The HARPS search for southern extra-solar planets. XLIII. A compact system of four super-Earth planets orbiting HD 215152

J.-B. Delisle, D. Ségransan, X. Dumusque, R. F. Diaz, F. Bouchy, C. Lovis, F. Pepe, S. Udry, R. Alonso, W. Benz, A. Coffinet, A. Collier Cameron, M. Deleuil, P. Figueira, M. Gillon, G. Lo Curto, M. Mayor, C. Mordasini, F. Motalebi, C. MoutouD. Pollacco, E. Pompei, D. Queloz, N. C. Santos, A. Wyttenbach

Research output: Contribution to journalArticlepeer-review

Abstract

We report the discovery of four super-Earth planets around HD 215152, with orbital periods of 5.76, 7.28, 10.86, and 25.2 d, and minimum masses of 1.8, 1.7, 2.8, and 2.9 M⊕ respectively. This discovery is based on 373 high-quality radial velocity measurements taken by HARPS over 13 years. Given the low masses of the planets, the signal-to-noise ratio is not sufficient to constrain the planet eccentricities. However, a preliminary dynamical analysis suggests that eccentricities should be typically lower than about 0.03 for the system to remain stable. With two pairs of planets with a period ratio lower than 1.5, with short orbital periods, low masses, and low eccentricities, HD 215152 is similar to the very compact multi-planet systems found by Kepler, which is very rare in radial-velocity surveys. This discovery proves that these systems can be reached with the radial-velocity technique, but characterizing them requires a huge amount of observations.
Original languageEnglish
Article numberA133
Number of pages9
JournalAstronomy & Astrophysics
Volume614
Early online date27 Jun 2018
DOIs
Publication statusPublished - Jun 2018

Keywords

  • Planets and satellites:general
  • Planets and satellites: detection
  • Planets and satellites: dynamical evolution and stability

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