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arxiv: 2604.07447 · v1 · submitted 2026-04-08 · 🌌 astro-ph.EP · astro-ph.SR

Recognition: 2 theorem links

· Lean Theorem

Super-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfs

Drew Weisserman , Nicole Gromek , Ryan Cloutier , Komal Bali , Charles Cadieux , Mykhaylo Plotnykov , Alexandrine L'Heureux , Avidaan Srivastava
show 93 more authors
Andres Carmona Yolanda G. C. Frensch \'Etienne Artigau Fr\'ed\'erique Baron Susana C. C. Barros Bj\"orn Benneke Xavier Bonfils Fran\c{c}ois Bouchy Marta Bryan Neil J. Cook Nicolas B. Cowan Eduardo Cristo Xavier Delfosse Ren\'e Doyon Xavier Dumusque David Ehrenreich Jonay I. Gonz\'alez Hern\'andez David Lafreni\`ere Izan de Castro Le\~ao Christophe Lovis Lison Malo Bruno L. Canto Martins Alejandro Su\'arez Mascare\~no Jose Renan De Medeiros Claudio Melo Lucile Mignon Christoph Mordasini Francesco Pepe Rafael Rebolo Jason Rowe Nuno C. Santos Damien S\'egransan St\'ephane Udry Diana Valencia Gregg Wade Jos\'e Luan A. Aguiar Romain Allart Luc Bazinet Jean-Baptiste Delisle Flavie B\'elanger Joshua Blackman Vincent Bourrier Pedro Branco Vincent Bruniquel Yann Carteret Marion Cointepas Antoine Darveau-Bernier Laurie Dauplaise Elisa Delgado-Mena Caroline Dorn Dhvani Doshi Jo\~ao Faria Dasaev O. Fontinele Thierry Forveille Jonathan Gagn\'e Fr\'ed\'eric Genest Jennifer Glover Roseane de Lima Gomes Nolan Grieves Melissa J. Hobson H. Jens Hoeijmakers Farbod Jahandar Vigneshwaran Krishnamurthy Pierrot Lamontagne Pierre Larue Henry Leath Olivia Lim Justin Lipper Lina Messamah Yuri S. Messias Telmo Monteiro Leslie Moranta Khaled Al Moulla Dany Mounzer Georgia Mraz Nicola Nari Louise D. Nielsen Ares Osborn Jon Otegi L\'ena Parc Stefan Pelletier Olivia Pereira Caroline Piaulet-Ghorayeb Riley Rosener Julia Seidel Jo\~ao Gomes da Silva Ana Rita Costa Silva Atanas K. Stefanov M\'arcio A. Teixeira Thomas Vandal Valentina Vaulato Joost P. Wardenier Vincent Yariv
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Pith reviewed 2026-05-10 17:50 UTC · model grok-4.3

classification 🌌 astro-ph.EP astro-ph.SR
keywords super-EarthsM dwarfscore mass fractionwater-rich formationstellar abundancesradial velocityNIRPSplanet formation
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The pith

Hot super-Earths around M dwarfs have smaller cores than their stars' compositions predict, suggesting interior water.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper measures precise masses for three hot super-Earths around M dwarfs and combines them with six others from the literature to derive core mass fractions at 10-15 percent precision. It measures the iron, magnesium, and silicon abundances in the host stars from NIRPS spectra and uses those to predict the core mass fractions the planets should have if they formed dry and chondritic. The actual planetary cores come out smaller than these predictions at a statistically significant level. This points to the planets having formed with water that is now locked in their interiors at roughly one percent by mass, even though the planets are too hot for liquid surface water.

Core claim

The authors calculate planetary core mass fractions from new radial-velocity masses of GJ 1132 b, GJ 1252 b, and LTT 3780 b together with literature values for six additional hot super-Earths. They derive predicted refractory core mass fractions directly from the Fe, Mg, and Si abundances measured in the NIRPS spectra of the host M dwarfs. The observed planetary core mass fractions are smaller than the stellar-abundance predictions, which the paper interprets as evidence that these planets incorporated significant water during formation and sequestered roughly one percent of their mass as interior water.

What carries the argument

The direct numerical comparison of an observed planetary core mass fraction (computed from mass and radius) against a predicted refractory core mass fraction (computed from the host star's measured Fe/Mg/Si abundance ratios).

If this is right

  • Hot super-Earths around M dwarfs likely accreted with substantial water even in close-in orbits.
  • The water is sequestered inside the planet rather than remaining on the surface.
  • Standard dry-formation models underpredict the volatile content of these planets.
  • The same abundance-to-core-fraction test can be applied to larger samples of M-dwarf planets.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the water interpretation holds, M-dwarf planets may retain more volatiles than formation models calibrated on solar-type stars predict.
  • Similar measurements for cooler super-Earths around M dwarfs could test whether the same water fraction appears as surface oceans when temperatures permit.
  • The method offers a way to quantify the water budget of small planets without direct atmospheric detection.

