adsabs/SciX_UAT_keywords huggingface dataset:
Silicon and Oxygen Isotope Evolution of the Inner Solar System

Enstatite chondrites have been regarded as major building blocks of the Earth and other differentiated inner planetary bodies due to the similarity of Δ17O (deviation of the δ17O value from the terrestrial silicate fractionation line) and nucleosynthetic isotope anomalies. However, this hypothesis has been rebutted by the fact that the Earth and enstatite chondrites show distinct Si isotopic compositions. It has been debated whether the origin of this Si isotope difference is the result of nebular or planetary processes. Here we show that the δ30Si (deviation of 30Si/28Si relative to NBS 28 standard) and the Δ17O values of chondrules in unequilibrated enstatite chondrites are between -0.20‰ and -0.54‰ and -0.36‰ and +0.26‰, respectively. Furthermore, the chondrules with higher Δ17O values tend to have lower δ30Si. The data exhibit values consistent with most of the noncarbonaceous group differentiated planetary bodies. This consistency suggests that the Si and O isotopic compositions of enstatite chondrules record those of the major precursors that formed the differentiated planetary bodies in the inner solar system. Model calculations based on the results reveal that the Si and O isotope variations of the enstatite chondrite chondrules were generated by an interaction between the evaporation-driven SiO-rich gas and partially or fully melted forsterite-rich precursor chondrules. The Mg/Si of the evaporated dust-gas mixtures increased with increasing silicate/metal ratio in the evaporated dust, which may have increased the bulk Mg/Si and δ30Si value of the inner planetary bodies.

Keywords: protoplanetary disks; solar system terrestrial planets; chondrites; chondrules; cosmochemistry
Updated Photon Scattering Coefficients (g_values) for Mercury's Exospheric Species

In an optically thin exosphere such as those of Mercury and the Moon, the optically stimulated emissions are directly proportional to the stimulating solar flux. An important quantity in relating measured emission to column abundance in remote-sensing observations is the g_value. The g_value is proportional to the f-value of the emission line and to the solar flux at the emission frequency. The solar flux varies inversely with the heliocentric distance from the Sun, but also with the heliocentric relative velocity of the emitting atom. The heliocentric relative velocity of the planet Mercury varies by ±10 km s-1, however, the atoms may additionally have high velocities relative to the planet owing to high-energy processes or through acceleration caused by radiation pressure. In this paper we extend g_values to heliocentric relative velocities ±50 km s-1. In addition to 12 species for which g_values have been published previously, we have computed g_values for two additional species, Mn and Al, that were discovered in Mercury's exosphere in the course of the MESSENGER mission. We have not included updated g_values for C or OH, as these were not observed by MESSENGER. In this work, we employ the TSIS-1 hybrid reference solar spectrum for most calculations, with the SOLSTICE data being used in the EUV/far-UV. We note that the method employed here could be extended for application at extrasolar planets and comets, with the solar spectrum substituted by an appropriate stellar spectrum.

Keywords: exosphere; astronomy data modeling; ultraviolet spectroscopy; mercury (planet)
Characterization of the Fireballs Detected by All-sky Cameras in Romania

Some of the fields of research that have captured the persistent interest of both scientists and the general public are meteor phenomena. The main goal in the study of meteoroid impacts into Earth's atmosphere is the recovery of the remnant matter after the ablation in the form of meteorites. This is a complementary approach, yet cheap alternative, to a sample return mission. Meteoroids are messengers since the time of the formation of the solar system due to the fact that they have preserved the same composition. The study of meteorites provides information regarding the chemical composition from which the planets formed. The increasing number of all-sky camera networks in recent years has resulted in a large set of events available for study. Thus, it is very important to use a method that determines whether the meteoroid could produce a meteorite or not. In this paper we study the meteors detected by the FRIPON network in Romania with the use of all-sky cameras. We focus on the events with noticeable deceleration (V f /V 0 < 0.8). We determine the ballistic coefficient α and the mass-loss parameter β for the selected sample. Based on this analysis the events are classified in three categories: (1) meteoroids that are likely to produce meteorites; (2) meteoroids that can possibly produce meteorites; (3) meteoroids that are unlikely to produce meteorites. The entry and final mass are determined for each event. From the recorded fireballs, we identified one possible meteorite dropper, and we analyzed its dynamical evolution.

