Aligned Major Axes in a Planetary System without Tidal Evolution: The 61 Virginis example

TL;DR

This paper investigates the 61 Virginis planetary system, demonstrating that aligned major axes can occur without tidal evolution, and suggests initial conditions and possible tidal damping influence the system's current orbital configuration.

Contribution

It shows that aligned major axes in planetary systems can result from initial conditions rather than tidal damping, challenging previous assumptions.

Findings

The 61 Virginis system's alignment is likely due to initial conditions.

Eigenmode analysis indicates no necessity of tidal damping for alignment.

System may have experienced some tidal damping, inferred from eigenmode amplitudes.

Abstract

Tidal damping of one of the orbits in a planetary system can lead to aligned major-axes (the so-called "fixed-point" condition), but currently aligned major axes do not necessarily imply such a history. An example is the nominal orbital solution for the 61 Virginis system where two orbits librate about alignment, but evaluation of the eigenmodes of the secular theory shows it could not be the result of tidal damping but rather of initial conditions. Nevertheless, the amplitudes of the eigenmodes suggest that this system may have undergone some degree of tidal damping.