Planetary Science Institute

Binary stars are as common as single stars. The number of detected planets orbiting binaries is rapidly increasing thanks to the synergy between transit surveys, Gaia, and high-resolution direct-imaging campaigns. However, global planet formation models around binary stars are still underdeveloped, which limits the theoretical understanding of planets orbiting binary star systems. We introduce the PAIRS project, which aims to build a global planet formation model for planets in binaries and to produce a planet population synthesis to statistically compare theory and observations. In this first paper, we present the adaptation of the circumstellar disc to simulate the formation of S-type planets. The presence of a secondary star tidally truncates and heats the outer part of the circumprimary disc (and vice versa for the circumsecondary disc), limiting the material to form planets. We implemented and quantified this effect for a range of binary parameters by adapting the Bern Model of planet formation in its pebble-based form and for in situ planet growth. We find that disc truncation has a strong impact on reducing the pebble supply for core growth and steadily suppresses planet formation for binary separations below 160 a when all the formed planets more massive than Mars are considered. Moreover, S-type planets tend to form close to the central star with respect to the binary separation and disc truncation radius. Our newly developed model will be the basis of future S-type planet population synthesis studies.

Abstract Recent three-dimensional flare models suggest that flare ribbon substructure is linked to the fragmentation of the reconnecting current sheet in the corona. Flare ribbon substructure can therefore potentially serve as a unique diagnostic tool for physical processes in the flare current sheet. In this paper, we describe a new method to quantify the evolution of ribbon substructure that first extracts the ribbon’s bright leading edge and then quantifies its morphology using the box-counting dimension and correlation dimension mapping (CDM). We first test our method using synthetic observations. We then apply it to an M6.5-class solar flare on 2015 June 22 observed by the Interface Region Imaging Spectrograph (IRIS) 1330 Å slit-jaw imager. We find that when the flare ribbon boundary has more multiple-spatial-scale features (a higher box-counting dimension), hard X-ray emission and magnetic reconnection rates are the strongest. We also find that the flare ribbon complexity characterized by CDM has a moderate correlation with the IRIS Si IV 1402.77 Å nonthermal velocity (in the negative polarity ribbon) and reconnection flux rates (in ribbons of both magnetic polarities). We conclude that the buildup of the spatial complexity of the ribbons at multiple spatial scales can serve as an observational proxy for current-sheet fragmentation in the corona.

Abstract The climate crisis is increasingly contributing to a mental health crisis. Policy and practice inadequately account for the mental health costs of climate change and the mental health benefits of climate action. The climate and mental health field is expanding rapidly but unevenly. Connecting Climate Minds (CCM), a global initiative, aimed to develop a guiding vision to ensure investment in and implementation of future research aligns with lived experience needs and appropriately informs policies. CCM convened 1184 contributors with diverse expertise across 126 countries, through 21 online and in-person dialogues. Their insights produced a Global Research and Action Agenda for climate change and mental health. This paper outlines the 53 research priorities structured into four high-level themes (impacts, risks and vulnerable groups; pathways and mechanisms; mental health benefits and risks of climate action; mental health interventions). It also outlines how to implement research and translate evidence to action.

