Reanalysis Of The Eclipses Of LHS 1140 c: No Evidence Of An Atmosphere And Implications For The Internal Structure Of The Planet
We present the reanalysis of three 15 micron JWST/MIRI secondary eclipses of LHS 1140 c, a warm super-Earth (Rp = 1.272 R⊕) in a 3.78-day orbit around an M4.5 dwarf.
We present a novel method for data reduction that leverages spatial derivatives of the point-spread function and compare it to widely used aperture photometry. Both methods yield eclipse depth consistent within 1 sigma of the values reported in the literature.
We measure an eclipse depth of 271+31−30 ppm corresponding to a brightness temperature of TB=595+33−34 K, consistent with a bare rock. The secondary eclipse occurs 4.1±0.8 minutes before the circular-orbit predicted time.
We explore the implications of our results on the internal structure of LHS 1140 c, the orbital architecture of the system and the possibility of future observations with JWST. We find a core-mass fraction (CMF) informed by the stellar abundances of refractory elements of 0.34±0.11, inflated compared to the CMF from radius and mass measurements, suggesting the possible presence of bulk volatiles in the interior.
Alexandra Rochon, Étienne Artigau, Drew Weisserman, Lisa Dang, René Doyon, Charles Cadieux, Ryan Cloutier
Comments: Submitted to AAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2510.11397 [astro-ph.EP] (or arXiv:2510.11397v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2510.11397
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Submission history
From: Alexandra Rochon
[v1] Mon, 13 Oct 2025 13:41:16 UTC (1,630 KB)
https://arxiv.org/abs/2510.11397
Astrobiology, Astronomy,
