Sazuna/UAT_keywords huggingface dataset:
The True Nature of the Brightest Local Triple Stellar Candidates within 100 pc in the Galaxy. We present a study of a sample of bright (V ≤ 10 mag) and close (d ≤ 100 pc) triple-stellar system candidates in the galaxy, consisting of eight systems in total. Our aim is to determine their actual multiplicity and the physical properties of each stellar component in the systems. The sample was analyzed using a complex spectrophotometric technique by Al-Wardat that utilizes ATLAS9 line-blanketed plane-parallel model atmospheres. Based on our analysis, we found that five of the systems (HIP 109951, HIP 105947, HIP 40523, HIP 35733, and HIP 23824) are indeed triples, while the remaining three systems (HIP 9642, HIP 59426, and HIP 101227) are more consistent with being quadruples. We estimated the physical properties of the individual components using the most recent parallax measurements from the GAIA Data Release 3 catalog. We also examined the applicability of the well-established Mass-Luminosity (M-L) relation for individual components of all the stellar systems that have been analyzed by the Al-Wardat technique. We found that generally, the components are in good agreement with the established relationship. This further supports the reliability of the method in determining the physical properties of multiple stellar systems. In addition, we investigated the M-L relation for each order of stellar multiplicity (i.e., binary, triple, and quadruple) by performing linear fitting to the data. It was found that the slopes for each multiplicity are consistent with each other. The relations also seem to shift down in luminosity for a given total mass, as the order of multiplicity increases from binary to quadruple.

Keywords: Multiple stars, Stellar properties, Stellar atmospheres, Stellar evolution
Magnetic Effects and 3D Structure in Theoretical High-resolution Transmission Spectra of Ultrahot Jupiters: the Case of WASP-76b. High-resolution spectroscopy has allowed for unprecedented levels of atmospheric characterization, especially for the hottest gas-giant exoplanets known as ultrahot Jupiters (UHJs). High-resolution spectra are sensitive to 3D effects, making complex 3D atmospheric models important for interpreting data. Moreover, these planets are expected to host magnetic fields that will shape their resulting atmospheric circulation patterns, but little modeling work has been done to investigate these effects. In this paper, we generate high-resolution transmission spectra from General Circulation Models for the canonical UHJ WASP-76b with three different magnetic treatments in order to understand the influence of magnetic forces on the circulation. In general, spectra from all models have increasingly blueshifted net Doppler shifts as transit progresses, but we find that the differing temperature and wind fields in the upper atmospheres of these models result in measurable differences. We find that magnetic effects may be contributing to the unusual trends previously seen in transmission for this planet. Our B = 3 Gauss active drag model in particular shows unique trends not found in the models with simpler or no magnetic effects. The net Doppler shifts are additionally influenced by the dominant opacity sources in each wavelength range considered, as each species probes different regions of the atmosphere and are sensitive to spatial differences in the circulation. This work highlights the ongoing need for models of planets in this temperature regime to consider both 3D and magnetic effects when interpreting high-resolution transmission spectra.

Keywords: High resolution spectroscopy, Hydrodynamical simulations, Hot Jupiters, Atmospheric circulation, Transmission spectroscopy, Exoplanet atmospheres, Magnetohydrodynamical simulations
The Emergence of a Neutral Wind Region in the Orbital Plane of Symbiotic Binaries during Their Outbursts. Accretion of mass onto a white dwarf (WD) in a binary system can lead to stellar explosions. If a WD accretes from stellar wind of a distant evolved giant in a symbiotic binary, it can undergo occasional outbursts in which it brightens by several magnitudes, produces a low- and high-velocity mass outflow, and, in some cases, ejects bipolar jets. In this paper, we complement the current picture of these outbursts by the transient emergence of a neutral region in the orbital plane of symbiotic binaries consisting of wind from the giant. We prove its presence by determining H0 column densities (N H) in the direction of the WD and at any orbital phase of the binary by modeling the continuum depression around the Lyα line caused by Rayleigh scattering on atomic hydrogen for all suitable objects, i.e., eclipsing symbiotic binaries, for which a well-defined ultraviolet spectrum from an outburst is available. The N H values follow a common course along the orbit with a minimum and maximum of a few times 1022 and 1024 cm-2 around the superior and inferior conjunction of the giant, respectively. Its asymmetry implies an asymmetric density distribution of the wind from the giant in the orbital plane with respect to the binary axis. The neutral wind is observable in the orbital plane owing to the formation of a dense disk-like structure around the WD during outbursts, which blocks ionizing radiation from the central burning WD in the orbital plane.

