Sazuna/UAT_keywords huggingface dataset:
Characterization of the Blue Straggler Star Populations, through Statistical, Photometric, and Spectral Energy Distribution Analysis, in the Old Open Cluster: NGC 2243. We present a statistical, photometric, and spectral energy distribution (SED) analysis of the poorly studied old open cluster: NGC 2243, to characterize its blue straggler star (BSS) population. We applied ensemble-based unsupervised machine learning methods to estimate the membership probabilities using Gaia Data Release 3 (DR3) astrometric data. NGC 2243 is an open cluster that is 3.67 Gyr old with a metallicity of ‑0.375 dex, situated at a distance of 3.65 kpc. By analyzing the position of cluster members on the color–magnitude diagram using MIST isochrones, we have identified 12 potential BSSs in NGC 2243. We fitted the radial surface density profile and investigated the dynamical state and mass segregation effect of the cluster. It is found that the BSSs are significantly concentrated within the central region. We used data from Swift/UVOT, Gaia DR3, Pan-STARRS1 DR2, 2MASS, and WISE to fit the SEDs of the 12 identified BSSs using VOSA. We estimated the masses of the BSSs from the Hertzsprung–Russell diagram and found that they ranged from 1.25 to 2.22 M ☉. Consequently, we concluded that the BSSs likely gained 0.11–1.08 M ☉ through the mass transfer or merger channels. We discovered a hot companion associated with one BSS candidate, which has a temperature of 19,000 K, a luminosity of 0.55 L ☉, and a radius of 0.065 R ☉. The hot companion is probably a white dwarf, with its mass estimated to be approximately 0.18–0.20 M ☉ and an age of 186 Myr, suggesting it is a post-mass-transfer (Case A or Case B) system.

Keywords: Hertzsprung Russell diagram, Ultraviolet astronomy, Open star clusters, Blue straggler stars, Stellar evolution
Modeling the Wavelength Dependence of Pixel Response Nonuniformity of a CCD Sensor. Precision measurements in astronomy require stringent control of systematics such as those arising from imperfect correction of sensor effects. In this work, we develop a parametric method to model the wavelength dependence of pixel response nonuniformity (PRNU) for a laser-annealed backside-illuminated charge-coupled device. The model accurately reproduces the PRNU patterns of flat-field images taken at nine wavelengths from 290 to 950 nm, leaving the rms residuals no more than 0.2% in most cases. By removing the large-scale nonuniformity in the flat fields, the rms residuals are further reduced. This model fitting approach gives more accurate predictions of the PRNU than cubic-spline interpolation does with fewer free parameters. It can be applied to make PRNU corrections for individual objects according to their spectral energy distribution to reduce the photometry errors caused by the wavelength-dependent PRNU, if sub-percent level precision is required.

Keywords: Astronomical detectors, Astronomical techniques, Astronomical instrumentation, CCD photometry
JWST COMPASS: The 3–5 μm Transmission Spectrum of the Super-Earth L 98-59 c. We present a JWST Near-InfraRed Spectrograph (NIRSpec) transmission spectrum of the super-Earth exoplanet L 98-59 c. This small (R  p  = 1.385 ± 0.085R ⊕, M  p  = 2.22 ± 0.26 R ⊕), warm (T eq = 553 K) planet resides in a multiplanet system around a nearby, bright (J = 7.933) M3V star. We find that the transmission spectrum of L 98-59 c is featureless at the precision of our data. We achieve precisions of 22 ppm in NIRSpec G395H's NRS1 detector and 36 ppm in the NRS2 detector at a resolution R ∼ 200 (30 pixel wide bins). At this level of precision, we are able rule out primordial H2–He atmospheres across a range of cloud pressure levels up to at least ∼0.1 mbar. By comparison to atmospheric forward models, we also rule out atmospheric metallicities below ∼300× solar at 3σ (or, equivalently, atmospheric mean molecular weights below ∼10 g mol‑1). We also rule out pure methane atmospheres. The remaining scenarios that are compatible with our data include a planet with no atmosphere at all, or higher-mean-molecular-weight atmospheres, such as CO2- or H2O-rich atmospheres. This study adds to a growing body of evidence suggesting that planets ≲1.5 R ⊕ lack extended atmospheres.

