arXiv subjects

Jesse Polman

Publications and source records attributed to Jesse Polman.

5 recordsLinked to original sources

arXiv2026

Energy deposition in planetary and exoplanetary atmospheres induced by cosmic rays

Cosmic rays can significantly alter the abundances of certain species in the upper layers of planetary atmospheres, especially in terms of their biosignatures. To fully understand the extent of this effect, it is essential to accurately model the interactions of cosmic rays with planetary magnetic fields. We used the CosmicTransmutation code to study the effect of a planetary magnetic field on the flux of galactic cosmic rays and stellar energetic particles. We found that both particle sources are significantly affected by magnetic fields, even though the effects are different due to the varying energy ranges that characterize each source. The stellar energetic particle energy flux is significantly higher for an Earth-like planet with no magnetic field, but with a magnetic field of 30\,$\mu$T or higher, the energy flux of the two sources becomes comparable. We find that the atmospheric pressures the cosmic rays reach are significantly lower than those found in previous studies using simpler models and that the effect of the atmospheric composition on this outcome is small. We found similar results using the model for the exoplanet K2-18b, even though the radius is significantly larger than Earth's. Because the two cosmic ray sources cover different energy ranges and are affected by the magnetic field in different ways as a result, both sources should be considered. Future studies should focus on combining an accurate modelling procedure of the interaction between cosmic rays and planetary magnetic fields with atmospheric chemistry models. This will require general circulation models to capture the latitudinal and longitudinal dependencies in full.

astro-ph.EP↗

arXiv2026

The formation of planetary systems: physics, populations, and architectures

We review the progresses made in global theoretical models of planetary system formation in the last decade using the example of the planetary system formation framework known as the Bern Model that has been continuously developed since before the beginning of the NCCR PlanetS. We highlight major developments and applications that have since been implemented, reflecting important recent advancements of planet formation theory overall, such as MHD wind-driven disk evolution, planetesimal evolution including fragmentation, dust evolution and pebble accretion, formation of planets in structured disks, interior structure models allowing for compositional gradients, as well as the analysis of the emerging planetary system architectures and the identification of different classes of architectures. We discuss how these new models impact the formation and evolution process and translate into different populations of planets and planetary systems. We also discuss the major strengths of the Bern Model, including successful predictions of the break in the planetary mass function at 30 MEarth, the prevalence of low-mass planets, the radius pile-up around 1 RJupiter, and the evaporation valley, with the recent New Generation Planetary Population Synthesis models with 100 seeds per disk providing quantitive matches to many RV-survey and Kepler diagnostics. This includes key characteristics of planetary system architectures. We also highlight the limitations of this model, some of them were addressed during the course of the NCCR PlanetS: the inclusion of the early phases of planet formation from dust to planetesimals, the hybrid pebble-planetesimals accretion of solids, simplified interior structure models, reliance on simplified parametrizations that may not encapsulate the full complexity of physical processes, and computational constraints.

astro-ph.EP↗

arXiv2025

Mapping the SO2 Shoreline in Gas Giant Exoplanets

JWST has revealed sulfur chemistry in giant exoplanet atmospheres, where molecules such as SO2 trace photochemistry, metallicity, and formation and migration. To ascertain the conditions that determine whether (or how much) SO2, H2S, and other sulfur-bearing species are present in exoplanet atmospheres, we present a grid of planetary atmospheres covering metallicities from 0.3-1000x Solar and temperatures from 250-2050 K. These models map out the 'SO2 shoreline,' the region of metallicity and irradiation for which SO2 may be sufficiently abundant to be detectable. SO2 is a sensitive indicator of metallicity; expected SO2 abundances also depend strongly on overall temperature and C/O ratio; the SO2 abundance depends surprisingly weakly on XUV irradiation, also weakly on Kzz (for Teq > 600 K), and is essentially independent of internal temperature. Despite its detection in a growing number of giant planets, SO2 is never the dominant sulfur-bearing molecule: depending on temperature and metallicity, H2S, S2, NS, SO, SH, and even S8 or atomic S are frequently as common (or more so) as SO2. Nonetheless SO2 remains the most easily detectable sulfur-bearing species, followed by H2S, though perhaps SO and SH could be detectable in some gas giants. Aside from a pressing need for additional observational constraints on sulfur, we also identify the need for future work to account for the effects of clouds and hazes, fully self-consistent atmospheric models, 2D and 3D models, a wider range of planetary masses and radii, and studies to measure and refine reaction rates and molecular opacities of sulfur-bearing species

astro-ph.EP↗

arXiv2025

On Linking Planet Formation Models, Protoplanetary Disk Properties, and Mature Gas Giant Exoplanet Atmospheres

Measuring a single elemental ratio (e.g., carbon-to-oxygen) provides insufficient information for understanding the formation mechanisms and evolution that affect our observations of gas giant planet atmospheres. Although the fields of planet formation, protoplanetary disks, and exoplanets are well established and interconnected, our understanding of how to self-consistently and accurately link the theoretical and observational aspects of these fields together is lacking. To foster interdisciplinary conversations, the Max-Planck Institut f\"ur Astronomie (MPIA) hosted a week-long workshop called, "Challenge Accepted: Linking Planet Formation with Present-Day Atmospheres." Here, we summarize the latest theories and results in planet formation modeling, protoplanetary disk observations, and atmospheric observations of gas giant atmospheres to address one of the challenges of hosting interdisciplinary conferences: ensuring everyone is aware of the state-of-the-art results and technical language from each discipline represented. Additionally, we highlight key discussions held at the workshop. Our main conclusion is that it is unclear what the ideal observable is to make this link between formation scenarios and exoplanet atmospheres, whether it be multiple elemental abundance ratios, measuring refractory budgets, or something else. Based on discussions held throughout the workshop, we provide several key takeaways of what the workshop attendees feel need the most improvement and exploration within each discipline.

astro-ph.EP↗

arXiv2024

Convective mixing in distant and close-in giant planets -- Dependences on the initial composition, luminosity, bloating and semi-convection

Recent structure models of Jupiter suggest the existence of an extended region in the deep interior with a high heavy element abundance, referred to as a dilute core. This finding has led to increased interest in modelling the formation and evolution processes with the goal of understanding how and under what circumstances such a structure is formed and retained, to in turn better understand the relation between atmospheric and bulk metallicity. We modelled the evolution of giant planets, varying various parameters relevant for the convective mixing process, such as the mixing length parameter and the size of the mesh, and parameters related to the general evolution, such as the orbital distance and the initial luminosity. We in particular studied hot Jupiters and find that the effect of bloating on the mixing process is small but can in some cases inhibit convective mixing by lowering the intrinsic luminosity for a given entropy. Semi-convection can significantly lower the extent of a dilute core if it is strong enough. We find that dilute cores are unable to persist for initial luminosities much higher than 3 x 1e3 LJ for a Jupiter-like planet for the initial heavy element profiles we studied. From this we conclude that, based on our model, it is unlikely that a large number of giant planets retain a dilute core throughout their evolution, although this is dependent on the assumptions and limitations of our method. Future work should focus on improving the link between formation and evolution models so that the mixing process is accurately modelled throughout a planet's lifetime and on improving the understanding of how to model convection near radiative-convective boundaries.

astro-ph.EP↗