Keywords: White dwarf stars, Symbiotic binary stars, Cataclysmic variable stars
Comparative Study of TESS Photometry and Radial Velocities on Six Early K-type Contact Binaries with Similar Periods around 0.268 Day. High-precision light curves were extracted from TESScut images. Together with APOGEE and LAMOST medium-resolution spectra, a joint study was made for six early K-type contact binary candidates selected unbiasedly with orbital periods around 0.268 day. It is found that all of them (RV CVn, EK Com, V384 Ser, V1038 Her, EH CVn, and CSS_J125403.7+503945) are W-subtype shallow contact systems, though with different mass ratios (1/q = 0.27-0.62). The effective temperature differences between the binary components are around a few hundred kelvins. The original definitions of the A and W subtypes were compared with the customarily used methods, which rely on the shape or photometric solutions of the light curves. The latter two methods are not always reliable; therefore, the radial velocity analysis is strongly recommended. Through a collection of all available K-type contact binaries with both photometric and spectroscopic measurements, it is found that almost all of them are W-subtype systems, except for a few objects that have nearly identical temperatures for binary components. This W-subtype phenomenon for K-type contact binaries should be further checked with more samples in the future. Finally, the physical parameters of the targets were determined with joint data analysis, and the multiplicity is discussed for these targets. Objects V384 Ser and RV CVn are confirmed to very likely be triple systems from comprehensive analysis, while V1038 Her is a candidate of a triple system based on photometric and spectroscopic solutions.

Keywords: Late-type stars, Fundamental parameters of stars, Eclipsing binary stars, Radial velocity, Contact binary stars
Spectral Energy Distributions for 258 Local Volume Galaxies. We present model spectral energy distribution (SED) fits to ultraviolet/optical/infrared observations for the 258 nearby galaxies in the Local Volume Legacy survey, a sample dominated by lower-luminosity dwarf irregular systems. The data for each galaxy include up to 26 spatially-integrated broadband and narrowband fluxes from the Galaxy Evolution Explorer, Spitzer Space Telescope, and Infrared Astronomical Satellite space-based platforms, and from the Sloan Digital Sky Survey, Two Micron All Sky Survey, and other ground-based efforts. The CIGALE SED fitting package is employed using a delayed star-formation history with an optional late burst or quenching episode to constrain 11 different free parameters that characterize the properties of each galaxy's stellar and dust emission, with the overriding constraint that the ultraviolet/optical emission absorbed by interstellar dust grains is emitted in equal energy portions at infrared wavelengths. The main results are: (i) 94% of the SED fits yield reduced χ 2 values less than 3; (ii) the modeled stellar masses agree with those derived from 3.6 μm-based measures with a scatter of 0.07 dex; (iii) for a typical galaxy in the sample the SED-derived star-formation rate averaged over the past 100 Myr is about 88% of the value derived from standard hybrid indicators on similar timescales; and (iv) there is a statistically significant inverse relation between the stellar mass fraction appearing in the late burst and the total stellar mass. These results build upon prior SED modeling efforts in the local volume and lay the groundwork for future studies of more distant low-metallicity galaxies with JWST.

