A System of Three Super Earths Transiting the Late K-Dwarf GJ 9827 at Thirty Parsecs

Abstract

We report the discovery of three small transiting planets orbiting GJ 9827, a bright (K = 7.2) nearby late K-type dwarf star. GJ 9827 hosts a $1.62\pm 0.11$ $R_{\oplus }$ super Earth on a 1.2 day period, a $1.269_{-0.089}^{+0.087}$ $R_{\oplus }$ super Earth on a 3.6 day period, and a $2.07\pm 0.14$ $R_{\oplus }$ super Earth on a 6.2 day period. The radii of the planets transiting GJ 9827 span the transition between predominantly rocky and gaseous planets, and GJ 9827 b and c fall in or close to the known gap in the radius distribution of small planets between these populations. At a distance of 30 parsecs, GJ 9827 is the closest exoplanet host discovered by K2 to date, making these planets well-suited for atmospheric studies with the upcoming James Webb Space Telescope. The GJ 9827 system provides a valuable opportunity to characterize interior structure and atmospheric properties of coeval planets spanning the rocky to gaseous transition.

9 pages, 4 figures, 3 tables, Accepted to the Astronomical Journal, Improved Global Fit

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Cited by in corpus (17)

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• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• Clouds and Clarity: Revisiting Atmospheric Feature Trends in Neptune-size Exoplanets
• Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337)
• Masses and radii for the three super-Earths orbiting GJ 9827, and implications for the composition of small exoplanets
• Caught in the Act: Core-powered Mass-loss Predictions for Observing Atmospheric Escape
• Validation of 13 Hot and Potentially Terrestrial TESS Planets
• Water absorption in the transmission spectrum of the water-world candidate GJ9827d
• A multi-wavelength look at the GJ 9827 system -- No evidence of extended atmospheres in GJ 9827 b and d from HST and CARMENES data
• Planetary parameters, XUV environments and mass-loss rates for nearby gaseous planets with X-ray detected host-stars
• Non-detection of Helium in the Hot Jupiter WASP-48b
• Absence of extended atmospheres in low-mass star radius-gap planets GJ 9827 b, GJ 9827 d and TOI-1235 b
• $\pi$ Earth: a 3.14-day Earth-sized Planet from $\text{K2}$'s Kitchen Served Warm by the SPECULOOS Team
• K2-280b -- a low density warm sub-Saturn around a mildly evolved star
• A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2