Discovery of WASP-174b: Doppler tomography of a near-grazing transit

TL;DR

This paper reports the discovery and tomographic detection of WASP-174b, a near-grazing transiting hot Jupiter around an F6V star, highlighting its orbital misalignment and the challenges in precisely determining its radius.

Contribution

It presents the first tomographic detection of a near-grazing hot Jupiter around a faint star, expanding the application of Doppler tomography in exoplanet studies.

Findings

WASP-174b has a sky-projected spin-orbit angle of 31 degrees.

The planet's radius is uncertain, ranging from 0.8 to 1.8 Jupiter radii.

WASP-174 is the faintest hot Jupiter system confirmed by tomography.

Abstract

We report the discovery and tomographic detection of WASP-174b, a planet with a near-grazing transit on a 4.23-d orbit around a $V$ = 11.9, F6V star with [Fe/H] = 0.09 $\pm$ 0.09. The planet is in a moderately misaligned orbit with a sky-projected spin-orbit angle of $\lambda$ = 31$^{\circ}$ $\pm$ 1$^{\circ}$. This is in agreement with the known tendency for orbits around hotter stars to be misaligned. Owing to the grazing transit the planet's radius is uncertain, with a possible range of 0.8-1.8 R$_{\rm Jup}$. The planet's mass has an upper limit of 1.3 M$_{\rm Jup}$. WASP-174 is the faintest hot-Jupiter system so far confirmed by tomographic means.