Keywords: Spectral energy distribution, Galaxies
Warm Jupiters Beyond the Tidal Synchronization Limit may Exhibit a Wide Range of Secondary Eclipse Depths. With the JWST we can now characterize the atmospheres of longer-orbit planets, but this moves us into a regime where we cannot assume that tidal forces from the star have eroded the planets' obliquities and synchronized their rotation rates. These rotation vectors may be tracers of formation and evolution histories and also enable a range of atmospheric circulation states. Here we delineate the orbital space over which tidal synchronization and alignment assumptions may no longer apply and present three-dimensional atmospheric models of a hypothetical warm Jupiter over a range of rotation rates and obliquities. We simulate the secondary eclipses of this planet for different possible viewing orientations and times during its orbital, seasonal cycle. We find that the eclipse depth can be strongly influenced by the rotation rate and obliquity through the timing of the eclipse relative to the planet's seasonal cycle, and advise caution in attempting to derive properties such as albedo or day-night transport from this measurement. We predict that if warm Jupiters beyond the tidal limit have intrinsic diversity in their rotation vectors, then this will manifest itself as dispersion in their secondary eclipse depths. We explore eclipse mapping as a way to uniquely constrain the rotation vector of warm Jupiters but find that the associated signals are likely at the edge of the JWST performance. Nevertheless, as the JWST begins to measure the secondary eclipses of longer-orbital-period planets, we should expect to observe the consequences of a wider range of rotation states and circulation patterns.

Keywords: Eclipses, Exoplanets, James Webb Space Telescope, Extrasolar gaseous planets, Atmospheric dynamics, Exoplanet atmospheres
Scaling K2. VI. Reduced Small-planet Occurrence in High-galactic-amplitude Stars. In this study, we performed a homogeneous analysis of the planets around FGK dwarf stars observed by the Kepler and K2 missions, providing spectroscopic parameters for 310 K2 targets -including 239 Scaling K2 hosts-observed with Keck/HIRES. For orbital periods less than 40 days, we found that the distribution of planets as a function of orbital period, stellar effective temperature, and metallicity was consistent between K2 and Kepler, reflecting consistent planet formation efficiency across numerous ~1 kpc sight-lines in the local Milky Way. Additionally, we detected a 3× excess of sub-Saturns relative to warm Jupiters beyond 10 days, suggesting a closer association between sub-Saturn and sub-Neptune formation than between sub-Saturn and Jovian formation. Performing a joint analysis of Kepler and K2 demographics, we observed diminishing super-Earth, sub-Neptune, and sub-Saturn populations at higher stellar effective temperatures, implying an inverse relationship between formation and disk mass. In contrast, no apparent host-star spectral-type dependence was identified for our population of Jupiters, which indicates gas-giant formation saturates within the FGK mass regimes. We present support for stellar metallicity trends reported by previous Kepler analyses. Using Gaia DR3 proper motion and radial velocity measurements, we discovered a galactic location trend; stars that make large vertical excursions from the plane of the Milky Way host fewer super-Earths and sub-Neptunes. While oscillation amplitude is associated with metallicity, metallicity alone cannot explain the observed trend, demonstrating that galactic influences are imprinted on the planet population. Overall, our results provide new insights into the distribution of planets around FGK dwarf stars and the factors that influence their formation and evolution.

Keywords: Exoplanet catalogs, Galactic archaeology, Astrostatistics, Exoplanet formation, Planet formation
Searching in H I for Massive Low Surface Brightness Galaxies: Samples from HyperLeda and the UGC. A search has been made for 21 cm H I line emission in a total of 350 unique galaxies from two samples whose optical properties indicate they may be massive. The first consists of 241 low surface brightness (LSB) galaxies of morphological type Sb and later selected from the HyperLeda database and the second consists of 119 LSB galaxies from the UGC with morphological types Sd-m and later. Of the 350 unique galaxies, 239 were observed at the Nançay Radio Telescope, 161 at the Green Bank Telescope, and 66 at the Arecibo telescope. A total of 295 (84.3%) were detected, of which 253 (72.3%) appear to be uncontaminated by any other galaxies within the telescope beam. Finally, of the total detected, uncontaminated galaxies, at least 31 appear to be massive LSB galaxies, with a total H I mass ≥ 1010 M ⊙, for H 0 = 70 kms-1 Mpc-1. If we expand the definition to also include galaxies with significant total (rather than just gas) mass, i.e., those with an inclination-corrected H I line width W 50,cor &gt; 500 km s-1, this brings the total number of massive LSB galaxies to 41. There are no obvious trends between the various measured global galaxy properties, particularly between mean surface brightness and galaxy mass.

