adsabs/SciX_UAT_keywords huggingface dataset:
KAPPA: A Package for the Synthesis of Optically Thin Spectra for the Non-Maxwellian κ-Distributions. III. Improvements to Ionization Equilibrium and Extension to κ < 2

The KAPPA package is designed for calculations of optically thin spectra for the non-Maxwellian κ-distributions. This paper presents an extension of the database to allow calculations of the spectra for extreme values of κ < 2, which are important for accurate diagnostics of the κ-distributions in the outer solar atmosphere. In addition, two improvements were made to the ionization equilibrium calculations within the database. First, the ionization equilibrium calculations now include the effects of electron impact multi-ionization (EIMI). Although relatively unimportant for Maxwellian distribution, EIMI becomes important for some elements, such as Fe and low values of κ, where it modifies the ionization equilibrium significantly. Second, the KAPPA database now includes the suppression of dielectronic recombination at high electron densities, evaluated via the suppression factors. We find that at the same temperature, the suppression of dielectronic recombination is almost independent of κ. The ionization equilibrium calculations for the κ-distributions are now provided for a range of electron densities.

Keywords: atomic spectroscopy; non-thermal radiation sources; line intensities; excitation rates; de-excitation rates; electron impact ionization; dielectronic recombination; solar coronal heating; solar flares
LAGER Lyα Luminosity Function at z 7: Implications for Reionization

We present a new measurement of the Lyα luminosity function (LF) at redshift z = 6.9, finding moderate evolution from z = 5.7 that is consistent with a fully or largely ionized z ~ 7 intergalactic medium. Our result is based on four fields of the LAGER (Lyman Alpha Galaxies in the Epoch of Reionization) project. Our survey volume of 6.1 × 106 Mpc3 is double that of the next largest z ~ 7 survey. We combine two new LAGER fields (WIDE12 and GAMA15A) with two previously reported LAGER fields (COSMOS and CDFS). In the new fields, we identify N = 95 new z = 6.9 Lyα emitter (LAEs) candidates, characterize our survey's completeness and reliability, and compute Lyα LFs. The best-fit Schechter LF parameters for all four LAGER fields are in good general agreement. Two fields (COSMOS and WIDE12) show evidence for a bright-end excess above the Schechter function fit. We find that the Lyα luminosity density declines at the same rate as the UV continuum LF from z = 5.7 to 6.9. This is consistent with an intergalactic medium that was fully ionized as early as redshift z ~ 7 or with a volume-averaged neutral hydrogen fraction of x H I < 0.33 at 1σ.

Keywords: high-redshift galaxies; lyman-alpha galaxies; reionization; luminosity function; galaxy evolution
Departure from the Exact Location of Mean Motion Resonances Induced by the Gas Disk in Systems Observed by Kepler

The statistical results of transiting planets show that there are two peaks, around 1.5 and 2.0, in the distribution of orbital period ratios. A large number of planet pairs are found near the exact location of mean motion resonances (MMRs). In this work, we find that the depletion and structures of the gas disk play crucial roles in driving planet pairs out of the exact location of MMRs. Under such a scenario, planet pairs are trapped into exact MMRs during orbital migration first and keep migrating at the same pace. The eccentricities can be excited. Due to the existence of a gas disk, eccentricities can be damped, leading to a change in orbital period, which will make planet pairs depart from the exact location of MMRs. With depletion timescales larger than 1 Myr, near-MMR configurations are formed easily. Planet pairs have higher possibilities of escaping from MMRs with a higher disk aspect ratio. Additionally, with a weaker corotation torque, planet pairs can depart farther from the exact location of MMRs. The final location of the innermost planets in the systems are directly related to the transition radius from the optically thick region to the outer optically thin disk. While the transition radius is smaller than 0.2 au at the late stage of the star evolution process, the period of the inner planets can reach around 10 days. Our formation scenario is a possible mechanism for explaining the formation of near-MMR configurations with the innermost planet farther than 0.1 au.

