Sazuna/UAT_keywords huggingface dataset:
What Does It Mean to be a "Depleted" Comet? High Spectral Resolution Observations of the Prototypical Depleted Comet 21P/Giacobini-Zinner from the McDonald Observatory. We present high spectral resolution optical observations of comet 21P/Giacobini-Zinner from six nights in 2018. The observations were obtained with the Tull Coudé Spectrograph on the 2.7 m Harlan J. Smith Telescope of the McDonald Observatory. This comet's spectrum shows strong depletions in C2, C3, CH, and NH2 relative to CN. We explore what it means for a comet to be depleted and show that all of the species are present in the spectrum at similar relative line intensities within a a molecular band compared with a typical comet. The depletions represent a much lower abundance of the species studied.

Keywords: Short period comets
Comet 41P/Tuttle-Giacobini-Kresak, 45P/Honda-Mrkos-Pajdusakova, and 46P/Wirtanen: Water Production Activity over 21 yr with SOHO/SWAN. In 2017, 2018, and 2019, comets 46P/Wirtanen, 45P/Honda-Mrkos-Pajdusakova, and 41P/Tuttle-Giacobini-Kresak all had perihelion passages. Their hydrogen comae were observed by the Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyα camera on the SOlar and Heliospheric Observer (SOHO) satellite: comet 46P for the fourth time and comets 45P and 41P for the third time each since 1997. Comet 46P/Wirtanen is one of a small class of so-called hyperactive comets whose gas production rates belie their small size. This comet was the original target comet of the Rosetta mission. The SWAN all-sky hydrogen Lyα camera on the SOHO satellite observed the hydrogen coma of comet 46P/Wirtanen during the apparitions of 1997, 2002, 2008, and 2018. Over the 22 yr, the activity decreased and its variation with heliocentric distance has changed markedly in a way very similar to that of another hyperactive comet, 103P/Hartley 2. Comet 45P/Honda-Mrkos-Pajdusakova was observed by SWAN during its perihelion apparitions of 2001, 2011, and 2017. Over this time period, the activity level has remained remarkably similar, with no long-term fading or abrupt decreases. Comet 41P/Tuttle-Giacobini-Kresak was observed by SWAN in its perihelion apparitions of 2001, 2006, and 2017 and has decreased in activity markedly over the same time period. In 1973 it was known for large outbursts, which continued during the 2001 (two outbursts) and 2006 (one outburst) apparitions. However, over the 2001 to 2017 time period covered by the SOHO/SWAN observations the water production rates have greatly decreased by factors of 10-30 over corresponding times during its orbit.

Keywords: Comets, Short period comets, Comae
Convex Shape and Rotation Model of Lucy Target (11351) Leucus from Lightcurves and Occultations. We report new photometric lightcurve observations of the Lucy Mission target (11351) Leucus acquired during the 2017, 2018, and 2019 apparitions. We use these data in combination with stellar occultations captured during five epochs to determine the sidereal rotation period, the spin axis orientation, a convex shape model, the absolute scale of the object, its geometric albedo, and a model of the photometric properties of the target. We find that Leucus is a prograde rotator with a spin axis located within a sky-projected radius of 3° (1σ) from J2000 Ecliptic coordinates (λ = 208°, β = +77°) or J2000 Equatorial Coordinates (R.A. = 248°, decl. = +58°). The sidereal period is refined to Psid = 445.683 ± 0.007 h. The convex shape model is irregular, with maximum dimensions of 60.8, 39.1, and 27.8 km. The convex model accounts for global features of the occultation silhouettes, although minor deviations suggest that local and global concavities are present. We determine a geometric albedo of pV = 0.043 ± 0.002. The derived phase curve supports a D-type classification for Leucus.

