With @xoplanets.bsky.social, @timlichtenberg.bsky.social, @climatebook.bsky.social, Richard Chatterjee, and Hamish Hay.

See also my explainer thread below!
bsky.app/profile/nich...

Finally and importantly, in this paper, we explain the atmospheric abundances inferred from JWST by invoking the photochemical production of SO2 from H2S.

Our models, which include realistic atmosphere structure calculations, show that the radius of this planet has shrunk over its ~5 Gyr lifetime from that of a sub-Neptune to that of a super-Earth at the present day. This also corresponds with age-radius trends in the Kepler Survey.

Instead, this planet has a mostly H2+H2S+SO2 atmosphere and an internal magma ocean which has been sustained across its multi-billion-year lifetime, making it an interesting window into interactions between atmospheres and magma oceans. It is molten by a greenhouse atmosphere and tidal heating.

In this new paper, we show that this planet must have formed rich in HCNS volatiles, particularly sulfur; incompatible with the typical "gas-dwarf" birth interpretation. Our analysis also finds that this planet’s interior must be geochemically reduced, which also opposes the "water-world" scenario.

L 98-59 d is known to have a low density but a high MMW. We calculate its complete evolutionary history using our fully-coupled open source planetary modelling framework (PROTEUS; Nicholls+24).

Water world
Gas dwarf
Sub-Venus
Bare rocks
Earth-like (define as you will)
Free floating planets

A time-lapse of some images of asteroid (52246) Donaldjohanson during the encounter by Lucy!

Images taken on April 20, 2025, from a distance of 1,600 to 1,100 km.

Credit: NASA/Goddard/SwRI/Johns Hopkins APL

science.nasa.gov/image-articl...

#PlanetSci #SciComm 🧪

This is the second paper derived from my PhD, and a direct follow-up from arxiv.org/abs/2411.19137

@climatebook.bsky.social @timlichtenberg.bsky.social

Additionally, synthetic planet-averaged emission spectra show absorption features associated with mantle redox (fO2). Deep near-isothermal stratospheres also indicate that cool brightness temperatures could be inferred if observed photometrically.

To do this, we develop a new radiative-convective atmosphere model which is integrated into the PROTEUS magma ocean framework.

These models find that TRAPPIST-1 c solidifies within 100 Myr. HD 63433 d maintains a permanent magma ocean.

Follow up paper coming soon :)

We used a coupled interior-atmosphere model to simulate how these planets evolve over time. Sometimes they solidify and sometimes they don't - but this strongly depends on the redox state of the mantle.

Looks great! Maybe you could add clouds?