[P-CG20] Origin and evolution of materials in space

[PCG20-P03] Infrared spectrum observation and classification of many protoplanetary disks analyzed by polycyclic hydrocarbon molecules

*Norio Ota¹, Aigen Li² (1.University of Tsukuba,Graduate school of pure and applied sciences, 2.University of Missouri)

Keywords:protoplanetary-disk, infrared spectrum, polycyclic hydrocarbon

Our life’s original base material may come from interstellar space. To check such idea, we observed and classified infrared spectrum of just born stars protoplanetary disks [1]. As shown on top of Fig.1, we found two typical spectra of Type-A and Type-B. Until now, Type-A was understood to come from ensemble of so many Polycyclic Aromatic Hydrocarbon molecules (PAH). We tried to identify specular PAH by Density Functional Theory (DFT). We found large PAH molecules of (C23H12) and (C53H18) as illustrated in Fig.1. Observed bands could be identified with DFT calculated bands in a wide wavelength range from 6 to 15 micrometer. Background molecule of Type-B had been unknown. Now, we found smaller ones of (C9H7) and (C12H8) as compared on right side of Fig.1. In Fig.2, central stars mass vs. effective temperature was mapped. Star of Type-A (blue dot) show larger mass and higher temperature than that of Type-B (red dot). At very early stage, our solar system (Teff~5000K, 1 solar mass) may had been surrounded by Type-B molecules. It was interesting that (C9H7) has similar molecular structure with biological nuclear acid, may play template for advanced molecules.
[1] J. Y. Seok and A. Li:Polycyclic Aromatic Hydrocarbon in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars, Astrophysical Journal, 835, 291 (2017).
[2] Norio Ota, Aigen Li, and Laszlo Nemes:Void-Defect Induced Magnetism and Structure Change of Carbon Material-III: Hydrocarbon Molecules, Journal of the magnetic society of Japan, 45, 86 (2021).