Keywords: Light curves, Stellar occultation, Jupiter trojans, CCD photometry
Spectral Modeling Using Radiative Transfer Theory with Packing Density Correction: Demonstration for Saturnian Icy Satellites. We demonstrate the capabilities of the radiative transfer theory with packed media correction (RTT-PM) in analyzing spectral data of planetary surfaces by modeling to first order the shape and band depths of spectra of icy satellites of Saturn acquired by Cassini Visual and Infrared Mapping Spectrometer (VIMS). The RTT-PM is an efficient and physically strict numerical method that employs a packing density correction, the static structure factor, to single-scattering properties of particles to simulate the light scattering by densely packed media. Originally created for layers formed by spherical homogeneous particles, the RTT-PM method has been recently updated to treat particles of arbitrary shapes and structures, including aggregates. We apply the RTT-PM method to roughly model Cassini VIMS spectra from Dione, Rhea, and Tethys as layers of spherical particles versus aggregates. The shape and structure of particles strongly affect the modeled spectra; the best model comparisons to the VIMS spectra were obtained when the surface icy particles were assumed to be small aggregates consisting of micron-sized monomers, which may imply rather compact, irregular particles. Our results suggest that presenting the icy regolith as a dense layer of nonspherical particles may noticeably affect the modeling results and bring a better understanding of the satellite surface structure and composition. The RTT-PM demonstrated itself to be a powerful tool for such studies: we computed a reflectance for 22 wavelengths within minutes using a regular desktop computer. The combination of such high efficiency and physical strictness makes the RTT-PM method advantageous for analyzing large spaceborne instrument data sets.

Keywords: Radiative transfer simulations, Saturnian satellites, Spectroscopy
Observational Completion Limit of Minor Planets from the Asteroid Belt to Jupiter Trojans. With the growing numbers of asteroids being discovered, identifying an observationally complete sample is essential for statistical analyses and for informing theoretical models of the dynamical evolution of the solar system. We present an easily implemented method of estimating the empirical observational completeness in absolute magnitude, ${H}_{\mathrm{lim}}$, as a function of semimajor axis. Our method requires fewer assumptions and decisions to be made in its application, making results more transportable and reproducible among studies that implement it, as well as scalable to much larger data sets of asteroids expected in the next decade with the Vera C. Rubin Observatory's Legacy Survey of Space and Time. Using the values of ${H}_{\mathrm{lim}}$ (a) determined at high resolution in semimajor axis, a, we demonstrate that the observationally complete sample size of the main belt asteroids is larger by more than a factor of 2 compared with using a conservative single value of ${H}_{\mathrm{lim}}$, an approach often adopted in previous studies. Additionally, by fitting a simple, physically motivated model of ${H}_{\mathrm{lim}}$ (a) to ∼7 × 105 objects in the Minor Planet Database, our model reveals statistically significant deviations between the main belt and the asteroid populations beyond the main belt (Hungarias, Hildas, and Trojans), suggesting potential demographic differences, such as in their size, eccentricity, or inclination distributions.

Keywords: Small Solar System bodies, Asteroids, Solar system, Astronomy data analysis, Main belt asteroids, Asteroid belt, Astronomical methods
Experimental Investigation of the Acetylene-Benzene Cocrystal on Titan. Acetylene and benzene are two common molecules formed in Titan's atmosphere, and are likely components of the lake evaporites. It is known that these two molecules can form a cocrystal, a molecule with a structure that is unique from that of the component molecules. Thus, we sought to study this cocrystal using an experimental setup that simulates Titan surface conditions (90 K, 1.5 bar). Using Fourier transform infrared (FTIR) spectroscopy, we characterize new spectral absorptions, band shifts, and morphological sample changes associated with this cocrystal from 1 to 2.6 μm, which overlaps with Cassini VIMS wavelength range (0.35-5.1 μm). This is the first study of the resulting acetylene-benzene cocrystal under Titan-relevant temperature and pressure. The cocrystal forms at 135 K and is stable down to 90 K. Our findings can be applied to the cocondensation process in Titan's atmosphere, as well as the ongoing effort to better characterize the composition and spectral properties of Titan's lake evaporites. These results can also provide a stepping stone to future surface missions such as Dragonfly, which will closely examine relevant surface materials on Titan.

