This is the second of two articles reviewing the burgeoning literature on recent ceramic analysis. The first (Journal of Archaeological Research, Vol. 4, No. 2, 1996) (pp. 133–163) surveyed functional and stylistic analyses and pottery origins. This article reviews compositional investigations and studies of pottery production, both of which have flourished in a period of heightened examination of specific techniques, assumptions, and concepts, such as standardization. In addition, researchers are exploring new analytical methods as well as approaches to “ceramic theory.” The review closes with a series of observations and critiques of current directions.

Recent ceramic analysis: 2. Composition, production, and theory

The use of a pottery vessel leaves markers on the ceramic wall that can inform archaeologists how the vessel functioned in the past. At present, archaeologists have little information for understanding how use-alteration reflects the complex nature of ceramic function and socioeconomic status. I conducted a 2-year ethnoarchaeological research project among the Gamo people of southwestern Ethiopia, who continue to produce and use pottery on a daily basis. This research indicates that interior surface attrition occurs primarily on pottery vessels used in wealthy households because of fermentation processes from high-status foods. Thus, the Gamo example suggests that there is a relationship between ceramic use-alteration and household socioeconomic status.

Pottery use-alteration as an indicator of socioeconomic status: An ethnoarchaeological study of the Gamo of Ethiopia.

The population of small, close-in exoplanets is bifurcated into super-Earths and sub-Neptunes. We calculate physically motivated mass–radius relations for sub-Neptunes, with rocky cores and H/He-dominated atmospheres, accounting for their thermal evolution, irradiation, and mass loss. For planets ≲10 M ⊕, we find that sub-Neptunes retain atmospheric mass fractions that scale with planet mass and show that the resulting mass–radius relations are degenerate with results for “water worlds” consisting of a 1:1 silicate-to-ice composition ratio. We further demonstrate that our derived mass–radius relation is in excellent agreement with the observed exoplanet population orbiting M dwarfs and that planet mass and radii alone are insufficient to determine the composition of some sub-Neptunes. Finally, we highlight that current exoplanet demographics show an increase in the ratio of super-Earths to sub-Neptunes with both stellar mass (and therefore luminosity) and age, which are both indicative of thermally driven atmospheric escape processes. Therefore, such processes should not be ignored when making compositional inferences in the mass–radius diagram.

Conclusive Evidence for a Population of Water Worlds around M Dwarfs Remains Elusive

We present a study of interstellar comet 2I/2019 Q4 (Borisov) using both preperihelion and postperihelion observations spanning late September 2019 through late January 2020. The intrinsic brightness of the comet was observed to continuously decline throughout the timespan, likely due to the decreasing effective scattering cross-section as a result of volatile sublimation with a slope of $-0.43 \\pm 0.02$ km$^{2}$ d$^{-1}$. We witnessed no significant change in the slightly reddish colour of the comet, with mean values of $\\left \\langle g - r \\right \\rangle = 0.68 \\pm 0.04$, $\\left \\langle r - i \\right \\rangle = 0.23 \\pm 0.03$, and the normalised reflectivity gradient across the $g$ and $i$ bands $\\overline{S'} \\left(g,i\\right) = \\left(10.6 \\pm 1.4\\right)$ % per $10^3$ A, all unremarkable in the context of solar system comets. Using the available astrometric observations, we confidently detect the nongravitational acceleration of the comet following a shallow heliocentric distance dependency of $r_{\\rm H}^{-1 \\pm 1}$. Accordingly, we estimate that the nucleus is most likely $\\lesssim$0.4 km in radius, and that a fraction of $\\gtrsim$0.2% of the total nucleus in mass has been eroded due to the sublimation activity since the earliest observation of the comet in 2018 December by the time of perihelion. Our morphology simulation suggests that the dust ejection speed increased from $\\sim$4 m s$^{-1}$ in September 2019 to $\\sim$7 m s$^{-1}$ around perihelion for the optically dominant dust grains of $\\beta \\sim 0.01$, and that the observable dust grains are no smaller than micron size.

