Sazuna/UAT_keywords huggingface dataset:
HST/WFC3 Light Curve Supports a Terrestrial Composition for the Closest Exoplanet to Transit an M Dwarf. Previous studies of the exoplanet LTT 1445Ac concluded that the light curve from the Transiting Exoplanet Survey Satellite (TESS) was consistent with both grazing and nongrazing geometries. As a result, the radius and hence density of the planet remained unknown. To resolve this ambiguity, we observed the LTT 1445 system for six spacecraft orbits of the Hubble Space Telescope (HST) using WFC3/UVIS imaging in spatial scan mode, including one partial transit of LTT 1445Ac. This imaging produces resolved light curves of each of the three stars in the LTT 1445 system. We confirm that the planet transits LTT 1445A and that LTT 1445C is the source of the rotational modulation seen in the TESS light curve, and we refine the estimate of the dilution factor for the TESS data. We perform a joint fit to the TESS and HST observations, finding that the transit of LTT 1445Ac is not grazing with 97% confidence. We measure a planetary radius of ${1.07}_{-0.07}^{+0.10}\,{R}_{\oplus }$ . Combined with previous radial velocity observations, our analysis yields a planetary mass of 1.37 ± 0.19 M ⊕ and a planetary density of ${5.9}_{-1.5}^{+1.8}$ g cm-3. LTT 1445Ac is likely an Earth analog with respect to its mass and radius, albeit with a higher instellation, and is therefore an exciting target for future atmospheric studies.

Keywords: M dwarf stars, Multiple stars, Transits, Exoplanets, Hubble Space Telescope, HST photometry, Exoplanet astronomy, Transit photometry
Mass Ratio of Single-line Spectroscopic Binaries with Visual Orbits Using Bayesian Inference and Suitable Priors. We present orbital elements for 22 single-line binaries, nine of them studied for the first time, determined from a joint spectroscopic and astrometric solution. The astrometry is based on interferometric measurements obtained with the HRCam Speckle camera on the SOAR 4.1 m telescope at Cerro Pachon, Chile, supplemented with historical data. The spectroscopic observations were secured using Echelle spectrographs (FEROS, FIDEOS, and HARPS) at La Silla, Chile. A comparison of our orbital elements and systemic velocities with previous studies, including Gaia radial velocities, shows the robustness of our estimations. By adopting suitable priors of the trigonometric parallax and spectral type of the primary component, and using a Bayesian inference methodology developed by our group, we were able to estimate mass ratios for these binaries. Combining the present results with a previous study of other single-line binaries from our team, we present a pseudo mass-to-luminosity relationship based on 23 systems (46 stars) in the mass range 0.6 ≤ M ⊙ ≤ 2.5. We find a reasonable correspondence with a fiducial mass-to-luminosity relationship. We conclude that our methodology does allow us to derive tentative mass ratios for these types of binaries. *Based in part on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovaçãoes (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

Keywords: Binary stars, Stellar properties, Bayesian statistics, Stellar luminosities, Posterior distribution, Spectroscopic binary stars, Mass ratio, Astrometric binary stars, Stellar masses, Interferometric binary stars, Visual binary stars, Prior distribution
The Extreme Stellar-signals Project. III. Combining Solar Data from HARPS, HARPS-N, EXPRES, and NEID. We present an analysis of Sun-as-a-star observations from four different high-resolution, stabilized spectrographs-HARPS, HARPS-N, EXPRES, and NEID. With simultaneous observations of the Sun from four different instruments, we are able to gain insight into the radial velocity precision and accuracy delivered by each of these instruments and isolate instrumental systematics that differ from true astrophysical signals. With solar observations, we can completely characterize the expected Doppler shift contributed by orbiting Solar System bodies and remove them. This results in a data set with measured velocity variations that purely trace flows on the solar surface. Direct comparisons of the radial velocities measured by each instrument show remarkable agreement with residual intraday scatter of only 15-30 cm s-1. This shows that current ultra-stabilized instruments have broken through to a new level of measurement precision that reveals stellar variability with high fidelity and detail. We end by discussing how radial velocities from different instruments can be combined to provide powerful leverage for testing techniques to mitigate stellar signals.

