The Aligned Orbit of the Eccentric Warm Jupiter K2-232b

Songhu Wang, Joshua N. Winn, Brett C. Addison, Fei Dai, Malena Rice, Bradford Holden, Jennifer A. Burt, Xian Yu Wang, R. Paul Butler, Steven S. Vogt, Gregory Laughlin

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Measuring the obliquity distribution of stars hosting warm Jupiters may help us to understand the formation of close-orbiting gas giants. Few such measurements have been performed due to practical difficulties in scheduling observations of the relatively infrequent and long-duration transits of warm Jupiters. Here, we report a measurement of the Rossiter-McLaughlin effect for K2-232 b, a warm Jupiter on an 11.17 day orbit with an eccentricity of 0.26. The data were obtained with the Automated Planet Finder during two separate transits. The planet's orbit appears to be well aligned with the spin axis of the host star, with a projected spin-orbit angle of λ = -11.?1 ? 6.?6. Combined with the other available data, we find that high obliquities are almost exclusively associated with planets that either have an orbital separation greater than 10 stellar radii or orbit stars with effective temperatures hotter than 6000 K. This pattern suggests that the obliquities of the closest-orbiting giant planets around cooler stars have been damped by tidal effects.

Original languageEnglish (US)
Article number50
JournalAstronomical Journal
Issue number2
StatePublished - Aug 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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