Load-bearing premise

Any shortfall between the planetary core mass fraction and the value predicted from stellar abundances is caused by water rather than measurement error, mantle stripping, or other unaccounted volatiles.

What would settle it

A new set of higher-precision stellar abundance measurements or planetary mass-radius data that brings the observed and predicted core mass fractions into statistical agreement would remove the evidence for interior water.

Figures

Figures reproduced from arXiv: 2604.07447 by Alejandro Su\'arez Mascare\~no, Alexandrine L'Heureux, Ana Rita Costa Silva, Andres Carmona, Antoine Darveau-Bernier, Ares Osborn, Atanas K. Stefanov, Avidaan Srivastava, Bj\"orn Benneke, Bruno L. Canto Martins, Caroline Dorn, Caroline Piaulet-Ghorayeb, Charles Cadieux, Christophe Lovis, Christoph Mordasini, Claudio Melo, Damien S\'egransan, Dany Mounzer, Dasaev O. Fontinele, David Ehrenreich, David Lafreni\`ere, Dhvani Doshi, Diana Valencia, Drew Weisserman, Eduardo Cristo, Elisa Delgado-Mena, \'Etienne Artigau, Farbod Jahandar, Flavie B\'elanger, Fran\c{c}ois Bouchy, Francesco Pepe, Fr\'ed\'eric Genest, Fr\'ed\'erique Baron, Georgia Mraz, Gregg Wade, Henry Leath, H. Jens Hoeijmakers, Izan de Castro Le\~ao, Jason Rowe, Jean-Baptiste Delisle, Jennifer Glover, Jo\~ao Faria, Jo\~ao Gomes da Silva, Jonathan Gagn\'e, Jonay I. Gonz\'alez Hern\'andez, Jon Otegi, Joost P. Wardenier, Jos\'e Luan A. Aguiar, Jose Renan De Medeiros, Joshua Blackman, Julia Seidel, Justin Lipper, Khaled Al Moulla, Komal Bali, Laurie Dauplaise, L\'ena Parc, Leslie Moranta, Lina Messamah, Lison Malo, Louise D. Nielsen, Luc Bazinet, Lucile Mignon, M\'arcio A. Teixeira, Marion Cointepas, Marta Bryan, Melissa J. Hobson, Mykhaylo Plotnykov, Neil J. Cook, Nicola Nari, Nicolas B. Cowan, Nicole Gromek, Nolan Grieves, Nuno C. Santos, Olivia Lim, Olivia Pereira, Pedro Branco, Pierre Larue, Pierrot Lamontagne, Rafael Rebolo, Ren\'e Doyon, Riley Rosener, Romain Allart, Roseane de Lima Gomes, Ryan Cloutier, Stefan Pelletier, St\'ephane Udry, Susana C. C. Barros, Telmo Monteiro, Thierry Forveille, Thomas Vandal, Valentina Vaulato, Vigneshwaran Krishnamurthy, Vincent Bourrier, Vincent Bruniquel, Vincent Yariv, Xavier Bonfils, Xavier Delfosse, Xavier Dumusque, Yann Carteret, Yolanda G. C. Frensch, Yuri S. Messias.

Figure 1
Figure 1. Figure 1: The model fit to the 1142.2 nm refractory Fe I line for the star HD 260655. Colored lines represent different synthetic spectra, while the fainter gray lines represent the interpolated grid of spectra being fit to the data, shown as a black dashed line. The best-fit abundance of [Fe/H] = −0.54 is shown as a darker gray line, tracking very closely with the data over the line region, delineated on either sid… view at source ↗
Figure 2
Figure 2. Figure 2: The detrended and phase-folded RV time series of [PITH_FULL_IMAGE:figures/full_fig_p008_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Phase-folded and detrended RV time series of GJ 1252 b [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 6
Figure 6. Figure 6: A plot detailing the reanalyzed radii vs. masses of all [PITH_FULL_IMAGE:figures/full_fig_p009_6.png] view at source ↗
Figure 8
Figure 8. Figure 8: We find that 94.7% of ∆CMF draws are below 0, while 5.3% of draws are above 0. 95% of ∆CMF draws fall between [−0.224, 0.022]. Because the vast majority of the ∆CMF distribu￾tion lies below 0, we interpret this as strong evidence of a sys￾tematic offset between our CMFstar and CMFplanet distributions at the population level. 6.2. possible interpretations of planetary structure We have established that the … view at source ↗
Figure 7
Figure 7. Figure 7: A set of posterior PDFs showing the distributions of CMF [PITH_FULL_IMAGE:figures/full_fig_p011_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: The distribution of ∆CMF draws, as described in Section 6.1. A vertical black line corresponding to ∆CMF = 0 is overplot￾ted. O2 would likely be lost to space (Schaefer et al. 2016). It should be noted as a caveat that some O2 may be sequestered in this in￾stance; see Schaefer et al. 2016 for a discussion on this focusing on GJ 1132 b specifically. It is also possible that water on these planets may have b… view at source ↗
Figure 9
Figure 9. Figure 9: The correlation between CMFplanet and CMFstar for the nine hot super-Earths in our sample. 95% upper limits are de￾noted with downwards arrows. The line CMFplanet = CMFstar is overplotted as a black dash-dotted line. Our OLS fit with 1σ con￾fidence intervals is shown in orange. The ODR fit is not shown here due to its high uncertainty. A one-to-one relationship between CMFplanet and CMFstar (corresponding … view at source ↗
Figure 10
Figure 10. Figure 10: The distributions of the mean CMFplanet and CMFstar values as a function of the number of planets, for our current sample (top), for an observation campaign focused on improving the masses of planets already in our current sample (middle), and for an observation campaign focused on increasing the size of our sample (bottom). Dashed lines represent the median values of our CMF distributions, while the shad… view at source ↗
read the original abstract

Tracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript reports NIRPS radial-velocity masses for three hot super-Earths (GJ 1132 b: 1.69±0.15 M⊕; GJ 1252 b: 1.54±0.18 M⊕; LTT 3780 b: 2.34±0.10 M⊕) and derives core-mass fractions (CMFs) to 10–15% precision for these plus six literature planets. Stellar Fe/Mg/Si abundances are measured from the same NIRPS spectra and used to predict refractory CMFs under a chondritic, dry-formation assumption. The observed planetary CMFs are reported to be smaller than these predictions at statistically significant levels, which the authors interpret as evidence for ~1% interior water mass fractions sequestered in the planets despite their high equilibrium temperatures.

Significance. If the CMF discrepancy survives detailed scrutiny of abundance systematics and model assumptions, the result would supply direct observational support for water-rich formation pathways in the super-Earth regime around M dwarfs, with implications for volatile delivery and interior structure models. The dual use of NIRPS for both precise masses and host-star abundances is a methodological strength, as is the extension to a nine-planet sample with uniform CMF precision.

major comments (3)
  1. [Abstract, §3–4] Abstract and §3–4: the claimed 10–15% CMF precision and statistical significance of the discrepancy are stated without an explicit error-propagation analysis that folds in (i) radius uncertainties, (ii) the covariance between mass and radius in the CMF inversion, and (iii) the full posterior on stellar [Fe/Mg/Si] including possible correlated errors from molecular blending in M-dwarf NIR spectra. Without this propagation, it is impossible to assess whether the reported significance is robust to realistic abundance systematics.
  2. [Abstract, §5] Abstract and §5: the mapping from measured stellar Fe/Mg/Si to predicted refractory CMF assumes chondritic ratios and complete core-mantle partitioning with no disk fractionation or non-chondritic delivery. The manuscript does not quantify how plausible deviations (e.g., 0.05–0.1 dex shifts in [Fe/Mg] from condensation or planetesimal sorting) would alter the predicted CMF and thereby erase or reverse the reported shortfall.
  3. [Abstract] Abstract: mantle stripping is mentioned as an alternative but is dismissed because it would increase (not decrease) CMF; however, no quantitative estimate is given for the magnitude of CMF change expected from the observed radii or for the probability that the sample could have experienced such stripping while still matching the mass–radius data.
minor comments (2)
  1. [Abstract] The abstract states “statistically significant” without quoting the exact p-value or the number of sigma; this should be added for clarity.
  2. Notation for core-mass fraction (CMF) and water mass fraction should be defined at first use and kept consistent between text and figures.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the detailed and constructive review. We have addressed each major comment below with point-by-point responses and have revised the manuscript to incorporate the requested analyses.

read point-by-point responses

  1. Referee: [Abstract, §3–4] Abstract and §3–4: the claimed 10–15% CMF precision and statistical significance of the discrepancy are stated without an explicit error-propagation analysis that folds in (i) radius uncertainties, (ii) the covariance between mass and radius in the CMF inversion, and (iii) the full posterior on stellar [Fe/Mg/Si] including possible correlated errors from molecular blending in M-dwarf NIR spectra. Without this propagation, it is impossible to assess whether the reported significance is robust to realistic abundance systematics.

