M2K. II. A triple-planet system orbiting HIP 57274

Debra A. Fischer, Eric Gaidos, Andrew W. Howard, Matthew J. Giguere, John A. Johnson, Geoffrey W. Marcy, Jason T. Wright, Jeff A. Valenti, Nikolai Piskunov, Kelsey I. Clubb, Howard Isaacson, Kevin Apps, Sebastien Lepine, Andrew Mann, John Moriarty, John Brewer, Julien F.P. Spronck, Christian Schwab, Andrew Szymkowiak

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with Msin i = 11.6 M (0.036M Jup), an orbital period of 8.135 0.004 days, and slightly eccentric orbit e = 0.19 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has Msin i = 0.4M Jup with an orbital period of 32.0 0.02 days in a nearly circular orbit (e = 0.05 0.03). The third planet has Msin i = 0.53M Jup with an orbital period of 432 8 days (1.18 years) and an eccentricity e = 0.23 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M that have been detected with Doppler surveys. We find that 56% 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% 8%, that are members of Doppler-detected, multi-planet systems.

Original languageEnglish (US)
Article number21
JournalAstrophysical Journal
Volume745
Issue number1
DOIs
StatePublished - Jan 20 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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