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 refine the orbital properties of the planet and its host star, and measure its obliquity for the first time. The measured sky-projected angle between the stellar spin-axis and the planet's orbital axis is compatible with an orbit well-aligned with the equator of the host star (λ=0.77±0.99deg). We are not able to detect any absorption feature of Hα, or any other atomic spectral features, in its high-resolution transmission spectra due to low S/N at the line cores. Despite previous claims regarding the presence of strong optical absorbers such TiO and VO gases in the atmosphere of WASP-74 b, the new ground-based photometry combined with a reanalysis of previously reported observations from the literature shows a slope in the low-resolution transmission spectrum steeper than expected from Rayleigh scattering alone.
@article{arxiv.2007.11851,
title = {Obliquity measurement and atmospheric characterization of the WASP-74 planetary system},
author = {R. Luque and N. Casasayas-Barris and H. Parviainen and G. Chen and E. Pallé and J. Livingston and V. J. S. Béjar and N. Crouzet and E. Esparza-Borges and A. Fukui and D. Hidalgo and Y. Kawashima and K. Kawauchi and P. Klagyivik and S. Kurita and N. Kusakabe and J. P. de Leon and A. Madrigal-Aguado and P. Montañés-Rodríguez and M. Mori and F. Murgas and N. Narita and T. Nishiumi and G. Nowak and M. Oshagh and M. Sánchez-Benavente and M. Stangret and M. Tamura and Y. Terada and N. Watanabe},
journal= {arXiv preprint arXiv:2007.11851},
year = {2020}
}
Comments
Accepted for publication in Astronomy & Astrophysics. 12 pages, 8 figures, 5 tables