Masses of Asteroids and the Total Mass of the Asteroid Main Belt

E. V. Pitjeva, N. P. Pitjev

Transactions of IAA RAS, issue 31, 3–10 (2014)

Keywords: Solar System, asteroid belt, planet ephemerides, asteroid masses.

Abstract

An updated database of planet and spacecraft observations, as well as asteroid data, has been used to improve the asteroid (included main belt asteroid) masses and perturbations caused by them on the motion of Solar System bodies. The direct estimation of the dynamical mass was obtained for a part of asteroids from their gravitation impacts on other celestial bodies. The masses of other large asteroids were calculated from their diameters and estimated densities. The mass of all the remaining small asteroids is estimated from the total gravitational influence caused by a two-dimensional ring with a constant mass distribution in the ecliptic plane. The work is based on the new version of the EPM2013 ephemerides and more than 792 000 positional observations (mainly radar ones) of planets and spacecraft made from 1913 to 2012. It is our first experience with a two-dimensional asteroid ring with dimensions obtained from its observable width instead of one-dimensional rings which we considered in our previous versions of EPM ephemerides for modeling perturbations of small asteroids. As a result, the accuracy of the two-dimensional asteroid ring's mass has grown considerably; orbits of all planets are obviously improved, and a particularly important gain is that the formal uncertainties o f the planets' semi-major axes has been halved. The total mass of the main asteroid belt is found: Mbelt = (12.25 ± 0.19) 10^-10 MSun or ≈ 2.5 MCeres.

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