High pressure can drastically alter chemical bonding and produce exotic compounds that defy conventional wisdom. Especially significant are compounds pertaining to oxygen cycles inside Earth, which hold key to understanding major geological events that impact the environment essential to life on Earth. Here we report the discovery of pressure-stabilized divalent ozonide CaO3 crystal that exhibits intriguing bonding and oxidation states with profound geological implications. Our computational study identifies a crystalline phase of CaO3 by reaction of CaO and O-2 at high pressure and high temperature conditions; ensuing experiments synthesize this rare compound under compression in a diamond anvil cell with laser heating. High-pressure x-ray diffraction data show that CaO3 crystal forms at 35 GPa and persists down to 20 GPa on decompression. Analysis of charge states reveals a formal oxidation state of -2 for ozone anions in CaO3. These findings unravel the ozonide chemistry at high pressure and offer insights for elucidating prominent seismic anomalies and oxygen cycles in Earth's interior. We further predict multiple reactions producing CaO3 by geologically abundant mineral precursors at various depths in Earth's mantle.

Rationale: Stroke is a leading causes of human death worldwide. Ischemic damage induces the sterile neuroinflammation, which directly determines the recovery of patients. Lipids, a major component of the brain, significantly altered after stroke. Cholesterol sulfate, a naturally occurring analog of cholesterol, can directly regulate immune cell activation, indicating the possible involvement of cholesterol metabolites in neuroinflammation. Sulfotransferase family 2b member 1 (Sult2b1) is the key enzyme that catalyzes the synthesis of cholesterol sulfate. This study aimed to investigate the function of Sult2b1 and cholesterol sulfate in the neuroinflammation after ischemic stroke.

We present the four-year survey results of monthly submillimeter monitoring of eight nearby (<500 pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb-Scargle Periodogram technique to search for and characterize variability on 295 submillimeter peaks brighter than 0.14 Jy beam(-1), including 22 disk sources (Class II), 83 protostars (Class 0/I), and 190 starless sources. We uncover 18 secular variables, all of them protostars. No single-epoch burst or drop events and no inherently stochastic sources are observed. We classify the secular variables by their timescales into three groups: Periodic, Curved, and Linear. For the Curved and Periodic cases, the detectable fractional amplitude, with respect to mean peak brightness, is similar to 4% for sources brighter than similar to 0.5 Jy beam(-1). Limiting our sample to only these bright sources, the observed variable fraction is 37% (16 out of 43). Considering source evolution, we find a similar fraction of bright variables for both Class 0 and Class I. Using an empirically motivated conversion from submillimeter variability to variation in mass accretion rate, six sources (7% of our full sample) are predicted to have years-long accretion events during which the excess mass accreted reaches more than 40% above the total quiescently accreted mass: two previously known eruptive Class I sources, V1647 Ori and EC 53 (V371 Ser), and four Class 0 sources, HOPS 356, HOPS 373, HOPS 383, and West 40. Considering the full protostellar ensemble, the importance of episodic accretion on few years timescale is negligible-only a few percent of the assembled mass. However, given that this accretion is dominated by events on the order of the observing time window, it remains uncertain as to whether the importance of episodic events will continue to rise with decades-long monitoring.

We present 12 new transit light curves and 16 new out-of-transit radial-velocity measurements for the XO-3 system. By modeling our newly collected measurements together with archival photometric and Doppler velocimetric data, we confirmed the unusual configuration of the XO-3 system, which contains a massive planet (M-P = 11.92(-0.63)(+0.59) M-J) on a relatively eccentric (e = 0.2853(-0.0026)(+0.0027)) and short-period (3.19152 +/- 0.00145 day) orbit around a massive star (M-* = 1.219(-0.095)(+0.090) M-circle dot). Furthermore, we find no strong evidence for a temporal change of either V sin i(*) (and by extension, the stellar spin vector of XO-3), or the transit profile (and thus orbital angular momentum vector of XO-3b). We conclude that the discrepancy in previous Rossiter-McLaughlin measurements (70.0 degrees +/- 15.0 degrees; Hebrard et al. 2008; 37.3 degrees +/- 3.7 degrees; Winn et al. 2009; 37.3 degrees +/- 3.0 degrees; Hirano et al. 2011) may have stemmed from systematic noise sources.

