HD152843 b & c: the masses and orbital periods of a sub-Neptune and a super-puff Neptune
Abstract
We present the characterisation of the two transiting planets around HD 152843 (TOI 2319, TIC 349488688) using an intensive campaign of HARPS-N radial velocities, and two sectors of TESS data. These data reveal a unique and fascinating system: HD 152843 b and c have near equal masses of around 9 M⊕ but differing radii of 3.05 ± 0.11 R⊕ and 5.94 -0.16 +0.18 R⊕, respectively, and orbital periods of 11.62071-0.000106+9.6e-05 days and 19.502104 -8.5e-05 +7.4e-05 days. This indicates that HD 152843 c is in the lowest fifth-percentile in density of the known exoplanet population, and has the longest orbital period among these low density planets. Further, HD 152843 c’s radius places it in the 'Saturn valley', the observed lack of planets larger than Neptune, but smaller than Saturn. The orbital periods of these planets indicate they are near a 5 : 3 mean motion resonance, indicating the possibility of transit timing variations, and hints at the possibility of interaction with a third planet at some point in the evolution of this system. Further, the brightness of the host star and the low density of HD 152843 c make it a key target for atmospheric characterisation.
Citation
Nicholson , B A , Aigrain , S , Eisner , N L , Cretignier , M , Barragán , O , Kaye , L , Taylor , J , Owen , J , Mortier , A , Affer , L , Boschin , W , Buchhave , L A , Cameron , A C , Damasso , M , Fabrizio , L D , DiTomasso , V , Dumusque , X , Ghedina , A , Latham , D W , López-Morales , M , Lorenzi , V , Fiorenzano , A F M , Molinari , E , Pedani , M , Pinamonti , M , Rice , K & Sozzetti , A 2024 , ' HD152843 b & c: the masses and orbital periods of a sub-Neptune and a super-puff Neptune ' , Monthly Notices of the Royal Astronomical Society , vol. 532 , no. 4 , pp. 4632–4644 . https://doi.org/10.1093/mnras/stae1821
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Description
Funding: BN would like to acknowledge support from STFC Consolidated Grant ST/S000488/1 (PI Balbus), and the University of Southern Queensland SAGE program. BN would also like to thank Dr Su Wang for her insights on planetary system dynamics. ACC acknowledges support from STFC consolidated grant number ST/V000861/1, and UKSA grant number ST/X002217/1. The HARPS-N project has been funded by the Prodex Program of the Swiss Space Office (SSO), the Harvard University Origins of Life Initiative (HUOLI), the Scottish Universities Physics Alliance (SUPA), the University of Geneva, the Smithsonian Astrophysical Observatory (SAO), and the Italian National Astrophysical Institute (INAF), the University of St Andrews, Queen’s University Belfast, and the University of Edinburgh.Collections
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