telescope. If these candidates were actually wide-orbit planets, then the light of the host would appear at a separation of 40-60 mas from the microlensing source star. No such stars are detected. We carry out injection and recovery simulations to estimate the sensitivity to putative host stars at different separations. Depending on the object, the presented observations rule out 11%-36% of potential hosts assuming that the probability of hosting a planet does not depend on the host mass. The results are sensitive to the latter assumption, and the probability of detecting the host star in the analyzed images may be a factor of 1.9 ± 0.1 larger, if the exoplanet hosting probability scales as the first power of the host star mass, as suggested by recent studies of planetary microlensing events. We argue that deeper observations, for example with JWST, are needed to confidently confirm or refute the free-floating planet hypothesis.

Keywords: Gravitational microlensing, Free floating planets, High-resolution microlensing event imaging
High-resolution, Mid-infrared Color Temperature Mapping of the Central 10″ of the Galaxy. The neighborhood of the Galactic black hole boasts a plethora of extended interstellar gas and dust features, as well as populations of compact (unresolved or marginally resolved) features such as the G objects. Most are well manifested in the infrared. To disentangle and characterize the infrared structure of the extended features and identify compact sources, we used 3.8 μm (L' filter) data from the NIRC2 imager at the Keck Observatory and 8.6 μm (PAH1 filter) data from the VISIR imager at the Very Large Telescope to produce the highest-resolution mid-IR color temperature map of the inner half-parsec of the Galactic center to date. From this map, we compile a catalog of features that stand out from their background. In particular, we identify 33 compact sources that stand out against the local background temperature, 11 of which are newly identified and candidates for being members of the G object population. Additionally, we resolve and newly characterize the morphology of several known extended features. These results prepare the way for ongoing and future JWST studies that have access to a greater range of mid-infrared wavelengths and thus will allow for refined estimation of the trends of dust temperatures.

Keywords: Infrared astronomy, Galactic center, Interstellar medium
Photometric Metallicity and Distance for the Two RR Lyrae in Segue II and Ursa Major II Dwarf Galaxies Based on Multiband Light Curves. Multiband light curves of two RR Lyrae variables in Segue II and Ursa Major II ultrafaint dwarf galaxies were collected from near simultaneous observations using the Lulin One-meter Telescope in Vgri bands. Together with Gaia G-band light curves, we determined photometric metallicities using empirical relations involving pulsation period and Fourier parameter as dependent parameters. We demonstrated that the RR Lyrae photometric metallicity can be determined accurately when these empirical relations were employed at multiple wavelengths, which can potentially improve the distance determination based on RR Lyrae stars. The photometric metallicities based on our approach were found to be -2.27 ± 0.13 dex and -1.87 ± 0.16 dex for the RR Lyrae in Segue II and Ursa Major II UFD, respectively, with corresponding distance moduli of 17.69 ± 0.15 mag and 17.58 ± 0.15 mag, in agreement with previous literature determinations. This approach of photometric metallicity of RR Lyrae based on multiband optical light curves will be particularly relevant for distance measurements in the era of the Vera C Rubin's Legacy Survey of Space and Time.

Keywords: RR Lyrae variable stars, Stellar distance, Metallicity, Dwarf galaxies
Atmospheric Metallicity and C/O of HD 189733 b from High-resolution Spectroscopy. We present high-resolution K-band emission spectra of the quintessential hot Jupiter HD 189733 b from the Keck Planet Imager and Characterizer. Using a Bayesian retrieval framework, we fit the dayside pressure-temperature profile, orbital kinematics, mass-mixing ratios of H2O, CO, CH4, NH3, HCN, and H2S, and the 13CO/12CO ratio. We measure mass fractions of ${\mathrm{logH}}_{2}{\rm{O}}=-{2.0}_{-0.4}^{+0.4}$ and $\mathrm{logCO}=-{2.2}_{-0.5}^{+0.5}$ , and place upper limits on the remaining species. Notably, we find logCH4 &lt; -4.5 at 99% confidence, despite its anticipated presence at the equilibrium temperature of HD 189733 b assuming local thermal equilibrium. We make a tentative (~3σ) detection of 13CO, and the retrieved posteriors suggest a 12C/13C ratio similar to or substantially less than the local interstellar value. The possible 13C enrichment would be consistent with accretion of fractionated material in ices or in the protoplanetary disk midplane. The retrieved abundances correspond to a substantially substellar atmospheric C/O = 0.3 ± 0.1, while the carbon and oxygen abundances are stellar to slightly superstellar, consistent with core-accretion models which predict an inverse correlation between C/O and metallicity. The specific combination of low C/O and high metallicity suggests significant accretion of solid material may have occurred late in the formation process of HD 189733 b.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Exoplanets, Hot Jupiters, Exoplanet atmospheres
Revisit of 77 Clusters Candidates with Multiple Main Sequences using Gaia DR3. Gaia DR3 data provide the latest and full astrometric data for more than 1.5 billion sources, and these allow us to revisit the 77 special open cluster candidates collected from LISC star cluster catalog. According to their unclear color-magnitude-diagram (CMD) morphology, they are difficult to be ensured as real open clusters (OCs), and their cluster properties are still poorly known. We perform a cluster census by reidentification for these clusters using pyUPMASK based on the photometric and astrometric stellar information. We have redetected these 77 objects and they should be real OCs, of which five clusters are potential binary clusters. Their basic parameters are obtained by fitting isochrones to observed CMDs. Our results show that their CMDs display more clean main sequences (MSs) and less member stars lying on the right of lower MSs relative to most of clusters in our initial sample, but broad MSs have not changed significantly. We suggest that efficient clustering algorithm combined with precision data can only partly reduce some stars lying on the right of lower MSs, and a simple stellar population of binary and rotating stars can partly reproduce multiple MS phenomena, including split and broad MSs.

