Sazuna/UAT_keywords huggingface dataset:
Persistent Periodic Signals from 51 Peg in TESS Lightcurves. Transiting Exoplanet Survey Satellite photometry of the archetypal main-sequence exoplanet host star 51 Peg in two 27 days sectors separated by 2 yr contains a 4.55 days periodic signal, distinct from the 4.23 orbit of the planet. The signal is associated with the pixels containing the most flux, and there is no evidence for a companion or suitably bright background object within that aperture. No similar signal appears in nearby stars of comparable brightness nor does the signal appear in uncontaminated background, bias, or readout frames. The signal is too large and at the wrong period to be reflected light from the planet. 4.55 days would represent a synodic period (e.g., a forced oscillation of the star by the planet) if the star rotates in 60 days. Such slow rotation seems unlikely but is not conclusively ruled out by available observations.

Keywords: Light curves, Star-planet interactions, Stellar oscillations, Stellar rotation, Planet hosting stars
Multiwavelength SITELLE Observations of the High-velocity System in NGC 1275. In this paper, we present multiwavelength observations of the High-velocity System (HVS) in the Perseus Cluster taken with the SITELLE instrument at the Canada–France–Hawai'i Telescope. Using the SN 1, SN 2, and SN 3 filters, we observe emission in [O III]5007, Hβ, [N II]6548, [N II]6583, and Hα. By applying a Bayesian approach, we can constrain the redshift of the HVS to 0.02669±0.00073. Our findings are consistent with those originally posited in A. P. Y. Yu et al., in which the authors argue that they observe evidence of ram pressure stripping, indicating that the HVS is actively interacting with the BCG of the Perseus Cluster.

Keywords: Galaxy clusters, Perseus Cluster, Galactic and extragalactic astronomy
Numerical Treatment of Shock-induced Nuclear Burning in Double Detonation Type Ia Supernovae. We present a benchmark problem to assess the treatment of shock-induced nuclear burning in the context of double detonation Type Ia supernovae. In a stratified white dwarf model, we implement a shock-detection criterion that suppresses burning in zones characterized by compression and significant pressure gradients, controlled by a tunable parameter, fshock. One-dimensional simulations, using the open-source Castro suite, were conducted across three treatments—burning fully enabled, and burning suppressed with fshock = 2/3 and fshock = 1—across three spatial resolutions (5.0, 2.5, and 0.3125 km). At the finest resolution, the burning-enabled and fshock = 1 models converge, while the fshock = 2/3 front continues to show slight offset behavior. Since most simulations are carried out at much lower resolutions, our tests support the idea that burning in shocks should always be disabled in practice. We also observe that the behavior of lower-resolution simulations remains extremely sensitive to the choice of fshock.

Keywords: Hydrodynamical simulations, Open source software, GPU computing, Type Ia supernovae
Potassium Bromide Glass: Simulating Exoplanet Settings for Infrared Spectroscopy. Potassium bromide (KBr) glasses are widely used in infrared spectroscopy for their optical transparency and ability to produce high-fidelity molecular spectra. They are used in astronomical studies to characterize molecular vibrations; however, their use in simulating exoplanetary conditions in laboratory settings remains underexplored. This Research Note emphasizes KBr glasses as a practical tool to study refractory molecules including polycyclic aromatic hydrocarbons under controlled chemical, pressure, and temperature conditions. These simulations can yield high-resolution reference spectra relevant to exoplanetary environments, supporting the interpretation of IR data from space telescopes such as the James Webb Space Telescope, and bridging laboratory spectroscopy to astrophysical observation.

Keywords: Planetary atmospheres, Chemical abundances, Exoplanet astronomy, Habitable planets, Exoplanet atmospheres
Determining the Mass and Characteristic Disk Radii of Per-Emb-14 Using Rotation and Infall. Class 0/I protostars are in the earliest phases of formation and are deeply embedded in their environments. The dense natal surroundings impede kinematic measurements of parameters such as protostellar masses and disk radii. We present a study of gas dynamical mass measurements of Class 0 protostar Per-Emb-14 in the Perseus Molecular Cloud. We use FERIA—a combined Keplerian disk and infalling-rotating envelope model—to create position–position–velocity cubes using a grid search method for comparison with ALMA C18O observations. We find a protostellar mass of 0.41 ± 0.17 M⊙, similar to simpler Keplerian disk fitting. We also report a maximum system outer radius Rout = 758 ± 177 au. However, the spatial resolution of the observations limits accuracy. We also find a centrifugal barrier radius of 430 ± 174 au, indicating Keplerian motions dominate over infall out to a relatively large radius.

