Minimizing the bias in exoplanet detection - application to radial velocities of LHS 1140
A rocky planet orbiting LHS 1140 with a period of 24.7d has been found based on the discovery of transits in its light and high precision radial velocity data (Dittmann et al. 2017). This discovery by two independent methods is an observational tour-de-force, however, we find that a conservative analysis of the data gives a different solution. A three planet system is apparent in the radial velocity data based on our diagnosis of stellar activity. We encourage further targeted photometric and radial velocity observations in order to constrain the mini-Neptune and super-Earth mass objects apparently causing the 3.8 and 90 day radial velocity signals. We use our package Agatha (this https URL) to provide a comprehensive strategy to disentangle planetary signals from stellar activity in radial velocity data.
This appears to be independent from the Charbonneau study. This study finds evidence of 3 planets -- the already detected planet, a second planet at 92 days, and a third at 3.8 days, but they're less confident about the third planet. So since we have independent detection (and transits, most notably) of the 3.8 day planet from Charbonneau et al, this would seem to secure LHS 1140 as a 3-planet system.