XO-4b: An Extrasolar Planet Transiting an F5V Star

TL;DR

This paper reports the discovery and detailed characterization of the exoplanet XO-4b, a gas giant transiting an F5V star, with precise photometry and potential for further space-based observations.

Contribution

The paper presents the first detailed photometric analysis and characterization of XO-4b, including its transit parameters and observational prospects with HST.

Findings

XO-4b has a 1.72 M_Jup mass and 1.34 R_Jup radius.

Transit depth is 1.0% with a duration of 4.4 hours.

The star XO-4 is suitable for continuous space-based observation.

Abstract

We report the discovery of the planet XO-4b, which transits the star XO-4 (GSC 03793-01994, V=10.7, F5V). Transits are 1.0% deep and 4.4 hours in duration. The star XO-4 has a mass of 1.32 M_sun.... The planet XO-4b has a mass of 1.72 M_Jup....radius of 1.34 R_Jup...orbital period 4.125 days. We analyze scintillation-limited differential R-band photometry of XO-4b in transit made with a 1.8-m telescope under photometric conditions, yielding photometric precision of 0.6 to 2.0 millimag per one-minute interval. The declination of XO-4 places it within the continuous viewing zone of the Hubble Space Telescope (HST), which permits observation without interruption caused by occultation by the Earth. Because the stellar rotation periods of the three hottest stars orbited by transiting gas-giant planets are 2.0, 1.1, and 2.0 times the planetary orbital periods, we note the possibility of resonant interaction.