A new analysis of the GJ581 extrasolar planetary system

TL;DR

This paper reevaluates the GJ581 exoplanetary system's observations, focusing on the existence of planets f and g, their orbital dynamics, and the habitable zone, highlighting the uncertainties and resonances involved.

Contribution

It provides a new analysis of the GJ581 system, clarifies the conditions for planets f and g's existence, and explores the dynamical features of the habitable zone.

Findings

Planet g's existence depends on the eccentricity of planet d.

Possible detection of planet f with a ~450-day period, but uncertain.

Identification of resonances shaping the habitable zone.

Abstract

We have done a new analysis of the available observations for the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the ocurrence of aliases and the additional bodies - the planets f and g - announced in Vogt et al. 2010. Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the Habitable Zone (HZ) of the star GJ581. This region,for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period $\approx 450$ days, but we are judicious about any affirmation concernig this body because its signal is in the threshold of detection and the high period is in a spectral region where the ocorruence of aliases is very common. Besides, we outline some dynamical features of the habitable zone with the dynamical map and point out the role played by some resonances laying there.