Keywords: meteoroids; meteors; meteorites
S-type Stars: Line List for the A2Π-X2Σ+ Band System of LaO

LaO bands are found in the spectra of cool S-type stars. The bands of the A2Π-X2Σ+ transition with $v^{\prime} \leqslant 3$ and v″ ≤ 4 are rotationally analyzed, providing spectroscopic constants for the A2Π state. Line strengths are calculated using an ab initio transition dipole moment function, and radiative lifetimes for the A2Π state have also been computed. A line list for the A2Π-X2Σ+ transition of LaO is provided and can be used to determine LaO stellar abundances.

Keywords: spectral line lists; line intensities; spectroscopy; line positions
Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regolith within Lunar Polar Craters: A Comparison of Apollo and Starship Landings

This work assesses the potential of midsized and large human landing systems to deliver water from their exhaust plumes to cold traps within lunar polar craters. It has been estimated that a total of between 2 and 60 T of surficial water was sensed by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project on the floors of the larger permanently shadowed south polar craters. This intrinsic surficial water sensed in the far-ultraviolet is thought to be in the form of a 0.3%–2% icy regolith in the top few hundred nanometers of the surface. We find that the six past Apollo Lunar Module midlatitude landings could contribute no more than 0.36 T of water mass to this existing, intrinsic surficial water in permanently shadowed regions (PSRs). However, we find that the Starship landing plume has the potential, in some cases, to deliver over 10 T of water to the PSRs, which is a substantial fraction (possibly >20%) of the existing intrinsic surficial water mass. This anthropogenic contribution could possibly overlay and mix with the naturally occurring icy regolith at the uppermost surface. A possible consequence is that the origin of the intrinsic surficial icy regolith, which is still undetermined, could be lost as it mixes with the extrinsic anthropogenic contribution. We suggest that existing and future orbital and landed assets be used to examine the effect of polar landers on the cold traps within PSRs.

Keywords: the moon; lunar craters; lunar science
Constraints to Efficiently Find Interstellar Object Generated Craters on the Moon

Recent observations of interstellar objects (ISO) crossing the solar system suggest the possible existence of ISO-generated craters on the Moon. We explore how different crater properties such as age, size, melt, and position can be used to search for ISO-generated craters on the lunar surface. We find that selecting young, small craters with a high volume of melt located away from the lunar poles increases the likelihood of association with a high-speed ISO by 100 fold as compared to selecting randomly, assuming high-speed ISO impacts generate melt. We note that craters from other sources however still massively outnumber ISO-generated craters.

Keywords: interstellar objects; lunar craters
Evidence for He I 10830 Å Absorption during the Transit of a Warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder

Understanding the dynamics and kinematics of outflowing atmospheres of hot and warm exoplanets is crucial to understanding the origins and evolutionary history of the exoplanets near the evaporation desert. Recently, ground-based measurements of the meta-stable helium atom's resonant absorption at 10830 Å has become a powerful probe of the base environment which is driving the outflow of exoplanet atmospheres. We report evidence for the He I 10830 Å in absorption (equivalent width ∼0.012 ± 0.002 Å) in the exosphere of a warm Neptune orbiting the M-dwarf GJ 3470, during three transits using the Habitable Zone Planet Finder near-infrared spectrograph. This marks the first reported evidence for He I 10830 Å atmospheric absorption for a planet orbiting an M-dwarf. Our detected absorption is broad and its blueshifted wing extends to -36 km s-1, the largest reported in the literature to date. We modeled the state of helium atoms in the exosphere of GJ3470b based on assumptions on the UV and X-ray flux of GJ 3470, and found our measurement of flux-weighted column density of meta-stable state helium $({N}_{\mathrm{He}{}_{3}^{2}{\rm{S}}}=2.4\times {10}^{10}\,{\mathrm{cm}}^{-2})$ , derived from our transit observations, to be consistent with the model, within its uncertainties. The methodology developed here will be useful to study and constrain the atmospheric outflow models of other exoplanets like GJ 3470b, which are near the edge of the evaporation desert.