• High-precision mass-dependent Ni isotope data are presented for Apollo lunar basalts and dunite 72415. • Diffusion modelling accounts for the extreme Ni isotope fractionation in lunar dunite 72415 (δ⁶⁰/⁵⁸Ni = +1.80‰). • Lunar mare basalts exhibit significant δ⁶⁰/⁵⁸Ni variability not primarily controlled by magmatic differentiation. • PMELTS modelling indicates Ni isotope fractionation during lunar magma ocean crystallization. • The estimated bulk silicate Moon δ⁶⁰/⁵⁸Ni (0.18 ± 0.20‰) overlaps with published bulk silicate Earth values (∼0.11‰). Although the Moon is thought to have formed through a giant impact between proto-Earth and a Mars-sized body, the processes responsible for the chemical and mass-dependent isotopic differences between Earth and Moon remain debated. We report high-precision mass-dependent Ni isotope data for 19 Apollo samples, including one dunite (72415), fifteen low-Ti basalts, and three high-Ti basalts, analyzed by double-spike technique using a multi-collector plasma-sourced mass spectrometer. The dunite 72415 shows an extremely high δ 60/58 Ni value of +1.80 ± 0.01‰, which we attribute to kinetic isotope fractionation from Ni diffusion during re-equilibration between olivine and a later melt. Diffusion modeling of Ni–Fe–Mg systematics reproduces the observed heavy Ni enrichment. In contrast, low-Ti basalts display a mean δ 60/58 Ni of 0.23 ± 0.20‰ (2SD), unaffected by cosmic-ray exposure, while high-Ti basalts are slightly isotopically lighter (0.06 ± 0.22‰, 2SD). Petrological modeling using pMELTS with recently constrained silicate mineral-melt fractionation factors suggests limited Ni isotope fractionation (<0.05‰) during lunar magma ocean crystallization and partial melting, yielding an estimated bulk silicate Moon (BSM) δ 60/58 Ni = 0.18 ± 0.20‰ (2SD). This overlaps with the bulk silicate Earth (BSE: 0.11 ± 0.07‰), indicating that Ni depletion in the lunar mantle, by a factor of ∼4 relative to Earth, can be caused by core formation (that does not fractionate Ni isotopes). However, our modelling shows evaporative loss of Ni can elevate δ 60/58 Ni value of < 0.23‰, which remains consistent with those of BSM within uncertainty. Hence, the mechanism of Ni evaporation cannot be ruled out.

Abstract We present a major update to the open-source atmospheric modeling package PICASO , designed for simulating the thermal structure and spectra of hydrogen-rich atmospheres of brown dwarfs and exoplanets. This release, PICASO 4.0 , expands upon the existing radiative-convective equilibrium model framework by incorporating several new capabilities. Key additions include the integration of Virga for self-consistent cloud modeling, new flexible treatments for rainout and cold trapping of volatile species, and support for photochemistry. We also introduce a parameterized energy injection scheme to simulate additional external or internal heating processes. These features are motivated by lessons from recent JWST observations that reveal the prevalence of nonequilibrium chemistry and clouds. We benchmark the new functionalities against previously published results in the literature, including the Sonora Diamondback grid, energy injected atmospheres, patchy cloud models, and other photochemical models of WASP-39b. PICASO continues to be actively developed as an open-source package aimed at enabling reproducible, community-driven atmospheric modeling of all substellar objects.

Abstract On 24 July 2024, an ML 4.6 earthquake occurred at 26.27° N, 104.74° E in Liupanshui City, Guizhou Province, China. The strongest ground shaking was felt in Fa’er Town, an area with several coal mines. To explore the seismogenic mechanism of this event, we analyzed broadband seismic waveforms from the China National Seismic Network to determine its source parameters, including its focal mechanism, centroid depth, and horizontal location. Because the earthquake was very close to the mining areas, we then constructed an elastic finite-element model to calculate the change in Coulomb failure stress (ΔCFS), aiming to evaluate the impact of mining activities on this event. The results show that the Liupanshui earthquake exhibited a thrust-slip focal mechanism with a centroid depth of ∼2 km. The relocated hypocenter was located directly beneath the coal mining area. Although the calculated ΔCFS in this region was relatively modest (∼4.5 kPa), the shallow depth and spatial correlation strongly suggest that the earthquake was likely induced by local mining activities.

Near-surface water ice in Phlegra Montes, Mars, could support human exploration and settlement. Orbital sounding radar provides strong evidence for the existence of this ice, as does morphology consistent with debris-covered glaciers. Impact excavation of these glacier-like features has exposed ice, visible in HiRISE images, but the distribution and quantity of this ice is uncertain, necessitating further evaluation for its potential to support human exploration. We are developing the Prototype Radar Sounding Experiment for Unveiling the Subsurface (PERSEUS) instrument to study debris-covered glaciers on Earth and Mars, and we propose D-PERSEUS, a mission to study a debris-covered glacier in Phlegra Montes using a drone-based Ground Penetrating Radar like this one. This mission could verify the presence of water ice in-situ and improve characterization of water ice resources, which could serve as exploratory work ahead of a potential Mars Life Explorer mission.