Sazuna/UAT_keywords huggingface dataset:
Development of the MICADO Flat-field and Wavelength Calibration Unit: From Design to Prototyping. We describe the evolution and the analysis of the design that led to the development of the Flat-field and wavelength Calibration Unit (FCU) for the Multi-AO Imaging CAmera for Deep Observations (MICADO) instrument. MICADO will be one of the first light instruments of the Extremely Large Telescope. The FCU challenge in terms of calibration is related to the large size of the MICADO entrance and final focal plane, ∼200 mm × 200 mm. Such a focal plane scale and its segmentation in 3 × 3 detectors, require significant design modifications with respect to the calibration units of the current and past generation of instruments. The design analysis and ray tracing calculations are complemented with the test and verification of lab prototypes to assess the reliability of the FCU architecture in terms of flat-field illumination uniformity and signal to noise, spectral calibration line coverage and radial velocity stability of the wavelength solution provided to the instrument.

Keywords: Fabry-Perot interferometers, Flux calibration
The MKID Exoplanet Camera for Subaru SCExAO. We present the MKID Exoplanet Camera (MEC), a z through J band (800-1400 nm) integral field spectrograph located behind The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) at the Subaru Telescope on Maunakea that utilizes Microwave Kinetic Inductance Detectors (MKIDs) as the enabling technology for high contrast imaging. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. The read noise free, fast time domain information attainable by MKIDs allows for the direct probing of fast speckle fluctuations that currently limit the performance of most high contrast imaging systems on the ground and will help MEC achieve its ultimate goal of reaching contrasts of 10-7 at 2 λ/D. Here we outline the instrument details of MEC including the hardware, firmware, and data reduction and analysis pipeline. We then discuss MEC's current on-sky performance and end with future upgrades and plans.

Keywords: Astronomical detectors, Direct imaging, Astronomical instrumentation
Stratification Dynamics of Titan's Lakes via Methane Evaporation. Saturn's moon Titan is the only extraterrestrial body known to host stable lakes and a hydrological cycle. Titan's lakes predominantly contain liquid methane, ethane, and nitrogen, with methane evaporation driving its hydrological cycle. Molecular interactions between these three species lead to nonideal behavior that causes Titan's lakes to behave differently than Earth's lakes. Here, we numerically investigate how methane evaporation and nonideal interactions affect the physical properties, structure, dynamics, and evolution of shallow lakes on Titan. We find that, under certain temperature regimes, methane-rich mixtures are denser than relatively ethane-rich mixtures. This allows methane evaporation to stratify Titan's lakes into ethane-rich upper layers and methane-rich lower layers, separated by a strong compositional gradient. At temperatures above 86 K, lakes remain well mixed and unstratified. Between 84 and 86 K, lakes can stratify episodically. Below 84 K, lakes permanently stratify and develop very methane-depleted epilimnia. Despite small seasonal and diurnal deviations (&lt;5 K) from typical surface temperatures, Titan's rain-filled ephemeral lakes and "phantom lakes" may nevertheless experience significantly larger temperature fluctuations, resulting in polymictic or even meromictic stratification, which may trigger ethane ice precipitation.

Keywords: Saturnian satellites
Possible Evidence of p-modes in Cassini Measurements of Saturn's Gravity Field. We analyze the range-rate residual data from Cassini's gravity experiment that cannot be explained with a static, zonally symmetric gravity field. We reproduce the data using a simple forward model of gravity perturbations from normal modes. To do this, we stack data from multiple flybys to improve sensitivity. We find a partially degenerate set of normal-mode energy spectra that successfully reproduce the unknown gravity signal from Cassini's flybys. Although there is no unique solution, we find that the models most likely to fit the data are dominated by gravitational contributions from p-modes between 500 and 700 μHz. Because f-modes at lower frequencies have stronger gravity signals for a given amplitude, this result would suggest strong frequency dependence in normal-mode excitation on Saturn. We predict peak amplitudes for p-modes on the order of several kilometers, at least an order of magnitude larger than the peak amplitudes inferred by Earth-based observations of Jupiter. The large p-mode amplitudes we predict on Saturn, if they are indeed present and steady state, would imply weak damping with a lower bound of Q &gt; 107 for these modes, consistent with theoretical predictions.

