The GAPS programme at TNG LXXXII. The first atmospheric investigation of the gas giant WASP-13b at high resolution with GIARPS
Abstract
Low-density transiting gas giant exoplanets are key benchmarks for atmospheric studies. Despite their large-scale heights, many of them remain poorly characterised. We present the first atmospheric investigation at high-resolution of the inflated (Rp∼1.4 RJ), hot Jupiter (T∼1500$ \mathrm{K}$) WASP-13 b aiming at constraining its atmospheric composition and refine its orbital geometry. We analysed four transits observed with GIARPS at the TNG. Updated stellar and planetary parameters were re-derived from the most precise literature values, and a new Rossiter-McLaughlin analysis was performed to measure the projected spin-orbit angle (λ) and stellar rotational velocity (vsini⋆). Atmospheric signals were searched using high-resolution spectroscopy, both with cross-correlation and single-line analyses, targeting key atomic and molecular species (e.g. \ion{He}{I}, Hα, \ion{Na}{I}, H2O, CO). We find a well-aligned orbit (λ = 2.7±1.1∘) and vsini⋆ = 4.5±0.1 km s−1, improving upon previous constraints. No significant atmospheric absorption is detected in either VIS or NIR data. Injection-and-recovery tests exclude an isothermal atmosphere with metallicity [M/H]≲10×[M/H]⊙ and simultaneously a grey cloud top pressure Pcloud≳10 mbar, under the assumption of chemical equilibrium. WASP-13 b appears to belong to the class of low-density hot Jupiters with weak or featureless transmission spectra, most likely shaped by the presence of high-altitude clouds. Although a highly metal-enriched atmosphere cannot be fully excluded, current evidence disfavours this scenario. Further observations with next-generation facilities will be essential to characterise the atmospheric properties of this challenging target.
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BibTeX
@misc{sicilia2026gaps,
title = {{The GAPS programme at TNG LXXXII. The first atmospheric investigation of the gas giant WASP-13b at high resolution with GIARPS}},
author = {D. Sicilia and M. Basilicata and G. Guilluy and G. Scandariato and F. Borsa and C. Di Maio and M. Brogi and A. Chiavassa and L. Fossati and F. Amadori and P. Giacobbe and A. S. Bonomo and A. Sozzetti and L. Mancini and G. Andreuzzi and S. Colombo and V. Fardella and A. Ghedina and G. Mantovan and G. Piccinini},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12677},
eprint = {2610.12677},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12677},
}
RIS
TY - UNPB
TI - The GAPS programme at TNG LXXXII. The first atmospheric investigation of the gas giant WASP-13b at high resolution with GIARPS
AU - D. Sicilia
AU - M. Basilicata
AU - G. Guilluy
AU - G. Scandariato
AU - F. Borsa
AU - C. Di Maio
AU - M. Brogi
AU - A. Chiavassa
AU - L. Fossati
AU - F. Amadori
AU - P. Giacobbe
AU - A. S. Bonomo
AU - A. Sozzetti
AU - L. Mancini
AU - G. Andreuzzi
AU - S. Colombo
AU - V. Fardella
AU - A. Ghedina
AU - G. Mantovan
AU - G. Piccinini
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.12677
UR - https://arxiv.org/abs/2610.12677
AB - Low-density transiting gas giant exoplanets are key benchmarks for atmospheric studies. Despite their large-scale heights, many of them remain poorly characterised. We present the first atmospheric investigation at high-resolution of the inflated (R_p∼1.4 R_J), hot Jupiter (T∼1500$ \mathrm{K}$) WASP-13 b aiming at constraining its atmospheric composition and refine its orbital geometry. We analysed four transits observed with GIARPS at the TNG. Updated stellar and planetary parameters were re-derived from the most precise literature values, and a new Rossiter-McLaughlin analysis was performed to measure the projected spin-orbit angle (λ) and stellar rotational velocity (vsini_⋆). Atmospheric signals were searched using high-resolution spectroscopy, both with cross-correlation and single-line analyses, targeting key atomic and molecular species (e.g. \ion{He}{I}, Hα, \ion{Na}{I}, H_2O, CO). We find a well-aligned orbit (λ = 2.7±1.1^∘) and vsini_⋆ = 4.5±0.1 km s^−1, improving upon previous constraints. No significant atmospheric absorption is detected in either VIS or NIR data. Injection-and-recovery tests exclude an isothermal atmosphere with metallicity [M/H]≲10×[M/H]_⊙ and simultaneously a grey cloud top pressure P_cloud≳10 mbar, under the assumption of chemical equilibrium. WASP-13 b appears to belong to the class of low-density hot Jupiters with weak or featureless transmission spectra, most likely shaped by the presence of high-altitude clouds. Although a highly metal-enriched atmosphere cannot be fully excluded, current evidence disfavours this scenario. Further observations with next-generation facilities will be essential to characterise the atmospheric properties of this challenging target.
ER -