Keywords: Exoplanet atmospheric composition , Exoplanets, Super Earths, Exoplanet astronomy, Exoplanet atmospheres
Moving Groups in the Solar Neighborhood with Gaia, APOGEE, GALAH, and LAMOST: Dynamical Effects Gather Gas and the Ensuing Star Formation Plays an Important Role in Shaping the Stellar Velocity Distributions. With Gaia, APOGEE, GALAH, and LAMOST data, we investigate the positional, kinematic, chemical, and age properties of nine moving groups in the solar neighborhood. We find that each moving group has a distinct distribution in the velocity space in terms of its metallicity, α abundance, and age. Comparison of the moving groups with their underlying background stars suggests that they have experienced the enhanced, prolonged star formation. We infer that any dynamical effects that gathered stars as a moving group in the velocity space also worked for gas. We propose for the first time that the ensuing newborn stars from such gas inherited the kinematic feature from the gas, shaping the current stellar velocity distributions of the groups. Our findings improve the understanding of the origins and evolutionary histories of moving groups in the solar neighborhood.

Keywords: Stellar ages, Stellar kinematics, Milky Way dynamics, Chemical abundances, Metallicity
Characterization of Blue and Yellow Straggler Stars of Berkeley 39. We characterize blue straggler stars (BSSs) and yellow straggler stars (YSSs) of the open cluster (OC) Berkeley 39 using multiwavelength observations including the Swift/Ultraviolet and Optical Telescope (UVOT). Our analysis also makes use of ultraviolet (UV) data from Galaxy Evolution Explorer, optical data from Gaia DR3 and Panoramic Survey Telescope and Rapid Response System, and infrared data from Two Micron All Sky Survey, Spitzer/IRAC, and Wide-field Infrared Survey Explorer. Berkeley 39 is a ∼6 Gyr old Galactic OC located at a distance of ∼4200 pc. We identify 729 sources as cluster members utilizing a machine-learning algorithm, ML-MOC, on Gaia DR3 data. Of these, 17 sources are classified as BSS candidates and four as YSS candidates. We construct multiwavelength spectral energy distributions (SEDs) of 16 BSS and two YSS candidates, within the Swift/UVOT field, to analyze their properties. Out of these, eight BSS candidates and both the YSS candidates are successfully fitted with single-component SEDs. Five BSS candidates show marginal excess in the near-UV (NUV; fractional residual &lt;0.3 in all but one UVOT filter), whereas three BSS candidates show moderate to significant excess in the NUV (fractional residual &gt;0.3 in at least two UVOT filters). We present the properties of the BSS and YSS candidates, estimated based on the SED fits.

Keywords: Stellar populations, Yellow straggler stars, Open star clusters, Ultraviolet astronomy, Blue straggler stars
Hic Sunt Dracones: Uncovering Dynamical Perturbers within the Habitable Zone. The continuing exploration of neighboring planetary systems is providing deeper insights into the relative prevalence of various system architectures, particularly with respect to the solar system. However, a full assessment of the dynamical feasibility of possible terrestrial planets within the habitable zones (HZs) of nearby stars requires detailed knowledge of the masses and orbital solutions of any known planets within these systems. Moreover, the presence of as-yet undetected planets in or near the HZ will be crucial for providing a robust target list for future direct imaging surveys. In this work, we quantify the distribution of uncertainties on planetary masses and semimajor axes for 1062 confirmed planets, finding median uncertainties of 11.1% and 2.2%, respectively. We show the dependence of these uncertainties on stellar mass and orbital period and discuss the effects of these uncertainties on dynamical analyses and the locations of mean motion resonance. We also calculate the expected radial velocity (RV) semiamplitude for a Neptune-mass planet in the middle of the HZ for each of the proposed Habitable Worlds Observatory target stars. We find that for more than half of these stars, the RV semiamplitude is less than 1.5 m s‑1 rendering them unlikely to be detected in archival RV data sets and highlighting the need for further observations to understand the dynamical viability of the HZ for these systems. We provide specific recommendations regarding stellar characterization and RV survey strategies that work toward the detection of presently unseen perturbers within the HZ.