Keywords: Helioseismology, Gravitational fields, Planetary interior
Testing the Isotropy of the Dark Energy Survey's Extreme Trans-Neptunian Objects. We test whether the population of "extreme" trans-Neptunian objects (eTNOs) detected in the first four years of the Dark Energy Survey (DES Y4) data exhibit azimuthal asymmetries that might be evidence of gravitational perturbations from an unseen super-Earth in a distant orbit. By rotating the orbits of the detected eTNOs, we construct a synthetic population that, when subject to the DES selection function, reproduces the detected distribution of eTNOs in the orbital elements a, e, and i as well as absolute magnitude H, but has uniform distributions in mean anomaly ${ \mathcal M }$ , longitude of ascending node Ω, and argument of perihelion ω. We then compare the detected distributions in each of Ω, ω, and the longitude of perihelion $\varpi \equiv {\rm{\Omega }}+\omega $ to those expected from the isotropic population, using Kuiper's variant of the Kolmogorov-Smirnov test. The three angles are tested for each of four definitions of the eTNO population, choosing among a &gt; (150, 250) au and perihelion q &gt; (30, 37) au. These choices yield 3-7 eTNOs in the DES Y4 sample. Among the 12 total tests, two have the likelihood of drawing the observed angles from the isotropic population at p &lt; 0.03. The three detections at a &gt; 250 and q &gt; 37 au and the four detections at a &gt; 250 and q &gt; 30 au have a Ω distribution with p ≈ 0.03 coming from the isotropic construction, but this is not strong evidence of anisotropy given the 12 different tests. The DES data taken on their own are thus consistent with azimuthal isotropy and do not require a "Planet 9" hypothesis. The limited sky coverage and object count mean, however, that the DES data by no means falsify this hypothesis.

Keywords: Kuiper belt, Trans-Neptunian objects
High Spatial and Spectral Resolution Observations of the Forbidden 1.707 μm Rovibronic SO Emissions on Io: Evidence for Widespread Stealth Volcanism. We present observations obtained with the 10 m Keck telescopes of the forbidden SO a1Δ → X3Σ- rovibronic transition at 1.707 μm on Io while in eclipse. We show its spatial distribution at a resolution of ∼0"12 and a spectral resolution of R ∼ 2500, as well as disk-integrated spectra at a high spectral resolution (R ∼ 15,000). Both the spatial distribution and the spectral shape of the SO emission band vary considerably across Io and over time. In some cases the SO emissions either in the core or the wings of the emission band can be identified with volcanoes, but the largest areas of SO emissions usually do not coincide with known volcanoes. We suggest that the emissions are caused by a large number of stealth plumes, produced through the interaction of silicate melts with superheated SO2 vapor at depth. The spectra, in particular the elevated wing of the emission band near 1.69 μm, and their spatial distribution strongly suggest the presence of nonlocal thermodynamic equilibrium processes in addition to the direct ejection of excited SO from the (stealth and other) volcanic vents. * In memory of Donald Charles Backer.

Keywords: Galilean satellites, Planetary atmospheres, Near infrared astronomy
Saturn's Atmospheric Helium Abundance from Cassini Composite Infrared Spectrometer Data. We use thermal infrared data from the Composite Infrared Spectrometer, which was on board the Cassini orbiter, to retrieve the helium abundance in Saturn's visible atmosphere. We find that the data is most consistent with a helium-to-hydrogen mole ratio in the range between 0.04 and 0.075, near the lower end of previous measurements, and implying a significant sequestration of helium in Saturn's interior. The primary sources of uncertainty are in the spectroscopic parameters for H2-H2 collision induced absorption and the nonuniqueness of the spectral inverse problem.

Keywords: Atmospheric composition, Saturn
Spatio-temporal Variation of Bright Ephemeral Features on Titan's North Pole. We identify and document the instances of bright ephemeral features (BEF)—bright areas that appear, disappear, and shift from flyby to flyby on Titan's north pole, using the Cassini Visual and Infrared Mapping Spectrometer data set, thereby developing a sense of their spatial distribution and temporal frequency. We find that BEFs have differing geographic location and spatial extents. However, they have similar observation geometries and orders of surface area coverage and are mostly accompanied by specular reflections. We find the BEFs to represent either broad specular reflection off of a recently wetted surface on the north pole of Titan or a near-surface fog—both owing to probable recent rainfalls. Our surface model constrains the surface roughness to be of 9°-15° indicating the approximate vertical relief of the region to be that of cobbles. We also find that within less than two Titan days the BEF (if on the surface) might infiltrate into the subsurface. We hypothesize the parts of BEFs that extend into the maria to be precipitation fog.

