A hot super-Earth planet in the WASP-84 planetary system
G Maciejewski, J. Golonka, Weronika Łoboda, J. Ohlert, M. Fernández, F. J. Aceituno
Abstract
ABSTRACT Hot Jupiters have been perceived as loners devoid of planetary companions in close orbital proximity. However, recent discoveries based on space-borne precise photometry have revealed that at least some fraction of giant planets coexists with low-mass planets in compact orbital architectures. We report detecting a 1.446-d transit-like signal in the photometric time series acquired with the Transiting Exoplanet Survey Satellite (TESS) for the WASP-84 system, which is known to contain a hot Jupiter on a circular 8.5-d orbit. The planet was validated based on TESS photometry, and its signal was distilled in radial velocity measurements. The joint analysis of photometric and Doppler data resulted in a multiplanetary model of the system. With a mass of $15\, \mathrm{ M}_{{\oplus }}$, radius of $2\, \mathrm{ R}_{{\oplus }}$, and orbital distance of 0.024 au, the new planet WASP-84 c was classified as a hot super-Earth with the equilibrium temperature of 1300 K. A growing number of companions to hot Jupiters indicates that a non-negligible part of them must have formed under a quiescent scenario such as disc migration or in situ formation.