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Abstract Type IIn supernovae (SNe IIn) are a highly heterogeneous subclass of core-collapse supernovae, spectroscopically characterized by signatures of interaction with a dense circumstellar medium (CSM). Here, we systematically model the light curves of 142 archival SNe IIn using the Modular Open Source Fitter for Transients. We find that the observed and inferred properties of SN IIn are diverse, but there are some trends. The typical supernova CSM is dense (∼10⁻¹²g cm⁻³) with highly diverse CSM geometry, with a median CSM mass of ∼1M_⊙. The ejecta are typically massive (≳10M_⊙), suggesting massive progenitor systems. We find positive correlations between the CSM mass and the rise and fall times of SNe IIn. Furthermore, there are positive correlations between the rise time and fall times and ther-band luminosity. We estimate the mass-loss rates of our sample (where spectroscopy is available) and find a high median mass-loss rate of ∼10⁻²M_⊙yr⁻¹, with a range between 10⁻³and 1M_⊙yr⁻¹. These mass-loss rates are most similar to the mass loss from great eruptions of luminous blue variables, consistent with the direct progenitor detections in the literature. We also discuss the role that binary interactions may play, concluding that at least some of our SNe IIn may be from massive binary systems. Finally, we estimate a detection rate of 1.6 × 10⁵yr⁻¹in the upcoming Legacy Survey of Space and Time at the Vera C. Rubin Observatory. 

Abstract A major challenge in understanding the oceanic carbon cycle is estimating the sinking flux of organic carbon exiting the sunlit surface ocean, termed carbon export. Existing algorithms derive carbon export from satellite ocean color, but neglect spatiotemporal offsets created by the temporal lag between production and export, and by horizontal advection. Here, we show that a Lagrangian “growth‐advection” (GA) satellite‐derived product, where plankton succession and export are mapped onto surface oceanic circulation following coastal upwelling, succeeds in representing in situ export off the California coast. In situ export is best represented by a combination of GA export (proportional to modeled zooplankton) and export derived from ocean color (related to local phytoplankton). Both products also correlate with a long‐term time series of abyssal carbon flux. These results provide insights on export spatiotemporal patterns and a path toward improving satellite‐derived carbon export in the California Current and beyond. 

Abstract The outer regions of the protoplanetary disc surrounding the T Tauri star HD 143006 show rings, dust asymmetries and shadows. Whilst rings and dust asymmetries can arise from companions and other mechanisms, shadows and misaligned discs in particular are typically attributed to the presence of misaligned planets or stellar-mass companions. To understand the mechanisms that drive these traits, the innermost regions of discs need to be studied. Using CHARA/MIRCX and VLTI/PIONIER, we observed the sub-au region of HD 143006 . We constrain the orientation of the inner disc of HD 143006 and probe whether a misalignment between the inner and outer disc could be the cause of the shadows. Modelling the visibilities using a geometric model, the inclination and position angle are found to be i = 22○ ± 3○ and PA = 158○ ± 8○ respectively, with an inner dust sublimation radius of ~0.04 au. The inner disc is misaligned by 39○ ± 4○ with respect to the outer disc, with the far side of the inner disc to the east and the far side of the outer disc to the west. We constrain h/R (scattering surface/radius of scattered light) of the outer disc at 18 au to be about 13 % by calculating the offset between the shadow position and the central star. No companion was detected, with a magnitude contrast of 4.4 in the H-band and placing an upper mass limit of 0.17M⊙ at separations of 0 − 8 au. Therefore, we cannot confirm or rule out that a low-mass star or giant planet is responsible for the misalignment and dust sub-structures. 

The anatomy and function of the respiratory systems of penguins are reviewed in relation to gas exchange and minimization of the risks of pulmonary barotrauma, decompression sickness and nitrogen narcosis during dives. Topics include available lung morphology and morphometry, respiratory air volumes determined with different techniques, review of possible physiological and biomechanical mechanisms of baroprotection, calculations of baroprotection limits and review of air sac and arterial partial pressure of oxygen (P_O2) profiles in relation to movement of air during breathing and during dives. Limits for baroprotection to 200, 400 and 600 m in Adélie, king and emperor penguins, respectively, would require complete transfer of air sac air and reductions in the combined tracheobronchial tree—parabronchial volume of 24% in Adélie, 53% in king penguins and 76% in emperor penguins. Air sac and arterial P_O2profiles at rest and during surface activity were consistent with unidirectional air flow through the lungs. During dives, P_O2profiles were more complex, but were consistent with compression of air sac air into the parabronchi and air capillaries with or without additional air mixing induced by potential differential air sac pressures generated by wing movements. This article is part of the theme issue ‘The biology of the avian respiratory system’. 

