adsabs/SciX_UAT_keywords huggingface dataset:
Architectures of Exoplanetary Systems. II. An Increase in Inner Planetary System Occurrence toward Later Spectral Types for Kepler's FGK Dwarfs

The Kepler mission observed thousands of transiting exoplanet candidates around hundreds of thousands of FGK dwarf stars. He et al. applied forward modeling to infer the distribution of intrinsic architectures of planetary systems, developed a clustered Poisson point process model for exoplanetary systems (SysSim) to reproduce the marginal distributions of the observed Kepler population, and they showed that orbital periods and planet radii are clustered within a given planetary system. Here, we extend the clustered model to explore correlations between planetary systems and their host-star properties. We split the sample of Kepler FGK dwarfs into two halves and model the fraction of stars with planets (0.5-10R⊕ and 3-300 days), fswpa, as a linear function of the Gaia DR2 color. We confirm previous findings that the occurrence of these planetary systems rises significantly toward later-type (redder) stars. The fraction of stars with planets increases from ${f}_{\mathrm{swpa}}={0.32}_{-0.11}^{+0.12}$ for F2V dwarfs to ${f}_{\mathrm{swpa}}={0.96}_{-0.19}^{+0.04}$ for mid-K dwarfs. About half ( ${f}_{\mathrm{swpa}}={0.57}_{-0.10}^{+0.14}$ ) of all solar-type (G2V) dwarfs harbor a planetary system between 3 and 300 days. This simple model can closely match the observed multiplicity distributions of both the bluer and redder halves in our sample, suggesting that the architectures of planetary systems around stars of different spectral types may be similar aside from a shift in the overall fraction of planet-hosting stars.

Keywords: exoplanet astronomy; exoplanet systems; planet hosting stars; astrostatistics; planetary system formation; extrasolar rocky planets; stellar colors
On Post-starburst Galaxies Dominating Tidal Disruption Events

A starburst induced by a galaxy merger may create a relatively thin central stellar disk at radius ≤100 pc. We calculate the rate of tidal disruption events (TDEs) by the inspiraling secondary supermassive black hole (SMBH) through the disk. With a small enough stellar velocity dispersion (σ /{V}c≤slant 0.1) in the disk, it is shown that 105-106 TDEs of solar-type main-sequence stars per post-starburst galaxy (PSB) can be produced to explain their dominance in producing observed TDEs. Although the time it takes to bring the secondary SMBH to the disk apparently varies in the range of ∼0.1-1 Gyr since the starburst, depending on its landing location and subsequently due to dynamical friction with stars exterior to the central stellar disk in question, the vast majority of TDEs by the secondary SMBH in any individual PSB occur within a time span shorter than ∼30 Myr. Five unique testable predictions of this model are suggested.

Keywords: dynamical friction; supermassive black holes; galaxy mergers; galaxy stellar disks; tidal disruption
Preliminary Results of Virtual Reality Mapping of E+A Galaxies and Candidates in Nearby Rich Clusters of Galaxies

In the study of large astronomical data sets, virtual reality (VR) can help build valuable spatial intuition for scientific discovery. We created VR visualizations of E+A galaxies and candidates in four nearby clusters of galaxies: Leo, Virgo, Hercules, and Coma. E+A's are a type of post-starburst galaxy in which all star formation has been recently (∼1 Gyr ago) quenched. Our E+A samples were assembled and cataloged by the Y/Dim collaboration through visual and quantitative analysis of SDSS DR16 spectra. The visualizations are designed for Oculus VR headsets, and utilize C# scripts which interface with the Unity engine, including public domain code and code developed by the lead author. We use these visualizations to find features of the aforementioned galaxy clusters: for instance, a "nose" of low velocity objects in the center of the Virgo cluster and a collection of E+A candidates along a galactic filament in the Coma cluster.

