Pinning down the mass of Kepler-10c: the importance of sampling and model comparison

Journal article

Initial RV characterisation of the enigmatic planet Kepler-10c suggested a mass of $\sim17$ M$_\oplus$, which was remarkably high for a planet with radius $2.32$ R$_\oplus$; further observations and subsequent analysis hinted at a (possibly much) lower mass, but masses derived using RVs from two different spectrographs (HARPS-N and HIRES) were incompatible at a $3\sigma$-level. We demonstrate here how such mass discrepancies may readily arise from sub-optimal sampling and/or neglecting to model even a single coherent signal (stellar, planetary, or otherwise) that may be present in RVs. We then present a plausible resolution of the mass discrepancy, and ultimately characterise Kepler-10c as having mass $7.37_{-1.19}^{+1.32}$ M$_\oplus$, and mean density $3.14^{+0.63}_{-0.55}$ g cm$^{-3}$.

Authors: Rajpaul, V; Buchhave, L; Aigrain, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society: Letters
• Volume: 471
• Issue: 1
• Pages: L125-L130
• Publication date: 2017-07-22
• Acceptance date: 2017-07-19
• DOI: 10.1093/mnrasl/slx116
• EISSN: 1745-3933
• ISSN: 1745-3925
• Keywords: techniques: radial velocities; methods: data analysis; stars: activity; planetary systems; stars: individual: Kepler-10