Keywords: exoplanet dynamics; exoplanet evolution; exoplanet formation
Oceanic Superrotation on Tidally Locked Planets

Is there oceanic superrotation on exoplanets? Atmospheric superrotation, characterized by west-to-east winds over the equator, is a common phenomenon in the atmospheres of Venus, Titan, Saturn, Jupiter, and tidally locked exoplanets. The stratospheric atmosphere of Earth is also superrotating during the westerly phase of the quasi-biennial oscillation. However, whether the same phenomenon can occur in the ocean is poorly known. Through numerical simulations, here we show that oceanic superrotation does occur on tidally locked terrestrial planets around low-mass stars. Its formation (spun up from rest) is associated with surface winds, the equatorward momentum convergence by Rossby waves, and the eastward propagation of Kelvin waves in the ocean. Its maintenance is driven by equatorward momentum transports of coupled Rossby-Kelvin waves in the ocean excited from the uneven stellar radiation distribution. The width of the superrotation is mainly constrained by the Rossby deformation radius in the ocean, while its strength is more complex. Many factors can influence the strength, including planetary rotation rate, stellar flux, greenhouse gas concentration, seawater salinity, and bottom drag, but a scaling theory for the strength of the oceanic superrotation is lacking. This work confirms that oceanic superrotation can occur on tidally locked terrestrial planets with seawater oceans and suggests that it may also occur on tidally locked hot planets with magma oceans that will possibly be observed in the near future.

Keywords: exoplanets; ocean planets
The IR Compactness of Dusty Galaxies Sets Star Formation and Dust Properties at z ∼ 0-2

The surface densities of gas, dust, and stars provide a window into the physics of star formation that, until the advent of high-resolution far-IR/submillimeter observations, has been historically difficult to assess among dusty galaxies. To study the link between IR surface densities and dust properties, we leverage the Atacama Large Millimetre/Submillimetre Array archive to measure the extent of cold dust emission in 15 z ~ 2 IR-selected galaxies selected on the basis of having available mid-IR spectroscopy from Spitzer. We use the mid-IR spectra to constrain the relative balance between dust heating from star formation and active galactic nuclei (AGNs), and to measure emission from polycylic aromatic hydrocarbons (PAHs), small dust grains that play a key role in the photoelectric heating of gas. In general, we find that dust-obscured star formation at high IR surface densities exhibits similar properties at low and high redshift, namely, local luminous IR galaxies (LIRGs) have comparable PAH luminosity to total dust mass ratios as high-z galaxies, and star formation at z ~ 0-2 is more efficient at high IR surface densities despite the fact that our sample of high-z galaxies is closer to the main sequence than local LIRGs. High star formation efficiencies are coincident with a decline in the PAH-to-IR luminosity ratio reminiscent of the deficit observed in far-IR fine-structure lines. Changes in the gas and dust conditions arising from high star formation surface densities might help drive the star formation efficiency up. This could help explain the high efficiencies needed to reconcile star formation and gas volume densities in dusty galaxies at cosmic noon.

Keywords: star formation; luminous infrared galaxies; polycyclic aromatic hydrocarbons; interstellar dust; galaxy evolution
The Role of Neutral Hydrogen in Setting the Abundances of Molecular Species in the Milky Way's Diffuse Interstellar Medium. I. Observational Constraints from ALMA and NOEMA