Keywords: exoplanet atmospheric composition; exoplanet atmospheres; exosphere; high resolution spectroscopy; near infrared astronomy; exoplanet astronomy
The 2020 Eclipse of R Aquarii in the Near-infrared: Mid-eclipse Observations of Disk Distress

The Mira in the bright, dusty, symbiotic binary R Aquarii undergoes eclipses of multiyear duration every ~44 yr by a large, opaque accretion disk. The 2020 eclipse was confirmed by I-band photometry. High-resolution M- and K-band spectra were observed near the midpoint of the eclipse, in 2020 August and September. The 4.5-5.5 μm spectrum during eclipse is a complex blend of disk and Mira features. Continuum emission from the disk region contributes to both the 2.3 μm and 4.6 μm region. The lowest energy vibration-rotation CO lines contain multiple absorption features from ~780 K gas flowing across the disk away from the Mira. CO fundamental and overtone emission lines are also present. The eccentricity of the orbit results in significant orbital variation in the size of the Roche lobes. At periastron the Roche radius of the secondary is ~4.0 au, smaller than both the 5 au geometric radius for the disk and estimates for the disk size from models. Fundamental band CO 2-1 emission originates from a thin, eccentric ring with inner radius ~4.75 au and outer radius ~6.9 au. The CO emission is identified with regions where the disk has been disrupted near the time of periastron. CO 3-2 fundamental band lines and low-excitation lines in the CO 2-0 and 3-1 overtone bands originate in a Mira-facing spot, 6.3 au from the accretion disk center, near the inner Lagrange point.

Keywords: eclipsing binary stars; circumstellar matter; mira variable stars; multiple star evolution; stellar accretion disks; symbiotic binary stars
A Bayesian Analysis of Physical Parameters for 783 Kepler Close Binaries: Extreme-mass-ratio Systems and a New Mass Ratio versus Period Lower Limit

Contact binary star systems represent the long-lived penultimate phase of binary evolution. Population statistics of their physical parameters inform an understanding of binary evolutionary pathways and end products. We use light curves and new optical spectroscopy to conduct a pilot study of ten (near) contact systems in the long-period (P > 0.5 days) tail of close binaries in the Kepler field. We use PHOEBE light-curve models to compute Bayesian probabilities on five principal system parameters. Mass ratios and third-light contributions measured from spectra agree well with those inferred from the light curves. Pilot study systems have extreme mass ratios q < 0.32. Most are triples. Analysis of the unbiased sample of 783 0.15 d < P < 2 days (near) contact binaries results in 178 probable contact systems, 114 probable detached systems, and 491 ambiguous systems for which we report best-fitting and 16th-/50th-/84th-percentile parameters. Contact systems are rare at periods P > 0.5 days, as are systems with q > 0.8. There exists an empirical mass ratio lower limit ${q}_{\min }(P)$ ≈ 0.05-0.15 below which contact systems are absent, supporting a new set of theoretical predictions obtained by modeling the evolution of contact systems under the constraints of mass and angular momentum conservation. Premerger systems should lie at long periods and near this mass ratio lower limit, which rises from q = 0.044 for P = 0.74 days to q = 0.15 at P = 2.0 days. These findings support a scenario whereby nuclear evolution of the primary (more massive) star drives mass transfer to the primary, thus moving systems toward extreme q and larger P until the onset of the Darwin instability at ${q}_{\min }$ precipitates a merger.

Keywords: contact binary stars; close binary stars; markov chain monte carlo; stellar evolution; multiple star evolution
SKYSURF-3: Testing Crowded Object Catalogs in the Hubble eXtreme Deep Field Mosaics to Study Sample Incompleteness from an Extragalactic Background Light Perspective

Extragalactic background light (EBL) studies have revealed a significant discrepancy between direct measurements-via instruments measuring "bare" sky from which Zodiacal and Galactic light models are subtracted-and measurements of the integrated galaxy light (IGL). This discrepancy could lie in either method, whether it be an incomplete Zodiacal model or missed faint galaxies in the IGL calculations. It has been proposed that the discrepancy is due to deep galaxy surveys, such as those with the Hubble Space Telescope, missing up to half of the faint galaxies with 24 ≲ m AB ≲ 29 mag. We address this possibility by simulating higher number densities of galaxies, and so assess incompleteness due to object overlap, with three replications of the Hubble UltraDeep Field (HUDF). SourceExtractor is used to compare the recovered counts and photometry to the original HUDF, allowing us to assess how many galaxies may have been missed due to confusion, i.e., due to blending with neighboring faint galaxies. This exercise reveals that, while up to 50% of faint galaxies with 28 ≲ m AB ≲ 29 mag were missed or blended with neighboring objects in certain filters, not enough were missed to account for the EBL discrepancy alone in any of the replications.

Keywords: galaxy counts; extragalactic astronomy; zodiacal cloud; hubble space telescope