We investigate the possibility that the dwarf galaxies Crater II and Hercules have previously been tidally stripped by the Milky Way. We present Magellan/IMACS spectra of candidate member stars in both objects. We identify 37 members of Crater II, 25 of which have velocity measurements in the literature, and we classify three stars within that subset as possible binaries. We find that including or removing these binary candidates does not change the derived velocity dispersion of Crater II. Excluding the binary candidates, we measure a velocity dispersion of sigma V-los = 2.7(-0.4)(+0.5) km s(-1), corresponding to M/L = 47(-13)(+17) M-circle dot/L-circle dot. We measure a mean metallicity of [Fe/H] = -1.95(-0.05)(+0.06),with a dispersion of sigma([Fe/H]) = 0.18(-0.08)(+0.06). Our velocity dispersion and metallicity measurements agree with previous measurements for Crater II, and confirm that the galaxy resides in a kinematically cold dark-matter halo. We also search for spectroscopic members stripped from Hercules in the possible extratidal stellar overdensities surrounding the dwarf. For both galaxies, we calculate proper motions using Gaia DR2 astrometry, and use their full 6D phase space information to evaluate the probability that their orbits approach sufficiently close to the Milky Way to experience tidal stripping. Given the available kinematic data, we find a probability of similar to 40% that Hercules has suffered tidal stripping. The proper motion of Crater II makes it almost certain to be stripped.

We present the first detailed elemental abundances in the ultra-faint Magellanic satellite galaxies Carina II (Car II) and Carina III (Car III). With high-resolution Magellan/MIKE spectroscopy, we determined the abundances of nine stars in Car II, including the first abundances of an RR Lyrae star in an ultra-faint dwarf galaxy (UFD), and two stars in Car III. The chemical abundances demonstrate that both systems are clearly galaxies and not globular clusters. The stars in these galaxies mostly display abundance trends matching those of other similarly faint dwarf galaxies: enhanced but declining [alpha/Fe] ratios, iron-peak elements matching the stellar halo, and unusually low neutron-capture element abundances. One star displays a low outlying [Sc/Fe] = -1.0. We detect a large Ba scatter in Car II, likely due to inhomogeneous enrichment by low-mass asymptotic giant branch star winds. The most striking abundance trend is for [Mg/Ca] in Car II, which decreases from +0.4 to -0.4 and indicates clear variation in the initial progenitor masses of enriching core-collapse supernovae. So far, the only UFDs displaying a similar [Mg/Ca] trend are likely satellites of the Large Magellanic Cloud. We find two stars with [Fe/H] <= -3.5 whose abundances likely trace the first generation of metal-free Population III stars and are well fit by Population III core-collapse supernova yields. An appendix describes our new abundance uncertainty analysis that propagates line-by-line stellar parameter uncertainties.

In this detailed geochemical, petrological, and microstructural study of felsite clast materials contained in Apollo breccia samples 12013, 14321, and 15405, little evidence was found for relatively enriched reservoirs of endogenic lunar volatiles. NanoSIMS measurements have revealed very low volatile abundances (<= 2-18 ppm hydrogen) in nominally anhydrous minerals (NAMS) plagioclase, potassic alkali feldspar, and SiO2 that make up a majority of these felsic lithologies. Yet these mineral assemblages and clast geochemistries on Earth would normally yield relatively high volatiles contents in their NAMS (similar to 20 to >= 80 ppm hydrogen). This difference is particularly notable in felsite 14321,1062 that exhibits extremely low volatile abundances (<= 2 ppm hydrogen) and a relatively low amount of microstructural evidence for shock metamorphism given that it is a clast of the most evolved (similar to 74 wt.% SiO2) rock-type returned from the Moon. If taken at face value, 'wet' felsic magmas (similar to 1 .2-1.7 wt.% water) are implied by the relatively high hydrogen contents of feldspar in felsite clasts in Apollo samples 12013 and 15405, but these results are likely misleading. These felsic clasts have microstructural features indicative of significantly higher shock stress than 14321,1062. These crustal lithologies likely obtained no more water from the lunar interior than the magma body producing 14321,1062. Rather, we suggest hydrogen was enriched in samples 12013 and 15405 by impact induced exchange, and/or partial assimilation of volatiles added to the surface of the Moon by a hydrated impactor (asteroid or comet) or the solar wind. Thus, the best estimate for magmatic water contents of felsic lunar magmas comes from 14321,1062 that leads to a calculated magmatic water content of <= 0.2 wt.%. This dry felsic magma has a slightly greater, but comparable water content to the ancient mafic magmas implied by the other lithologies that we have studied. Based on this and expanding evidence for a significantly dry ancient or early degassed Moon it is likely that some recent estimates (100's ppm) of the water abundances in the lunar parental magma ocean have been overestimated. Published by Elsevier Ltd.

