2025RNAAS...9..127U

I present an analysis of the stellar line variability of WASP-107, focusing on the metastable helium triplet at 1083 nm (He I*), which has become a key tracer of atmospheric escape in exoplanets. With high-resolution spectra from Canada-France-Hawaii Telescope/SPIRou collected over approximately one year. I asses the out-of-transit variability of He I* and nearby stellar features. An injection and recovery test demonstrates equivalent widths are reliably recovered above input depths of 0.005 nm, with low signal-to-noise ratios leading to slight systematic underestimation. The observed upper limit variability in three lines is 1.8%, 2.6%, and 2.0%, respectively, while nearby Mg I and Si I lines vary by 1.2%, including both stellar and instrumental effects. These results underscore the importance of quantifying variability in the triplet to accurately interpret absorption signals.