Keywords: Exoplanet detection methods, Stellar activity, Spectrometers, Astronomical instrumentation, Solar activity, Radial velocity
Fast Globally Optimal Catalog Matching using MIQCP. We propose a novel exact method to solve the probabilistic catalog matching problem faster than previously possible. Our new approach uses mixed integer programming and introduces quadratic constraints to shrink the problem by multiple orders of magnitude. We also provide a method to use a feasible solution to dramatically speed up our algorithm. This gain in performance is dependent on how close to optimal the feasible solution is. Also, we are able to provide good solutions by stopping our mixed integer programming solver early. Using simulated catalogs, we empirically show that our new mixed integer program with quadratic constraints is able to be set up and solved much faster than previous large linear formulations. We also demonstrate our new approach on real-world data from the Hubble Source Catalog. This paper is accompanied by publicly available software to demonstrate the proposed method.

Keywords: Bayes factor, Photometry, Astronomical methods, Catalogs
Using Photometrically Derived Properties of Young Stars to Refine TESS's Transiting Young Planet Survey Completeness. The demographics of young exoplanets can shed light on their formation and evolution processes. Exoplanet properties are derived from the properties of their host stars. As such, it is important to accurately characterize the host stars since any systematic biases in their derivation can negatively impact the derivation of planetary properties. Here we present a uniform catalog of photometrically derived stellar effective temperatures, luminosities, radii, and masses for 4865 young (&lt;1 Gyr) stars in 31 nearby clusters and moving groups within 200 pc. We compared our photometrically derived properties to a subset of those derived from spectra and found them to be in good agreement. We also investigated the effect of stellar properties on the detection efficiency of transiting short-period young planets with TESS as calculated in Fernandes et al. (2022) and found an overall increase in the detection efficiency when the new photometrically derived properties were taken into account. Most notably, there is a 1.5 × increase in the detection efficiencies for sub-Neptunes/Neptunes (1.8-6 R ⊕) implying that, for our sample of young stars, better characterization of host star properties can lead to the recovery of more small transiting planets. Our homogeneously derived catalog of updated stellar properties, along with a larger unbiased stellar sample and more detections of young planets, will be a crucial input to the accurate estimation of the occurrence rates of young short-period planets.

Keywords: Exoplanet detection methods, Transits, Exoplanets, Hot Neptunes, Young star clusters, Planet hosting stars, Mini Neptunes
The Eclipse-mapping Null Space: Comparing Theoretical Predictions with Observed Maps. High-precision exoplanet eclipse light curves, like those possible with JWST, enable flux and temperature mapping of exoplanet atmospheres. These eclipse maps will have unprecedented precision, providing an opportunity to constrain current theoretical predictions of exoplanet atmospheres. However, eclipse mapping has unavoidable mathematical limitations because many map patterns are unobservable. This "null space" has implications for making comparisons between predictions from general circulation models (GCMs) and the observed planet maps and thus affects our understanding of the physical processes driving the observed maps. We describe the eclipse-mapping null space and show how GCM forward models can be transformed to their observable modes for more appropriate comparison with retrieved eclipse maps, demonstrated with applications to synthetic data of an ultrahot Jupiter and a cloudy warm Jupiter under JWST best-case and extreme-precision observing scenarios. We show that the effects of the null space can be mitigated and manipulated through observational design, and JWST exposure times are short enough to not increase the size of the null space. Furthermore, we show the mathematical connection between the null space and the "eigenmapping" method, demonstrating how eigenmaps can be used to understand the null space in a model-independent way. We leverage this connection to incorporate null-space uncertainties in retrieved maps, which increases the uncertainties to encompass the ground truth for synthetic data. The comparisons between observed maps and forward models that are enabled by this work, and the improved eclipse-mapping uncertainties, will be critical to our interpretation of multidimensional aspects of exoplanets in the JWST era.

Keywords: Exoplanets, Eclipses, Exoplanet atmospheres
Astrometric Calibration and Performance of the Dark Energy Spectroscopic Instrument Focal Plane. The Dark Energy Spectroscopic Instrument, consisting of 5020 robotic fiber positioners and associated systems on the Mayall telescope at Kitt Peak, Arizona, is carrying out a survey to measure the spectra of 40 million galaxies and quasars and produce the largest 3D map of the universe to date. The primary science goal is to use baryon acoustic oscillations to measure the expansion history of the universe and the time evolution of dark energy. A key function of the online control system is to position each fiber on a particular target in the focal plane with an accuracy of 11 μm rms 2D. This paper describes the set of software programs used to perform this function along with the methods used to validate their performance.