Keywords: Amorphous irregular galaxies, Radio astronomy, Spiral galaxies, Low surface brightness galaxies
Nondetection of Helium in the Hot Jupiter WASP-48b. Hot Jupiters orbiting extremely close to their host star may experience atmospheric escape due to the large amounts of high-energy radiation they receive. Understanding the conditions under which this occurs is critical, as atmospheric escape is believed to be a driving factor in sculpting planetary populations. In recent years, the near-infrared 10833 Å helium feature has been found to be a promising spectral signature of atmospheric escape. We use transmission spectroscopy to search for excess helium absorption in the extended atmosphere of WASP-48b, a hot Jupiter orbiting a slightly evolved, rapidly rotating F star. The data were collected using the Habitable-zone Planet Finder spectrograph on the Hobby-Eberly Telescope. Observations were taken over the course of seven nights, from which we obtain three transits. No detectable helium absorption is seen, as absorption depth is measured to -0.0025 ± 0.0021, or 1.2σ from a null detection. This nondetection follows our current understanding of decreasing stellar activity (and thus high-energy radiation) with age. We use a 1D isothermal Parker wind model to compare with our observations and find that our nondetection can best be explained with a low planetary mass-loss rate and high thermosphere temperature. We explore our results within the context of the full sample of helium detections and nondetections to date. Surprisingly, comparing helium absorption with the stellar activity index $\mathrm{log}\ {R}_{\mathrm{HK}}^{{\prime} }$ reveals a large spread in the correlation between these two factors, suggesting that there are additional parameters influencing the helium absorption strength.

Keywords: High resolution spectroscopy, Hot Jupiters, Transmission spectroscopy, Exoplanet astronomy, Exoplanet atmospheres
The Occurrence Rate of Terrestrial Planets Orbiting Nearby Mid-to-late M Dwarfs from TESS Sectors 1-42. We present an analysis of a volume-complete sample of 363 mid-to-late M dwarfs within 15 pc of the Sun with masses between 0.1 and 0.3 M ⊙ observed by TESS within sectors 1-42. The median stellar mass of the sample is 0.17 M ⊙. We search the TESS light curves for transiting planets with orbital periods below 7 days and recover all six known planets within the sample, as well as a likely planet candidate orbiting LHS 475. Each of these planets is consistent with a terrestrial composition, with planet radii between 0.91 and 1.31 R ⊕. We characterize the transit detection sensitivity for each star as a function of planet radius, insolation, and orbital period. We obtain a cumulative occurrence rate of ${0.61}_{-0.19}^{+0.24}$ terrestrial planets per star with radii above 0.5 R ⊕ and orbital periods between 0.4 and 7 days. We find that for comparable insolations, planets larger than 1.5 R ⊕ (sub-Neptunes) are significantly less abundant around mid-to-late M dwarfs compared to earlier-type stars, while the occurrence rate of terrestrial planets is comparable to that of more massive M dwarfs. We estimate that overall, terrestrials outnumber sub-Neptunes around mid-to-late M dwarfs by 14 to 1, in contrast to GK dwarfs, where they are roughly equinumerous. We place a 1σ upper limit of 0.07 planets larger than 1.5 R ⊕ per star within the orbital period range of 0.5-7 days. We find evidence for a downturn in occurrence rates for planet radii below 0.9 R ⊕, suggesting that Earth-sized and larger terrestrials may be more common around mid-to-late M dwarfs.

