Optical phase curve of the ultra-hot Jupiter WASP-121b
Heng, K.; Ehrenreich, D.; Lendl, M.; Lovis, C.; Nascimbeni, V.; Ricker, G. R.; Seager, S.; Udry, S.; Allart, R.; Pepe, F.; Bourrier, V.; Jenkins, J.; Vanderspek, R.; Dumusque, X.; Murgas, F.; Wyttenbach, A.; Astudillo-Defru, N.; Pino, L.; Cretignier, M.; Lavie, B.; Segransan, D.; Caldwell, D. A.; Kitzmann, D.; Henze, C. E.; Cegla, H. M.; Hoeijmakers, H. J.; Melo, C.; Suárez-Mascareño, A.; Kuntzer, T.; Giles, H.; Rose, M. E.
Switzerland, Italy, Netherlands, Chile, United States, Spain
Abstract
We present the analysis of TESS optical photometry of WASP-121b, which reveals the phase curve of this transiting ultra-hot Jupiter. Its hotspot is located at the sub-stellar point, showing inefficient heat transport from the dayside (2870 ± 50 K) to the nightside (<2500 K at 3σ) at the altitudes probed by TESS. The TESS eclipse depth, measured at the shortest wavelength to date for WASP-121b, confirms the strong deviation from blackbody planetary emission. Our atmospheric retrieval on the complete emission spectrum supports the presence of a temperature inversion, which can be explained by the presence of VO and possibly TiO and FeH. The strong planetary emission at short wavelengths could arise from an H- continuum.
The reduced light curve of WASP-121, phase-folded at the planet orbital period and binned (Fig. 2) is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/637/A36