We have complemented existing observations of H I absorption with new observations of HCO+, C2H, HCN, and HNC absorption from the Atacama Large Millimeter/submillimeter Array and the Northern Extended Millimeter Array in the directions of 20 background radio continuum sources with 4° ≤ ∣b∣ ≤ 81° to constrain the atomic gas conditions that are suitable for the formation of diffuse molecular gas. We find that these molecular species form along sightlines where A V ≳ 0.25, consistent with the threshold for the H I-to-H2 transition at solar metallicity. Moreover, we find that molecular gas is associated only with structures that have an H I optical depth >0.1, a spin temperature <80 K, and a turbulent Mach number ≳ 2. We also identify a broad, faint component to the HCO+ absorption in a majority of sightlines. Compared to the velocities where strong, narrow HCO+ absorption is observed, the H I at these velocities has a lower cold neutral medium fraction and negligible CO emission. The relative column densities and linewidths of the different molecular species observed here are similar to those observed in previous experiments over a range of Galactic latitudes, suggesting that gas in the solar neighborhood and gas in the Galactic plane are chemically similar. For a select sample of previously observed sightlines, we show that the absorption line profiles of HCO+, HCN, HNC, and C2H are stable over periods of ~3 yr and ~25 yr, likely indicating that molecular gas structures in these directions are at least ≳100 au in size.

Keywords: interstellar absorption; interstellar phases; interstellar atomic gas; diffuse molecular clouds; molecule formation
Electromagnetic Fireworks: Fast Radio Bursts from Rapid Reconnection in the Compressed Magnetar Wind

One scenario for the generation of fast radio bursts (FRBs) is magnetic reconnection in a current sheet of the magnetar wind. Compressed by a strong magnetic pulse induced by a magnetar flare, the current sheet fragments into a self-similar chain of magnetic islands. Time-dependent plasma currents at their interfaces produce coherent radiation during their hierarchical coalescence. We investigate this scenario using 2D radiative relativistic particle-in-cell simulations to compute the efficiency of the coherent emission and to obtain frequency scalings. Consistent with expectations, a fraction of the reconnected magnetic field energy, f ~ 0.002, is converted to packets of high-frequency fast magnetosonic waves, which can escape from the magnetar wind as radio emission. In agreement with analytical estimates, we find that magnetic pulses of 1047 erg s-1 can trigger relatively narrowband GHz emission with luminosities of approximately 1042 erg s-1, sufficient to explain bright extragalactic FRBs. The mechanism provides a natural explanation for a downward frequency drift of burst signals, as well as the ~100 ns substructure recently detected in FRB 20200120E .

Keywords: radio transient sources; magnetars; magnetic fields; plasma astrophysics
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). II. The Spatially Resolved Recent Star Formation History of M33

We measure the spatially resolved recent star formation history (SFH) of M33 using optical images taken with the Hubble Space Telescope as part of the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) survey. The area covered by the observations used in this analysis covers a de-projected area of ~38 kpc2 and extends to ~3.5 and ~2 kpc from the center of M33 along the major and semimajor axes, respectively. We divide the PHATTER optical survey into 2005 regions that measure 24 arcsec, ~100 pc, on a side and fit color-magnitude diagrams for each region individually to measure the spatially resolved SFH of M33 within the PHATTER footprint. There are significant fluctuations in the SFH on small spatial scales and also galaxy-wide scales that we measure back to about 630 Myr ago. We observe a more flocculent spiral structure in stellar populations younger than about 80 Myr, while the structure of the older stellar populations is dominated by two spiral arms. We also observe a bar in the center of M33, which dominates at ages older than about 80 Myr. Finally, we find that the mean star formation rate (SFR) over the last 100 Myr within the PHATTER footprint is 0.32 ± 0.02 M⊙ yr-1. We measure a current SFR (over the last 10 Myr) of 0.20 ± 0.03 M⊙ yr-1. This SFR is slightly higher than previous measurements from broadband estimates, when scaled to account for the fraction of the D25 area covered by the PHATTER survey footprint.

