An alternative explanation of the orbital expansion of Titan and other bodies in the Solar system

TL;DR

This paper proposes that the observed orbital expansion of Titan and other bodies may be partly due to local Hubble expansion effects, challenging the standard resonance locking explanation and suggesting a reevaluation of tidal quality factors.

Contribution

It introduces the hypothesis that local Hubble expansion influences orbital dynamics, providing an alternative explanation to resonance locking for Titan's recession speed.

Findings

Local Hubble expansion can account for a significant part of Titan's orbital recession.

The discrepancy in Saturn's tidal quality factor estimates may be due to unaccounted local expansion effects.

Observations of Solar system and galactic expansion support the hypothesis.

Abstract

Recently it was found from Cassini data that the mean recession speed of Titan from Saturn is $v=11.3\pm 2.0$ cm/yr which corresponds to a tidal quality factor of Saturn $Q\cong 100$ while the standard estimate yields $Q\ge 6\cdot 10^4$. It was assumed that such a large speed $v$ is due to a resonance locking mechanism of five inner mid-sized moons of Saturn. In this paper, we show that an essential part of $v$ may come from a local Hubble expansion, where the Hubble-Lema\^{\i}tre constant $H_0$ recalculated to the Saturn-Titan distance $D$ is 8.15 cm/(yr $D$). Our hypothesis is based on many other observations showing a slight expansion of the Solar system and also of our Galaxy at a rate comparable with $H_0$. We demonstrate that the large disproportion in estimating the $Q$ factor can be just caused by the local expansion effect.