Keywords: Surface ices, Molecular spectroscopy, Experimental techniques
Outbursting Quasi-Hilda Asteroid P/2010 H2 (Vales). Quasi-Hilda asteroid P/2010 H2 (Vales) underwent a spectacular photometric outburst by ≥7.5 mag (factor of ≥103) in 2010. Here, we present our optical observations of this event in the four month period from April 20 to August 10. The outburst, starting UT 2010 April 15.70, released dust particles of total cross-section 17,600 km2 (albedo 0.1 assumed) and mass ∼1.2 × 109 kg, this being about 10-4 of the mass of the nucleus, taken as a sphere of radius 1.5 km and density 500 kg m-3. While the rising phase of the outburst was very steep (brightness doubling time of hours), subsequent fading occurred slowly (fading timescales increasing from weeks to months), as large, low velocity particles drifted away from the nucleus. A simple model of the fading lightcurve indicates that the ejected particles occupied a broad range of sizes, from ∼1 μm to 6 cm, and followed a differential power-law distribution with index 3.6 ± 0.1 (similar to that in other comets). The fastest particles had speeds ≥210 m s-1, indicating gas-drag acceleration of small grains well coupled to the flow. Low-energy processes known to drive mass loss in active asteroids, including rotational disruption; thermal and desiccation stress cracking; and electrostatic repulsion, cannot generate the high particles speeds measured in P/Vales, and are discounted. Impact origin is unlikely given the short dynamical lifetimes of the quasi-Hildas and the low collision probabilities of these objects. The specific energy of the ejecta is estimated at 220 J kg-1. The outburst follows a series of encounters with Jupiter in the previous century, consistent with the delayed activation of buried supervolatiles (and/or the crystallization of subsurface amorphous ice) by conducted heat following an inward displacement of the perihelion. A potential origin in the debris cloud produced by avalanche is also considered.

Keywords: Asteroids, Small Solar System bodies, Short period comets, Hilda group, Comets
Recovery and Validation of Venus Ionospheric Electron Density Profiles from Pioneer Venus Orbiter Radio Occultation Observations. The Pioneer Venus Orbiter radio occultation experiment acquired vertical profiles of electron density in the ionosphere of Venus. These profiles were not readily accessible to researchers. Here we report the recovery and validation of a set of electron density profiles from Pioneer Venus Orbiter. More than 200 profiles spanning solar zenith angles of 30°-170° were deemed acceptable for scientific analysis. These profiles sample solar minimum, moderate, and maximum conditions. The profiles are publicly available and ready for use in scientific investigations of the ionosphere of Venus and related topics.

Keywords: Venus
Recovery and Validation of Venus Neutral Atmospheric Profiles from Pioneer Venus Orbiter Radio Occultation Observations. The Pioneer Venus Orbiter radio occultation experiment acquired vertical profiles of neutral atmospheric temperature in the ionosphere of Venus. These profiles were not readily accessible to researchers. Here we report the recovery and validation of a set of neutral atmospheric temperature profiles from Pioneer Venus Orbiter. More than 40 profiles spanning many latitudes and local solar times were deemed acceptable for scientific analysis. These temperature profiles are consistent with temperature profiles measured by the four Pioneer Venus entry probes. The profiles are publicly available and ready for use in scientific investigations of the neutral atmosphere of Venus and related topics.

Keywords: Venus
On the Occurrence of Clathrate Hydrates in Extreme Conditions: Dissociation Pressures and Occupancies at Cryogenic Temperatures with Application to Planetary Systems. We investigate the thermodynamic stability of clathrate hydrates at cryogenic temperatures from the 0 K limit to 200 K in a wide range of pressures, covering the thermodynamic conditions of interstellar space and the surface of the hydrosphere in satellites. Our evaluation of the phase behaviors is performed by setting up quantum partition functions with variable pressures on the basis of a rigorous statistical mechanics theory that requires only the intermolecular interactions as input. Noble gases, hydrocarbons, nitrogen, and oxygen are chosen as the guest species, which are key components of the volatiles in such satellites. We explore the hydrate/water two-phase boundary of those clathrate hydrates in water-rich conditions and the hydrate/guest two-phase boundary in guest-rich conditions, either of which occurs on the surface or subsurface of icy satellites. The obtained phase diagrams indicate that clathrate hydrates can be in equilibrium with either water or the guest species over a wide range far distant from the three-phase coexistence condition and that the stable pressure zone of each clathrate hydrate expands significantly on intense cooling. The implication of our findings for the stable form of water in Titan is that water on the surface exists only as clathrate hydrate with the atmosphere down to a shallow region of the crust, but clathrate hydrate in the remaining part of the crust can coexist with water ice. This is in sharp contrast to the surfaces of Europa and Ganymede, where the thin oxygen air coexists exclusively with pure ice.