Keywords: Protostars, Protoplanetary disks
Discerning Galaxies from Brown Dwarfs in JWST/MIRI Coronagraphy Using Color–Color Diagrams. JWST's Mid-Infrared Instrument (MIRI) features observing modes covering a wavelength range of ∼5–28 μm. Particularly, its coronagraphic modes promise to expand exoplanet and brown dwarf direct imaging by providing unparalleled sensitivity to substellar objects, and its wide-field imager allows galactic and extragalactic surveys to complement those conducted at shorter wavelengths. MIRI is sensitive to both substellar objects and faint, unresolved galaxies, necessitating a method for discerning the two in MIRI data. This investigation aims to determine if color comparison is a viable method to determine whether an unresolved point source is more likely to be a substellar object or a galaxy. We model populations of galaxies and substellar objects and compare them in color–color space. We find that some of the coldest substellar objects overlap with galaxy populations, but varying substellar atmospheric properties and galaxy types produce parameter spaces where objects are better differentiated.

Keywords: Galaxies, Brown dwarfs, Direct imaging, Exoplanets
Are There Spectral Features in the MIRI/LRS Transmission Spectrum of K2-18b?. Determining the composition of an exoplanet atmosphere relies on the presence of detectable spectral features. The strongest spectral features, including dimethyl sulphide (DMS), look approximately Gaussian. Here, I perform a suite of Gaussian feature analyses to find any statistically significant spectral features in the recently published MIRI/LRS spectrum of K2-18b. In N. Madhusudhan et al., they claim a 3.4σ detection of spectral features compared to a flat line. In 5 out of 6 tests, I find the data preferred a flat line over a Gaussian model, with a   of 1.06. When centering the Gaussian where the absorptions for DMS and DMDS peak, I find ln(B) = 1.21 in favour of the Gaussian model, with a   of 0.99. With only ∼2σ in favour of Gaussian features, I conclude no strong statistical evidence for spectral features.

Keywords: Exoplanet astronomy, Exoplanet atmospheres
A Preliminary Search for Planets and Exozodiacal Emission Around α Centauri A with JWST/MIRI. We present F1550C (15.5 μm) coronagraphic imaging observations of the nearest solar-type star α Cen A using the James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI). The observations, executed in 2025 February, were compromised by having only one successful roll and degraded performance due to a position mismatch (Δr ∼ 10 mas) between α Cen A and the best-matching reference observation behind the MIRI coronagraph. We set preliminary upper limits on both the presence of a planet and an exozodiacal dust disk. The observations are sensitive to a planet heated by α Cen A (200–250 K) with a radius ≳1 RJup at a separation of 1 5 (2 au) and zodiacal dust emission at the level of ≳5–10 times the brightness of our own zodiacal cloud. A complete analysis of all JWST/MIRI observations of α Cen A is forthcoming in Paper I (Beichman &amp; Sanghi et al. 2025, in preparation) and Paper II (Sanghi &amp; Beichman et al. 2025, in preparation).

Keywords: Coronagraphic imaging, James Webb Space Telescope, Extrasolar gaseous giant planets, Exozodiacal dust
Numerical Considerations in the Reconstruction of Sunspot Numbers from ADF: A Precision Update. In this note, we revisit the use of the polynomial expression published by V. M. S. Carrasco et al. to estimate the sunspot number from the active day fraction (ADF). While the original article presented rounded coefficients of the polynomial equation for readability, we note that the use of these rounded coefficients can lead to a slight overestimation of the sunspot number values, especially at high ADF values (reaching ∼2%).

Keywords: Sunspot number
Spectroscopic Evidence for a New Supernova Remnant in IC 1613. We present evidence for the existence of a second supernova remnant (SNR) in the nearby dwarf galaxy IC 1613 based on data obtained with the imaging Fourier transform spectrometer SITELLE at the Canada–France–Hawaii Telescope. Located near the western edge of its host galaxy, this shell-like structure with a diameter of 55 pc exhibits distinctive SNR spectroscopic features including a high [S II]:Hα ratio, the presence of the [O I]λ6300 line, and a significant velocity dispersion.