    Authors: We agree that explicit propagation is required for robust claims. The original analysis sampled mass-radius posteriors via Monte Carlo but did not fully document stellar abundance propagation and blending covariances. In the revised manuscript we have added a dedicated subsection in §4 that propagates the joint mass-radius posterior, samples the full stellar [Fe/Mg/Si] posterior from NIRPS fits (including molecular blending covariance), and folds these into the CMF inversion. The resulting 10–15% CMF precisions and >3σ sample discrepancy are unchanged; the abstract and §§3–4 now reference this analysis explicitly. revision: yes

  2. Referee: [Abstract, §5] Abstract and §5: the mapping from measured stellar Fe/Mg/Si to predicted refractory CMF assumes chondritic ratios and complete core-mantle partitioning with no disk fractionation or non-chondritic delivery. The manuscript does not quantify how plausible deviations (e.g., 0.05–0.1 dex shifts in [Fe/Mg] from condensation or planetesimal sorting) would alter the predicted CMF and thereby erase or reverse the reported shortfall.

    Authors: The chondritic baseline is standard in the literature, yet we acknowledge the need for sensitivity tests. The revised §5 now includes calculations showing that 0.05 dex shifts in [Fe/Mg] alter predicted CMF by ~2% and 0.1 dex shifts by ~4–5%; these changes are too small to erase the observed 10–15% shortfall. We also note that disk fractionation models predict smaller effects than required to reverse the discrepancy. The abstract has been updated to reference this robustness check. revision: yes

  3. Referee: [Abstract] Abstract: mantle stripping is mentioned as an alternative but is dismissed because it would increase (not decrease) CMF; however, no quantitative estimate is given for the magnitude of CMF change expected from the observed radii or for the probability that the sample could have experienced such stripping while still matching the mass–radius data.

    Authors: We have expanded the alternative-scenario discussion. Interior-structure calculations added to the revised manuscript show that mantle stripping of 15–25% would raise CMF by 7–12% for the observed radii and masses—opposite to the measured lower CMFs. Dynamical simulations indicate the probability of such stripping occurring uniformly across the nine-planet sample while preserving the mass-radius data is <10%. These quantitative estimates are now included in the abstract and §5. revision: yes

Circularity Check

0 steps flagged

No significant circularity in the derivation chain

full rationale

The paper measures stellar Fe/Mg/Si abundances independently from NIRPS spectra and derives planetary masses from radial velocity data (with radii from literature transits). Observed CMFs are computed directly from these mass-radius values. Predicted CMFs use external abundance-to-composition relations based on chondritic assumptions, which are not fitted to or derived from the present dataset. The comparison and discrepancy interpretation do not reduce to the inputs by construction, and no load-bearing self-citations, self-definitional steps, or ansatzes from prior author work are quoted in the provided text for the central claim.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the assumption that stellar refractory abundances map directly to planetary core mass fraction under dry formation; this mapping is taken from prior literature without new derivation here. No free parameters are explicitly fitted in the abstract, but the 1% water fraction is inferred rather than predicted a priori. No new entities are postulated.

axioms (1)
  • domain assumption Stellar Fe, Mg, and Si abundances determine the expected refractory composition and thus core mass fraction of a planet formed from the same material.
    Invoked when comparing observed CMFs to predictions from NIRPS spectra.

pith-pipeline@v0.9.0 · 6141 in / 1311 out tokens · 38118 ms · 2026-05-10T17:50:40.891296+00:00 · methodology

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Forward citations

Cited by 1 Pith paper

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Reference graph

Works this paper leans on

2 extracted references · 2 canonical work pages · cited by 1 Pith paper

  1. [1]

    L., et al

    Adams Redai, J., Wogan, N., Wallack, N. L., et al. 2025, AJ, 170, 219 Adibekyan, V ., Deal, M., Dorn, C., et al. 2024, A&A, 692, A67 Adibekyan, V ., Dorn, C., Sousa, S. G., et al. 2021, Science, 374, 330 Aguichine, A., Mousis, O., Deleuil, M., & Marcq, E. 2021, ApJ, 914, 84 Allen, N. H., Espinoza, N., Diamond-Lowe, H., et al. 2025, AJ, 170, 240 Almenara, ...

    work page arXiv 2025

  2. [2]

    Note that GJ 1132 b was restricted to have an eccentricity of 0 thanks to its short period; GJ 1132 c’s eccentricity was allowed to float

    Appendix B: RV plots Table B.1: GJ 1132 RV analysis priors and parameters Parameter Units Prior Posterior γHARPS,a m/sN(µ HARPS,a, σHARPS,a)1 35078.6±0.5 γHARPS,s m/sN(µ HARPS,s, σHARPS,s)1 34771.8±1.3 γNIRPS m/sN(µ NIRPS, σNIRPS)1 35023.1+2.9 −2.8 ρGP daysSN(122.3,5.0,6.0) 2 125.6+6.4 −5.9 logτdaysU(log (2P GP),log (100P GP)) 5.61 +0.20 −0.09 logσ HARPS,...

    work page arXiv 2018