Keywords: Exoplanet dynamics, Exoplanet catalogs, Exoplanets, Exoplanet systems, Exoplanet astronomy, Astrobiology, Habitable zone, Habitable planets
KIC 6362386: An Eclipsing Binary with γ Doradus–type Pulsations and Starspots. KIC 6362386 is an eclipsing binary system that exhibits both γ Doradus (γ Dor)–type pulsations and starspots. In this study, we investigated this binary system using the Kepler photometry and the spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. After employing the PHOEBE program for light-curve and radial-velocity-curve synthesis, analyses reveal that the binary is a circle (e ∼ 0.0006), has a small mass ratio (q ∼ 0.311), and is a detached system consisting of an F-type primary star and an M-type secondary star with masses and radii of M 1 = 1.43 ± 0.13 M ⊙, R 1 = 1.68 ± 0.08 R ⊙ and M 2 = 0.44 ± 0.18 M ⊙, R 2 = 0.46 ± 0.06 R ⊙, respectively. Utilizing the Padova isochrone, we estimate the age of the binary system to be   Gyr. By analyzing the out-of-eclipse residuals, we identify variations in the residuals attributed to both starspots and stellar pulsations. The autocorrelation function analysis indicates the decay time of starspots is approximately 37 days with the rotation period aligning with the orbital period. Considering the masses, radii, and positions of the two components on the Hertzsprung–Russell diagram, we deduce that the γ Dor–type g-mode pulsations came from the primary star where the main frequency is 0.1642c/d. Consequently, KIC 6362386 becomes a valuable target for the investigation of γ Dor–type pulsations and asteroseismology in a binary system.

Keywords: Starspots, Binary stars, Pulsating variable stars, Stellar physics, Gamma Doradus variable stars
Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population. Planets and the stars they orbit are born from the same cloud of gas and dust, and the primordial compositions of rocky exoplanets have been assumed to have iron and refractory abundance ratios consistent with their host star. To test this assumption, we modeled the interior iron-to-rock ratio of 20 super-Earth-sized (1─1.8 R ⊕) exoplanets around stars with homogeneously measured stellar parameters. We computed the core mass fraction (CMF) for each planet and an equivalent "core mass fraction" for each host star based on its Fe and Mg abundances. We then fit a linear correlation using two methods (ordinary least squares and orthogonal distance regression) between planetary and stellar CMF, obtaining substantially different slopes between these two methods (m = 1.3 ± 1.0 and m = 5.6 ± 1.6, respectively). Additionally, we find that 75% of planets have a CMF consistent with their host star to within 1σ, and do not identify a distinct population of high-density super-Mercuries. Overall, we conclude that current uncertainties in observational data and differences in modeling methods prevent definitive conclusions about the relationship between planet and host-star chemical compositions.

Keywords: Exoplanet astronomy, Extrasolar rocky planets
The Radiative–Convective Gap: Fact or Fiction?. Gaia characterizes the stellar populations of nearby open clusters with unprecedented precision. We investigate the Böhm-Vitense gap, which has been found as a prominent feature in the stellar sequence of open clusters. Using PARSEC isochrone fitting, we derive astrophysical parameters for more than 1100 bona fide single stars each in Praesepe, identify more than 1100 bona fide single stars in the α Persei (Melotte 20) open cluster, and confirm their approximate match in terms of age (≈710 and ≈45 Myr) and metallicity ([M/H] ≈ +0.15 and ≈+0.13 dex) to the Hyades and Pleiades, respectively. By merging data of the cluster pairs, we improve number statistics. We do not find a clear gap in the combined observational G abs versus BP ‑ RP color–magnitude diagram (CMD) in the stellar mass range corresponding to the location of the Böhm-Vitense gap. We reproduce gaps in simulated Hyades-type CMDs randomly drawn from an initial mass function. There is no strong evidence for a discontinuity originating in the transition from radiative to convective energy transport in the stellar photosphere. We conclude that the observed gaps in the stellar sequences of open clusters could be explained by small number statistics and the uneven mass–color relation at the transition from spectral type A to F.

