Gravitational Atmospheric Tides As A Probe Of Titan's Interior: Application To Dragonfly


Amplitude of the tidal pressure variations (top panel) and phase (bottom panel) as a function of longitude and latitude, without interior deformation (left) and with interior deformation (right). The latter is computed with 1+<(k2 − h2)=0.08 and =(k2 − h2)=0.01. The black cross indicates Dragonfly’s landing site.

Context: Saturn's massive gravity is expected to causes a tide in Titan's atmosphere, producing a surface pressure variation through the orbit of Titan and tidal winds in the troposphere. The future Dragonfly mission could analyse this exotic meteorological phenomenon.

Aims: We analyse the effect of Saturn's tides on Titan's atmosphere and interior to determine how pressure measurements by Dragonfly could constrain Titan's interior.

Methods: We model atmospheric tides with analytical calculations and with a 3D Global Climate Model (the IPSL-Titan GCM), including the tidal response of the interior.

Results: We predict that the Love numbers of Titan's interior should verify 1 + Re(k2 - h2) ~ 0.02-0.1 and Im(k2 - h2) < 0.04. The deformation of Titan's interior should therefore strongly weaken gravitational atmospheric tides, yielding a residual surface pressure amplitude of only ~ 5 Pa, with a phase shift of 5-20 hours. Tidal winds are very weak, of the order of 3*10^-4 m/s in the lower troposphere. Finally, constraints from Dragonfly data may permit the real and the imaginary parts of k2 - h2 to be estimated with a precision of ~0.01-0.03.

Conclusions: Measurements of pressure variations by Dragonfly over the whole mission could give valuable constraints on the thickness of Titan's ice shell, and via geophysical models, its heat flux and the density of Titan's internal ocean.

Benjamin Charnay, Gabriel Tobie, Sébastien Lebonnois, Ralph D. Lorenz

Comments: Accepted for publication in A&A. 10 pages, 8 figures, 1 table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2111.02199 [astro-ph.EP] (or arXiv:2111.02199v1 [astro-ph.EP] for this version)
Submission history
From: Benjamin Charnay
[v1] Wed, 3 Nov 2021 13:11:47 UTC (2,916 KB)
https://arxiv.org/abs/2111.02199
Astrobiology

Please follow Astrobiology on Twitter.


  • submit to reddit