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Description
We report the discovery of four super-earth planets around HD215152, with orbital periods of 5.76, 7.28, 10.86, and 25.2d, and minimum masses of 1.8, 1.7, 2.8, and 2.9M_Earth_ respectively. This discovery is based on 373 high quality radial velocity measurements taken by HARPS over thirteen years. Given the low masses of the planets, the S/N is not sufficient to constrain the planets 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 smaller than 1.5, with short orbital periods, small masses, and small eccentricities, HD215152 is similar to the very compact multi-planet systems found by Kepler, and very rare in RV surveys. This discovery proves that those systems are reachable with the RV technique, however they require a huge amount of observations to be characterized.
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