Atmospheric constraints on GJ 1214 b from CRIRES+ and prospects for characterisation with ANDES

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Autori principali: Peláez-Torres, A., Sánchez-López, A., Jiang, C., Pallé, E., Orell-Miquel, J., López-Puertas, M., Parker, L. T., Diamond-Lowe, H.
Natura: Preprint
Pubblicazione: 2026
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author Peláez-Torres, A.
Sánchez-López, A.
Jiang, C.
Pallé, E.
Orell-Miquel, J.
López-Puertas, M.
Parker, L. T.
Diamond-Lowe, H.
author_facet Peláez-Torres, A.
Sánchez-López, A.
Jiang, C.
Pallé, E.
Orell-Miquel, J.
López-Puertas, M.
Parker, L. T.
Diamond-Lowe, H.
contents In this study, we aim to constrain the atmospheric composition of GJ 1214 b using all available transits observed with the upgraded CRIRES+ spectrograph at the VLT by searching for the signatures of water vapour, methane, and carbon dioxide. We analysed eight CRIRES+ transit datasets covering the K band (1.90-2.45 microns) at a resolving power of R ~ 100,000. We used the SysRem algorithm to correct for telluric and stellar contributions and employed the cross-correlation technique with templates from petitRADTRANS to search for H2O, CH4, and CO2. Injection-recovery tests across a grid of metallicities (Z) and cloud-deck pressures (pc) were performed to quantify detection limits. We also generated predictions for ANDES observations using end-to-end simulated datasets with EXoPLORE. We detect no significant H2O, CH4, or CO2 signatures. Injection-recovery tests show that such non-detections exclude atmospheres with low-altitude clouds and moderate or low metallicities. CH4 yields the tightest empirical limits, with CO2 unexpectedly ruling out intermediate metallicities (~ 100xsolar) with clouds deeper due to its rapidly rising opacity in compressed, high-Z atmospheres. Our constraints are in line with either a high-Z or a high-altitude aerosol layer, in agreement with recent JWST inferences. The combined analysis of eight CRIRES+ datasets provides the most stringent high-resolution constraints on the atmospheric properties of GJ 1214 b to date. Simulations of a single transit observed with ANDES on the ELT predict modest improvements for H2O, a substantially expanded detectable region for CH4, and the strongest gains for CO2, making the latter a particularly effective tracer for characterising high-metallicity atmospheres in sub-Neptunes.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14343
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Atmospheric constraints on GJ 1214 b from CRIRES+ and prospects for characterisation with ANDES
Peláez-Torres, A.
Sánchez-López, A.
Jiang, C.
Pallé, E.
Orell-Miquel, J.
López-Puertas, M.
Parker, L. T.
Diamond-Lowe, H.
Earth and Planetary Astrophysics
In this study, we aim to constrain the atmospheric composition of GJ 1214 b using all available transits observed with the upgraded CRIRES+ spectrograph at the VLT by searching for the signatures of water vapour, methane, and carbon dioxide. We analysed eight CRIRES+ transit datasets covering the K band (1.90-2.45 microns) at a resolving power of R ~ 100,000. We used the SysRem algorithm to correct for telluric and stellar contributions and employed the cross-correlation technique with templates from petitRADTRANS to search for H2O, CH4, and CO2. Injection-recovery tests across a grid of metallicities (Z) and cloud-deck pressures (pc) were performed to quantify detection limits. We also generated predictions for ANDES observations using end-to-end simulated datasets with EXoPLORE. We detect no significant H2O, CH4, or CO2 signatures. Injection-recovery tests show that such non-detections exclude atmospheres with low-altitude clouds and moderate or low metallicities. CH4 yields the tightest empirical limits, with CO2 unexpectedly ruling out intermediate metallicities (~ 100xsolar) with clouds deeper due to its rapidly rising opacity in compressed, high-Z atmospheres. Our constraints are in line with either a high-Z or a high-altitude aerosol layer, in agreement with recent JWST inferences. The combined analysis of eight CRIRES+ datasets provides the most stringent high-resolution constraints on the atmospheric properties of GJ 1214 b to date. Simulations of a single transit observed with ANDES on the ELT predict modest improvements for H2O, a substantially expanded detectable region for CH4, and the strongest gains for CO2, making the latter a particularly effective tracer for characterising high-metallicity atmospheres in sub-Neptunes.
title Atmospheric constraints on GJ 1214 b from CRIRES+ and prospects for characterisation with ANDES
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2602.14343