Disentangling Planets and Stellar Activity for Gliese 667C
Gliese 667C is an M1.5V star with a multi-planet system, including planet candidates in the habitable zone (HZ).
The exact number of planets in the system is unclear, because the existing radial velocity (RV) measurements are known to contain contributions from stellar magnetic activity. Following our analysis of Gliese 581 (Robertson et al. 2014), we have analyzed the effect of stellar activity on the HARPS/HARPS-TERRA RVs of GJ 667C, finding significant RV-activity correlation when using the width (FWHM) of the HARPS cross-correlation function to trace magnetic activity.
When we correct for this correlation, we confirm the detections of the previously-observed planets b and c in the system, while simultaneously ascribing the RV signal near 90 days (“planet d”) to an artifact of the stellar rotation. We are unable to confirm the existence of the additional RV periodicities described in Anglada-Escude et al. (2013) in our activity-corrected data.
Paul Robertson (1 and 2), Suvrath Mahadevan (1 and 2 and 3) ((1) Department of Astronomy and Astrophysics, The Pennsylvania State University, (2) Center for Exoplanets & Habitable Worlds, The Pennsylvania State University, (3) The Penn State Astrobiology Research Center, The Pennsylvania State University)
(Submitted on 29 Aug 2014)
Comments: Accepted for publication in the Astrophysical Journal Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1409.0021 [astro-ph.EP] (or arXiv:1409.0021v1 [astro-ph.EP] for this version)
Submission history From: Paul Robertson [view email] [v1] Fri, 29 Aug 2014 20:04:10 GMT (672kb) http://arxiv.org/abs/1409.0021
