When the core ate the atmosphere

The initial volatile element inventories in a planet's atmosphere, mantle, and core are established by delivery and transport during planetary growth. The new analysis still awaits peer review, but it already lays out the central claim clearly.

It matters because astrophysics becomes persuasive only when an observed signal can be tied to a physically defensible explanation. Compact objects such as neutron stars and black holes are natural laboratories for extreme physics, but the distance and complexity of these systems make interpretation difficult without multi-wavelength coverage and careful modeling. A detection without a mechanism is only half a result. the other half comes from showing that the signal fits quantitatively inside a coherent physical picture rather than merely being consistent with a broad family of models. Conversely, the volatile abundances of Earth's planetary reservoirs record its accretion pathway. We model here volatile transport during planet formation for two different delivery scenarios, via pebble and planetesimal accretion, to predict the volatile inventories of.

We find that the distributions of volatiles between the atmosphere, mantle, and core exhibit strong sensitivity to volatile delivery timing, metal-silicate partition coefficients. In particular, the early volatile delivery expected in pebble accretion scenarios substantially enhances core sequestration of hydrogen and carbon relative to continuous delivery.

With our fiducial partition coefficients, the pebble accretion model produces a 760 bar carbon-dominated atmosphere with 39 bar of hydrogen and water and a few bars of nitrogen. The corresponding planetesimal accretion model produces a more massive ($\sim$$1350$ bar) atmosphere with similar composition.

The core stores $\sim$$70$% of both the H and the C budget in the early-delivery scenario, but $\lesssim$$50$% in the corresponding continuous delivery scenario. Overall our results demonstrate that substantial amounts of volatiles are sequestered into rocky planet cores during planet formation and that the volatile inventory of bulk.

The broader interest lies in turning an observational clue into something that can be weighed against competing models of the underlying physics. Astrophysics does not have the luxury of controlled experiments; everything is inferred from radiation that traveled across cosmic distances under conditions that cannot be reproduced in a terrestrial laboratory. This makes the interpretation chain longer and more uncertain than in bench science, but it also means that a well-constrained measurement of an extreme object carries theoretical information that no earthbound experiment can provide.

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Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to see whether independent datasets and physical modeling converge on the same interpretation. Multi-wavelength follow-up, combining X-ray, radio and optical data where possible, is typically what separates a compelling detection from a robust physical characterization. In high-energy astrophysics, results that initially looked definitive have been revised when data from a second messenger arrived; the current result should be read with that history in mind. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

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