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Equilibrium temperatures of porous spheres and their relevance to astrobiology

Published online by Cambridge University Press:  21 August 2007

S.G. Coulson
Affiliation:
Centre for Astrobiology, School of Mathematics, Cardiff University, 2 North Road, Cardiff CF10 3DY, UK e-mail: coulson@aldpartners.com; wickramasinghe@cf.ac.uk
N.C. Wickramasinghe
Affiliation:
Centre for Astrobiology, School of Mathematics, Cardiff University, 2 North Road, Cardiff CF10 3DY, UK e-mail: coulson@aldpartners.com; wickramasinghe@cf.ac.uk

Abstract

Equilibrium temperatures are calculated for porous, organic spheres at a Solar distance of around 1 AU. It is found that the equilibrium temperature of porous grains is highly sensitive to their composition and radius. For porous organic grains of radius 0.1 μm the temperature ranges from 355 to 386 K as the porosity (vacuum volume fraction) increases from 0 to 0.9; for organic grains of radius 0.1 μm with 10% charring the corresponding range is from 448 to 431 K. Such superheated submicron grains, porous or otherwise, may have only a limited role as transporters of fragile biomolecules. Clumps of biological particles with radii in excess of 5 μm are, however, at low enough temperatures to permit such transport at 1 AU.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2007

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