A Double Planetary System around the Evolved Intermediate-Mass Star HD 4732

TL;DR

This paper reports the discovery of a double planetary system around the evolved star HD 4732, with detailed measurements of the planets' masses, orbits, and stability analysis, contributing to understanding planetary systems around intermediate-mass stars.

Contribution

First detection of a double planetary system around an evolved intermediate-mass star using precise Doppler measurements, with dynamical stability analysis to constrain planetary masses.

Findings

Two giant planets with minimum masses of 2.4 M_J orbit HD 4732.

Planets have orbital periods of 360.2 and 2732 days with moderate eccentricities.

System stability analysis limits planetary masses to about 28 M_J.

Abstract

We report the detection of a double planetary system orbiting around the evolved intermediate-mass star HD 4732 from precise Doppler measurements at Okayama Astrophysical Observatory (OAO) and Anglo-Australian Observatory (AAO). The star is a K0 subgiant with a mass of 1.7 M_sun and solar metallicity. The planetary system is composed of two giant planets with minimum mass of msini=2.4 M_J, orbital period of 360.2 d and 2732 d, and eccentricity of 0.13 and 0.23, respectively. Based on dynamical stability analysis for the system, we set the upper limit on the mass of the planets to be about 28 M_J (i>5 deg) in the case of coplanar prograde configuration.