HAT-P-30b: A transiting hot Jupiter on a highly oblique orbit

TL;DR

HAT-P-30b is a transiting hot Jupiter with a highly oblique orbit around a star hotter than 6250 K, demonstrating the prevalence of tilted orbits in such systems.

Contribution

This paper reports the discovery and characterization of HAT-P-30b, including its highly oblique orbit, using transit and radial velocity measurements.

Findings

The planet has a period of 2.8106 days.

The orbit is tilted at approximately 73.5 degrees.

The host star is hotter than 6250 K, supporting the pattern of tilted orbits around such stars.

Abstract

We report the discovery of HAT-P-30b, a transiting exoplanet orbiting the V=10.419 dwarf star GSC 0208-00722. The planet has a period P=2.810595+/-0.000005 d, transit epoch Tc = 2455456.46561+/-0.00037 (BJD), and transit duration 0.0887+/-0.0015 d. The host star has a mass of 1.24+/-0.04 Msun, radius of 1.21+/-0.05 Rsun, effective temperature 6304+/-88 K, and metallicity [Fe/H] = +0.13+/-0.08. The planetary companion has a mass of 0.711+/-0.028 Mjup, and radius of 1.340+/-0.065 Rjup yielding a mean density of 0.37+/-0.05 g cm^-3. We also present radial velocity measurements that were obtained throughout a transit that exhibit the Rossiter-McLaughlin effect. By modeling this effect we measure an angle of \lambda = 73.5+/-9.0 deg between the sky projections of the planet's orbit normal and the star's spin axis. HAT-P-30b represents another example of a close-in planet on a highly tilted orbit, and conforms to the previously noted pattern that tilted orbits are more common around stars with Teff > 6250 K.