We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus.II, Tucana.IV, and Tucana.V. We measure systemic velocities of vhel = -110.0. 0.5 km s-1, = v 15.9+ hel 1.71.8 km s-1, and = - v 36.2+ hel 2.22.5 km s-1 for the three objects, respectively. Their large relative velocities demonstrate that the satellites are unrelated despite their close physical proximity. We determine a velocity dispersion for Tuc.IV of s = 4.3+ 1.01.7 km s-1, but we cannot resolve the velocity dispersions of the other two systems. For Gru.II, we place an upper limit (90%.confidence) on the dispersion of s.<.1.9 km s-1, and for Tuc.V, we do not obtain any useful limits. All three satellites have metallicities below[Fe H] = -2.1, but none has a detectable metallicity spread. We determine proper motions for each satellite based on Gaia astrometry and compute their orbits around the Milky Way. Gru.II is on a tightly bound orbit with a pericenter of 25+ 76 kpc and orbital eccentricity of 0.45+ 0.050.08. Tuc.V likely has an apocenter beyond 100.kpc and could be approaching the Milky Way for the first time. The current orbit of Tuc.IV is similar to that of Gru.II, with a pericenter of 25+ 811 kpc and an eccentricity of 0.36+ 0.060.13. However, a backward integration of the position of Tuc.IV demonstrates that it collided with the Large Magellanic Cloud at an impact parameter of 4. kpc 120.Myr ago, deflecting its trajectory and possibly altering its internal kinematics. Based on their sizes, masses, and metallicities, we classify Gru.II and Tuc.IV as likely dwarf galaxies, but the nature of Tuc.V remains uncertain.

We present a Bayesian method to identify multiple (chemodynamic) stellar populations in dwarf spheroidal galaxies (dSphs) using velocity, metallicity, and positional stellar data without the assumption of spherical symmetry. We apply this method to a new Keck/Deep Imaging Multi-Object Spectrograph (DEIMOS) spectroscopic survey of the Ursa Minor (UMi) dSph. We identify 892 likely members, making this the largest UMi sample with line-of-sight velocity and metallicity measurements. Our Bayesian method detects two distinct chemodynamic populations with high significance (in logarithmic Bayes factor, ln B similar to 33). The metal-rich ([Fe/H] = -2.05 +/- 0.03) population is kinematically colder (radial velocity dispersion of sigma(v) =4.9(-1.0)(+0.8)km s(-1)) and more centrally concentrated than the metal-poor ([Fe/H]=-2.29(-0.06)(+0.05)) and kinematically hotter population (sigma(v)=11.5(-0.8)(+0.9)km s(-1)). Furthermore, we apply the same analysis to an independent Multiple Mirror Telescope (MMT)/Hectochelle data set and confirm the existence of two chemodynamic populations in UMi. In both data sets, the metal-rich population is significantly flattened (epsilon = 0.75 +/- 0.03) and the metal-poor population is closer to spherical (epsilon=0.33(-0.09)(+0.12)). Despite the presence of two populations, we are able to robustly estimate the slope of the dynamical mass profile. We found hints for prolate rotation of order similar to 2 km s(-1) in the MMT data set, but further observations are required to verify this. The flattened metal-rich population invalidates assumptions built into simple dynamical mass estimators, so we computed new astrophysical dark matter annihilation (J) and decay profiles based on the rounder, hotter metal-poor population and inferred log(10)(J(0 degrees.5)/GeV(2)cm(-5))approximate to 19.1 for the Keck data set. Our results paint a more complex picture of the evolution of UMi than previously discussed.

This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).