HARPS-N radial velocities confirm the low densities of the Kepler-9 planets
Abstract
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.
Citation
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
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Description
Funding: 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).Collections
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