Kepler-102: Masses and Compositions for a Super-Earth and Sub-Neptune Orbiting an Active Star

Casey Brinkman*, James Cadman, Lauren Weiss, Eric Gaidos, Ken Rice, Daniel Huber, Zachary R. Claytor, Aldo S. Bonomo, Lars A. Buchhave, Andrew Collier Cameron, Rosario Cosentino, Xavier Dumusque, Aldo F Martinez Fiorenzano, Adriano Ghedina, Avet Harutyunyan, Andrew Howard, Howard Isaacson, David W. Latham, Mercedes Lopez-Morales, Luca MalavoltaGiuseppina Micela, Emilio Molinari, Francesco Pepe, David F Philips, Ennio Poretti, Alessandro Sozzetti, Stephane Udry

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Radial velocity (RV) measurements of transiting multiplanet systems allow usto understand the densities and compositions of planets unlike those in theSolar System. Kepler-102, which consists of 5 tightly packed transitingplanets, is a particularly interesting system since it includes a super-Earth(Kepler-102d) and a sub-Neptune-sized planet (Kepler-102e) for which masses canbe measured using radial velocities. Previous work found a high density forKepler-102d, suggesting a composition similar to that of Mercury, whileKepler-102e was found to have a density typical of sub-Neptune size planets;however, Kepler-102 is an active star, which can interfere with RV massmeasurements. To better measure the mass of these two planets, we obtained 111new RVs using Keck/HIRES and TNG/HARPS-N and modeled Kepler-102's activityusing quasi-periodic Gaussian Process Regression. For Kepler-102d, we report amass upper limit of Md<5.3 M⊕ [95\% confidence], a best-fitmass of Md=2.5 ± 1.4 M⊕, and a density of ρd=5.6± 3.2 g/cm3 which is consistent with a rocky composition similar indensity to the Earth. For Kepler-102e we report a mass of Me=4.7 ± 1.7M⊕ and a density of ρe=1.8 ± 0.7 g/cm3. Thesemeasurements suggest that Kepler-102e has a rocky core with a thick gaseousenvelope comprising 2-4% of the planet mass and 16-50% of its radius. Our studyis yet another demonstration that accounting for stellar activity in stars withclear rotation signals can yield more accurate planet masses, enabling a morerealistic interpretation of planet interiors.
Original languageEnglish
Article number74
Pages (from-to)1-14
Number of pages14
JournalAstronomical Journal
Issue number2
Publication statusPublished - 27 Jan 2023

Keywords / Materials (for Non-textual outputs)

  • astro-ph.EP
  • astro-ph.SR


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