Keywords: Solid matter physics
Exploring Trans-Neptunian Space with TESS: A Targeted Shift-stacking Search for Planet Nine and Distant TNOs in the Galactic Plane. We present results from a new pipeline custom-designed to search for faint, undiscovered solar system bodies using full-frame image data from the NASA Transiting Exoplanet Survey Satellite (TESS) mission. This pipeline removes the baseline flux of each pixel before aligning and coadding frames along plausible orbital paths of interest. We first demonstrate the performance of the pipeline by recovering the signals of three trans-Neptunian objects—90377 Sedna (V = 20.64), 2015 BP519 (V = 21.81), and 2007 TG422 (V = 22.32)—both through shift-stacking along their known sky-projected paths and through a blind recovery. We then apply this blind-search procedure in a proof-of-concept survey of TESS Sectors 18 and 19, which extend through a portion of the Galactic plane in the Northern Hemisphere. We search for dim objects at geocentric distances d = 70-800 au in a targeted search for Planet Nine and any previously unknown detached Kuiper Belt objects that may shed light on the Planet Nine hypothesis. With no input orbital information, our present pipeline can reliably recover the signals of distant solar system bodies in the Galactic plane with V &lt; 21 and current distances d ≲ 150 au, and we elaborate on paths forward to push these limits in future optimizations. The methods described in this paper will serve as a foundation for an all-sky shift-stacking survey of the distant solar system with TESS.

Keywords: Planetary theory, Trans-Neptunian objects, Sky surveys, Small Solar System bodies, Solar system planets, Surveys, Solar system, Natural satellites (Solar system), Planetary science, Detached objects, Solar system astronomy
Volatile-rich Asteroids in the Inner Solar System. Bennu (101195), target of the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) mission, is a type-B asteroid with abundant spectral evidence for hydrated silicates, low thermal inertia "boulders" and frequent bursts of particle emission. We suggest that Bennu's parent body formed in the outer solar system before it was perturbed into the asteroid belt and then evolved into a near-Earth object. We show that this is consistent with models of planetesimal evolution. Bennu has many characteristics expected for a dormant comet, and could potentially contain a minimum of 1 wt.% adsorbed water if its gross mineralogy is consistent with the Orgueil meteorite. This is in addition to any ice or water contained within the hydrous minerals themselves. Based on this hypothesis, we predict the properties of the samples that will be returned to Earth by the OSIRIS-REx mission, including abundant phyllosilicate minerals, amorphous hydrated silicates and low-density, very high-porosity aggregates, already observed by the OSIRIS-REx instrument suite. We predict enrichments in D/H and 15N/14N, high C/Mg ratios (&gt;∼7 wt%), and a greater range of organic compositions than found in meteorites, including an organic component poor in aromatics, and a more labile organic fraction. Ammonium salts, ranging from NH4Cl to ammonium-organic acid salts could carry much of the nitrogen in comets, yet only NH4CH3COO and heavier salts are sufficiently stable to be found in these returned samples. Water adsorbed onto highly porous grains should also be detected provided that the sample return capsule remains below 300 K during Earth return, and this water should be isotopically heavy.

Keywords: Meteorites, Near-Earth objects, Main-belt comets
Intensity Distribution in the Heads of Comets. In optical wavelengths, the light emitted by comets consists of sunlight, reflected by dust, and the emission features of atoms and molecules. In his paper from 1957, L. Haser develops the mathematical framework to describe the density distribution of cometary comas. When comet scientists refer to the Haser model, they mostly point to the density distribution of parent and fragment molecules in the coma. However, in his paper, Haser (1957) presented the analytic solution over the line of sight (column density) and considers two particular observation configurations of a nonhomogeneous coma. This translation of the paper, originally in French, stays as close to the source as possible, including using the original figures. Minor typesetting corrections were introduced and are annotated in the text. The Haser model is foundational in cometary atmosphere science, but Haser's paper was not widely read due to language barriers and a lack of digital availability. This translation is presented in an effort to make Haser's work accessible to the wider community. We would like to thank Drs Emmanuel Jehin (Univ. Liège) and Kumar Venkataramani (Auburn Univ.) for critically reading this translation.

