http://arxiv.org/abs/2012.14245
Recently, the possibility that putative massive natural satellites (exomoons) of extrasolar Jupiter-like giant planets orbiting main sequence stars may be habitable has gained increasing attention. Typically, such an exomoon is expected to orbit its parent planet in the equatorial plane of the latter, with its spin $\boldsymbol S$ aligned with its orbital angular momentum $\boldsymbol L$ which, in turn, is parallel to the planetary spin $\boldsymbol J$. Thus, if the common tilt of such angular momenta to the satellite-planet ecliptic plane assumes certain values, the overall irradiation experienced by the exomoon may allow it to sustain life as we know it, at least for certain orbital configurations. A telluric body orbiting different gaseous giant primaries at $5-10$ planetary radii $R$ whose spin is initially tilted to the ecliptic by the same angle $\varepsilon_0=23.44^\circ$ as Earth is considered. A similar system does actually exist in our Solar System, being made of Saturn and its moon Titan whose obliquity to the ecliptic is $26.7^\circ$. Here, I show that the de Sitter and Lense-Thirring precessions of the satellite’s spin due to the general relativistic post-Newtonian (pN) field of the host planet may have a non-negligible impact on the exomoon’s habitability through induced long-term variations $\Delta\varepsilon\left(t\right)$ of the obliquity $\varepsilon$ of the satellite’s spin $\boldsymbol S$ to the ecliptic plane which may be as large as tens of degrees over $\simeq 0.1-1$ millions of years.
L. Iorio
Tue, 29 Dec 20
3/66
Comments: LaTex2e, 19 pages, 3 figures, no tables