Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres
arXiv:2507.21290 · doi:10.1051/0004-6361/202452856
Abstract
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.
16 pages, including 10 figures and 3 tables. Submitted 04 November 2024 and accepted 15 January 2025 to Astronomy & Astrophysics (A&A)
References in corpus (28)
- Array Programming with NumPy
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- The Transiting Exoplanet Survey Satellite
- SOAP 2.0: A tool to estimate the photometric and radial velocity variations induced by stellar spots and plages
- Search for exoplanets with the radial-velocity technique: quantitative diagnostics of stellar activity
- SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
- Exoplanet HD 209458b : Evaporation strengthened
- Atmospheric escape from HD 189733b observed in HI Lyman-alpha: detailed analysis of HST/STIS September 2011 observations
- New observations of the extended hydrogen exosphere of the extrasolar planet HD209458b
- High-resolution confirmation of an extended helium atmosphere around WASP-107b
- Confirmation of WASP-107b's extended Helium atmosphere with Keck II/NIRSPEC
- The Upper Edge of the Neptune Desert Is Stable Against Photoevaporation
- YARARA: Significant improvement of RV precision through post-processing of spectral time-series
- The GAPS programme at TNG XXII. The GIARPS view of the extended helium atmosphere of HD189733 b accounting for stellar activity
- Radial Velocity Fitting Challenge. I. Simulating the data set including realistic stellar radial-velocity signals
- RASSINE: Interactive tool for normalising stellar spectra I. Description and performance of the code
- Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultra-Narrowband Photometry
- The post-transit tail of WASP-107b observed at 10830A
- Stellar Surface Magneto-Convection as a Source of Astrophysical Noise III. Sun-as-a-star Simulations and Optimal Noise Diagnostics
- Caught in the Act: Core-powered Mass-loss Predictions for Observing Atmospheric Escape
- YARARA V2: Reaching sub m/s precision over a decade using PCA on line-by-line RVs
- MOVES III. Simultaneous X-ray and ultraviolet observations unveiling the variable environment of the hot Jupiter HD 189733b
- Automatic model-based telluric correction for the ESPRESSO data reduction software. Model description and application to radial velocity computation
- Stellar signal components seen in HARPS and HARPS-N solar radial velocities
- Characterisation of the upper atmospheres of HAT-P-32 b, WASP-69 b, GJ 1214 b, and WASP-76 b through their He I triplet absorption
- Combined analysis of stellar and planetary absorption lines via global forward-transit simulations
- Estimating Magnetic Filling Factors From Simultaneous Spectroscopy and Photometry: Disentangling Spots, Plage, and Network
- NIGHT: a compact, near-infrared, high-resolution spectrograph to survey helium in exoplanet systems