Hydrated silicates on Edgeworth-Kuiper objects – probable ways of formation

Busarev, V.V.; Dorofeeva, V.A.; Makalkin, A.B.

Авторы: Busarev V.V., Dorofeeva V.A., Makalkin A.B.
Журнал: Earth, Moon and Planets
Том: 92
Год издания: 2003
Издательство: Springer Nature
Местоположение издательства: Switzerland
Первая страница: 345
Последняя страница: 357
Аннотация: Visible-range absorption bands at 600-750 nm are recently detected on two Edgeworth-Kuiper objects (EKOs) (Boehnhardt et al., 2002). Most probably the spectral features may be attributed to hydrated silicates originated in the bodies. We consider possibilities for silicate dressing and silicate aqueous alteration within them. According to present models of the protoplanetary disk, the temperatures and pressures at the EKOs’ belt distances (30-50 AU) at the time of formation of the objects (106 to 108 yr) were very low (15-30 K and 10-9 - 10-10 bar). At these thermodynamic conditions all volatiles excluding hydrogen, helium and neon were in the solid state. An initial mass fraction of silicates (silicates /(ices + dust) ) in parent EKOs may be estimated as 0.15 – 0.30. Decay of the short-lived 26Al in the bodies at the early stage of their evolution and their mutual collisions (at velocities  1.5 km s-1) at the subsequent stage were probably the main sources of their heating, sufficient for melting of water ice. Because of these processes, large EKOs (≥100 km) could contain a large amount of liquid water in their interiors for the period of about 106 yr. Freezing of the internal ocean might have been at the age  5106 yr after formation of the solar nebula (and CAIs). As a result, aqueous alteration of silicates in the bodies could occur. A probable mechanism of silicate dressing was sedimentation of silicates with refractory organics, resulted in accumulation of large silicate-rich cores. Crushing and removing icy covers under collisions and exposing EKOs’ interiors with increased silicate content could facilitate detection of phyllosilicate spectral features.
Добавил в систему: Бусарев Владимир Васильевич

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