Chirality in interstellar dust and in comets: Life from dead stars

Abstract

Interstellar dust grains have mantles of prebiotic organic molecules. A large fraction of the clouds of interstellar dust grains pass close enough to neutron stars for the circularly polarized ultraviolet radiation to produce a 10% or higher enantiomeric excess in the organic grain mantles. The time between such close passages is about ten times larger than the average lifetime of the molecular clouds so that the most prestellar and protostellar clouds contain predominantly left or right handed prebiotic molecules. Comets as agglomerated interstellar dust preserve the initial enantiomeric excess. Even if only 0.1% of the comet material survives as small comet dust particles which preserve their prebiotic molecules, there could be ∼10251 chances for life to originate from one of these if it lands in water.