Engineering topics

Makalkin, A. B.

Publications and source records attributed to Makalkin, A. B..

5 records

NASA NTRS1993

On high-temperature formation of iron-rich olivine in the early solar system

A kinetic restriction on the formation of fayalite-rich olivine in equilibrium with the cooling solar-composition gas appears to exist at the low temperature of approximately 500 K. We offer a high-temperature formation mechanism (different from simple condensation) which operates at high hydrogen depletion (up to 300 times) relative to solar abundance. We show how the necessary depletion rate decreases with temperature (thermodynamical equilibrium is suggested). The consequences for planet formation are considered.

Dorofeyeva, V. A.↗

NASA NTRS1993

Recondensation of chondritic material in the early solar system: Results of thermodynamic simulation

We have performed a thermodynamic simulation of the recondensation of evaporated meteoritic material. We suggest that evaporation and recondensation occurred in impact events during the intercollision of planetesimals during the early evolution of the solar system. The source materials adopted for our model are the chondrites CI Orgueil and H5 Richardton. These chondrites are representative examples of the two extremes regarding volatile content and oxidation state. We calculated equilibrium mineral compositions of the closed systems of the Orgueil's and Richardton's elemental composition at the P-T conditions characteristic of the explosion cloud formed at a planetesimal collision. The P-T conditions are as follows: 10(exp -4) bar, and 1500 and 2000 K. The results are presented.

Dorofeyeva, V. A.↗

NASA NTRS1993

Possible sources of H2 to H2O enrichment at evaporation of parent chondritic material

One of the results obtained from thermodynamic simulation of recondensation of the source chondritic material is that at 1500-1800 K it's possible to form iron-rich olivine by reaction between enstatite, metallic iron and water vapor in the case of (H2O)/(H2) approximately equal to 0.1. This could be reached if the gas depletion in hydrogen is 200-300 times relative to solar abundance. To get this range of depletion one needs some source material more rich in hydrogen than the carbonaceous CI material which is the richest in volatiles among chondrites. In the case of recondensation at impact heating and evaporation of colliding planetesimals composed of CI material, we obtain insufficiently high value of (H2)/(H2O) ratio. In the present paper we consider some possible source materials and physical conditions necessary to reach gas composition with (H2)/(H2O) approximately 10 at high temperature.

Makalkin, A. B.↗

NASA NTRS1993

Recondensation in the early solar system: Physical conditions and source material

Many physical processes in the solar nebula led to fractionation of the gaseous phase of the preplanetary material. Some of these processes are listed with corresponding type of fractionation in terms of Rock/Ice/Gas. Recondensation from fractionated gas phase yields different compositions of condensates. In some detail, one type of fractionation is considered: impact heating with evaporation and subsequent recondensation of material during intercollisions of planetesimals. For thermodynamical simulation of recondensation in such a process one needs (1) P-T parameters and (2) some initial source material to be heated, evaporated, and recondensed. These two problems are addressed.

Vityazev, A. V.↗

NASA NTRS1991

Formation and evolution of the protoplanetary disk

A disk formation model during collapse of the protosolar nebula, yielding a low-mass protoplanetary disk is presented. The following subject areas are covered: (1) circumstellar disks; (2) conditions for the formation of stars with disks; (3) early evolution of the protoplanetary disk; and (4) temperature conditions and the convection in the protoplanetary disk.

Ruzmaikina, Tamara V.↗