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author Mercier, Samson J.
Dumusque, Xavier
Bourrier, Vincent
Moulla, Khaled Al
Cretignier, Michael
Dethier, William
Curto, Gaspare Lo
Figueira, Pedro
Lovis, Christophe
Pepe, Francesco
Santos, Nuno C.
Udry, Stéphane
Wildi, François
Allart, Romain
Baron, Frédérique
Bouchy, François
Carmona, Andres
Cointepas, Marion
Doyon, René
Frensch, Yolanda
Grieves, Nolan
Mignon, Lucile
Nielsen, Louise D.
author_facet Mercier, Samson J.
Dumusque, Xavier
Bourrier, Vincent
Moulla, Khaled Al
Cretignier, Michael
Dethier, William
Curto, Gaspare Lo
Figueira, Pedro
Lovis, Christophe
Pepe, Francesco
Santos, Nuno C.
Udry, Stéphane
Wildi, François
Allart, Romain
Baron, Frédérique
Bouchy, François
Carmona, Andres
Cointepas, Marion
Doyon, René
Frensch, Yolanda
Grieves, Nolan
Mignon, Lucile
Nielsen, Louise D.
contents With more than a dozen significant detections, the helium triplet has emerged as a key tracer of evaporating exoplanet atmospheres. This near-infrared feature can be observed from the ground and holds great promise, especially with upcoming observations provided by new-generation instruments such as the Near Infrared Planet Searcher (NIRPS). However, as the helium triplet is also present in stellar spectra, careful removal of the average stellar contribution is necessary to accurately characterize the atmospheres of transiting exoplanets. In this study, we analyze multi-epoch observations of the Sun obtained with NIRPS to investigate the temporal variability of the helium triplet. Our findings reveal significant variability across different timescales, ranging from minutes to days. We identify telluric contamination and stellar activity as likely sources for the short-term and long-term variability, respectively. Importantly, we demonstrate that this variability has minimal impact on the retrieval of planetary parameters crucial to the study of atmospheric escape.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21290
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres
Mercier, Samson J.
Dumusque, Xavier
Bourrier, Vincent
Moulla, Khaled Al
Cretignier, Michael
Dethier, William
Curto, Gaspare Lo
Figueira, Pedro
Lovis, Christophe
Pepe, Francesco
Santos, Nuno C.
Udry, Stéphane
Wildi, François
Allart, Romain
Baron, Frédérique
Bouchy, François
Carmona, Andres
Cointepas, Marion
Doyon, René
Frensch, Yolanda
Grieves, Nolan
Mignon, Lucile
Nielsen, Louise D.
Earth and Planetary Astrophysics
With more than a dozen significant detections, the helium triplet has emerged as a key tracer of evaporating exoplanet atmospheres. This near-infrared feature can be observed from the ground and holds great promise, especially with upcoming observations provided by new-generation instruments such as the Near Infrared Planet Searcher (NIRPS). However, as the helium triplet is also present in stellar spectra, careful removal of the average stellar contribution is necessary to accurately characterize the atmospheres of transiting exoplanets. In this study, we analyze multi-epoch observations of the Sun obtained with NIRPS to investigate the temporal variability of the helium triplet. Our findings reveal significant variability across different timescales, ranging from minutes to days. We identify telluric contamination and stellar activity as likely sources for the short-term and long-term variability, respectively. Importantly, we demonstrate that this variability has minimal impact on the retrieval of planetary parameters crucial to the study of atmospheric escape.
title Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2507.21290