Keywords: Transits, Exoplanets, Exoplanet systems, Low mass stars, Transit photometry
Spectroscopic Follow-up of Gaia Exoplanet Candidates: Impostor Binary Stars Invade the Gaia DR3 Astrometric Exoplanet Candidates. In this paper, we report on the follow-up of six potential exoplanets detected with Gaia astrometry and provide an overview of what is currently known about the nature of the entire Gaia astrometric exoplanet candidate sample, 72 systems in total. We discuss the primary false-positive scenario for astrometric planet detections: binary systems with alike components that produce small photocenter motions, mimicking exoplanets. These false positives can be identified as double-lined binaries (SB2) through analysis of high-resolution spectra. Doing so we find that three systems, Gaia DR3 1916454200349735680, Gaia DR3 2052469973468984192, and Gaia DR3 5122670101678217728, are indeed near-equal-mass double-star systems rather than exoplanetary systems. The spectra of the other two analyzed systems, HD 40503 and HIP 66074, are consistent with the exoplanet scenario in that no second set of lines can be found in the time series of publicly available high-resolution spectra. However, their Gaia astrometric solutions imply radial-velocity semiamplitudes ~3 (HD 40503) and ~15 (HIP 66074) larger than what was observed with ground-based spectrographs. The Gaia astrometry orbital solutions and ground-based radial-velocity measurements exhibit inconsistencies in six out of a total of 12 exoplanet candidate systems where such data are available, primarily due to substantial differences between observed ground-based radial-velocity semiamplitudes and those implied by the Gaia orbits. We investigated various hypotheses as to why this might be the case, and although we found no clear perpetrator, we note that a mismatch in orbital inclination offers the most straightforward explanation.

Keywords: Brown dwarfs, Binary stars, Astrometric exoplanet detection, Exoplanets, Exoplanet astronomy, Spectroscopic binary stars, Astrometric binary stars, Astrometry, Radial velocity
Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O<SUB>2</SUB> Levels in Nearby Transiting Habitable-zone Exoplanets. Molecular oxygen is a strong indicator of life on Earth and may indicate biological processes on exoplanets too. Recent studies proposed that Earth-like O2 levels might be detectable on nearby exoplanets using high-resolution spectrographs on future extremely large telescopes (ELTs). However, these studies did not consider constraints like relative velocities, planet occurrence rates, and target observability. We expanded on past studies by creating a homogeneous catalog of 286,391 main-sequence stars within 120 pc using Gaia DR3 and used the Bioverse framework to simulate the likelihood of finding nearby transiting Earth analogs. We also simulated a survey of M dwarfs within 20 pc accounting for η ⊕ estimates, transit probabilities, relative velocities, and target observability to determine how long ELTs and theoretical 50-100 m ground-based telescopes need to observe to probe for Earth-like O2 levels with an R = 100,000 spectrograph. This would only be possible within 50 yr for up to ~21% of nearby M-dwarf systems if a suitable transiting habitable-zone Earth analog was discovered, assuming signals from every observable partial transit from each ELT can be combined. If so, Earth-like O2 levels could be detectable on TRAPPIST-1 d-g within 16-55 yr, respectively, and about half that time with an R = 500,000 spectrograph. These results have important implications for whether ELTs can survey nearby habitable-zone Earth analogs for O2 via transmission spectroscopy. Our work provides the most comprehensive assessment to date of the ground-based capabilities to search for life beyond the solar system.

Keywords: Exoplanets, Fundamental parameters of stars, Exoplanet systems, Biosignatures, Exoplanet atmospheres
HIP 33609 b: An Eccentric Brown Dwarf Transiting a V = 7.3 Rapidly Rotating B Star. We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. HIP 33609 b is a large (R b = ${1.580}_{-0.070}^{+0.074}$ R J) brown dwarf on a highly eccentric (e = ${0.560}_{-0.031}^{+0.029}$ ) orbit with a 39 days period. The host star is a bright (V = 7.3 mag), T eff = 10,400 ${}_{-660}^{+800}$ K star with a mass of M * = ${2.383}_{-0.095}^{+0.10}$ M ☉ and radius of R * = ${1.863}_{-0.082}^{+0.087}$ R ☉, making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M b = ${68.0}_{-7.1}^{+7.4}$ M J as well as the host star's rotation rate ( $v\sin {i}_{* }=55.6\pm 1.8$ km s-1). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.

Keywords: High resolution spectroscopy, CCD photometry, Brown dwarfs, Exoplanets, Young star clusters, Exoplanet evolution, Direct imaging