Challenges of the Doppler technique in the presence of stellar noise for the detection of Earth-like exoplanets

The Doppler method is still the most efficient one in detecting exoplanets around nearby stars which are amenable for further characterization. In particular, planets as small as the Earth can in principle be detected in hot orbits around sun-like stars (G and K dwarfs), and warm to temperate orbits around M-dwarfs (M<0.5 sun) in orbital periods from a few days to tens of days. Unfortunately, these time-scales are plagued with structured noise caused by stellar activity. In addition to this, one or more low mass planets can be packed in few week orbits, further adding confusion and complicating the analysis of the data. I will review the evolution of the data-analysis methods to put in context the current state-of-the art in exoplanet detection in the presence of stellar noise, and discuss some controversial recent cases. I will briefly discuss the different data-analysis and observational strategies being investigated to address these issues. I will finally introduce the #palereddot program (observations start Jan 16th, 2016) , which will obtain regularly sampled Doppler measurements with HARPS over 60 consecutive nights on a very nearby star, combined with quasi-simultaneous multi-band photometry obtained with two telescope networks (LCOGT and Gloria/Bootes). The program will also be used as an outreach opportunity to promote astronomy and exoplanets to the public. The results and data of this study (which will be released within a few months after the observations are obtained) shall be used as a benchmark case for future high precision programs.