Mercury's tides and interior structure

Abstract

An accurate tide-generating potential series for Mercury has been calculated on the basis of VSOP87 ephemerides for the solar system planets. Due to the 3:2 spin-orbit resonance, the tides on Mercury cannot be divided into the three classically known tidal frequency bands for the Earth: the diurnal, semidiurnal, and long-period tides. Instead, the tides all have periods of the order of one Mercury day, or, equivalently, one Mercury year, and their amplitudes have been calculated with an accuracy of 10-5 m2S-2. Basic Mercury models with varying inner and outer core radii and core sulfur concentration have been constructed in order to test the sensitivity of tides to these parameters. To determine the reaction of Mercury to the tidal forcing, the Love numbers h, l, and k and the gravimetric factor δ were calculated for the interior models. Tidal displacements, gravity variations, and external gravitational potential variations have also been calculated for the models. It is shown that especially the measurement of the external potential variations will be extremely useful for constraining the inner and outer core. Copyright 2003 by the American Geophysical Union.