We conducted survey observations of a glycine precursor, methanimine or methylenimine (CH2NH), with the NRO 45 m telescope and the SMT telescope towards 12 high-mass and two low-mass star-forming regions in order to increase number of CH2NH sources and to better understand the characteristics of CH2NH sources. As a result of our survey, CH2NH was detected in eight sources, including four new sources. The estimated fractional abundances were ~108 in Orion KL and G10.47+0.03, while they were ~109 towards the other sources. Our hydrogen recombination line and past studies suggest that CH2NH-rich sources have less evolved HII regions. The less destruction rates by UV flux from the central star would be contributed to the high CH2NH abundances towards CH2NH-rich sources. Our gas-grain chemical simulations suggest that CH2NH is mostly formed in the gas-phase by neutral-neutral reactions rather than the product of thermal evaporation from the dust surfaces.
@article{arxiv.1605.02161,
title = {Survey Observations of a Possible Glycine Precursor, Methanimine (CH$_2$NH)},
author = {Taiki Suzuki and Masatoshi Ohishi and Tomoya Hirota and Masao Saito and Liton Majumdar and Valentine Wakelam},
journal= {arXiv preprint arXiv:1605.02161},
year = {2016}
}