Pith Number

pith:A2AVUXK5

pith:2026:A2AVUXK53RWECZMSSWAWT2YJ33

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Three-dimensional transport-induced chemistry on temperate sub-Neptune K2-18b, Part II: the combined effects of atmospheric dynamics and chemical reactions

Duncan Christie, Jiachen Liu, Jun Yang, Krisztian Kohary

Vertical transport on K2-18b lifts CO and CO2 abundances in the upper atmosphere to ~10^{-3} while equilibrium chemistry predicts levels below 10^{-15}.

arxiv:2604.07987 v2 · 2026-04-09 · astro-ph.EP

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Record completeness

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4 Citations open

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Claims

C1strongest claim

Vertical transport affects the chemical structure significantly, making CO2 and CO more abundant (~10^{-3}) in the upper atmosphere compared to the chemical equilibrium abundance (<10^{-15}), and horizontal winds further homogenize the chemical composition zonally in this region.

C2weakest assumption

That the chosen 180x solar metallicity, the specific chemical network, and the GCM resolution together produce realistic chemical timescales and transport without missing key processes such as clouds or photochemistry.

C3one line summary

3D GCM modeling of K2-18b finds that transport-induced disequilibrium raises upper-atmosphere CO and CO2 to ~10^{-3} while horizontal winds homogenize composition, yielding spectra that match JWST observations.

References

3 extracted · 3 resolved · 0 Pith anchors

[1] S., et al., 2016, A&A, 595, A36 BaeyensR.,KoningsT.,VenotO.,CaroneL.,DecinL.,2022,MNRAS,512, 4877 Barrier E 2016 · doi:10.5281/zenodo.8305232

[2] ed RS Stepleman et al Hu R., Damiano M., 2021, Deep Characterization of the Atmosphere of a Temperate Sub-Neptune, JWST Proposal. Cycle 1, ID. #2372 Hu R., Damiano M., Scheucher M., Kite E., Seager S. 2021 · doi:10.1007/978-94-010-1799-2_4

[3] Results are derived from simulated data over the first 100 d, in which the horizontal temperature contrast begins to form, with an output interval of 10 d 2026

Receipt and verification

First computed	2026-06-03T14:05:47.281787Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

06815a5d5ddc6c416592958169eb09dec54034c38e3b7c6330f8955b73204af9

Aliases

arxiv: 2604.07987 · arxiv_version: 2604.07987v2 · doi: 10.48550/arxiv.2604.07987 · pith_short_12: A2AVUXK53RWE · pith_short_16: A2AVUXK53RWECZMS · pith_short_8: A2AVUXK5

Agent API

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Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/A2AVUXK53RWECZMSSWAWT2YJ33 \
  | jq -c '.canonical_record' \
  | python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: 06815a5d5ddc6c416592958169eb09dec54034c38e3b7c6330f8955b73204af9

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "cab359cee9c8b0fdf29c69a3a77384b2ec7f8f5c1167d83097fbd503c261fa07",
    "cross_cats_sorted": [],
    "license": "http://creativecommons.org/licenses/by/4.0/",
    "primary_cat": "astro-ph.EP",
    "submitted_at": "2026-04-09T08:55:46Z",
    "title_canon_sha256": "5d4e530cdef2dd4f931f3d244a5365f0fd5f8e9c3826c78430e44cbcf1f35911"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2604.07987",
    "kind": "arxiv",
    "version": 2
  }
}