Keywords: Astronomical techniques, Calibration, Wide-field telescopes
Peculiar Orbital Characteristics of Earth Quasi-Satellite 469219 Kamo'oalewa: Implications for the Yarkovsky Detection and Orbital Uncertainty Propagation. 469219 Kamo'oalewa is selected as one of the primary targets of Tianwen-2 mission, which is currently believed to be the most stable quasi-satellite of Earth. Here we derive a weak detection of the Yarkovsky effect for Kamo'oalewa, giving A 2 = (-1.075 ± 0.447) × 10-13 au day-2, with the available ground-based optical observations from Minor Planet Center and a relatively conservative weighting scheme. Due to the quasi-satellite resonance with Earth, we show that the detection of the Yarkovsky effect by orbital fitting with astrometric observations becomes difficult, as its orbital drift shows a slow oscillatory growth resulting from the Yarkovsky effect. In addition, we extensively explore the characteristics of orbital uncertainty propagation and find that the positional uncertainty mainly arises from the geocentric radial direction in 2010-2020 and then concentrates in the heliocentric transverse direction in 2020-2030. Furthermore, the heliocentric transverse uncertainty is clearly monthly dependent, which can arrive at a minimum around January and a maximum around July as the orbit moves toward the leading and trailing edges, respectively, in 2025-2027. Finally, we investigate a long-term uncertainty propagation in the quasi-satellite regime, implying that the quasi-satellite resonance with Earth may play a crucial role in constraining the increase of uncertainty over time. Such an interesting feature further implies that the orbital precision of Kamo'oalewa is relatively stable at its quasi-satellite phase, which may also be true for other quasi-satellites of Earth.

Keywords: Asteroids, Asteroid dynamics
Three-dimensional MHD Simulations of the Magnetic Pileup at Mars. In this study, we introduced a quantitative parameter, the magnetic field strength difference, to denote the intensity of the magnetic pileup effect at Mars. Using a three-dimensional multispecies MHD model, the effects of the interplanetary magnetic field (IMF) and the solar wind dynamic pressure (P  d ) constituted with different densities and velocities on the magnetic pileup were examined. Our results show that: (1) the magnetic pileup at Mars mainly occurs at the dayside region and its magnitude is generally decreasing with increasing solar zenith angle. The magnetic pileup is generally weak in the intense crustal field region, while it is strong in the weak crustal field region. (2) The perpendicular IMF components, B  Y  and B  Z , dominate the magnetic pileup, while the radial IMF component, B  X , has little effect. In the intense crustal field region, when the IMF and crustal field are primarily in the same direction, the magnetic field is piled up and the pileup magnitude is generally strong. While the directions of the crustal field and IMF are opposite, the occurrence of magnetic reconnection can weaken the local magnetic pileup. (3) Under the same P  d , a higher solar wind velocity results in a higher intensity and a larger region of the magnetic pileup. When P  d  increases, the magnitude of the magnetic pileup is enhanced, but the pileup region shrinks. In addition, for an increasing P  d , at the center of the induced magnetotail, the asymmetric current sheet can lead to similar asymmetries of the pileup.

Keywords: Planetary magnetospheres, Mars, Solar wind, Interplanetary magnetic fields
Exploring the Structures and Substructures of the Andromeda Satellite Dwarf Galaxies Cassiopeia III, Perseus I, and Lacerta I. We present results from wide-field imaging of the resolved stellar populations of the dwarf spheroidal galaxies Cassiopeia III (And XXXII) and Perseus I (And XXXIII), two satellites in the outer stellar halo of the Andromeda galaxy (M31). Our WIYN pODI photometry traces the red giant star population in each galaxy to ~2.5-3 half-light radii from the galaxy center. We use the tip of the red giant branch (TRGB) method to derive distances of (m - M)0 = 24.62 ± 0.12 mag (839 ${}_{-45}^{+48}$ kpc, or ${156}_{-13}^{+16}$ kpc from M31) for Cas III and 24.47 ± 0.13 mag (738 ${}_{-45}^{+48}$ kpc, or 351 ${}_{-16}^{+17}$ kpc from M31) for Per I. These values are consistent within the errors with TRGB distances derived from a deeper Hubble Space Telescope study of the galaxies' inner regions. For each galaxy, we derive structural parameters, total magnitude, and central surface brightness. We also place upper limits on the ratio of neutral hydrogen gas mass to optical luminosity, confirming the gas-poor nature of both galaxies. We combine our data set with corresponding data for the M31 satellite galaxy Lacerta I (And XXXI) from earlier work and search for substructure within the RGB star populations of Cas III, Per I, and Lac I. We find an overdense region on the west side of Lac I at a significance level of 2.5σ-3σ and a low-significance filament extending in the direction of M31. In Cas III, we identify two modestly significant overdensities near the center of the galaxy and another at two half-light radii. Per I shows no evidence for substructure in its RGB star population, which may reflect this galaxy's isolated nature.

