Formation of satellite systems of small bodies and the embryos of the Moon and the Earth
Abstract
Ipatov showed [1] that the angular velocities of condensations used in [2] as initial data for computer simulations of compression of rarefied condensations leading to the formation of satellite systems of trans-Neptunian objects could be obtained at collisions of condensations. Such considered model of the formation explains well the observed dependencies of the orbital elements and masses of the components of binary trans-Neptunian objects [3]. The initial angular momenta of the condensations were not sufficient for the formation of satellite systems of small bodies. The angular momentum of the condensation used by E.M. Galimov and A.M. Krivtsov [4] in their computer simulations of compression of the condensation leading to the formation of embryos of the Earth and the Moon could be obtained at a collision of two condensations. I showed that the angular momentum of the present Earth-Moon system could be acquired at a collision of two rarefied condensations with a total mass not smaller than 0.1M_E, where M_E is the mass of the Earth. The mass of the condensation that was a parent for the embryos of the Earth and the Moon could be relatively small (0.02M_E or even less), if we take into account the growth of the angular momentum of the embryos at the time when they accumulated solid planetesimals. If, as it is considered in [4], initial embryos of the Earth and the Moon were almost iron free, the initial mass of the Moon embryo could be less by only a factor of 1.3 than its present mass if it accumulated planetesimals of the same composition as the Earth. In the case of small relative velocities of planetesimals, the effective radius of an embryo is proportional to the square of the radius of the considered embryo. For such a model, for the growth of the mass of the Moon embryo by a factor of 1.3, the mass of the Earth embryo grew by less than a factor of 3. Besides direct collisions with planetesimals, the Moon embryo could also grow by accumulation of almost iron-free material ejected from the Earth embryo at many impacts of planetesimals with the Earth embryo. The work was supported in part by the grant of Russian Foundation for Basic Research _ 17-02-00507 _ (formation of satellite systems of small bodies) and by the grant of Russian Science Foundation _ 17-17-01279 (formation of the Earth-Moon system). [1] Ipatov S.I. Solar System Research, 2017, 51, 294-314, https://arxiv.org/abs/1801.05217. [2] Nesvornyi D., et al., Astron. J, 2010, 140, 785-793. [3] Ipatov S.I. Solar System Research, 2017, 51, 409-416, https://arxiv.org/abs/1801.05254. [4] Galimov E.M. and Krivtsov A.M. Origin of the Moon. / De Gruyter. Berlin, 2012, 168 p.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E1558I