Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Poster

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS09] Origin and evolution of materials in space

Tue. May 22, 2018 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Shogo Tachibana(UTokyo Organization for Planetary and Space Science, University of Tokyo), Hitoshi Miura(Graduate School of Natural Sciences, Department of Information and Basic Science, Nagoya City University), Hideko Nomura(東京工業大学理学院地球惑星科学系, 共同), Takafumi Ootsubo(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

[PPS09-P02] Reproduction of Young Star's Infrared Spectrum by Acenaphthylene (C12H8) Molecule

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

Keywords:interstellar dust, infrared spectrum, PAH

Recently, infrared spectra of new born young star were studied and listed (1). Among 53 examples, half one show well observed bands and could be reproduced by previously identified coronene (C24H12) based molecules (2) (3). On the other hand, rest half show unusual behavior. In this study, carrier molecules of such unusual spectrum were identified by the quantum chemical calculation. Chemical evolution model is applied to phenalene (C13H10), which would be modified to acenaphthylene (C12H8) through a void creation by high speed proton attack.

Result-1 HD144432: Model molecule is acenaphthylene (C12H8). By high energy photon irradiation, molecule became cation (C12H8)n+ (n=0, 1, 2, and 3). Compared with an observed spectrum of HD144432 and calculated result of di-cation (C12H8)2+, they show very good coincidence as follows,
Observed wavelength (micron): 8.3, 9.2, 10.0, 11.3, 14.0, 14.6
Calculated wavelength(micron): 8.2, 9.2, 9.9, 11.3, 14.0, 14.6

Result-2 HD37357: Spectrum of this young star is very complex. Looking carefully calculated results on every cationic state, it was found that a suitable combination of di-cation (A) and tri-cation acenaphthylene (B) could reproduce observed feature as follows,
Observed wavelength (micron) : 6.3, 7.5, 7.8, 8.2, 8.6, 9.2, 10.0, 11.2, 14.0, 14.6
Calculation of (A ) (micron)..... : 6.1, --- , ---- , 8.2, 8.6, 9.2, 9.9, 11.3, 14.0, 14.6
Calculation of (B) (micron)...... : 6.3, 7.4, 7.8, -----, ---, -----, ---, 11.1, -----, 14.6

It should be noted that acenaphthylene has a similar skeleton with biological basic molecules and has a potential of capable resource for Life.

(1) B.Acke et al, The Astrophysical Journal, 718:558 (2010)
(2) Norio Ota,arXiv.org 1703.05931 (2017)
(3) Norio Ota, arXiv.org 1709.04560 (2017)