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

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

Astronomy and Astrophysics, Volume 614, id.A133, 9 pp.

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6
2018
Number of authors
25
IAC number of authors
1
Citations
48
Refereed citations
46
Description
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 yr. 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. The HARPS data used in this article are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/614/A133
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