TY - JOUR

T1 - On the asphericity of the figures of Pluto and Charon

AU - Kholshevnikov, Konstantin V.

AU - Borukha, Maria A.

AU - Eskin, Boris B.

AU - Mikryukov, Denis V.

PY - 2020/2

Y1 - 2020/2

N2 - The NASA spacecraft New Horizons allowed us to refine many physical, chemical, topographic, and geological characteristics of main bodies of the Pluto – Charon system significantly. Their sizes have been clarified. Their shapes were approximated by triaxial ellipsoids. But measurement errors of the axes differences a−c, a−b have exceeded their values. So the asphericity of the figures was not revealed. The same concerns the asphericity of the gravitational fields of Pluto and Charon. So measurements during future space missions must be more accurate. To evaluate the necessary precision we need bilateral theoretical boundaries of the possible values of polar and equatorial oblatenesses α=(a−c)/a, β=(a−b)/a, as well as the second zonal and sectorial harmonics I2, I22 for both bodies. In the present paper we have obtained them under the assumption of the hydrostatic equilibrium of the Pluto and Charon figures. Pressure, centrifugal forces, and gravity (tidal interaction included) were taken into account. It turns out that the influence of rotation and tides are comparable; tides change the Charon shape more than the Pluto one; dimensionless quantities α, β, I2, I22 are of the order of 10-5÷10-4 for Pluto, and 10-4÷10-3 for Charon.

AB - The NASA spacecraft New Horizons allowed us to refine many physical, chemical, topographic, and geological characteristics of main bodies of the Pluto – Charon system significantly. Their sizes have been clarified. Their shapes were approximated by triaxial ellipsoids. But measurement errors of the axes differences a−c, a−b have exceeded their values. So the asphericity of the figures was not revealed. The same concerns the asphericity of the gravitational fields of Pluto and Charon. So measurements during future space missions must be more accurate. To evaluate the necessary precision we need bilateral theoretical boundaries of the possible values of polar and equatorial oblatenesses α=(a−c)/a, β=(a−b)/a, as well as the second zonal and sectorial harmonics I2, I22 for both bodies. In the present paper we have obtained them under the assumption of the hydrostatic equilibrium of the Pluto and Charon figures. Pressure, centrifugal forces, and gravity (tidal interaction included) were taken into account. It turns out that the influence of rotation and tides are comparable; tides change the Charon shape more than the Pluto one; dimensionless quantities α, β, I2, I22 are of the order of 10-5÷10-4 for Pluto, and 10-4÷10-3 for Charon.

KW - Charon

KW - Kuiper belt

KW - Planets

KW - Pluto

KW - Satellites

KW - SYSTEM

KW - LIAPUNOV SERIES

KW - CONVERGENCE

KW - SATELLITES

UR - http://www.scopus.com/inward/record.url?scp=85075342402&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/0dd673e4-562b-3840-97be-393982f26237/

U2 - 10.1016/j.pss.2019.104777

DO - 10.1016/j.pss.2019.104777

M3 - Article

AN - SCOPUS:85075342402

VL - 181

JO - Planetary and Space Science

JF - Planetary and Space Science

SN - 0032-0633

M1 - 104777

ER -