Keywords: Supernova remnants, Irregular galaxies, Interstellar medium
Recent Atomic Data for Cr II Improves Non-LTE Model for Sirius A Spectrum. Sirius A (α Canis Majoris), with its slow rotation and stable atmospheric conditions, serves as an ideal candidate for 1D stellar atmosphere spectral synthesis. Its mass, radius, and surface gravity are known to great precision (≃1%), however, its elemental composition is one of its most uncertain parameters. To improve the accuracy of spectral synthesis, we have updated the Cr II model atom used in the PHOENIX stellar atmosphere code to include the latest atomic data available in the literature. Comparison of the synthetic non-local thermodynamic equilibrium spectrum with the observed spectrum, from the Very Large Telescope Ultraviolet and Visible Echelle Spectrograph, shows great improvement for four lines: 3084.46 Å and 3173.56 Å, 4539.59 Å, and 4565.74 Å relative to earlier models with less accurate  log(gf)  values. These Cr II lines are in need of experimental  log(gf)  values: 3495.38, 4150.99, 4224.85, and 4912.45 Å.

Keywords: Stellar abundances, Atomic data, Stellar photospheres, A dwarf stars, Stellar spectral lines, Stellar atmospheres
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å. XX. HD 77350. The weak line of Hg II located at 5677.10 Å is not detected in ELODIE spectra of the HgMn star HD 77350. The moderate abundance excess of mercury partly explains why this intrinsically weak transition at 5677.10 Å is not detected. Abundances of helium, magnesium, phosphorus, sulfur, titanium, chromium, manganese, iron are measured from the synthesis of several spectral intervals. The new abundances derived here agree well with previous synthesis using two spectra obtained at different dates. If HD 77350 does have such a low excess of mercury, this may represent the regime in which the line at 5677.10 Å is no longer useful.

Keywords: Mercury-manganese stars, Chemically peculiar stars
Kast Optical Spectra of Unclassified Stars Within 20 pc of the Sun. M- and L-type dwarfs are abundant in the Milky Way, yet many of these nearest sources remain poorly characterized. We present optical spectra for 67 low-luminosity sources within 20 pc of the Sun, 41 of which are optically classified for the first time. We determine spectral classifications spanning M3–L3, and report indicators of metallicity and magnetic activity. We identify two sources with discrepant classifications in the literature, and report a likely binary system LP 546-37.

Keywords: M dwarf stars, Stellar classification, L subdwarfs, L dwarfs
Assessment of Martian Lake Hydrologic Index. Large lakes are sensitive to climate shifts. This study investigated an established terrestrial lake metric as a tool for differentiating climate regimes on Mars. A global survey of martian lake hydrologic index (HI), the ratio of lake area to drainage area, showed that most sites have intermediate values (0.30–0.65). This is a null result as such values do not meaningfully differentiate between warm-wet and cold-dry conditions. However, one regional cluster of extreme low HI values (&lt;0.10) is identified, and is consistent with extreme aridity. This corridor along the equatorial dichotomy boundary in northern Terra Cimmeria formed during the Hesperian epoch or younger.

Keywords: Surface processes, Remote sensing, Mars
Investigating Spectral Stability in the Vicinity of the Metastable Helium Triplet of WASP-107. I present an analysis of the stellar line variability of WASP-107, focusing on the metastable helium triplet at 1083 nm (He I*), which has become a key tracer of atmospheric escape in exoplanets. With high-resolution spectra from Canada–France–Hawaii Telescope/SPIRou collected over approximately one year. I asses the out-of-transit variability of He I* and nearby stellar features. An injection and recovery test demonstrates equivalent widths are reliably recovered above input depths of 0.005 nm, with low signal-to-noise ratios leading to slight systematic underestimation. The observed upper limit variability in three lines is 1.8%, 2.6%, and 2.0%, respectively, while nearby Mg I and Si I lines vary by 1.2%, including both stellar and instrumental effects. These results underscore the importance of quantifying variability in the triplet to accurately interpret absorption signals.

Keywords: Exoplanets, Planet hosting stars
The NIRSpec IFU Point Spread Function. I provide characterizations of the point-spread function (PSF) of the high-resolution observing mode of the NIRSpec integral field unit on JWST. Using observations of an isolated late-type star, the two-dimensional shape of the star was modeled with concentric Gaussian profiles. The widths and weights of the representative Gaussian components that comprise the PSF model for a variety of drizzle reference frames and final spaxel sizes are presented. The PSF is noticeably elongated, with an axis ratio of ∼0.75. Both elongated PSF models as well as circular approximations to the PSF shape are included. The PSF is generally well-represented by a pair of concentric Gaussians, with ∼75% of the flux contained in a narrow core with a width on the order of a single spaxel, and the other ∼25% of the flux in a more extended halo.

