WASP-169, WASP-171, WASP-175 and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-south

Abstract

We present the discovery of four new giant planets from \WASP, three hot Jupiters and one bloated sub-Saturn mass planet; WASP-169b, WASP-171b, WASP-175b and WASP-182b. Besides the discovery photometry from \wasp\ we use radial velocity measurements from CORALIE and HARPS as well as follow-up photometry from EulerCam, TRAPPIST-North and -South and SPECULOOS. WASP-169b is a low density Jupiter ($M=0.561\pm 0.061{\mathrm{M}}_{\mathrm{Jup}},R=1.304_{-0.073}^{+0.150}{\mathrm{R}}_{\mathrm{Jup}}$) orbiting a V=12.17 F8 sub-giant in a 5.611~day orbit. WASP-171b is a typical hot Jupiter ($M=1.084\pm 0.094{\mathrm{M}}_{\mathrm{Jup}},R=0.98_{-0.04}^{+0.07}{\mathrm{R}}_{\mathrm{Jup}}$, $P=3.82\mathrm{days}$) around a V=13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 years, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter ($M=0.99\pm 0.13{\mathrm{M}}_{\mathrm{Jup}},R=1.208\pm 0.081{\mathrm{R}}_{\mathrm{Jup}}$, $P=3.07\mathrm{days}$) around a V=12.04 F7 star, which possibly is part of a binary system with a star 7.9\arcsec\ away. WASP-182b is a bloated sub-Saturn mass planet ($M=0.148\pm 0.011{\mathrm{M}}_{\mathrm{Jup}},R=0.850\pm 0.030{\mathrm{R}}_{\mathrm{Jup}}$) around a metal rich V=11.98 G5 star ([Fe/H]$=0.27\pm 0.11$). With a orbital period of $P=3.377\mathrm{days}$, it sits right in the apex of the sub-Jovian desert, bordering the upper- and lower edge of the desert in both the mass-period and radius-period plane. WASP-169b, WASP-175b and WASP-182b are promising targets for atmospheric characterisation through transmission spectroscopy, with expected transmission signals of 121, 150 and 264 ppm respectively.

Published in MNRAS Aug 23, 2019