Keywords: astronomy software; e+a galaxies; post-starburst galaxies; coma cluster; galaxy clusters; virgo cluster; galaxy quenching; galaxy evolution
Magnetic Field of Molecular Gas Measured with the Velocity Gradient Technique I. Orion A

Magnetic fields play an important role in the evolution of molecular clouds and star formation. Using the velocity gradient technique (VGT) model, we measured the magnetic field in Orion A using the 12CO, 13CO, and C18O(1-0) emission lines at a scale of ~0.07 pc. The measured B field shows an east-west orientation that is perpendicular to the integral shaped filament of Orion A at large scale. The VGT magnetic fields obtained from 13CO and C18O are in agreement with the B field that is measured from the Planck 353 GHz dust polarization at a scale of ~0.55 pc. Removal of density effects by using a velocity decomposition algorithm can significantly improve the accuracy of the VGT in tracing magnetic fields with the 12CO(1-0) line. The magnetic field strengths of seven subclouds, OMC-1, OMC-2, OMC-3, OMC-4, OMC-5, L 1641-N, and NGC 1999, have also been estimated with the Davis-Chandrasekhar-Fermi and the Two Mach Numbers technique, and these are found to be in agreement with previous results obtained from dust polarization at far-infrared and submillimeter wavelengths. At smaller scales, the VGT prove a good method to measure magnetic fields.

Keywords: interstellar medium; interstellar magnetic fields; interstellar dynamics
Revisiting the Architecture of the KOI-89 System

While high stellar obliquities observed in exoplanetary systems may be attributed to processes that tilt the planetary orbits, it is also possible that they reflect misalignments between protoplanetary disks and stellar spins. This latter hypothesis predicts the presence of coplanar multiplanetary systems misaligned with their central stars. Here we reevaluate the evidence of such an architecture that has been claimed for the KOI-89 system. An early-type star, KOI-89 has one validated transiting planet, KOI-89.01/Kepler-462b (period 84.7 days, radius 3.0 R⊕), and one transiting planet candidate, KOI-89.02 (period 207.6 days, radius 4.0 R⊕), where the latter exhibits transit timing variations (TTVs). A previous modeling of the stellar gravity-darkening effect in the transit light curves inferred a high stellar obliquity of ≈70°. We perform photodynamical modeling of the Kepler transit light curves and use the resulting constraints on the orbital configuration and transit times to update the gravity-darkened transit model. As a result, we find no firm evidence for the gravity-darkening effect in the transit shapes and conclude that stellar obliquity is not constrained by the data. Given the evidence for low orbital eccentricities from the dynamical analysis, the system architecture can thus be consistent with many other multitransiting systems with flat, near-circular orbits aligned with the stellar spin. We find that the TTVs imparted on its neighbor imply that KOI-89.01 has a mass ≳20 M⊕. This would render it one of the densest known sub-Neptunes, mostly composed of a solid core. Lower masses are possible if the TTVs are instead due to an unseen third planet.

Keywords: exoplanet astronomy; exoplanet dynamics; exoplanets; exoplanet systems; exoplanet structure
Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II.Kinematics

Combining LAMOST radial velocities with Gaia parallaxes and proper motions, we present 3D Galactic space motions and the orbits of 182 single-lined hot subdwarf stars. These stars were identified by Lei et al. in Gaia DR2 with LAMOST DR6 and DR7 spectra. He-rich hot subdwarf stars with $\mathrm{log}(y)\geqslant 0$ show the largest standard deviations of the Galactic velocity components and orbital parameters, while those with $-1\leqslant \mathrm{log}(y)\lt 0$ exhibit the second largest standard deviations. The two groups of He-deficient stars with $\mathrm{log}(y)\lt -1$ show similar standard deviations, which are systematically lower compared to He-rich stars. We also present a kinematic population classification of the four hot subdwarf helium groups based on their positions in the U - V velocity diagram, the ${J}_{Z}-$ eccentricity diagram, and their Galactic orbits. The overall tendency of the fractional distributions of the four hot subdwarf helium groups in the halo, thin disk, and thick disk is largely consistent with the findings reported by Luo et al. based on LAMOST DR5, which appears to support predictions of binary population synthesis. He-deficient stars with $-2.2\leqslant \mathrm{log}(y)\lt -1$ likely originate from a stable Roche lobe overflow channel, He-deficient stars with $\mathrm{log}(y)\lt -2.2$ from the common envelope ejection channel, and He-rich stars with $\mathrm{log}(y)\geqslant 0$ from the merger channel of double He white dwarf stars. The fraction of He-rich hot subdwarf stars with $-1\leqslant \mathrm{log}(y)\lt 0$ in the thin disk and the halo is far higher than that in the thick disk, which implies that these stars have different formation channels in the thin disk and in the halo.