Keywords: Comets, Comet volatiles , History of astronomy
Seeing the Bigger Picture: Rosetta Mission Amateur Observing Campaign and Lessons for the Future. Amateur astronomers can make useful contributions to the study of comets. They add temporal coverage and multiscale observations that can aid the study of fast-changing and large-scale comet features. We document and review the amateur observing campaign set up to complement the Rosetta space mission, including the data submitted to date, and consider the campaign's effectiveness in the light of experience from previous amateur comet campaigns. We report the results of surveys of campaign participants, the amateur astronomy community, and schools who participated in a comet 46P observing campaign. We draw lessons for future campaigns, which include the need for clarity of objectives; recognizing the wider impact campaigns can have on increasing science capital; clear, consistent, timely, and tailored guidance; easy upload procedures with built-in quality control; and regular communication, feedback, and recognition.

Keywords: Amateur astronomy, Short period comets, Amateur astronomers, Remote telescope astrophotography, Astrophotography, Comets
Spatial Variations in the Altitude of the CH<SUB>4</SUB> Homopause at Jupiter's Mid-to-high Latitudes, as Constrained from IRTF-TEXES Spectra. We present an analysis of IRTF-TEXES spectra of Jupiter's mid-to-high latitudes in order to test the hypothesis that the CH4 homopause altitude is higher in Jupiter's auroral regions compared to elsewhere on the planet. A family of photochemical models, based on Moses &amp; Poppe (2017), were computed with a range of CH4 homopause altitudes. Adopting each model in turn, the observed TEXES spectra of H2 S(1), CH4, and CH3 emission measured on 2019 April 16 and August 20 were inverted, the vertical temperature profile was allowed to vary, and the quality of the fit to the spectra was used to discriminate between models. At latitudes equatorward of Jupiter's main auroral ovals (&gt;62°S, &lt;54°N, planetocentric), the observations were adequately fit assuming a homopause altitude lower than ∼360 km (above 1 bar). At 62°N, inside the main auroral oval, we derived a CH4 homopause altitude of ${461}_{-39}^{+147}$ km, whereas outside the main oval at the same latitude, a 1σ upper limit of 370 km was derived. Our interpretation is that a portion of energy from the magnetosphere is deposited as heat within the main oval, which drives vertical winds and/or higher rates of turbulence and transports CH4 and its photochemical by-products to higher altitudes. Inside the northern main auroral oval, a factor of ∼3 increase in CH3 abundance was also required to fit the spectra. This could be due to uncertainties in the photochemical modeling or an additional source of CH3 production in Jupiter's auroral regions.

Keywords: High resolution spectroscopy, Planetary polar regions, Atmospheric circulation, Planetary atmospheres, Aeronomy, Jupiter, Infrared astronomy, Planetary magnetospheres
Risks for Life on Proxima b from Sterilizing Impacts. We consider the implications that a debris belt located between Proxima b and Proxima c would pose for the rate of large asteroid impacts that could sterilize life from Proxima b. Future observations by the Atacama Large Millimeter/submillimeter Array or the James Webb Space Telescope could constrain the existence of an asteroid belt in the life-threatening regime. We generalize our rate calculation of sterilizing impacts for habitable planets in systems with an asteroid belt and an outer planet.

Keywords: M dwarf stars, Impact phenomena, Asteroid belt, Debris disks, Habitable planets
What GW170729's Exceptional Mass and Spin Tells Us about Its Family Tree. Gravitational-wave observations give a unique insight into the formation and evolution of binary black holes. We use gravitational-wave measurements to address the question of whether GW170729's source, which is (probably) the most massive binary and the system with the highest effective inspiral spin, could contain a black hole which is a previous merger remnant. Using the inferred mass and spin of the system, and the empirically determined population of binary black holes, we compute the evidence for the binary being second-generation compared with first-generation. We find moderate evidence (a Bayes factor of ~6-7) that the mass and spin better match a second-generation merger, but folding in the expectation that only a small fraction of mergers are second-generation, we conclude that there is no strong evidence that GW170729 was the result of a second-generation merger. The results are sensitive to the assumed mass distribution, and future detections will provide more robust reconstructions of the binary black hole population.

Keywords: Gravitational wave astronomy, Gravitational wave sources, Astrophysical black holes