Keywords: star formation; triangulum galaxy; stellar populations; local group
The McDonald Accelerating Stars Survey: Architecture of the Ancient Five-planet Host System Kepler-444

We present the latest and most precise characterization of the architecture for the ancient (≈11 Gyr) Kepler-444 system, which is composed of a K0 primary star (Kepler-444 A) hosting five transiting planets and a tight M-type spectroscopic binary (Kepler-444 BC) with an A-BC projected separation of 66 au. We have measured the system's relative astrometry using the adaptive optics imaging from Keck/NIRC2 and Kepler-444 A's radial velocities from the Hobby-Eberly Telescope and reanalyzed relative radial velocities between BC and A from Keck/HIRES. We also include the Hipparcos-Gaia astrometric acceleration and all published astrometry and radial velocities in an updated orbit analysis of BC's barycenter. These data greatly extend the time baseline of the monitoring and lead to significant updates to BC's barycentric orbit compared to previous work, including a larger semimajor axis ( $a={52.2}_{-2.7}^{+3.3}$ au), a smaller eccentricity (e = 0.55 ± 0.05), and a more precise inclination ( $i=85\buildrel{\circ}\over{.} {4}_{-0\buildrel{\circ}\over{.} 4}^{+0\buildrel{\circ}\over{.} 3}$ ). We have also derived the first dynamical masses of B and C components. Our results suggest that Kepler-444 A's protoplanetary disk was likely truncated by BC to a radius of ≈8 au, which resolves the previously noticed tension between Kepler-444 A's disk mass and planet masses. Kepler-444 BC's barycentric orbit is likely aligned with those of A's five planets, which might be primordial or a consequence of dynamical evolution. The Kepler-444 system demonstrates that compact multiplanet systems residing in hierarchical stellar triples can form at early epochs of the universe and survive their secular evolution throughout cosmic time.

Keywords: binary stars; planetary system formation; astrometry
Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late Infall Causing Disk Misalignment and Dynamic Structures in SU Aur

Gas-rich circumstellar disks are the cradles of planet formation. As such, their evolution will strongly influence the resulting planet population. In the ESO DESTINYS large program, we study these disks within the first 10 Myr of their development with near-infrared scattered-light imaging. Here we present VLT/SPHERE polarimetric observations of the nearby class II system SU Aur in which we resolve the disk down to scales of ∼7 au. In addition to the new SPHERE observations, we utilize VLT/NACO, HST/STIS, and ALMA archival data. The new SPHERE data show the disk around SU Aur and extended dust structures in unprecedented detail. We resolve several dust tails connected to the Keplerian disk. By comparison with ALMA data, we show that these dust tails represent material falling onto the disk. The disk itself shows an intricate spiral structure and a shadow lane, cast by an inner, misaligned disk component. Our observations suggest that SU Aur is undergoing late infall of material, which can explain the observed disk structures. SU Aur is the clearest observational example of this mechanism at work and demonstrates that late accretion events can still occur in the class II phase, thereby significantly affecting the evolution of circumstellar disks. Constraining the frequency of such events with additional observations will help determine whether this process is responsible for the spin-orbit misalignment in evolved exoplanet systems. * Based on observations performed with VLT/SPHERE under program ID 1104.C-0415(E).

Keywords: polarimetry; direct imaging; circumstellar disks; circumstellar dust; exoplanets
Diversity of Dust Properties in External Galaxies Confirmed by Polarization Signals from Type II Supernovae

Investigating interstellar (IS) dust properties in external galaxies is important not only to infer the intrinsic properties of astronomical objects but also to understand the star/planet formation in the galaxies. From the non-Milky Way-like extinction and interstellar polarization (ISP) observed in reddened Type Ia supernovae (SNe), it has been suggested that their host galaxies contain dust grains whose properties are substantially different from the Milky Way (MW) dust. It is important to investigate the universality of such non-MW-like dust in the universe. Here we report spectropolarimetry of two highly extinguished Type II SNe (SN 2022aau and SN 2022ame). SN 2022aau shows a polarization maximum at a shorter wavelength than MW stars, which is also observed in some Type Ia SNe. This is clear evidence for the existence of non-MW-like dust in its host galaxy (i.e., NGC 1672). This fact implies that such non-MW-like dust might be more common in some environments than expected, and thus it might affect the picture of the star/planet formation. On the other hand, SN 2022ame shows MW-like ISP, implying the presence of MW-like dust in its host galaxy (i.e., NGC 1255). Our findings confirm that dust properties of galaxies are diverse, either locally or globally. The present work demonstrates that further investigation of IS dust properties in external galaxies using polarimetry of highly reddened SNe is promising, providing a great opportunity to study the universality of such non-MW-like dust grains in the universe.