Keywords: Saturnian satellites
Unsupervised Learning for Thermophysical Analysis on the Lunar Surface. We investigate the use of unsupervised machine learning to understand and extract valuable information from thermal measurements of the lunar surface. We train a variational autoencoder (VAE) to reconstruct observed variations in lunar surface temperature from over 9 yr of Diviner Lunar Radiometer Experiment data and in doing so learn a fully data-driven thermophysical model of the lunar surface. The VAE defines a probabilistic latent model that assumes the observed surface temperature variations can be described by a small set of independent latent variables and uses a deep convolutional neural network to infer these latent variables and to reconstruct surface temperature variations from them. We find it is able to disentangle five different thermophysical processes from the data, including (1) the solar thermal onset delay caused by slope aspect, (2) effective albedo, (3) surface thermal conductivity, (4) topography and cumulative illumination, and (5) extreme thermal anomalies. Compared to traditional physics-based modeling and inversion, our method is extremely efficient, requiring orders of magnitude less computational power to invert for underlying model parameters. Furthermore our method is physics-agnostic and could therefore be applied to other space exploration data sets, immediately after the data is collected and without needing to wait for physical models to be developed. We compare our approach to traditional physics-based thermophysical inversion and generate new, VAE-derived global thermal anomaly maps. Our method demonstrates the potential of artificial intelligence-driven techniques to complement existing physical models as well as for accelerating lunar and space exploration in general.

Keywords: Convolutional neural networks, The Moon, Lunar composition
138175 (2000 EE104) and the Source of Interplanetary Field Enhancements. We present the first optical observations taken to characterize the near-Earth object 138175 (2000 EE104). This body is associated with interplanetary field enhancements (IFEs), thought to be caused by interactions between the solar wind magnetic field and solid material trailing in the orbit of the parent body. Based on optical photometry, the radius (in meters) and mass (in kilograms) of an equal-area sphere are found to be ${r}_{n}=250{(0.1/{p}_{R})}^{1/2}$ and ${M}_{n}={10}^{11}{(0.1/{p}_{R})}^{3/2}$ , respectively, where pR is the red geometric albedo and a density of ρ = 1500 kg m-3 is assumed. The measured colors are intermediate between those of C-type (primitive) and S-type (metamorphosed) asteroids but, with correction for the likely effects of phase reddening, are more consistent with a C-type classification than with S-type. No evidence for co-moving companions larger than ∼40(0.1/pR) m in radius is found, and no dust particle trail is detected, setting a limit to the trail optical depth of τ ≤ 2 × 10-9. Consideration of the size distribution produced by impact pulverization makes it difficult to generate the mass of nanodust (minimum 105-106 kg) required to account for IFEs, unless the size distribution is unusually steep. Furthermore, impact pulverization timescales for source objects of the required size are much longer than the dynamical timescale. While the new optical data do not definitively refute the hypothesis that boulder pulverization is the source of IFEs, neither do they provide any support for it.

Keywords: Near-Earth objects, Interplanetary magnetic fields, Asteroids
Citlalmitl: A Laser-based Device for Meteoritical Sample Fabrication with Arbitrary Thermal Histories. We present Citlalmitl (the word for meteorite in the Nahuatl language), a new experimental device designed and built to simulate high-temperature processes relevant for meteoritics, including chondrule formation and the atmospheric entry of micrometeorites (MMs). The main component of Citlalmitl is a 50 W CO2 laser, used to melt samples that simulate the precursors of meteoritical materials. As examples of the operation of our device, we have irradiated silicate samples controlling the laser duty cycle to reproduce heating profiles predicted by shock-wave simulations. Citlalmitl records the sample temperature during and after irradiation, a unique feature that allows us to directly measure the thermal history of the sample, a key parameter for the characteristics observed in MMs and chondrules. We demonstrate that Citlalmitl can reproduce different heating profiles useful to mimic thermal histories in meteoritical processes.

