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# Revisiting the exoplanet radius valley with host stars from SWEET-Cat

## Details

**Authors** J. Kamulali, V. Adibekyan, B. Nsamba, S. G. Sousa, T. L. Campante, A. Weiss, B. Kabugho, N. Moedas, N. C. Santos, O. Trust

**Year** 2026

**Publisher** Astronomy & Astrophysics

**Kind of work** article

**Discipline** Astronomy

**Applied** false

[Read it at the publisher](https://doi.org/10.1051/0004-6361/202557554) 
10.1051/0004-6361/202557554

## In authors' words

### Abstract

Context. The radius valley, a deficit in the number of planets with radii around 2 R⊕, was observed among exoplanets that have sizes of ≲5 R and orbital periods of <100 days by NASA's Kepler mission. This feature separates two distinct populations: super-Earths (rocky planets with radii ≲1.9 R⊕) and sub-Neptunes (planets with substantial volatile envelopes and radii ≳2 R⊕). The valley has been proposed to stem from either planet formation conditions or evolutionary atmospheric loss processes. Disentangling these mechanisms has led to numerous studies of population-level trends, although the resulting interpretations remain sensitive to sample selection and the robustness of host-star parameters. Aims. Our aim is to re-examine the existence and depth of the radius valley, and how its location varies with orbital period, incident flux, stellar mass, and stellar age. Methods. We derived robust fundamental stellar parameters of 1221 main-sequence stars (hosting 1405 confirmed planets) from the SWEET-Cat database using a grid-based machine-learning tool (MAISTEP), which incorporates effective temperatures and metallicities from spectroscopy, as well as Gaia-based luminosities.

### What they set out to do (purpose)

To re-examine the existence and depth of the exoplanet radius valley and test how its location depends on orbital period, incident stellar flux, stellar mass, and stellar age.

### Who or what was studied (sample)

1,221 main-sequence FGK host stars hosting 1,405 confirmed exoplanets from the SWEET-Cat database, narrowed to a final analysis sample of 893 planets around 779 stars.

### How they did it (methods)

Stellar parameters were derived with a machine-learning grid-based tool (MAISTEP) combining spectroscopic temperatures and metallicities with Gaia luminosities, then the radius-valley location and depth were modeled as a function of orbital period, incident flux, stellar mass, and stellar age.

### What they found (results)

The radius valley was confirmed near 2 Earth radii and found to become shallower and shift to larger radii with increasing host-star age, a pattern favoring core-powered mass loss over photoevaporation as the dominant mechanism separating rocky super-Earths from sub-Neptunes.

## Commentary

### In short

The finding treats the radius valley as a genuine distinction separating two planet populations and shows the position of that boundary is governed by a relationship with stellar age, evidence for a specific causal mechanism reshaping the boundary over time.

**Patterns it shows** D, R

**Added** 2026-09-28

**How to cite this** J. Kamulali, V. Adibekyan, B. Nsamba, S. G. Sousa, T. L. Campante, A. Weiss, B. Kabugho, N. Moedas, N. C. Santos, O. Trust (2026). Revisiting the exoplanet radius valley with host stars from SWEET-Cat. Astronomy & Astrophysics.