Year: 2025
Type: article
Abstract: Stellar activity remains one of the primary challenges in the detection and characterization of low-mass exoplanets, as it can induce radial velocity (RV) variations that mask or mimic planetary signals. Identifying reliable activity proxies is essential in order to distinguish stellar variability from genuine planetary signatures. In this study, we examine the variability of the chromospheric He I D3 line in high-resolution solar spectra and assess its potential as an activity indicator. We find a strong correlation between the He I D3 line intensity variation and the Sun’s unsigned magnetic flux derived from Solar Dynamics Observatory/Helioseismic and Magnetic Imager data as well as with the solar RVs. Our results suggest that the He I D3 line offers a promising and straightforward proxy for magnetic activity, which may complement existing stellar activity indicators. Its inclusion could help disentangle stellar signals in RV measurements and ultimately improve the detection of Earth-like exoplanets.
Source: The Astrophysical Journal
Authors: Momo Ellwarth, Joe Llama, Lily L. Zhao, John M. Brewer, Andrew Szymkowiak, Rachael M. Roettenbacher, James T. Sikora, Alex S. Polanski, Steven H. Saar
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G1684164280, Tunable Fabry-Perot Frequency Comb for Precision Doppler Measurements, Collaborative Research: EXPRES Search for Low Mass Planets, MRI Development: EXPRES - the Extreme Precision Spectrograph for Exoplanet Studies, The Planet Whisperer: Toward Characterizing Low-mass Planets from Doppler Surveys in the Presence of Stellar Activity
OpenAlex ID: W7106020411