Keywords: stellar kinematics; subdwarf stars
Modeling and Calibration of Gaia, Hipparcos, and Tycho-2 Astrometric Data for the Detection of Dark Companions

Hidden within the Gaia satellite's multiple data releases lies a valuable cache of dark companions. To facilitate the efficient and reliable detection of these companions via combined analyses involving the Gaia, Hipparcos, and Tycho-2 catalogs, we introduce an astrometric modeling framework. This method incorporates analytical least-square minimization and nonlinear parameter optimization techniques to a set of common calibration sources across the different space-based astrometric catalogs. This enables us to discern the error inflation, astrometric jitter, differential parallax zero-points, and frame rotation of various catalogs relative to Gaia Data Release 3 (DR3). Our findings yield the most precise Gaia DR2 calibration parameters to date, revealing notable dependencies on magnitude and color. Intriguingly, we identify submilliarcsecond frame rotation between Gaia DR1 and DR3, along with an estimated astrometric jitter of 2.16 mas for the revised Hipparcos catalog. In a thorough comparative analysis with previous studies, we offer recommendations on calibrating and utilizing different catalogs for companion detection. Furthermore, we provide a user-friendly pipeline (https://github.com/ruiyicheng/Download_HIP_Gaia_GOST) for catalog download and bias correction, enhancing accessibility and usability within the scientific community.

Keywords: astrometry; astrometric exoplanet detection; astrometric binary stars; bayes factor
A Lens Finder Map to Check Claimed High-z Galaxies behind SMACS J0723.3-7327

The first science image released by the James Webb Space Telescope (JWST) reveals numerous galaxies in the distant background of the galaxy cluster SMACS J0723.3-7327. Some have claimed redshifts of up to z ≃ 20, challenging standard cosmological models for structure formation. Here, we present a lens model for SMACS J0723.3-7327 anchored on five spectroscopically confirmed systems at 1.38 ≤ z ≤ 2.21 that are multiply lensed, along with 12 other systems with proposed image counterparts sharing common colors, spectral energy distributions, and morphological features, but having unknown redshifts. Constrained only by their image positions, and where available, redshifts, our lens model correctly reproduces the positions and correctly predicts the morphologies and relative brightnesses of all these image counterparts, as well as providing geometrically determined redshifts spanning 1.4 ≲ z ≲ 6.7 for the 12 candidate multiply lensed galaxies lacking spectroscopic measurements. From this lens model, we create a lens finder map that defines regions over which galaxies beyond a certain redshift are predicted to be multiply lensed. Applying this map to three galaxies claimed to be at 10 ≲ z ≲ 20, we find no image counterparts at locations (with an uncertainty of ∼0.″5) where they ought to be sufficiently magnified to be detectable—suggesting instead that these galaxies lie at z ≲ 1.7–3.2. In lieu of spectroscopy, the creation of reliable lens finder maps for cluster fields is urgently needed to test and constrain redshifts inferred from photometry for a rapidly increasing number of candidate high-z galaxies found with JWST.

Keywords: strong gravitational lensing; galaxy clusters
An Ensemble Study of Turbulence in Extended QSO Nebulae at z ≈ 0.5–1

Turbulent motions in the circumgalactic medium play a critical role in regulating the evolution of galaxies, yet their detailed characterization remains elusive. Using two-dimensional velocity maps constructed from spatially extended [O II] and [O III] emission, Chen et al. measured the velocity structure functions (VSFs) of four quasar nebulae at z ≈ 0.5–1.1. One of these exhibits a spectacular Kolmogorov relation. Here, we carry out an ensemble study using an expanded sample incorporating four new nebulae from three additional quasi-stellar object (QSO) fields. The VSFs measured for all eight nebulae are best explained by subsonic turbulence revealed by the line-emitting gas, which in turn strongly suggests that the cool gas (T ∼ 104 K) is dynamically coupled to the hot ambient medium. Previous work demonstrates that the largest nebulae in our sample reside in group environments with clear signs of tidal interactions, suggesting that environmental effects are vital in seeding and enhancing the turbulence within the gaseous halos, ultimately promoting the formation of the extended nebulae. No discernible differences are observed in the VSF properties between radio-loud and radio-quiet QSO fields. We estimate the turbulent heating rate per unit volume, Q turb, in the QSO nebulae to be ∼10‑26–10‑22 erg cm‑3 s‑1 for the cool phase and ∼10‑28–10‑25 erg cm‑3 s‑1 for the hot phase. This range aligns with measurements in the intracluster medium and star-forming molecular clouds but is ∼103 times higher than the Q turb observed inside cool gas clumps on scales ≲1 kpc using absorption-line techniques. We discuss the prospect of bridging the gap between emission and absorption studies by pushing the emission-based VSF measurements to below ≈10 kpc.