Keywords: James Webb Space Telescope, Astronomical instrumentation
Metagalactic Ultraviolet Background Tables for Calculating Diffuse Astrophysical Plasma Properties. In developing a deeper understanding of the Circumgalactic Medium, one feature that is poorly understood is the nature of the ultraviolet background (UVB) and its impact on observed column densities. A wide array of UVB models have been created over the years by many different authors, each based on the latest observational data available at the time. In addition to having a large variance between model properties, the formatting between released models is also inconsistent. This data release provides reformatted versions of several widely used ultraviolet background models—Faucher-Giguère et al., Haardt &amp; Madau, Puchwein et al., and Faucher-Giguère 2020—such that each model is in the same units and thus can be utilized to directly compare these models over a wide redshift range. This release also includes code to run a cloudy_cooling_tools pipeline to generate ionization tables for different UVB models.

Keywords: Astronomy databases, Circumgalactic medium
Growing Pains: Binaries Suppress Planetary Systems at a Young Age. Planet-hosting stars in the Kepler field have been shown to disfavor a close (ρ &lt; 50 au) stellar companion compared to field binary rates, suggesting a suppression of the occurrence of planets by close binaries. I analyzed 78 young (&lt;500 Myr), transiting planetary systems for stellar multiplicity to determine if this suppression is still seen at young ages. Based on Gaia common proper motion, RUWE values, and a literature review, I found 21 planet-hosting stars to be in binary systems, with 4 being closely separated. This close binary rate (5.1% ± 3.4%) is less than the field binary rate (15.2% ± 2.0%), suggesting that the suppression of planetary systems by binaries must occur at very early ages, which is consistent with rapid disk dissipation and dynamic instability models.

Keywords: Exoplanet astronomy, Close binary stars, Planet hosting stars
The Relationship Between Eddington Ratio and Column Density in U/LIRG AGN. The local X-ray Active Galactic Nuclei (AGN) population appears to follow a growth cycle regulated by the AGN's own radiation, marked by changes in their obscuration and Eddington ratio during accretion events. Because AGN in infrared-selected galaxies are more likely to be Compton-thick and have evidence for over-massive black holes, we explore whether infrared-selected AGN follow the radiation-regulated AGN growth scheme. We calculate the Eddington ratios of nine (Ultra)Luminous InfraRed Galaxy AGN with dynamical BH mass measurements, finding that though the number of objects is limited, AGN in IR-selected galaxies appear consistent with radiation pressure-regulated growth. We suggest that enlarging the sample of dynamical BH mass measurements in IR-selected systems will provide more stringent tests of whether their AGN are primarily regulated by radiation pressure.

Keywords: Ultraluminous infrared galaxies, Active galactic nuclei, Luminous infrared galaxies
TESS Science Processing Operations Center Photometric Precision Archival Product. We report the delivery to the Mikulski Archive for Space Telescopes (MAST) of tables containing rms Combined Differential Photometric Precision (CDPP) values for all TESS 2 minutes cadence targets with Science Processing Operations Center (SPOC) light curves in Sectors 1–90. Each comma-separated values file contains CDPP values for all 2 minutes light curves in the given sector. The tables include robust rms CDPP values for the 15 trial transit pulse durations searched in the SPOC 2 minutes processing pipeline, ranging from 0.5 to 15.0 hr. For each pulse duration, CDPP is computed in the transit search for a trial transit centered on every cadence. The rms value of the CDPP time series is a metric that may be employed to estimate signal-to-noise ratio for transits with the given duration and a specified depth. We will continue to deliver the rms CDPP tables to MAST for each observing sector.

Keywords: Exoplanet detection methods, Transit photometry
Enhanced Merger Fractions in a Reionization-era Protocluster. Mergers play a critical role in galaxy evolution, but their relationship to their surrounding environments is unexplored at high redshift. We investigate the galaxy merger rate among 124 [O III] emitters at 5.3 &lt; z &lt; 6.9 as a function of local galaxy density. Identified in the ASPIRE JWST/NIRCam grism survey, we investigate three density regimes: a z = 6.6 quasar-centered protocluster, two overdensities at z = 5.4 and z = 6.2, and field galaxies. We evaluate merger candidates through close pair and morphological criteria in NIRCam imaging, finding that the z = 6.6 protocluster contains the highest fraction of galaxies meeting either criterion. We observe a &gt;3σ enhancement of the merger fraction amongst all three overdense structures compared to the field. Eleven galaxies are classified as "active mergers" satisfying both merger criteria, all of which occur within the overdensity samples. We conclude that environment affects the merger rates of galaxies at z &gt; 6, leading to increased specific star formation at the 4σ level.