Keywords: Galaxy clusters, Open star clusters
Insight into the Formation of β Pic b through the Composition of Its Parent Protoplanetary Disk as Revealed by the β Pic Moving Group Member HD 181327. It has been suggested that β Pic b has a supersolar metallicity and subsolar C/O ratio. Assuming solar carbon and oxygen abundances for the star β Pic and therefore the planet's parent protoplanetary disk, β Pic b's C/O ratio suggests that it formed via core accretion between its parent protoplanetary disk's H2O and CO2 ice lines. However, β Pic b's high metallicity is difficult to reconcile with its mass M p = 11.7 M Jup. Massive stars can present peculiar photospheric abundances that are unlikely to record the abundances of their former protoplanetary disks. This issue can be overcome for early-type stars in moving groups by inferring the elemental abundances of the FGK stars in the same moving group that formed in the same molecular cloud and presumably share the same composition. We infer the photospheric abundances of the F dwarf HD 181327, a β Pic moving group member that is the best available proxy for the composition of β Pic b's parent protoplanetary disk. In parallel, we infer updated atmospheric abundances for β Pic b. As expected for a planet of its mass formed via core-accretion beyond its parent protoplanetary disk's H2O ice line, we find that β Pic b's atmosphere is consistent with stellar metallicity and confirm that it has superstellar carbon and oxygen abundances with a substellar C/O ratio. We propose that the elemental abundances of FGK dwarfs in moving groups can be used as proxies for the otherwise difficult-to-infer elemental abundances of early-type and late-type members of the same moving groups.

Keywords: Exoplanet atmospheric composition , Exoplanet migration, Stellar abundances, Exoplanet systems, Exoplanet astronomy, Planet hosting stars, Exoplanet formation, Exoplanet atmospheres
Statistical Distribution Function of Orbital Spacings in Planetary Systems. The minimum orbital separation of planets in long-stable planetary systems is often modeled as a step function, parameterized with a single value ${{\rm{\Delta }}}_{\min }$ (measured in mutual Hill radius of the two neighboring planets). Systems with smaller separations are considered unstable, and planet pairs with greater separations are considered stable. Here we report that a log-normal distribution function for ${{\rm{\Delta }}}_{\min }$ , rather than a single threshold value, provides a more accurate model. From our suite of simulated planetary systems, the parameters of the best-fit log-normal distribution are μ = 1.97 ± 0.02 and σ = 0.40 ± 0.02, such that the mean, median, and mode of ${{\rm{\Delta }}}_{\min }$ are 7.77, 7.17, and 6.11, respectively. This result is consistent with previous estimates for ${{\rm{\Delta }}}_{\min }$ threshold values in the range ~5-8. We find a modest dependence of the distribution of ${{\rm{\Delta }}}_{\min }$ on multiplicity within the system, as well as on planetary mass ratios of the closest planet pair. The overall distribution of nearest-neighbor planetary orbital spacings (measured in the mutual Hill radii and denoted simply as ∆) in long-term stable systems is also well fit with a log-normal distribution, with parameters μ = 3.14 ± 0.03 and σ = 0.76 ± 0.02. In simulations of sets of many planets initially packed very close together, we find that the orbital spacings of long-term stable systems is statistically similar to that in the observed Kepler sample of exoplanetary systems, indicating a strong role of sculpting of planetary architectures by dynamical instabilities.

