ИСТИНА

We have shown a possibility of a water ocean formation in the early Edgeworth-Kuiper objects (EKOs) [1]. A study of the most reliable data on matter content of the known comets, interplanetary dust particles, carbonaceous chondrites and utilization of the model distributions of the physico-chemical parameters of the matter in the solar proto-planetary disk allows to estimate an initial content of the short-lived Al26 radionuclide in EKOs materials. A thermal balance calcula-tion for the large bodies (R>100 km) shows that the quantity of heat discharged due to Al26 decay in some first millions of years of their existence was sufficient to fully melt the water ice being in up to 30% proportion of their mass. An additional mechanism of EKOs’ material heating up was probably a process of heat discharge under intensive col-lisional events in the mentioned and subse-quent time. From analytical estimations [1] we have found that the water ocean might have been in a liquid state (at temperatures ~3-7°С) in EKOs’ interiors for ~107 yr before complete freezing. This time was enough for the silicate fully sedimentation and serpen-tinisation, the silicate core formation (up to 0.5-0.6R of the bodies) and for the dissolution or floating of the main part of organics to the upper water boundary [2]. The proposed model of EKOs’ initial thermal evolution agrees well with available observational data on the bodies. Additionally, it makes possible to predict the physico-chemical properties of some new comets or to explain those of the known. The comets could come from Kuiper belt as debris of differentiated EKOs (e. g., [3]) and may be distinguished by a large content of organic matter or dust as compared to the other comets. However, some of them are probably among observed dusty comets such as 21P Giacobini-Zinner, C/1987 P1 Brad-field, C/1988 A1 Liller and so on (e. g., [4]). References: [1] Busarev V. V. et al. (2003) EM&P, 92, 345-357). [2] Busarev V. V. et al. (2005) LPSC 36th, abs. #1074. [3] Ipatov S. I., Mather J. C. (2003) EM&P, 92, 89-98. [4] Kiselev et al. (2000), P&SS, 48, 1005-1009.