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arXiv · 1707.06192

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

Vinesh Rajpaul·Lars A. Buchhave·Suzanne Aigrain
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Abstract

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$^{-3}$.

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Vinesh Rajpaul, Lars A. Buchhave, Suzanne Aigrain. 2017-07-19. Pinning down the mass of Kepler-10c: the importance of sampling and model comparison. https://doi.org/10.1093/mnrasl/slx116

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