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We use Atacama Large Millimeter Array (ALMA) measurements of 870μm thermal emission from a sample of midsized (15–40 km diameter) Jupiter Trojan asteroids to search for high-albedo objects in this population. We calculate the diameters and albedos of each object using a thermal model which also incorporates contemporaneous Zwicky Transient Facility photometry to accurately measure the absolute magnitude at the time of the ALMA observation. We find that while many albedos are lower than reported from WISE, several small Trojans have high albedos independently measured both from ALMA and from WISE. The number of these high-albedo objects is approximately consistent with expectations of the number of objects that recently have undergone large-scale impacts, suggesting that the interiors of freshly-crated Jupiter Trojans could contain high-albedo materials such as ices.

 

We present spatially resolved (0.″1–1.″0) radio maps of Neptune taken from the Very Large Array and Atacama Large Millimeter/submillimeter Array between 2015 and 2017. Combined, these observations probe from just below the main methane cloud deck at ∼1 bar down to the NH₄SH cloud at ∼50 bar. Prominent latitudinal variations in the brightness temperature are seen across the disk. Depending on wavelength, the south polar region is 5–40 K brighter than the mid-latitudes and northern equatorial region. We use radiative transfer modeling coupled to Markov Chain Monte Carlo methods to retrieve H₂S, NH₃, and CH₄abundance profiles across the disk, though only strong constraints can be made for H₂S. Below all cloud formation, the data are well fit by${53.8}_{-13.4}^{+18.9}\times$and${3.9}_{-3.1}^{+2.1}\times$protosolar enrichment in the H₂S and NH₃abundances, respectively, assuming a dry adiabat. Models in which the radio-cold mid-latitudes and northern equatorial region are supersaturated in H₂S are statistically favored over models following strict thermochemical equilibrium. H₂S is more abundant at the equatorial region than at the poles, indicative of strong, persistent global circulation. Our results imply that Neptune's sulfur-to-nitrogen ratio exceeds unity, as H₂S is more abundant than NH₃in every retrieval. The absence of NH₃above 50 bar can be explained either by partial dissolution of NH₃in an ionic ocean at GPa pressures or by a planet formation scenario in which hydrated clathrates preferentially delivered sulfur rather than nitrogen onto planetesimals, or a combination of these hypotheses.

 

Abstract We present the localization and host galaxies of one repeating and two apparently nonrepeating fast radio bursts (FRBs). FRB 20180301A was detected and localized with the Karl G. Jansky Very Large Array to a star-forming galaxy at z = 0.3304. FRB20191228A and FRB20200906A were detected and localized by the Australian Square Kilometre Array Pathfinder to host galaxies at z = 0.2430 and z = 0.3688, respectively. We combine these with 13 other well-localized FRBs in the literature, and analyze the host galaxy properties. We find no significant differences in the host properties of repeating and apparently nonrepeating FRBs. FRB hosts are moderately star forming, with masses slightly offset from the star-forming main sequence. Star formation and low-ionization nuclear emission-line region emission are major sources of ionization in FRB host galaxies, with the former dominant in repeating FRB hosts. FRB hosts do not track stellar mass and star formation as seen in field galaxies (more than 95% confidence). FRBs are rare in massive red galaxies, suggesting that progenitor formation channels are not solely dominated by delayed channels which lag star formation by gigayears. The global properties of FRB hosts are indistinguishable from core-collapse supernovae and short gamma-ray bursts hosts, and the spatial offset (from galaxy centers) of FRBs is mostly inconsistent with that of the Galactic neutron star population (95% confidence). The spatial offsets of FRBs (normalized to the galaxy effective radius) also differ from those of globular clusters in late- and early-type galaxies with 95% confidence.