Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

Abstract We present a new algorithm for precision radial velocity (pRV) measurements, line-by-line (LBL) approach designed to handle outlying spectral information in simple but efficient manner. The effectiveness of the LBL method is demonstrated on two data sets, one obtained with SPIRou Barnard’s star, and other High Accuracy Radial Planet Searcher (HARPS) Proxima Centauri. In near-infrared, provides framework meters-per-second-level accuracy pRV measurements despite challenges associated telluric absorption sky emission lines. confirm spanning 2.7 yr that candidate super-Earth 233 day orbit around star an artifact due combination time sampling activity. analysis Centauri HARPS post-upgrade alone easily recovers b signal also 2 σ detection recently confirmed 5 d planet, argues against presence c period 1900 days. provide evidence small, unaccounted systematic effects affecting HARPS-TERRA template-matching extraction long-period signals. Finally, very effective activity indicator, akin FWHM derived from cross-correlation function, which we infer rotation 92.1 − 3.5 + 4.2 days Proxima.