Keywords: Local Group, Stellar populations, Dwarf galaxies, Galaxy stellar content, Dwarf spheroidal galaxies, Broad band photometry, Sloan photometry, Andromeda Galaxy
TESS Spots a Super-puff: The Remarkably Low Density of TOI-1420b. We present the discovery of TOI-1420b, an exceptionally low-density (ρ = 0.08 ± 0.02 g cm-3) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire Privé du Mont, Whitin, Wendelstein, OAUV, Ca l'Ou, and KeplerCam, along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of R p = 11.9 ± 0.3R ⊕ and a mass of M p = 25.1 ± 3.8M ⊕. TOI-1420b is the largest known planet with a mass less than 50M ⊕, indicating that it contains a sizeable envelope of hydrogen and helium. We determine TOI-1420b's envelope mass fraction to be ${f}_{\mathrm{env}}={82}_{-6}^{+7} \% $ , suggesting that runaway gas accretion occurred when its core was at most four to five times the mass of the Earth. TOI-1420b is similar to the planet WASP-107b in mass, radius, density, and orbital period, so a comparison of these two systems may help reveal the origins of close-in low-density planets. With an atmospheric scale height of 1950 km, a transmission spectroscopy metric of 580, and a predicted Rossiter-McLaughlin amplitude of about 17 m s-1, TOI-1420b is an excellent target for future atmospheric and dynamical characterization.

Keywords: Exoplanet structure, Transits, Exoplanets
Developing a Drift Rate Distribution for Technosignature Searches of Exoplanets. A stable-frequency transmitter with relative radial acceleration to a receiver will show a change in received frequency over time, known as a "drift rate." For a transmission from an exoplanet, we must account for multiple components of drift rate: the exoplanet's orbit and rotation, the Earth's orbit and rotation, and other contributions. Understanding the drift rate distribution produced by exoplanets relative to Earth, can (a) help us constrain the range of drift rates to check in a Search for Extraterrestrial Intelligence project to detect radio technosignatures, and (b) help us decide validity of signals-of-interest, as we can compare drifting signals with expected drift rates from the target star. In this paper, we modeled the drift rate distribution for ~5300 confirmed exoplanets, using parameters from the NASA Exoplanet Archive (NEA). We find that confirmed exoplanets have drift rates such that 99% of them fall within the ±53 nHz range. This implies a distribution-informed maximum drift rate ~4 times lower than previous work. To mitigate the observational biases inherent in the NEA, we also simulated an exoplanet population built to reduce these biases. The results suggest that, for a Kepler-like target star without known exoplanets, ±0.44 nHz would be sufficient to account for 99% of signals. This reduction in recommended maximum drift rate is partially due to inclination effects and bias toward short orbital periods in the NEA. These narrowed drift rate maxima will increase the efficiency of searches and save significant computational effort in future radio technosignature searches.

