TITLE:
The Effect of Radiogenic Heating on the Amino Acid Content of an Early Cometary Body
AUTHORS:
Carlo Canepa
KEYWORDS:
Amino Acids; Radiogenic Heating; Comet; Prebiotic Chemistry
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.3 No.3,
September
3,
2013
ABSTRACT:
This study compares the rates for the formation and
destruction of amino acids in the liquid cometary core subjected to radiogenic
heating by the β+ decay
of the cosmogenic nuclide 26Al. The evolution of the
temperature and mass of the comet were computed along with the dynamics of
relatively complex organic species such as amino acids. Given the
experimentally determined rate coefficient for the radiolysis of amino acids in
water solution, the destruction of amino acids is virtually completed after an
absorbed radiation dose of ~1 kGy. The calculations suggest that the
liquid water core in comets with an initial radionuclide abundance that is
sufficient to crystallize and melt the original amorphous ice is subjected to a
dose of 100 - 1500 kGy. Any amino acid concentration formed in water either by radiolysis
of simpler compounds or by thermal processes such as the synthesis of Strecker
could not survive the irradiation delivered by the decay of 26Al.