Keywords: Meteorites, Micrometeorites, Chondrules, Astronomical instrumentation
Tidal Currents Detected in Kraken Mare Straits from Cassini VIMS Sun Glitter Observations. We present Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of sun glitter—wave-induced reflections from a liquid surface offset from a specular point—on Kraken Mare. sun glitter reveals rough sea surfaces around Kraken Mare, namely the coasts and narrow straits. The sun glitter observations indicate wave activity driven by the winds and tidal currents in Kraken Mare during northern summer. T104 Cassini VIMS observations show three sun glitter features in Bayta Fretum indicative of variegated wave fields. We cannot uniquely determine one source for the coastal Bayta waves, but we lean toward the interpretation of surface winds, because tidal currents should be too weak to generate capillary-gravity waves in Bayta Fretum. T105 and T110 observations reveal wave fields in the straits of Seldon Fretum, Lulworth Sinus, and Tunu Sinus that likely originate from the constriction of tidal currents. Coastlines of Bermoothes and Hufaidh Insulae adjoin rough sea surfaces, suggesting a complex interplay of wind-roughened seas and localized tidal currents. Bermoothes and Hufaidh Insulae may share characteristics of either the Torres Strait off Australia or the Åland region of Finland, summarized as an island-dense strait with shallow bathymetry that hosts complex surface circulation patterns. Hufaidh Insulae could host seafloor bedforms formed by tidal currents with an abundant sediment supply, similar to the Torres Strait. The coastlines of Hufaidh and Bermoothes Insulae likely host ria or flooded coastal inlets, suggesting that the Insulae may be local peaks of primordial crust isolated by an episode of sea-level rise or tectonic uplift.

Keywords: Ocean-atmosphere interactions, Saturnian satellites
A Volatile-poor Formation of LHS 3844b Based on Its Lack of Significant Atmosphere. Exoplanet discoveries have reached into the realm of terrestrial planets that are becoming the subject of atmospheric studies. One such discovery is LHS 3844b, a 1.3 Earth radius planet in a 0.46 day orbit around an M4.5-5 dwarf star. Follow-up observations indicate that the planet is largely devoid of substantial atmosphere. This lack of significant atmosphere places astrophysical and geophysical constraints on LHS 3844b, primarily the degree of volatile outgassing and the rate of atmosphere erosion. We estimate the age of the host star as 7.8 ± 1.6 Gyr and find evidence of an active past comparable to that of Proxima Centauri. We use geodynamical models of volcanic outgassing and atmospheric erosion to show that the apparent lack of atmosphere is consistent with a volatile-poor mantle for LHS 3844b. We show the core is unlikely to host enough C to produce a sufficiently volatile-poor mantle, unless the bulk planet is volatile-poor relative to Earth. While we cannot rule out a giant impact stripping LHS 3844b's atmosphere, we show that this mechanism would require significant mantle stripping, potentially leaving LHS 3844b as an Fe-rich "super-Mercury." Atmospheric erosion by smaller impacts is possible, but only if the planet has already begun degassing and is bombarded by 103 impactors of radius 500-1000 km traveling at escape velocity. We discuss formation and migration scenarios that could account for a volatile-poor origin, including the potential for an unobserved massive companion planet. A relatively volatile-poor composition of LHS 3844b suggests that the planet formed interior to the system snow line.

Keywords: Exoplanets, Exoplanet atmospheres, Stellar activity, Planetary interior, Planet formation
Distinguishing between Shock-darkening and Space-weathering Trends in Ordinary Chondrite Reflectance Spectra. space-weathering as well as shock effects can darken meteorite and asteroid reflectance spectra. We present a detailed comparative study on shock-darkening and space-weathering using different lithologies of the Chelyabinsk LL5 chondrite. Compared to space-weathering, the shock processes do not cause significant spectral slope changes and are more efficient in attenuating the orthopyroxene 2 μm absorption band. This results in a distinct shock vector in the reflectance spectra principal component analysis, moving the shocked silicate-rich Chelyabinsk spectra from the S-complex space into the C/X complex. In contrast to this, the space-weathering vector stays within the S complex, moving from Q type to S type. Moreover, the 2 μm to 1 μm band depth ratio (BDR) as well as the 2 μm to 1 μm band area ratio (BAR) are not appreciably affected by shock-darkening or shock melting. space-weathering, however, causes significant shifts in both BDR and BAR toward higher values. Application of the BDR method to the three distinct areas on the asteroid Itokawa reveals that Itokawa is rather uniformly space-weathered and not influenced by regolith roughness or relative albedo changes.

