Stellar activity mimics a habitable-zone planet around Kapteyn's star

@article{Robertson2015StellarAM,
  title={Stellar activity mimics a habitable-zone planet around Kapteyn's star},
  author={Paul Robertson and Arpita Roy and Suvrath Mahadevan Department of Astronomy and Astrophysics and Pennsylvania State University and Center for ExoplanetsHabitable Worlds and The Penn State Astrobiology Research Center},
  journal={arXiv: Earth and Planetary Astrophysics},
  year={2015}
}
Kapteyn's star is an old M subdwarf believed to be a member of the Galactic halo population of stars. A recent study has claimed the existence of two super-Earth planets around the star based on radial velocity (RV) observations. The innermost of these candidate planets--Kapteyn b (P = 48 days)--resides within the circumstellar habitable zone. Given recent progress in understanding the impact of stellar activity in detecting planetary signals, we have analyzed the observed HARPS data for… 

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