Keywords: James Webb Space Telescope, Galaxy mergers, High-redshift galaxy clusters
CASA/rPICARD Calibration Strategy and PolyFiX Firmware Update for Phased NOEMA in the Context of Event Horizon Telescope Observations. NOrthern Extended Millimeter Array (NOEMA) joined regular Event Horizon Telescope (EHT) observations in 2021, in which phase jumps were detected in the NOEMA phase bandpass. These anomalies were traced to the signal processing pipeline of NOEMA's PolyFiX correlator. This research note presents a dedicated CASA calibration strategy for EHT data from 2021 to 2023, as well as a PolyFiX firmware update that fully corrects the NOEMA phase bandpass, effective 2024 January.

Keywords: Interferometric correlation, Calibration, Very long baseline interferometry, Astronomy software
Modeling Supernova 2023ixf: Lightcurve Degeneracies and Morphological Differences. Supernova 2023ixf, a type II-P supernova in the spiral galaxy M101, which was first observed in 2023 May, is the closest yet observed this decade. Combining the observed brightness and duration with theoretical scaling relations, we model its lightcurve to reveal the properties of the progenitor at the time of explosion, including its mass, radius, and explosion energy. We simulate these explosions using the stellar evolution/radiation-hydrodynamics codes MESA+STELLA. We find that SN 2023ixf is not easily explained with "normal" stellar evolution, and only models with a small H-rich ejecta mass can fit the lightcurve. We also find that the late-time properties of the lightcurve are better fit by a higher initial-mass (M ≳ 20M⊙) star with substantial mass loss during its lifetime, compared to models with lower initial mass (M ≲ 13M⊙) and less mass loss.

Keywords: Type II supernovae, Massive stars, Transient sources
Finite Star Factors with Stellar Limb Darkening for Optically Thin Dipole Scattering in Circumstellar Envelopes. A calculation for the finite star correction factors with stellar limb darkening is presented. The application is for dipole scattering, such as free electrons or Rayleigh scattering, in the context of optically thin envelopes that scatter unpolarized starlight. Two previous calculations that presented results with limb darkening employed the wrong geometrical angle. However, the previous approaches did achieve the correct limiting behavior, close to the star and at great distance. The new calculations for finite star correction factors of total scattered light and of depolarization deviate modestly from prior results. Overall, the depolarization factor remains slightly more depolarizing at the crucial distances of a few tenths of a stellar radius above the atmosphere.

Keywords: Circumstellar envelopes, Starlight polarization, Early-type stars
Asteroseismic Mass and Radius of the Naked-eye Red Giant HD 145250. We present the first asteroseismic analysis of the bright, nearby red giant star, HD 145250. We calculate the global seismic quantities of the star from single-sector, 2 minutes TESS photometry, and determine its mass and radius to be ∼1.4 M⊙ and ∼16 R⊙ using asteroseismic scaling relations. Our values agree with published non-seismic mass and radius estimates based on comparisons with stellar evolutionary models.

Keywords: Stellar photometry, Stellar astronomy, Asteroseismology
Puffy but Cool: Investigating the Inflated Radii of TOI-7018.01 and TOI-7081.01. A few gas giants with equilibrium temperatures below 1000 K exhibit unexpectedly large radii, challenging conventional models of radius inflation. I investigate two such cases: TOI-7018.01 and TOI-7081.01 (TESS Object of Interest), which both appear to be puffy cool Jupiters with radii of 1.61 ± 0.04 RJup and 1.65 ± 0.05 RJup, respectively. Using TESS photometry, Gaia astrometry, and stellar spectral energy distributions, I performed a joint fit with EXOFASTv2 to refine the stellar and planetary parameters. This analysis confirms that both planets have unusually large radii after the parameter revision. Neither host star shows signs of binarity or extreme youth, and no significant errors in stellar radii are identified. These results suggest that TOI-7018.01 and TOI-7081.01 are genuinely inflated cool giants, indicating that unknown mechanisms may drive radius inflation in low-irradiation environments.

Keywords: Exoplanet astronomy, Transits, Exoplanets