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Accepted earlier this year in A&A, work led by Mara Attia (@marattia.bsky.social) tackles a core problem in exoplanet interiors: "PALEOS: Multiphase equations of state and mass-radius relations for exoplanet interiors" 🌍 Read: https://arxiv.org/abs/2605.03741 #Exoplanets

Forming Worlds Lab

@formingworlds.space

8 Sept

Measure an exoplanet's mass and radius and you get its density, and density is usually read as composition: how much iron, how much rock, how much water. That reading assumes the inside is cold and solid.

Forming Worlds Lab

@formingworlds.space

Heat it and the rock expands. For low-mass silicate planets the radius grows by more than 1% above 1500 K and up to 16% at 4000 K. That is as large as the spread from changing bulk composition, and as large as the typical transit radius uncertainty. 🌋

8/9/26, 6:50 pm1 repost0 likes

Forming Worlds Lab

@formingworlds.space

8 Sept

So the same mass and radius can be two different planets. WASP-47 e and TOI-1807 b each admit two purely rocky solutions, identical in mass and radius: one fully solid, one with a deep magma ocean on a liquid iron core.

Forming Worlds Lab

@formingworlds.space

8 Sept

Lead images: Mara Attia and the paper abstract. Below: core size vs temperature (measured radius as contour, solutions A and B), and mass-radius curves at four temperatures. Behind it is PALEOS, 17 phases, checked against Earth to 0.3%: https://github.com/maraattia/PALEOS

Forming Worlds Lab

@formingworlds.space

8 Sept

A point on the mass-radius diagram is not an interior until you know the temperature. 🔭 With @timlichtenberg.bsky.social, Ema Jungová and @marianasastre.bsky.social at @kapteynastro.bsky.social.