Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system
Tamura, M.; Pallé, E.; Béjar, V. J. S.; Narita, N.; Nowak, G.; Klagyivik, P.; Casasayas-Barris, N.; Stangret, M.; Sánchez-Benavente, M.; Luque, R.; Oshagh, M.; Chen, G.; Esparza-Borges, E.; Murgas, F.; Fukui, A.; Crouzet, N.; Hidalgo, D.; Parviainen, H.; Watanabe, N.; Kusakabe, N.; Mori, M.; Terada, Y.; de Leon, J. P.; Nishiumi, T.; Livingston, J.; Kawauchi, K.; Kurita, S.; Madrigal-Aguado, A.; Montañés-Rodríguez, P.; Kawashima, Y.
Spain, China, Japan, Netherlands, Germany
Abstract
We present new transit observations of the hot Jupiter WASP-74 b (Teq ~ 1860 K) using the high-resolution spectrograph HARPS-N and the multi-colour simultaneous imager MuSCAT2. We refined the orbital properties of the planet and its host star and measured its obliquity for the first time. The measured sky-projected angle between the stellar spin-axis and the orbital axis of the planet is compatible with an orbit that is well-aligned with the equator of the host star (λ = 0.77 ± 0.99 deg). We are not able to detect any absorption feature of Hα or any other atomic spectral features in the high-resolution transmission spectra of this source owing to low S/N at the line cores. Despite previous claims regarding the presence of strong optical absorbers such as TiO and VO gases in the atmosphere of WASP-74 b, new ground-based photometry combined with a reanalysis of previously reported observations from the literature show a slope in the low-resolution transmission spectrum that is steeper than expected from Rayleigh scattering alone.
Light curve data are only 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/642/A50