arXiv subjects

Leander Schlarmann

Publications and source records attributed to Leander Schlarmann.

4 recordsLinked to original sources

arXiv2026

Interactions of sublimated frost with volcanic plumes: Modelling Io's SO$_2$ atmosphere using the DSMC method

Io's tenuous atmosphere consists primarily of sulphur dioxide (SO$_2$) with observed column densities of approximately $10^{16}{-}10^{17}$ cm$^{-2}$. However, it remains uncertain whether the sublimation of SO$_2$ surface frost or volcanic outgassing is the primary source of the SO$_2$ atmosphere. In this study, we produce a 2D model of Io's SO$_2$ atmosphere using the Direct Simulation Monte Carlo (DSMC) method. For this purpose, we conduct a literature review on thermophysical parameters of Io's SO$_2$ surface frost to refine the surface temperature model in accordance with the most recent observations, which enables accurate modelling of Io's sublimated atmosphere. We find that the thermal conductivity, which shifts the peak temperature and SO$_2$ column density away from the subsolar point, has a pronounced effect on sublimation-driven winds and interactions with volcanic plumes. Furthermore, a background atmosphere could reduce sublimation-driven winds in Io's atmosphere, while the SO$_2$ column and number densities are not substantially altered. Moreover, we study the influence of the eclipse, when Io passes through Jupiter's shadow, finding that it reduces the average column density on the sub-Jovian hemisphere by a factor of ${\sim}$5.5 in relation to the anti-Jovian hemisphere. We also investigate the interaction of the sublimated atmosphere with a medium-sized plume at various locations relative to the subsolar point. We find a strong influence, especially on the dayside, where the atmosphere is enhanced with material being displaced by the plume, most pronounced when the plume is positioned near the point of maximum sublimation in the early afternoon.

astro-ph.EP↗

arXiv2026

Active moons in our Solar System and beyond -- Io, Europa, Enceladus, Triton, and exomoons

The outgassing signatures of Io, Europa, Enceladus, Triton, and Io-like exomoons are the focus of this review chapter. The rocky volcanic world of Io is unique in our Solar System, with plumes reaching to hundreds of kilometres in altitude. Io-like exomoons could leave signatures strong enough to be detected with ground-based telescopes. The icy moons Europa and Enceladus, with their subsurface oceans, are currently the best candidates for life. Triton is different in many ways and raises unexplored questions. Our knowledge of these active moons is derived from space- and ground-based observations. To understand their origin, we discuss moon formation in general, before examining evidence and signatures of plumes on these moons. Given the accessibility of subsurface oceanic material through the occurrence of plumes, we expand on possibilities to investigate biosignatures.

astro-ph.EP↗

arXiv2026

Climates of Terrestrial Exoplanets and Biosignatures

Understanding the climates of terrestrial exoplanets and the detectability of biosignatures is an inherently interdisciplinary challenge, requiring the integration of insights from Solar System exploration, exoplanet observations and climate science. Building from Earth as the only known inhabited planet, NCCR PlanetS has developed models, tools and observational strategies to assess planetary environments far beyond direct reach. Between 2018 and 2025, PlanetS made major contributions across theory, modelling, instrumentation and mission preparation. On the modelling side, the Generic Planetary Climate Model enabled climate studies across a wide range of planetary regimes, from early Venus to temperate terrestrial exoplanets including Proxima b, incorporating advanced developments such as a dynamical slab ocean. In parallel, the THOR global climate model was developed to avoid Earth-centric assumptions and to stably simulate diverse atmospheric regimes. PlanetS has also advanced atmospheric retrieval techniques combining forward modelling, Bayesian inference and machine learning, applied to targets ranging from Solar System bodies to exoplanet phase curves and directly imaged spectra. These efforts have helped assess the scientific return of future missions, notably the Large Interferometer for Exoplanets (LIFE) and to define instrumental requirements for detecting Earth-like atmospheres and biosignatures. Within the Solar System, PlanetS contributed key technologies for biosignature detection, including ORIGIN and SenseLife, enabling in-situ and remote detection of organics, isotopic ratios and microstructures. Finally, PlanetS has played a major role in preparing the next generation of observatories, from JWST, VLT and ELT instruments to LIFE and the Habitable Worlds Observatory. Together, these contributions form an integrated framework advancing the search for life beyond Earth.

astro-ph.EP↗

arXiv2021

C$_{60}^+$ diffuse interstellar band correlations and environmental variations

The Diffuse Interstellar Bands (DIBs) are absorption features seen in the spectra of astronomical objects, that arise in the interstellar medium. Today more than 500 DIBs have been observed mostly in the optical and near-infrared wavelengths. The origin of the DIBs are unclear; only ionized buckminsterfullerene C$_{60}^+$ has been identified as a viable candidate for two strong and three weaker DIBs. In this study, we investigate the correlations between the strengths of the two strongest C$_{60}^+$ DIBs as well as their environmental behaviour. Therefore, we analysed measurements of the strengths of the two C$_{60}^+$ DIBs at 9577 and 9633 $Å$ for 26 lines of sight. We used two different methods, including Monte Carlo simulations, to study their correlations and the influence of measurement errors on the correlation coefficients. Furthermore, we examined how the strength of the C$_{60}^+$ DIBs changes as a result of different environmental conditions, as measured by the concentration of H/H$_2$ and the strength of the ambient UV radiation. In contrast to results recently reported by Galazutdinov et al. (2021), we find a high correlation between the strengths of the C$_{60}^+$ DIBs. We also discovered that the behaviour of the correlated C$_{60}^+$ bands is quite distinct from other DIBs at 5780, 5797 and 6203 $Å$ in different environments.

astro-ph.GA↗