Methanol and complex organic molecules have been found in cold starless cores, where a standard warm-up scenario would not work because of the absence of heat sources. A recent chemical model attributed the presence of methanol and large organics to the efficient chemical desorption and a class of neutral-neutral reactions that proceed fast at low temperatures in the gas phase. The model calls for a high abundance of methanol ice at the edge of the CO freeze-out zone in cold cloud cores. We performed medium resolution spectroscopy toward 3 field stars behind the starless core L1544 at 3 μm to constrain the methanol ice abundance and compare it with the model predictions. One of the field stars shows a methanol-ice abundance of 11% with respect to water ice. This is higher than the typical methanol abundance previously found in cold cloud cores (4%), but is 4.5 times smaller than predicted. The reason for the disagreement between the observations and the model calculations is not yet understood.
@article{arxiv.2012.10883,
title = {Water and Methanol Ice in L1544},
author = {Miwa Goto and A. I. Vasyunin and B. M. Giuliano and I. Jiménez-Serra and P. Caselli and C. G. Román-Zúñiga and J. Alves},
journal= {arXiv preprint arXiv:2012.10883},
year = {2021}
}