Keywords: Meteorites, Chondrites
Barycentric Corrections for Precise Radial Velocity Measurements of Sunlight. We provide formulae for the calculation of precise Doppler velocities of sunlight, in both the case of direct observations of the Sun and in reflection from the surfaces of solar system objects such as the Moon or asteroids. We discuss the meaning of a "barycentric correction" of measurements of these Doppler velocities, which is a different procedure from the analogous correction for starlight, and provide a formula for reducing such measurements to the component of the Sun's motion in the direction of Earth or other solar system object. We have implemented this procedure in the public barycorrpy Python package and use it to explore the properties of the barycentric-corrected Doppler velocity of sunlight over 30 yr. When measured directly, we show that it is dominated by nonperiodic motion due to Jupiter and that the signals of the other planets, including Venus, are not discernible in Fourier space. We show that "detecting" Venus in Doppler velocities of sunlight will require either observing sunlight in reflection from an asteroid or modeling their individual contributions to the motion of the Sun in counterfactual kinematic or dynamical simulations of the solar system with and without them.

Keywords: Radial velocity, Ephemerides
Oxidation of the Interiors of Carbide Exoplanets. Astrophysical measurements have shown that some stars have sufficiently high carbon-to-oxygen ratios such that the planets they host would be mainly composed of carbides instead of silicates. We studied the behavior of silicon carbide in the presence of water under the high pressure-temperature conditions relevant to planetary interiors in the laser-heated diamond-anvil cell. When reacting with water, silicon carbide converts to silica (stishovite) and diamond at pressures up to 50 GPa and temperatures up to 2500 K: $\mathrm{SiC}+2{{\rm{H}}}_{2}{\rm{O}}\to {\mathrm{SiO}}_{2}+{\rm{C}}+2{{\rm{H}}}_{2}$ . Therefore, if water can be incorporated into carbide planets during their formation or through later delivery, they could be oxidized and have mineralogy dominated by silicates and diamond in their interiors. The reaction could produce CH4 at shallower depths and H2 at greater depths that could be degassed from the interior, causing the atmospheres of the converted carbon planets to be rich in reducing gases. Excess water after the reaction can be stored in dense silica polymorphs in the interiors of the converted carbon planets. Such conversion of mineralogy to diamond and silicates would decrease the density of carbon-rich planet, making the converted planets distinct from silicate planets in mass-radius relations for the 2-8 Earth mass range.

Keywords: Exoplanet structure, Exoplanet evolution, Carbon planets, Exoplanet atmospheres
Craters on Charon: Impactors from a Collisional Cascade Among Trans-Neptunian Objects. We consider whether equilibrium size distributions from collisional cascades match the frequency of impactors derived from New Horizons crater counts on Charon. Using an analytic model and a suite of numerical simulations, we demonstrate that collisional cascades generate wavy size distributions; the morphology of the waves depends on the binding energy of solids ${Q}_{D}^{\star }$ and the collision velocity vc. For an adopted minimum size of solids, ${r}_{\min }$ = 1 μm, and collision velocity vc = 1-3 km s-1, the waves are rather insensitive to the gravitational component of ${Q}_{D}^{\star }$ . If the bulk strength component of ${Q}_{D}^{\star }$ is ${Q}_{s}{r}^{{e}_{s}}$ for particles with radius r, size distributions with small Qs are much wavier than those with large Qs; systems with es ≈ -0.4 have stronger waves than systems with es ≈ 0. Detailed comparisons with the New Horizons data suggest that a collisional cascade among solids with a bulk strength intermediate between weak ice and normal ice produces size distributions fairly similar to that of impactors on Charon. If the surface density Σ of the protosolar nebula varies with semimajor axis a as Σ ≈ 30 g cm-2 (a/1 au)-3/2, the timescale for a cascade to generate an approximate equilibrium is 100-300 Myr at 45 au and 10-30 Myr at 25 au. Although it is necessary to perform more complete evolutionary calculations of the Kuiper Belt, collisional cascades are a viable model for producing the size distribution of solids that impacted Charon throughout its history.

Keywords: Solar system formation, Solar system, Kuiper belt, Pluto