Updated Masses for the Gas Giants in the Eight-planet Kepler-90 System Via Transit-timing Variation and Radial Velocity Observations

Abstract The eight-planet Kepler-90 system exhibits the greatest multiplicity of planets found to date. All eight planets are transiting and were discovered in photometry from the NASA Kepler primary mission. The two outermost planets, g ( P g = 211 days) and h ( P h = 332 days), exhibit significant transit-timing variations (TTVs), but were only observed six and three times, respectively, by Kepler. These TTVs allow for the determination of planetary masses through dynamical modeling of the pair’s gravitational interactions, but the paucity of transits allows a broad range of solutions for the masses and orbital ephemerides. To determine accurate masses and orbital parameters for planets g and h, we combined 34 radial velocities (RVs) of Kepler-90, collected over a decade, with the Kepler transit data. We jointly modeled the transit times of the outer two planets and the RV time series, then used our two-planet model to predict their future times of transit. These predictions led us to recover a transit of Kepler-90 g with ground-based observatories in 2024 May. We then combined the 2024 transit and several previously unpublished transit times of planets g and h with the Kepler photometry and RV data to update the masses and linear ephemerides of the planets, finding masses for g and h of 15.0 ± 1.3 M ⊕ and 203 ± 16 M ⊕, respectively, from a Markov Chain Monte Carlo analysis. These results enable further insights into the architecturally rich Kepler-90 system and pave the way for atmospheric characterization with space-based facilities.

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Publication Details

Journal
The Astronomical Journal
Published
2025-08-05
DOI
https://doi.org/10.3847/1538-3881/ade67b
Citations
1
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
1.15

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article

Updated Masses for the Gas Giants in the Eight-planet Kepler-90 System Via Transit-timing Variation and Radial Velocity Observations

D. Crocker, Isa Khan, Ramotholo Sefako, M. Gillon et al.
1 citations
The Astronomical Journal
Stellar, planetary, and galactic studies
1.15
article

Updated Masses for the Gas Giants in the Eight-planet Kepler-90 System Via Transit-timing Variation and Radial Velocity Observations

D. Crocker, Isa Khan, Ramotholo Sefako, M. Gillon, Akihiko Fukui, Cristilyn N. Watkins, Daniel C. Fabrycky, Howard M. Relles, Karen A. Collins, Chris Stockdale, Adam Popowicz, Richard P. Schwarz, Khalid Barkaoui, Sarah Ballard, Avi Shporer, Robert Taylor, D. M. Terndrup, Joao Gregorio, Norio Narita, Lauren M. Weiss, John F. Kielkopf, Eric Agol, Allyson Bieryla, Fabian Rodriguez Frustaglia, D A Shaw, Kylee Carden, Adam Lark, Beibei Chen, Katherine Linnenkohl, Owen Mitchem, Amelie Heying
article en
1 citations

Abstract

Abstract The eight-planet Kepler-90 system exhibits the greatest multiplicity of planets found to date. All eight planets are transiting and were discovered in photometry from the NASA Kepler primary mission. The two outermost planets, g ( P g = 211 days) and h ( P h = 332 days), exhibit significant transit-timing variations (TTVs), but were only observed six and three times, respectively, by Kepler. These TTVs allow for the determination of planetary masses through dynamical modeling of the pair’s gravitational interactions, but the paucity of transits allows a broad range of solutions for the masses and orbital ephemerides. To determine accurate masses and orbital parameters for planets g and h, we combined 34 radial velocities (RVs) of Kepler-90, collected over a decade, with the Kepler transit data. We jointly modeled the transit times of the outer two planets and the RV time series, then used our two-planet model to predict their future times of transit. These predictions led us to recover a transit of Kepler-90 g with ground-based observatories in 2024 May. We then combined the 2024 transit and several previously unpublished transit times of planets g and h with the Kepler photometry and RV data to update the masses and linear ephemerides of the planets, finding masses for g and h of 15.0 ± 1.3 M ⊕ and 203 ± 16 M ⊕, respectively, from a Markov Chain Monte Carlo analysis. These results enable further insights into the architecturally rich Kepler-90 system and pave the way for atmospheric characterization with space-based facilities.

The Astronomical JournalVol. 170(3)
University of Notre Dame (US), Silesian University of Technology (PL), Planetary Science Institute (US), Oregon Research Institute (US), University of Louisville (US), University of Liège (BE), Hamilton College (US), University of Washington (US), University of Florida (US), University of Chicago (US), Astrobiology Center (JP), South African Radio Astronomy Observatory (ZA), Center for Astrophysics Harvard & Smithsonian (US), Instituto de Astrofísica de Canarias (ES), Observatori de l'Ebre (ES), Tokyo Metropolitan Komaba High School (JP), Universidade Politécnica de Portalegre (PT), Ellinbank Observatory (AU), The Ohio State University (US), Massachusetts Institute of Technology (US), The University of Tokyo (JP)
National Aeronautics and Space Administration, Heising-Simons Foundation, Fonds De La Recherche Scientifique - FNRS
Openalex Percentile: Top 17%
Stellar, planetary, and galactic studies
1.15
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