Keywords: Stellar luminosities, Stellar ages, Stellar abundances, Stellar effective temperatures, Stellar colors, Stellar masses, Open star clusters, Stellar atmospheres, Stellar evolution
A Radio Technosignature Search of TRAPPIST-1 with the Allen Telescope Array. Planet–planet occultations (PPOs) occur when one exoplanet occults another exoplanet in the same system, as seen from the Earth's vantage point. PPOs may provide a unique opportunity to observe radio "spillover" from extraterrestrial intelligences' radio transmissions or radar being transmitted from the farther exoplanet toward the nearer one for the purposes of communication or scientific exploration. Planetary systems with many tightly packed, low-inclination planets, such as TRAPPIST-1, are predicted to have frequent PPOs. Here, the narrowband technosignature search code turboSETI was used in combination with the newly developed NbeamAnalysis filtering pipeline to analyze 28 hr of beamformed data taken with the Allen Telescope Array during 2022 late October and early November, from 0.9 to 9.3 GHz, targeting TRAPPIST-1. During this observing window, seven possible PPO events were predicted using the NbodyGradient code. The filtering pipeline reduced the original list of 25 million candidate signals down to 6 million by rejecting signals that were not sky-localized and, from these, identified a final list of 11,127 candidate signals above a power-law cutoff designed to segregate signals by their attenuation and morphological similarity between beams. All signals were plotted for visual inspection, 2264 of which were found to occur during PPO windows. We report no detections of signals of nonhuman origin, with upper limits calculated for each PPO event exceeding equivalent isotropic radiated powers of 2.17–13.3 TW for minimally drifting signals and 40.8–421 TW in the maximally drifting case. This work constitutes the longest single-target radio search for extraterrestrial intelligence of TRAPPIST-1 to date.

Keywords: Exoplanet dynamics, Astronomy software, Technosignatures, Astrobiology, Search for extraterrestrial intelligence, Radio interferometry, Radio astronomy
The Breakthrough Listen Search for Intelligent Life: Galactic Center Search for Scintillated Technosignatures. The search for extraterrestrial intelligence at radio frequencies has focused on spatial filtering as a primary discriminant from terrestrial interference. Individual search campaigns further choose targets or frequencies based on criteria that theoretically maximize the likelihood of detection, serving as high-level filters for interesting targets. Most filters for technosignatures do not rely on intrinsic signal properties, as the radio-frequency interference (RFI) environment is difficult to characterize. In B. Brzycki et al. (2023), we proposed that the effects of interstellar medium (ISM) scintillation on narrowband technosignatures may be detectable under certain conditions. In this work, we perform a dedicated survey for scintillated technosignatures toward the Galactic center and Galactic plane at the C band (3.95–8.0 GHz) using the Robert C. Byrd Green Bank Telescope (GBT) as part of the Breakthrough Listen program. We conduct a Doppler drift search and directional filter to identify potential candidates and analyze results for evidence of scintillation. We characterize the C-band RFI environment at the GBT across multiple observing sessions spread over months and detect RFI signals with confounding scintillation-like intensity modulation. We do not find evidence of putative narrowband transmitters with drift rates between ±10 Hz s‑1 toward the Galactic center, ISM-scintillated or otherwise, above an equivalent isotropic radiated power of 1.9 × 1017 W up to 8.5 kpc.

Keywords: Astronomy data modeling, Technosignatures, Interstellar plasma, Astrobiology, Interstellar scintillation, Search for extraterrestrial intelligence, Maximum likelihood estimation
Observations of Molecular CN toward S-type Asymptotic Giant Branch Stars. S-type asymptotic giant branch (AGB) stars are defined by their carbon-to-oxygen (C/O) ratio approaching unity. However, observations of circumstellar molecules in these stars are limited and challenging. In this study, we used the James Clerk Maxwell Telescope to search for cyanide (CN) in 12 selected S-type AGB stars, with only 4 of these stars displaying CN spectral line signals. The column density and fractional abundance of CN were calculated assuming local thermodynamic equilibrium, and the average CN-to-hydrogen-cyanide (HCN) abundance ratio of the four sources is about 0.036. We investigate, for the first time, the relationship between CN and HCN fractional abundances in all types of AGB stars, finding that the ratio is similar in O-rich and S-type stars, while those in C-rich stars are quite different. This result supports the idea that the level of HCN photodissociation plays a crucial role in determining the CN abundance in the circumstellar envelopes of AGB stars at various stages of their evolution.

