WASP-189b: an ultra-hot Jupiter transiting the bright A star HR 5599 in a polar orbit

• Published in: arXiv.org 2018-09
• Main Authors: Anderson, D R, Temple, L Y, Nielsen, L D, Burdanov, A, Hellier, C, Bouchy, F, Brown, D J A, A Collier Cameron, Gillon, M, Jehin, E, Maxted, P F L, Pepe, F, Pollacco, D, Pozuelos, F J, Queloz, D, Ségransan, D, Smalley, B, A H M J Triaud, Turner, O D, Udry, S, West, R G
• Format: Article
• Language: English
• Subjects: Albedo; Extrasolar planets; Gas giant planets; Orbits; Polar orbits; Rocket launches; Satellites; Spectrographs; Stellar rotation; Transit
• ISSN: 2331-8422

We report the discovery of WASP-189b: an ultra-hot Jupiter in a 2.72-d transiting orbit around the \(V = 6.6\) A star WASP-189 (HR 5599). We detected periodic dimmings in the star's lightcurve, first with the WASP-South survey facility then with the TRAPPIST-South telescope. We confirmed that a planet is the cause of those dimmings via line-profile tomography and radial-velocity measurements using the HARPS and CORALIE spectrographs. Those reveal WASP-189b to be an ultra-hot Jupiter (\(M_{\rm P}\) = 2.13 \(\pm\) 0.28 \(M_{\rm Jup}\); \(R_{\rm P}\) = 1.374 \(\pm\) 0.082 \(R_{\rm Jup}\)) in a polar orbit (\(\lambda = 89.3 \pm 1.4^\circ\); \(\Psi = 90.0 \pm 5.8^\circ\)) around a rapidly rotating A6IV-V star (\(T_{\rm eff}\) = 8000 \(\pm\) 100 K; \(v_* \sin i_*\) \(\approx\) 100 km\, s\(^{-1}\)). We calculate a predicted equilibrium temperature of \(T_{\rm eql}\) = 2641 \(\pm\) 34 K, assuming zero albedo and efficient redistribution, which is the third hottest for the known exoplanets. WASP-189 is the brightest known host of a transiting hot Jupiter and the third-brightest known host of any transiting exoplanet. We note that of the eight hot-Jupiter systems with \(T_{\rm eff}\) \(>\) 7000 K, seven have strongly misaligned orbits, and two of the three systems with \(T_{\rm eff}\) \(\geq\) 8000 K have polar orbits (the third is aligned).