The CORALIE survey for southern extra-solar planets. X. A Hot Jupiter orbiting HD73256

TL;DR

This paper reports the discovery of a Hot Jupiter exoplanet orbiting HD 73256 with a very short period, using radial velocity measurements, and discusses stellar activity effects on the observations.

Contribution

First detection of a Hot Jupiter around HD 73256 using CORALIE radial velocity data, with analysis of stellar activity influence on measurements.

Findings

Discovery of a 1.85 M_Jup Hot Jupiter with a 2.55-day orbit.

Identification of stellar activity affecting radial velocity and photometry.

No planetary transit detected despite photometric follow-up.

Abstract

Recent radial-velocity measurements obtained with the CORALIE spectrograph on the 1.2-m Euler Swiss telescope at La Silla unveil the presence of a new Jovian-mass Hot Jupiter around HD 73256. The 1.85-M_Jup planet moves on an extremely short-period (P=2.5486 d), quasi-circular orbit. The best Keplerian orbital solution is presented together with an unsuccessful photometric planetary-transit search performed with the SAT Danish telescope at La Silla. Over the time span of the observations, the photometric follow-up of the candidate has nevertheless revealed a P=14-d photometric periodicity corresponding to the rotational period of the star. This variation as well as the radial-velocity jitter around the Keplerian solution are shown to be related to the fair activity level known for HD 73256.