New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet Search

TL;DR

This paper reports the discovery of eight new giant exoplanets and updates on four known ones, analyzing their properties and population trends using radial velocity data from multiple instruments.

Contribution

It presents new exoplanet discoveries and provides insights into population correlations like mass distribution and metallicity effects.

Findings

Discovered 8 new giant planets with diverse properties.

Confirmed that low-mass planets are more common around metal-poor stars.

Identified potential period-metallicity correlation for certain exoplanets.

Abstract

We report the discovery of eight new giant planets, and updated orbits for four known planets, orbiting dwarf and subgiant stars using the CORALIE, HARPS, and MIKE instruments as part of the Calan-Hertfordshire Extrasolar Planet Search. The planets have masses in the range 1.1-5.4MJs, orbital periods from 40-2900 days, and eccentricities from 0.0-0.6. They include a double-planet system orbiting the most massive star in our sample (HD147873), two eccentric giant planets (HD128356b and HD154672b), and a rare 14 Herculis analogue (HD224538b). We highlight some population correlations from the sample of radial velocity detected planets orbiting nearby stars, including the mass function exponential distribution, confirmation of the growing body of evidence that low-mass planets tend to be found orbiting more metal-poor stars than giant planets, and a possible period-metallicity correlation for planets with masses >0.1MJ, based on a metallicity difference of 0.16 dex between the population of planets with orbital periods less than 100 days and those with orbital periods greater than 100 days.