Radial velocity follow-up of GJ1132 with HARPS: A precise mass for planet b and the discovery of a second planet

BONFILS, X.; ALMENARA, J.-M.; CLOUTIER, R.; WÜNSCHE, A.; ASTUDILLO-DEFRU, N.; BERTA-THOMPSON, Z.; BOUCHY, F.; CHARBONNEAU, D.; DELFOSSE, X.; DÍAZ, R.F.; DITTMANN, J.; DOYON, R.; FORVEILLE, T.; IRWIN, J.; LOVIS, C.; MAYOR, M.; MENOU, K.; MURGAS, F.; NEWTON, E.; PEPE, F.; SANTOS, N.C.; UDRY, S.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Año: 2018 vol. 618

0004-6361

The source GJ1132 is a nearby red dwarf known to host a transiting Earth-size planet. After its initial detection, we pursued an intense follow-up with the HARPS velocimeter. We now confirm the detection of GJ1132b with radial velocities alone. We refined its orbital parameters, and in particular, its mass (m b = 1.66 ± 0.23 M), density (ρ b = 6.3 ± 1.3 g cm -3 ), and eccentricity (e b < 0.22; 95%). We also detected at least one more planet in the system. GJ1132c is a super-Earth with period P c = 8.93 ± 0.01 days and minimum mass m c sini c = 2.64 ± 0.44 M. Receiving about 1.9 times more flux than Earth in our solar system, its equilibrium temperature is that of a temperate planet (T eq = 230-300 K for albedos A = 0.75 - 0.00), which places GJ1132c near the inner edge of the so-called habitable zone. Despite an a priori favorable orientation for the system, Spitzer observations reject most transit configurations, leaving a posterior probability