Thursday, October 29, 2015

WASP-41 and WASP-47 hot Jupiter Systems Have Other Giant Exoplanets

Hot Jupiters with relatives: discovery of additional planets in orbit around WASP-41 and WASP-47


Neveu-VanMalle et al


We report the discovery of two additional planetary companions to WASP-41 and WASP-47. WASP-41 c is a planet of minimum mass 3.18 ± 0.20 MJup, eccentricity 0.29 ± 0.02 and orbiting in 421 ± 2 days. WASP-47 c is a planet of minimum mass 1.24 ± 0.22 MJup, eccentricity 0.13 ± 0.10 and orbiting in 572 ± 7 days. Unlike most of the planetary systems including a hot Jupiter, these two systems with a hot Jupiter have a long period planet located at only ∼1 AU from their host star. WASP-41 is a rather young star known to be chromospherically active. To differentiate its magnetic cycle from the radial velocity effect due the second planet, we use the emission in the Hα line and find this indicator well suited to detect the stellar activity pattern and the magnetic cycle. The analysis of the Rossiter-McLaughlin effect induced by WASP-41 b suggests that the planet could be misaligned, though an aligned orbit cannot be excluded. WASP-47 has recently been found to host two additional transiting super Earths. With such an unprecedented architecture, the WASP-47 system will be very important for the understanding of planetary migration.

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