Context.Acetone (CH₃COCH₃) is one of the most abundant three-carbon oxygen-bearing complex organic molecules (O-COMs) that have been detected in space. The previous detections were made in the gas phase toward star-forming regions that are chemically rich, mostly in protostellar systems. Recently, acetone ice has also been reported as (tentatively) detected toward two low-mass protostars, allowing comparisons in acetone abundances between gas and ice. The detection of acetone ice warrants a more systematic study of its gaseous abundances which is currently lacking. Aims.We aim to measure the gas-phase abundances of acetone in a large sample obtained from the CoCCoA program, and investigate the chemical evolution of acetone from ice to gas in protostellar systems. Methods.We fit the ALMA spectra to determine the column density, excitation temperature, and line width of acetone in 12 high-mass protostars as part of CoCCoA. We also constrained the physical properties of propanal (C₂H₅CHO), ketene (CH₂CO), and propyne (CH₃CCH), which might be chemically linked with acetone. We discuss the possible formation pathways of acetone by making comparisons in its abundances between gas and ice and between observations and simulations. Results.We firmly detect acetone, ketene, and propyne in the 12 high-mass protostars. The observed gas-phase abundances of acetone are surprisingly high compared to those of two-carbon O-COMs (especially aldehydes). Propanal is considered as tentatively detected due to lack of unblended lines covered in our data. The derived physical properties suggest that acetone, propanal, and ketene have the same origin from hot cores as other O-COMs, while propyne tends to trace the more extended outflows. The acetone-to-methanol ratios are higher in the solid phase than in the gas phase by one order of magnitude, which suggests gas-phase reprocessing after sublimation. There are several suggested formation pathways of acetone (in both ice and gas) from acetaldehyde, ketene, and propylene. The observed ratios between acetone and these three species are rather constant across the sample, and can be well reproduced by astrochemical simulations. Conclusions.On the one hand, the observed high gas-phase abundances of acetone along with dimethyl ether (CH₃OCH₃) and methyl formate (CH₃OCHO) may hint at specific chemical mechanisms that favor the production of ethers, esters, and ketones over alcohols and aldehydes. On the other hand, the overall low gas-phase abundances of aldehydes may result from destruction pathways that are overlooked or underestimated in previous studies. The discussed formation pathways of acetone from acetaldehyde, ketene, and propylene seem plausible from observations and simulations, but more investigations are needed to draw more solid conclusions. We emphasize the importance of studying acetone, which is an abundant COM that deserves more attention in the future. 

Abstract The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) provides continuous global maps of Birkeland currents, using magnetic field perturbations (dB) obtained by calibrating and detrending data from engineering magnetometers on the 66 polar‐orbiting Iridium satellites in the communications constellation. Here, we provide an assessment of AMPERE dBaccuracy, as compared with magnetic field observations from the Swarm satellite mission. The CHAOS v8.1 model (Finlay et al., 2020,https://doi.org/10.1186/s40623‐020‐01252‐9) was used to remove the main field and other non‐ionospheric contributions from both data sets. In a nearest‐neighbor comparison covering August 2022, AMPERE's calibrated and detrended dBdata from the Iridium NEXT satellites are found to have root‐mean‐square deviations of 31 and 33 nT (for dB_θand dB_φ, respectively) as compared with data from Swarm, while the biases are −7 and −2 nT. For the same interval, AMPERE's fitted maps have root‐mean‐square errors of <40 nT, rising to 109–185 nT in active conditions (defined as Swarm dB > 250 nT). However, there is evidence that small scale (<400‐km along Swarm track direction) dBstructures are not fully resolved. Overall, we find that the AMPERE dBdata and fitted products are unbiased and are typically in excellent agreement with the Swarm data. 

In this paper, we present improvements to the pointing accuracy of the South Pole Telescope (SPT) using machine learning. The ability of the SPT to point accurately at the sky is limited by its structural imperfections, which are impacted by the extreme weather at the South Pole. Pointing accuracy is particularly important during SPT participation in observing campaigns with the Event Horizon Telescope (EHT), which requires stricter accuracy than typical observations with the SPT. We compile a training dataset of historical observations of astronomical sources made with the SPT-3G and EHT receivers on the SPT. We train two XGBoost models to learn a mapping from current weather conditions to two telescope drive control arguments — one which corrects for errors in azimuth and the other for errors in elevation. Our trained models achieve root mean squared errors on withheld test data of 2[Formula: see text]14 in cross-elevation and 3[Formula: see text]57 in elevation, well below our goal of 5[Formula: see text] along each axis. We deploy our models on the telescope control system and perform further in situ test observations during the EHT observing campaign in April 2024. Our models result in significantly improved pointing accuracy: for sources within the range of input variables where the models are best trained, average combined pointing error improved 33%, from 15[Formula: see text]9 to 10[Formula: see text]6. These improvements, while significant, fall shy of our ultimate goal, but they serve as a proof of concept for the development of future models. Planned upgrades to the EHT receiver on the SPT will necessitate even stricter pointing accuracy which will be achievable with our methods.