Keywords: Exoplanet dynamics, Exoplanet systems
Observations of the Ultraviolet-bright Star ZNG 1 in the Globular Cluster M5 (NGC 5904). We have analyzed archival spectra of the hot UV-bright star ZNG 1 in the globular cluster M5 (NGC 5904) obtained with the Far Ultraviolet Spectroscopic Explorer and the Space Telescope Imaging Spectrograph. From these data, we derive an effective temperature T eff = 43,000 ± 1400 K, a surface gravity $\mathrm{log}g$ = 4.47 ± 0.08, a rotational velocity $v\sin i$ = 157 ± 12 km s-1, and a mass M = 0.92 ± 0.17 M ☉. The atmosphere is helium-rich (Y = 0.99) and enhanced in CNO (relative to the cluster). The spectrum exhibits wind features with a terminal velocity near 1500 km s-1 and strong discrete absorption components. The high helium abundance, stellar mass, and rotational velocity suggest that the star is a merger remnant, and its parameters are consistent with models of a pair of merging He-core white dwarfs.

Keywords: Helium-rich stars, Stellar abundances, Stellar atmospheres, Stellar evolution
Signs of Similar Stellar Obliquity Distributions for Hot and Warm Jupiters Orbiting Cool Stars. Transiting giant planets provide a natural opportunity to examine stellar obliquities, which offer clues about the origin and dynamical histories of close-in planets. Hot Jupiters orbiting Sun-like stars show a tendency for obliquity alignment, which suggests that obliquities are rarely excited or that tidal realignment is common. However, the stellar obliquity distribution is less clear for giant planets at wider separations where realignment mechanisms are not expected to operate. In this work, we uniformly derive line-of-sight inclinations for 47 cool stars (T eff &lt; 6200 K) harboring transiting hot and warm giant planets by combining rotation periods, stellar radii, and $v\sin i$ measurements. Among the systems that show signs of spin-orbit misalignment in our sample, three are identified as being misaligned here for the first time. Of particular interest are Kepler-1654, one of the longest-period (1047 days; 2.0 au) giant planets in a misaligned system, and Kepler-30, a multiplanet misaligned system. By comparing the reconstructed underlying inclination distributions, we find that the inferred minimum misalignment distributions of hot Jupiters spanning a/R * = 3-20 (≈0.01-0.1 au) and warm Jupiters spanning a/R * = 20-400 (≈0.1-1.9 au) are in good agreement. With 90% confidence, at least ${24}_{-10}^{+7} \% $ of warm Jupiters and ${14}_{-8}^{+5} \% $ of hot Jupiters around cool stars are misaligned by at least 10°. Most stars harboring warm Jupiters are therefore consistent with spin-orbit alignment. The similarity of the hot and warm Jupiter misalignment rates suggests that either the occasional misalignments are primordial and originate in misaligned disks, or the same underlying processes that create misaligned hot Jupiters also lead to misaligned warm Jupiters.

Keywords: Exoplanet migration, Exoplanet formation, Exoplanets
Distribution of Hα Emitters in Merging Galaxy Clusters. Studies of star formation in various galaxy cluster mergers have reached apparently contradictory conclusions regarding whether mergers stimulate star formation, quench it, or have no effect. Because the mergers studied span a range of time since pericenter (TSP), it is possible that the apparent effect on star formation is a function of the TSP. We use a sample of 12 bimodal mergers to assess the star formation as a function of TSP. We measure the equivalent width of the Hα emission line in ~100 member galaxies in each merger, classify galaxies as emitters or nonemitters, and then classify emitters as star-forming galaxies (SFGs) or active galactic nucleus (AGN) based on the [N II] λ6583 line. We quantify the distribution of SFG and AGN relative to nonemitters along the spatial axis defined by the subcluster separation. The SFG and AGN fractions vary from merger to merger but show no trend with TSP. The spatial distribution of SFG is consistent with that of nonemitters in eight mergers, but show significant avoidance of the system center in the remaining four mergers, including the three with the lowest TSP. If there is a connection between star formation activity and TSP, probing it further will require more precise TSP estimates and more mergers with TSP in the range of 0-400 Myr.

Keywords: Galaxy clusters, Star formation
The APO-K2 Catalog. I.  7500 Red Giants with Fundamental Stellar Parameters from APOGEE DR17 Spectroscopy and K2-GAP Asteroseismology. We present a catalog of fundamental stellar properties for ~7500 evolved stars, including stellar radii and masses, determined from the combination of spectroscopic observations from the Apache Point Observatory Galactic Evolution Experiment, part of the Sloan Digital Sky Survey IV, and asteroseismology from K2. The resulting APO-K2 catalog provides spectroscopically derived temperatures and metallicities, asteroseismic global parameters, evolutionary states, and asteroseismically derived masses and radii. Additionally, we include kinematic information from Gaia. We investigate the multidimensional space of abundance, stellar mass, and velocity with an eye toward applications in Galactic archaeology. The APO-K2 sample has a large population of low-metallicity stars (~288 with [M/H] ≤ -1), and their asteroseismic masses are larger than astrophysical estimates. We argue that this may reflect offsets in the adopted fundamental temperature scale for metal-poor stars rather than metallicity-dependent issues with interpreting asteroseismic data. We characterize the kinematic properties of the population as a function of α enhancement and position in the disk and identify those stars in the sample that are candidate components of the Gaia-Enceladus merger. Importantly, we characterize the selection function for the APO-K2 sample as a function of metallicity, radius, mass, ${\nu }_{\max }$ , color, and magnitude referencing Galactic simulations and target selection criteria to enable robust statistical inferences with the catalog.

