Possibility Of Condensation Of Glycine Near The Surface Of Comet 67P/Churyumov-Gerasimenko.

The cometary materials are thought to be the reservoir of primitive materials in the solar system. The recent detection of glycine and CH$_3$NH$_2$ by the ROSINA mass spectrometer in the coma of 67P/Churyumov-Gerasimenko suggests that amino acids and their precursors have been formed in such an early evolutionary phase of the Solar System. We use our chemical modeling for low-mass star-forming regions to investigate if we can explain observed Glycine/CH$_3$NH$_2$ ratio. As a result, the predicted molecular ratio of CH$_3$NH$_2$/Glycine during star-formation is less than 10$^{-2}$, while the ROSINA measurement has shown this value to be unity. With the hypothesis that glycine is condensed in the cometary surface during the numerous passages of perihelion after the formation of the Solar System, we develop the numerical model to discuss this condensation process. Our modeling results suggest that glycine is highly likely condensed in the cometary surface due to its high binding energy, and Glycine/CH$_3$NH$_2$ ratio will be highly enhanced if the outbursts eject the materials condensed on cometary surface.