Keywords: Exoplanets, Technosignatures, Astrobiology, Search for extraterrestrial intelligence, Radio astronomy
Clustering Properties of Intermediate and High-mass Young Stellar Objects. We have selected 337 intermediate- and high-mass young stellar objects (YSOs; 1.5-20 M ☉) well-characterized with spectroscopy. By means of the clustering algorithm HDBSCAN, we study their clustering and association properties in the Gaia DR3 catalog as a function of stellar mass. We find that the lower-mass YSOs (1.5-4 M ☉) have clustering rates of 55%-60% in Gaia astrometric space, a percentage similar to that found in the T Tauri regime. However, intermediate-mass YSOs in the range 4-10 M ☉ show a decreasing clustering rate with stellar mass, down to 27%. We find tentative evidence suggesting that massive YSOs (&gt;10 M ☉) often (yet not always) appear clustered. We put forward the idea that most massive YSOs form via a mechanism that demands many low-mass stars around them. However, intermediate-mass YSOs form in a classical core-collapse T Tauri way, yet they do not appear often in the clusters around massive YSOs. We also find that intermediate- and high-mass YSOs become less clustered with decreasing disk emission and accretion rate. This points toward an evolution with time. For those sources that appear clustered, no major correlation is found between their stellar properties and the cluster sizes, number of cluster members, cluster densities, or distance to cluster centers. In doing this analysis, we report the identification of 55 new clusters. We tabulated all of the derived cluster parameters for the considered intermediate- and high-mass YSOs. * Table is also available online at the CDS in the VizieR archive service.

Keywords: Herbig Ae/Be stars, Emission line stars, Massive stars, Young star clusters, T Tauri stars, Young stellar objects, Star formation, Clustering, Protoplanetary disks, Star clusters
Finding Substructures in Protostellar Disks in Ophiuchus. High-resolution, millimeter observations of disks at the protoplanetary stage reveal substructures such as gaps, rings, arcs, spirals, and cavities. While many protoplanetary disks host such substructures, only a few at the younger protostellar stage have shown similar features. We present a detailed search for early disk substructures in Atacama Large Millimeter/submillimeter Array 1.3 and 0.87 mm observations of ten protostellar disks in the Ophiuchus star-forming region. Of this sample, four disks have identified substructure, two appear to be smooth disks, and four are considered ambiguous. The structured disks have wide Gaussian-like rings (σ  R /R disk ~ 0.26) with low contrasts (C &lt; 0.2) above a smooth disk profile, in comparison to protoplanetary disks where rings tend to be narrow and have a wide variety of contrasts (σ  R /R disk ~ 0.08 and C ranges from 0 to 1). The four protostellar disks with the identified substructures are among the brightest sources in the Ophiuchus sample, in agreement with trends observed for protoplanetary disks. These observations indicate that substructures in protostellar disks may be common in brighter disks. The presence of substructures at the earliest stages suggests an early start for dust grain growth and, subsequently, planet formation. The evolution of these protostellar substructures is hypothesized in two potential pathways: (1) the rings are the sites of early planet formation, and the later observed protoplanetary disk ring-gap pairs are secondary features, or (2) the rings evolve over the disk lifetime to become those observed at the protoplanetary disk stage.

Keywords: Millimeter astronomy, Young stellar objects, Star formation, Circumstellar disks, Protostars
Systematically Measuring Ultradiffuse Galaxies (SMUDGes). IV. Ultradiffuse Satellites of Milky Way Analogs. To better understand the formation of large, low-surface-brightness galaxies, we measure the correlation function between ultradiffuse galaxy (UDG) candidates and Milky Way analogs (MWAs). We find that: (1) the projected radial distribution of UDG satellites (projected surface density ∝r -0.84±0.06) is consistent with that of normal satellite galaxies; (2) the number of UDG satellites per MWA (S UDG) is ~0.5 ± 0.1 over projected radii from 20 to 250 kpc and -17 &lt; M  r  &lt; -13.5; (3) S UDG is consistent with a linear extrapolation of the relationship between the number of UDGs per halo versus halo mass obtained over galaxy group and cluster scales; (4) red UDG satellites dominate the population of UDG satellites (~80%); (5) over the range of satellite magnitudes studied, UDG satellites comprise ~10% of the satellite galaxy population of MWAs; and (6) a significant fraction of these (~13%) have estimated total masses &gt;1010.9 M ⊙ or, equivalently, at least half the halo mass of the LMC, and populate a large fraction (~18%) of the expected subhalos down to these masses. All of these results suggest a close association between the overall low-mass galaxy population and UDGs, which we interpret as favoring models where UDG formation principally occurs within the general context of low-mass galaxy formation over models invoking more exotic physical processes specifically invoked to form UDGs.

Keywords: Galaxy properties, Low surface brightness galaxies