Classifying Protoplanetary disks Infrared Spectrum and Analysis by c-C${}_3$H${}_2$ C${}_5$H${}_5$ C${}_9$H${}_7$ C${}_{12}$H${}_8$ C${}_{23}$H${}_{12}$ and C${}_{53}$H${}_{18}$ to be Capable Template for Biological Molecule

Abstract

Protoplanetary disk around a just born young star contains a lot of cosmic dust. especially polycyclic-aromatic-hydrocarbon (PAH), which would become basic component to create biological organics. This study classified many astronomically observed infrared spectra of protoplanetary disks to three typical spectra. Type-A show well known astronomical bands of 6.2, 7.8, 8.6 and 11.3 micrometer. Whereas Type-B included unknown complex bands. Type-(A+B) was their mixed type. We tried to find specific molecule by Density Functional Theory (DFT) calculation. We found that Type-A could be explained by large PAH molecules of (C${}_{23}$H${}_{12}$) and (C${}_{53}$H${}_{18}$), which are hexagon-pentagon combined molecular structure. Background molecule of Type-B was smaller ones of (c-C${}_3$H${}_2$), (C${}_5$H${}_5$), (C${}_9$H${}_7$) and (C${}_{12}$H${}_8$). Type-(A+B) was reproduced well by mixing those molecules of A and B. Astronomical detailed observation shows that central star of Type-A has larger mass and higher temperature than that of Type-B. This suggests that at very early stage of our solar system, our protoplanetary disk had been made up by Type-B molecules. It was interesting that (C${}_5$H${}_5$) and (C${}_9$H${}_7$) of Type-B molecules has similar molecular structure with biological nucleic-acid on our earth. Type-B molecules was supposed to become the template for synthesizing biological organics and finally for creating our life.

10 pages, 20 figures, 1 table, 27 references