Keywords: Circumstellar envelopes, Asymptotic giant branch, Astrochemistry
Analyzing the Onset of Cometary Activity by the Jupiter-family Comet 2023 RN<SUB>3</SUB>. We utilize serendipitous observations from the Asteroid Terrestrial-impact Last Alert System (ATLAS) and the Zwicky Transient Facility in addition to targeted follow-up observations from the Las Cumbres Observatory (LCO) and Liverpool Telescope to analyze the first observed instance of cometary activity by the newly discovered Jupiter-family comet C/2023 RN3 (ATLAS), whose orbital dynamics place it close to residing on a Centaur-like orbit. Across our 7 month baseline, we observe an epoch of cometary activity commencing in 2023 August with an increase in brightness of &gt;5.4 mag. The lightcurve of 2023 RN3 indicates the presence of continuous cometary activity across our observations, suggesting the onset of a new period of sustained activity. We find no evidence of any outbursts on top of the observed brightening nor do we find any significant color evolution across our observations. 2023 RN3 is visibly extended in LCO and Liverpool Telescope observations, indicating the presence of a spatially extended coma. Numerical integration of 2023 RN3's orbit reveals the comet to have recently undergone a slight increase in semimajor axis due to a planetary encounter with Jupiter; however, whether this orbital change could trigger 2023 RN3's cometary activity is unclear. Our estimate for the maximum dust production metric of Af ρ ∼ 400 cm is consistent with previous measurements for the Jupiter-family comet and Centaur populations.

Keywords: Centaur group, Small Solar System bodies, Comae, Wide-field telescopes, Orbital evolution, Broad band photometry, Comets
Clouds in Partial Atmospheres of Lava Planets and Where to Find Them. With dayside temperatures hot enough to sustain a magma ocean and a silicate atmosphere, lava planets are the best targets for studying the atmosphere of a rocky world. In the absence of nightside heating, the entire atmosphere collapses near the day–night terminator, so condensation seems inevitable, but the impact of clouds on radiative transfer, dynamics, and observables has not yet been studied in the nonglobal atmospheric regime. Therefore, we simulate cloud formation and determine which lava planets should be most affected by clouds. We find that despite the scattering of visible light by clouds, heat advection compensates for the cooling effect of clouds in the atmosphere. On the other hand, surface temperatures are significantly affected and can drop by 100–200 K under a cloudy sky. We find that among our targets, HD213885b and HD20329b are most affected by cloud formation: there is a discernible difference between having clouds and not having them, but the precision required to make such an inference is at the limit of current instruments.

Keywords: Exoplanet atmospheres
Demography of Stellar Radio Population within 500 pc: A VLASS-Gaia DR3 Study. In this work, we have carried out a systematic analysis of the Very Large Array Sky Survey (VLASS) quick look catalogs together with Gaia DR3 to identify the optical counterparts of 3 GHz radio emitters within 500 pc to obtain a homogeneous statistical sample of stellar radio sources. We have identified distinct populations of 3 GHz emitters across the Gaia DR3 color–magnitude diagram. We also present candidate sources (transient, highly variable, or background artifacts) that can be confirmed by follow-up observations. A majority of the detected sources constitute main-sequence G-, K-, and M-type stars, including ultracool dwarfs. Pinning down the origin of radio emission from these populations can help us gain further insights into the origin of stellar and planetary magnetic fields. By analyzing the variation of brightness temperature of the sources with their spectral type, we have tentatively associated possible emission mechanisms with different object types. We inspected the correlation between quiescent radio and X-ray emission for our sample, which can provide crucial insights into the current understanding of the Gudel–Benz relationship, which is essential for modeling steady radio emission and coronal heating. This VLASS-Gaia DR3 analysis acts as a pilot study for follow-up observations at multiple wavelengths to better understand stellar structure, model flaring activities, and detect radio emission caused by star–planet interactions.

Keywords: Radio astronomy, Stellar properties, Radio source catalogs, Stellar magnetic fields, Radio continuum emission, Gaia