CFHT UM2025 - Presentation Details
Abstract Details
Title: A Thermometer for the Stars: Effective Temperature as a New Probe of Stellar Variability
Presenter: Étienne Artigau
Abstract:
The detection of stellar variability is traditionally based on specific activity indicators, such as coronal and chromospheric emission lines. In contrast, stellar effective temperature is typically regarded as a fundamental parameter rather than an activity probe. In this talk, I will present a novel approach for measuring disk-averaged temperature variations with sub-Kelvin precision, leveraging techniques inspired by precision radial velocity (pRV) analysis. This method uses the full spectral content rather than predefined lines and can be directly applied to high-resolution spectroscopic data without requiring any coding expertise, as it is available out-of-the-box within the open-source LBL framework. I will review its application to recent SPIRou observations, demonstrating its ability to recover rotation periods and temperature modulations in stars such as Barnard’s Star and AU Mic. I will also discuss its potential for ESPADONS and, in the near future, Wenaokeao. Additionally, I will highlight how this method enables the exploration of archival CFHT data for long-term stellar variability studies—though only a small fraction of available data has been analyzed so far. Beyond its role in characterizing stellar activity, effective temperature variations provide an excellent tool for training Gaussian process regressions to mitigate stellar activity in radial velocity analysis. Recent developments and refinements of the technique will be presented, showcasing its potential to improve the interpretation of exoplanet transit and radial velocity observations.