Keywords: agn host galaxies; quasars; surveys; circumgalactic medium; galaxy environments
Radial and Vertical Constraints on the Icy Origin of H2CO in the HD 163296 Protoplanetary Disk

H2CO is a small organic molecule widely detected in protoplanetary disks. As a precursor to grain-surface formation of CH3OH, H2CO is considered an important precursor of O-bearing organic molecules that are locked in ices. Still, since gas-phase reactions can also form H2CO, there remains an open question on the channels by which organics form in disks, and how much the grain versus the gas pathways impact the overall organic reservoir. We present spectrally and spatially resolved Atacama Large Millimeter/submillimeter Array observations of several ortho- and para-H2CO transitions toward the bright protoplanetary disk around the Herbig Ae star HD 163296. We derive column density, excitation temperature, and ortho-to-para ratio (OPR) radial profiles for H2CO, as well as disk-averaged values of N T ∼ 4 × 1012 cm‑2, T ex ∼ 20 K, and OPR ∼ 2.7, respectively. We empirically determine the vertical structure of the emission, finding vertical heights of z/r ∼ 0.1. From the profiles, we find a relatively constant OPR ∼ 2.7 with radius, but still consistent with 3.0 among the uncertainties, a secondary increase of N T in the outer disk, and low T ex values that decrease with disk radius. Our resulting radial, vertical, and OPR constraints suggest an increased UV penetration beyond the dust millimeter edge, consistent with an icy origin but also with cold gas-phase chemistry. This Herbig disk contrasts previous results for the T Tauri disk, TW Hya, which had a larger contribution from cold gas-phase chemistry. More observations of other sources are needed to disentangle the dominant formation pathway of H2CO in protoplanetary disks.

Keywords: astrochemistry; protoplanetary disks; interstellar molecules; high angular resolution
Probing Axial Symmetry Breaking in the Galaxy with Gaia Data Release 2

We study a set of solar neighborhood (d < 3 kpc) stars from Gaia Data Release 2 to determine azimuthal star count differences, I.e., left and right of the line from the Galactic Center (GC) through the Sun - and compare these differences north and south. In this companion paper to Gardner et al., we delineate our procedures to remove false asymmetries from sampling effects, incompleteness, and/or interloper populations, as this is crucial to tests of axisymmetry. Particularly, we have taken care to make appropriate selections of magnitude, color, in-plane Galactocentric radius, and Galactic $| b| $ and $| z| $ . We find that requiring parallax determinations of high precision induces sampling biases, so that we eschew such requirements and exclude, e.g., regions around the lines of sight to the Magellanic Clouds, along with their mirror-image lines of sight, to ensure well-matched data sets. After making conservative cuts, we demonstrate the existence of azimuthal asymmetries and find differences in those, north and south. These asymmetries give key insights into the nature and origins of the perturbations on Galactic matter, allowing us to assess the relative influence of the Magellanic Clouds (LMC and SMC), the Galactic bar, and other masses on the Galactic mass distribution, as described in Gardner et al. The asymmetry's radial dependence reveals variations that we attribute to the Galactic bar, and it changes sign at a radius of (0.95 ± 0.03)R0, with R0 the Sun-GC distance, to give us the first direct assessment of the outer Lindblad resonant radius.

Keywords: milky way dark matter halo; milky way galaxy; galaxy structure; milky way dynamics
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å in Late B-type Stars: Paper I—HD 35548 and HD 89822

The weak line of Hg II located at 5677.10 Å is used to measure the mercury abundance in two mercury rich stars, HD 35548 and HD 89822. The synthesis of this line, using the current atomic parameters available in NIST, confirms that mercury is very abundant in both stars. The abundance derived from this line is in very good agreement with the abundance derived from the commonly used line at 3983.93 Å for HD 35548 but it is smaller for HD 89822.