Keywords: interstellar dust; type ii supernovae; spectropolarimetry
GOALS-JWST: NIRCam and MIRI Imaging of the Circumnuclear Starburst Ring in NGC 7469

We present James Webb Space Telescope (JWST) imaging of NGC 7469 with the Near-Infrared Camera and the Mid-InfraRed Instrument. NGC 7469 is a nearby, z = 0.01627, luminous infrared galaxy that hosts both a Seyfert Type-1.5 nucleus and a circumnuclear starburst ring with a radius of ~0.5 kpc. The new near-infrared (NIR) JWST imaging reveals 66 star-forming regions, 37 of which were not detected by Hubble Space Telescope (HST) observations. Twenty-eight of the 37 sources have very red NIR colors that indicate obscurations up to A v ~ 7 and a contribution of at least 25% from hot dust emission to the 4.4 μm band. Their NIR colors are also consistent with young (<5 Myr) stellar populations and more than half of them are coincident with the mid-infrared (MIR) emission peaks. These younger, dusty star-forming regions account for ~6% and ~17% of the total 1.5 and 4.4 μm luminosity of the starburst ring, respectively. Thanks to JWST, we find a significant number of young dusty sources that were previously unseen due to dust extinction. The newly identified 28 young sources are a significant increase compared to the number of HST-detected young sources (4-5). This makes the total percentage of the young population rise from ~15% to 48%. These results illustrate the effectiveness of JWST in identifying and characterizing previously hidden star formation in the densest star-forming environments around active galactic nuclei (AGN).

Keywords: luminous infrared galaxies; infrared astronomy; infrared sources; star forming regions
A Repository of Vanilla Long-term Integrations of the Solar System

We share the source code and a 121 GB data set of 96 long-term N-body simulations of the solar system. This data set can be analyzed by itself to study the dynamics of the solar system. In addition, our simulations can be the starting point for future studies wishing to explore different initial conditions or additional physical effects on the solar system. Our simulations can also be used as a comparison and benchmark for new numerical algorithms.

Keywords: celestial mechanics; n-body simulations; solar system
The Near-infrared Ca II Triplet as a Stellar Activity Indicator: A Library and Comparative Study

We have established and released a new stellar index library of the Ca II triplet, which serves as an indicator for characterizing the chromospheric activity of stars. The library is based on data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Low-Resolution Spectroscopic Survey (LRS) Data Release 9. To better reflect the chromospheric activity of stars, we have defined new indices R and R +. The library includes measurements of R and R + for each Ca II infrared triplet (IRT) from 699,348 spectra of 562,863 F, G, and K-type solar-like stars with a signal-to-noise ratio higher than 100, as well as the stellar atmospheric parameters and basic information inherited from the LAMOST LRS catalog. We compared the differences between the three individual indices of the Ca II triplet and also conducted a comparative analysis of ${R}_{\lambda 8542}^{+}$ to the Ca II H and K S and ${R}_{\mathrm{HK}}^{+}$ index databases. We observe the fraction of less active stars decreases with T eff and the fraction of more active stars first decreases with decreasing temperature and turns to increase with decreasing temperature at 5800 K. We also find that a significant fraction of stars that show a high activity index in both Ca II H and K and IRT are binaries with low activity; some of them could be discriminated in the Ca II H and K S index and ${R}_{\lambda 8542}^{+}$ space. This new stellar library serves as a valuable resource for studying chromospheric activity in stars and can be used to improve our comprehension of stellar magnetic activity and other astrophysical phenomena.

Keywords: stellar activity; stellar chromospheres; astronomy databases