HARPS-N radial velocities confirm the low densities of the Kepler-9 planets
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We investigated the discrepancy between planetary mass determinations using the transit timing variations (TTVs) and radial velocities (RVs),by analysing the multiplanet system Kepler-9. Despite being the first system characterized with TTVs, there are several discrepant solutions in the literature, with those reporting lower planetary densities being apparently in disagreement with high-precision RV observations. To resolve this, we gathered HARPS-N RVs at epochs that maximized the difference between the predicted RV curves from discrepant solutions inthe literature. We also reanalysed the full Kepler data set and performed a dynamical fit, within a Bayesian framework, using the newly derived central and duration times of the transits. We compared these results with the RV data and found that our solution better describes the RV observations, despite the masses of the planets being nearly half that presented in the discovery paper. We therefore confirm that the TTV method can provide mass determinations that agree with those determined using high-precision RVs. The low densities of the planets place them in the scarcely populated region of the super-Neptunes/inflated sub-Saturns in the mass-radius diagram.
Borsato , L , Malavolta , L , Piotto , G , Buchhave , L A , Mortier , A , Rice , K , Cameron , A C , Coffinet , A , Sozzetti , A , Charbonneau , D , Cosentino , R , Dumusque , X , Figueira , P , Latham , D W , Lopez-Morales , M , Mayor , M , Micela , G , Molinari , E , Pepe , F , Phillips , D , Poretti , E , Udry , S & Watson , C 2019 , ' HARPS-N radial velocities confirm the low densities of the Kepler-9 planets ' , Monthly Notices of the Royal Astronomical Society , vol. 484 , no. 3 , pp. 3233-3243 . https://doi.org/10.1093/mnras/stz181
Monthly Notices of the Royal Astronomical Society
© 2019, the Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with the publisher's policies. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/stz181
DescriptionFunding: European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement number 313014 (ETAEARTH) and the UK Science & Technology Facilities Council (STFC) consolidated grant number ST/R000824/1 (CC).
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