First-author publications

First author 2026 Submitted to ApJ

Thermal evolution of lava planets across system ages: predictions for Hell of a Survey

M. Sastre, T. Lichtenberg, L. Dang, A. Piette, H. S. Wang, M. López-Morales, et al.

Ultra-short-period rocky planets can be hot enough on their daysides to keep a magma ocean for their whole lives. Using the PROTEUS coupled interior–atmosphere framework, I ran a grid of simulations and sorted the outcomes into six categories, based on how much of the interior stays molten and whether an atmosphere survives that can carry heat around the planet. I then made predictions for five targets of the JWST Cycle 4 Hell of a Survey program (8864): TOI-1807 b, TOI-2260 b, TOI-431 b, TOI-6255 b and TOI-2431 b.

• Most targets evolve towards a bare-rock end state, with a global melt fraction of 20% or less.
• Whether an atmosphere survives depends on the escape efficiency. There is a minimum efficiency below which volatile envelopes survive energy-limited escape.
• A molten surface raises the partial pressure of most species. S₂ is the exception: it is enhanced when the surface is solid, so it may trace the interior's melt state.
• These predictions will help interpret the survey's MIRI-LRS phase curves.

  arXiv:2609.20155

First author 2026 A&A 713, A159

Geophysical and atmospheric implications of fO₂-dependent melting on rocky exoplanets

M. Sastre, T. Lichtenberg, L. Soucasse, D. J. Bower, H. Nicholls, I. Kamp

Most models of magma oceans assume Earth-like (oxidised) conditions or very hydrogen-rich (sub-Neptune) ones, which leaves the range in between largely unexplored. In this paper I look at how the redox state of the mantle, measured by its oxygen fugacity (fO₂), changes its melting curves. I then follow how those curves shape the planet's thermal evolution, melt fraction and atmosphere. I applied the model to the super-Earth GJ 1132 b using the PROTEUS framework.

• Reduced mantles tend to build H₂–CO-rich atmospheres. Oxidised mantles tend to build thinner H₂O–CO₂ envelopes.
• In volatile-poor planets, redox-dependent melting noticeably shifts when the magma ocean crystallises. In volatile-rich planets, the effect on solidification time is small.
• The volatile inventory and the surface oxygen fugacity are the main controls on the thermal state. Redox-dependent melting is a secondary effect.
• The predicted atmospheric compositions give spectral signatures that JWST can test.

  Read in A&A   arXiv:2606.20249

Collaborative papers

• Co-author Super-Earth Interiors Shrink by About 10% as They Crystallise

  T. Lichtenberg, M. Attia, H. Nicholls, M. Sastre, D. J. Bower, K. Stuitje, F. C. Pascal, L. Soucasse, D. Apai, P. Bos, R. Calder, L. Cesario, L. Dang, E. Decocq, M. van Dijk, M. Farhat, K. Hakim, T. Kimura, I. Kisvárdai, S. Krijt, Y. Miguel, I. Panagiotou, E. Postolec, M. Schlecker, S. Seager, A. Shahar, O. Shorttle, P. A. Sossi, W. van Westrenen

  2026
• Co-author PALEOS: Multiphase equations of state and mass–radius relations for exoplanet interiors

  M. Attia, T. Lichtenberg, E. Jungová, M. Sastre

  2026
• Co-author Coupled atmospHere Interior modeL Intercomparison (CHILI)—Protocol Version 1.0: A CUISINES Intercomparison Project of Magma Ocean Models

  T. Lichtenberg, L. Schaefer, J. Krissansen-Totton, Y. Miguel, D. E. Sergeev, P. Baumeister, J. Cmiel, L. J. Janssen, T. G. Nguyen, Y. Miyazaki, H. Nicholls, A. Papesh, H. Pelissard, B. Peng, J. Perez, E. Postolec, M. Sastre, A. Salvador, H. Spreeuw, A. Zorzi, T. J. Fauchez, K. Hamano, J. Leconte, M. Maurice, L. Noack, L. Soucasse

  2026
• Co-author Estimation of the tidal heating in the TRAPPIST-1 planets

  E. Bolmont, M. Sastre, A. Revol, M. Kervazo, G. Tobie

  2026
• Co-author Drifts of the substellar points of the TRAPPIST-1 planets

  A. Revol, É. Bolmont, M. Sastre, G. Tobie, A.-S. Libert, M. Kervazo, S. Blanco-Cuaresma

  2024

Master thesis

• Master thesis Geodynamical regimes in Earth-like exoplanets

  Astronomical Observatory of Geneva, University of Geneva, Switzerland