The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD4113 and HD156846

TL;DR

This paper reports the discovery of two highly eccentric exoplanets orbiting stars HD4113 and HD156846 using radial velocity measurements, revealing their orbital parameters and potential companion objects, and discussing their dynamical origins.

Contribution

The study presents the detection and characterization of two eccentric exoplanets with detailed orbital parameters and possible companion objects, expanding understanding of planetary system dynamics.

Findings

HD4113b has a mass of 1.6 M_Jup, period of 526.59 days, eccentricity 0.903.

HD156846b has a mass of 10.45 M_Jup, period of 359.51 days, eccentricity 0.847.

Both planets' high eccentricities may result from Kozai oscillations induced by third objects.

Abstract

We report the detection of two very eccentric planets orbiting HD4113 and HD156846 with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope at La Silla. The first planet, HD4113b, has minimum mass of $m\sin{i}=1.6\pm0.2 M_{\rm Jup}$, a period of $P=526.59\pm0.21$ days and an eccentricity of $e=0.903\pm0.02$. It orbits a metal rich G5V star at $a=1.28$ AU which displays an additional radial velocity drift of 28 m s$^{-1}$/yr observed during 8 years. The combination of the radial-velocity data and the non-detection of any main sequence stellar companion in our high contrast images taken at the VLT with NACO/SDI, characterizes the companion as a probable brown dwarf or as a faint white dwarf. The second planet, \object{HD 156846 b}, has minimum mass of $m\sin{i}=10.45\pm0.05$ M$_{\rm Jup}$, a period of $P=359.51\pm0.09 $ days, an eccentricity of $e=0.847\pm0.002$ and is located at $a=1.0$ AU from its parent star. HD156846 is a metal rich G0 dwarf and is also the primary of a wide binary system ($a>250$ AU, $P>4000$ years). Its stellar companion, \object{IDS 17147-1914 B}, is a M4 dwarf. The very high eccentricities of both planets can be explained by Kozai oscillations induced by the presence of a third object.