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Small Planets Changed Composition With Their Host Stars

Population models inferred rockier planets around Sun-like stars and tightly bounded volatile inventories around M dwarfs.

Published Updated Story ID: mp-2026-09-10-027
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Summary

Population models inferred rockier planets around Sun-like stars and tightly bounded volatile inventories around M dwarfs.

A mixture model linked interior structures to the measured density distributions of small planets in three samples. Under one rocky-population parameterization, planets around FGK stars had characteristic core mass fractions about 16 percent higher than planets around M dwarfs. An alternative model estimated 89.9 to 97.0 percent of FGK-hosted planets as rocky, while the M-dwarf rocky share remained much less certain. Volatile-bearing planets were common in the model but concentrated at small atmospheric and water fractions. These are population-level inferences shaped by sample selection and interior-model assumptions, not direct compositional measurements of individual worlds.

Why it matters

Population models inferred rockier planets around Sun-like stars and tightly bounded volatile inventories around M dwarfs.

Limits and context

  • These are population-level inferences shaped by sample selection and interior-model assumptions, not direct compositional measurements of individual worlds.

Key claims

  1. Population models inferred rockier planets around Sun-like stars and tightly bounded volatile inventories around M dwarfs.

    Qualification: These are population-level inferences shaped by sample selection and interior-model assumptions, not direct compositional measurements of individual worlds.

    Evidence: source-2026-09-10-016

Sources

  1. arXiv preprint 2609.09319arXiv · primary research

Corrections

No corrections have been recorded for this story.