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Viscoelastic Tides of Mercury and the Determination of its Inner Core Size
Author(s) -
Steinbrügge G.,
Padovan S.,
Hussmann H.,
Steinke T.,
Stark A.,
Oberst J.
Publication year - 2018
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2018je005569
Subject(s) - mantle (geology) , moment of inertia , geology , inner core , geophysics , geoid , mercury (programming language) , viscoelasticity , geodesy , physics , thermodynamics , classical mechanics , computer science , programming language , measured depth
We computed interior structure models of Mercury and analyzed their viscoelastic tidal response. The models are consistent with MErcury Surface, Space Environment, GEochemistry, and Ranging mission inferences of mean density, mean moment of inertia, moment of inertia of mantle and crust, and tidal Love number k 2 . Based on these constraints we predict the tidal Love number h 2 to be in the range from 0.77 to 0.93. Using an Andrade rheology for the mantle the tidal phase‐lag is predicted to be 4° at maximum. The corresponding tidal dissipation in Mercury's silicate mantle induces a surface heat flux smaller than 0.16 mW/m 2 . We show that, independent of the adopted mantle rheological model, the ratio of the tidal Love numbers h 2 and k 2 provides a better constraint on the maximum inner core size with respect to other geodetic parameters (e.g., libration amplitude or a single Love number), provided it responds elastically to the solar tide. For inner cores larger than 700 km, and with the expected determination of h 2 from the upcoming BepiColombo mission, it may be possible to constrain the size of the inner core. The measurement of the tidal phase‐lag with an accuracy better than ≈0.5° would further allow constraining the temperature at the core‐mantle boundary for a given grain size and therefore improve our understanding of the physical structure of Mercury's core.