Disentangling Planets and Stellar Activity for Gliese 667C

Abstract

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.

Accepted for publication in the Astrophysical Journal Letters

References in corpus (4)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Stellar Activity Masquerading as Planets in the Habitable Zone of the M dwarf Gliese 581
• The Na I D resonance lines in main sequence late-type stars

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