Keywords: chemically peculiar stars; mercury-manganese stars
Evaluating the Evidence for Water World Populations Using Mixture Models

Water worlds have been hypothesized as an alternative to photoevaporation in order to explain the gap in the radius distribution of Kepler exoplanets. We explore water worlds within the framework of a joint mass-radius-period distribution of planets fit to a sample of transiting Kepler exoplanets, a subset of which have radial velocity mass measurements. We employ hierarchical Bayesian modeling to create a range of ten mixture models that include multiple compositional subpopulations of exoplanets. We model these subpopulations-including planets with gaseous envelopes, evaporated rocky cores, evaporated icy cores, intrinsically rocky planets, and intrinsically icy planets-in different combinations in order to assess which combinations are most favored by the data. Using cross-validation, we evaluate the support for models that include planets with icy compositions compared to the support for models that do not, finding broad support for both. We find significant population-level degeneracies between subpopulations of water worlds and planets with primordial envelopes. Among models that include one or more icy-core subpopulations, we find a wide range for the fraction of planets with icy compositions, with a rough upper limit of 50%. Improved data sets or alternative modeling approaches may be able to better distinguish between these subpopulations of planets.

Keywords: exoplanet catalogs; exoplanet structure; exoplanet formation; bayesian statistics; astrostatistics; model selection; hierarchical models; mixture model
A Far Ultraviolet Spectroscopic Explorer Survey of Interstellar Molecular Hydrogen in the Galactic Disk

We report results from a Far Ultraviolet Spectrographic Explorer (FUSE) survey of interstellar molecular hydrogen (H2) in the Galactic disk toward 139 O-type and early B-type stars at Galactic latitudes ∣b∣ ≤ 10°, with updated photometric and parallax distances. H2 absorption is measured using the far-UV Lyman and Werner bands, including strong R(0), R(1), and P(1) lines from rotational levels J = 0 and J = 1 and excited states up to J = 5 (sometimes J = 6 and 7). For each sight line, we report column densities NH2, NHI, N(J), and NH = NHI + 2NH2 and the molecular fraction fH2 = 2NH2/NH. Our survey extends the 1977 Copernicus H2 survey up to NH ≈ 5 × 1021 cm-2. The lowest rotational states have excitation temperatures and rms dispersions ⟨T01⟩ = 88 ± 20 K and ⟨T02⟩ = 77 ± 18 K, suggesting that J = 0, 1, 2 are coupled to the gas kinetic temperature. Populations of higher-J states exhibit mean excitation temperatures ⟨T24⟩ = 237 ± 91 K and ⟨T35⟩ = 304 ± 108 K, produced primarily by UV radiative pumping. Correlations of fH2 with E(B - V) and NH show a transition to fH2 ≥ 0.1 at NH ≳ 1021 cm-2 and E(B - V) ≳ 0.2, interpreted with an analytic model of H2 formation-dissociation equilibrium and attenuation of the far-UV radiation field by self-shielding and dust opacity. Results of this disk survey are compared to previous FUSE studies of H2 in translucent clouds, at high Galactic latitudes, and in the Magellanic Clouds. Using updated distances to the target stars, we find average sight-line values ⟨fH2⟩ = 0.20 and ⟨NH/E(B - V)⟩ = 6.07 × 1021 cm-2 mag-1.

Keywords: diffuse interstellar clouds; milky way disk; interstellar molecules; ultraviolet astronomy; ultraviolet extinction
OGLE-2017-BLG-1434Lb: Confirmation of a Cold Super-Earth Using Keck Adaptive Optics

The microlensing event OGLE-2017-BLG-1434 features a cold super-Earth planet that is 1 of 11 microlensing planets with a planet-host-star mass ratio of q < 1 × 10-4. We provide an additional mass-distance constraint on the lens host using near-infrared adaptive optics photometry from Keck/NIRC2. We are able to determine a flux excess of KL = 16.96 ± 0.11, which most likely comes entirely from the lens star. Combining this with constraints from the large Einstein ring radius, θE = 1.40 ± 0.09 mas, and OGLE parallax we confirm this event as a super-Earth with a mass of mp = 4.43 ± 0.25M⊕. This system lies at a distance of DL = 0.86 ± 0.05 kpc from Earth and the lens star has a mass of ML = 0.234 ± 0.012M⊙. We confirm that with a star-planet mass ratio of q = 0.57 × 10-4, OGLE-2017-BLG-1434 lies near the inflexion point of the planet-host mass-ratio power law.

Keywords: exoplanets; gravitational microlensing