Keywords: Stellar kinematics, Galactic archaeology, Stellar astronomy, Spectroscopy, Asteroseismology
Evolved Massive Stars at Low Metallicity. VI. Mass-loss Rate of Red Supergiant Stars in the Large Magellanic Cloud. Mass loss is a crucial process that affects the observational properties, evolution path, and fate of highly evolved stars. However, the mechanism of mass loss is still unclear, and the mass-loss rate (MLR) of red supergiant stars (RSGs) requires further research and precise evaluation. To address this, we utilized an updated and complete sample of RSGs in the Large Magellanic Cloud (LMC) and employed the 2-DUST radiation transfer model and spectral energy distribution fitting approach to determine the dust-production rates (DPRs) and dust properties of the RSGs. We have fitted 4714 selected RSGs with over 100,000 theoretical templates of evolved stars. Our results show that the DPR range of RSGs in the LMC is 10-11 M ⊙ yr-1-10-7 M ⊙ yr-1, and the total DPR of all RSGs is 1.14 ×10-6 M ⊙ yr-1. We find that 63.3% RSGs are oxygen-rich, and they account for 97.2% of the total DPR. The optically thin RSG, which comprise 30.6% of our sample, contribute only 0.1% of the total DPR, while carbon-rich RSGs (6.1%) produce 2.7% of the total DPR. Overall, 208 RSGs contributed 76.6% of the total DPR. We have established a new relationship between the MLR and luminosity of RSGs in the LMC, which exhibits a positive trend and a clear turning point at $\mathrm{log}L/{L}_{\odot }\approx 4.4$ .

Keywords: Red supergiant stars, Large Magellanic Cloud, Stellar mass loss, Interstellar medium, Circumstellar dust
An Automatic Approach for Grouping Sunspots and Calculating Relative Sunspot Number on SDO/HMI Continuum Images. The relative sunspot number is one of the major parameters for the study of long-term solar activity. The automatic calculation of the relative sunspot number is more stable and accurate as compared to manual methods. In this paper, we propose an algorithm that can detect sunspots, and divide them into groups to automatically calculate the relative sunspot number. Mathematical morphology was adopted to detect sunspots then group them. The data set used were the continuum images from SDO/HMI. The process was carried out on the overall HMI data available on the timespan from 2022 January to 2023 May with a time cadence of one day. The experimental results indicated that the method achieved high accuracy of 85.3%. It was well fitted with the international relative sunspot number provided by Solar Influences Data Analysis Center (CC = 0.91). We calculated the conversion factor K value of SDO/HMI for calculating the relative sunspots number (K = 1.03).

Keywords: Solar physics, Sunspot groups, Sunspot number
Precision Speckle Pattern Reconstruction for High-contrast Imaging. In high-contrast imaging, a large instrumental, technological, and algorithmic effort is made to reduce residual speckle noise and improve the detection capabilities. In this work, we explore the potential of using a precise physical description of speckle images, in conjunction with the optimal detection statistic to perform high-contrast imaging. Our method uses short-exposure speckle images, reconstructing the point-spread function (PSF) of each image with phase retrieval algorithms. Using the reconstructed PSFs, we calculate the optimal detection statistic for all images. We analyze the arising bias due to the use of a reconstructed PSF and correct for it completely up to its accumulation over 104 images. We measure in simulations the method's sensitivity loss due to overfitting in the reconstruction process and get to an estimated 5σ detection limit of 5 × 10-7 flux ratio at angular separations of 0.″1-0.″5 for a 1h observation of Sirius A with a 2 m telescope.

Keywords: High contrast techniques, Astronomical seeing, Astronomy data analysis
TESS Hunt for Young and Maturing Exoplanets (THYME). XI. An Earth-sized Planet Orbiting a Nearby, Solar-like Host in the 400 Myr Ursa Major Moving Group. Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433 d—a nearby (22 pc), Earth-sized planet transiting a young Sun-like star (TOI-1726, HD 63433). HD 63433 d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 ± 23 Myr) Ursa Major moving group, whose membership we update using new data from the third data release of the Gaia mission and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1 R ⊕ and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host (V ≃ 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe the atmospheric loss in a young Earth-sized world.

Keywords: Exoplanet systems