Physical Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)

We present high spectral resolution optical spectra obtained with the ARCES instrument at Apache Point Observatory showing detection of the [O i] 6300 A line in interstellar comet 2I/Borisov. We employ the observed flux in this line to derive an H2O production rate of (6.3 ± 1.5) × 1026 mol s−1. Comparing to previously reported observations of CN, this implies a CN/H2O ratio of ~0.3%–0.6%. The lower end of this range is consistent with the average value in comets, while the upper end is higher than the average value for solar system comets, but still within the range of observed values. C2/H2O is depleted, with a value likely less than 0.1%. The dust-to-gas ratio is consistent with the normal value for solar system comets. Using a simple sublimation model we estimate an H2O active area of 1.7 km2, which for current estimates for the size of Borisov suggests active fractions between 1% and 150%, consistent with values measured in solar system comets. More detailed characterization of 2I/Borisov, including compositional information and properties of the nucleus, is needed to fully interpret the observed H2O production rate.

Detection of a Water Tracer in Interstellar Comet 2I/Borisov

The composition of comets in the Solar System come in multiple groups thought to encode information about their formation in different regions of the outer protosolar disk. The recent discovery of the second interstellar object, 2I/Borisov, allows for spectroscopic investigations into its gas content and a preliminary classification of it within the Solar System comet taxonomies to test the applicability of planetesimal formation models to other stellar systems. We present spectroscopic and imaging observations from 2019 September 20th to October 26th at the Bok, MMT, and LBT telescopes. We identify CN in the comet's spectrum and set precise upper limits on the abundance of C2 on all dates. We use a Haser model to convert our integrated fluxes to production rates and find Q(CN) = 5.0 +/- 2.0 * 10^24 mol/s on September 20th and Q(CN) = 1.1 - 1.9 * 10^24 mol/s on later dates, both consistent with contemporaneous observations. We set our lowest upper limit on a C2 production rate, Q(C2) < 1.6 * 10^23 mol/s, on October 10th. The measured ratio upper limit for that date, Q(C2)/Q(CN) < 0.095 indicates that 2I/Borisov is strongly in the (carbon chain) 'depleted' taxonomic group. The only comparable Solar System comets have detected ratios near this limit, making 2I/Borisov statistically likely to be more depleted than any known comet. Most 'depleted' comets are Jupiter Family Comets, perhaps indicating a similiarity in formation conditions between the most depleted of the JFCs and 2I/Borisov. More work is needed to understand the applicability of our knowledge of Solar System comet taxonomies onto interstellar objects, and we discuss future work that could help clarify the usefulness of the approach.

Carbon Chain Depletion of 2I/Borisov

An experimental study of the effects of salt erosion on pottery

Kepler’s short-period exoplanet population has revealed evolutionary features such as the Radius Valley and the Hot Neptune desert that are likely sculpted by atmospheric loss over time. These findings suggest that the primordial planet population is different from the Gyr-old Kepler population, and motivates exoplanet searches around young stars. Here, we present pterodactyls, a data reduction pipeline specifically built to address the challenges in discovering exoplanets around young stars and to work with TESS Primary Mission 30-minute cadence photometry, since most young stars were not preselected TESS two-minute cadence targets. pterodactyls builds on publicly available and tested tools in order to extract, detrend, search, and vet transiting young planet candidates. We search five clusters with known transiting planets: the Tucana–Horologium Association, IC 2602, Upper Centaurus Lupus, Ursa Major, and Pisces–Eridani. We show that pterodactyls recovers seven out of the eight confirmed planets and one out of the two planet candidates, most of which were initially detected in two-minute cadence data. For these clusters, we conduct injection-recovery tests to characterize our detection efficiency, and compute an intrinsic planet occurrence rate of 49% ± 20% for sub-Neptunes and Neptunes (1.8–6 R ⊕) within 12.5 days, which is higher than Kepler’s Gyr-old occurrence rates of 6.8% ± 0.3%. This potentially implies that these planets have shrunk with time due to atmospheric mass loss. However, a proper assessment of the occurrence of transiting young planets will require a larger sample unbiased to planets already detected. As such, pterodactyls will be used in future work to search and vet for planet candidates in nearby clusters and moving groups.

https://iopscience.iop.org/article/10.3847/1538-3881/ac7b29/pdf

pterodactyls: A Tool to Uniformly Search and Vet for Young Transiting Planets in TESS Primary Mission Photometry

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Carbon Chain Depletion of 2I/Borisov

An experimental study of the effects of salt erosion on pottery

Carbon Chain Depletion of 2I/Borisov

pterodactyls: A Tool to Uniformly Search and Vet for Young Transiting Planets in TESS Primary Mission Photometry

Institutional review boards and quality assurance activities.