ALMA Detection of Interstellar Methoxymethanol (CH$_3$OCH$_2$OH)

TL;DR

This study reports the first detection of interstellar methoxymethanol in a high-mass star-forming region using ALMA, revealing its abundance and discussing potential formation pathways and implications for astrochemical models.

Contribution

First detection of interstellar methoxymethanol with detailed analysis of its abundance and formation mechanisms in a high-mass star-forming region.

Findings

Methoxymethanol detected with a column density of 4x10^{18} cm^{-2}.

Abundance is ~34 times less than methanol.

Detection challenges existing astrochemical models.

Abstract

We report the detection of interstellar methoxymethanol (CH$_3$OCH$_2$OH) in ALMA Bands 6 and 7 toward the MM1 core in the high-mass star-forming region NGC 6334I at ~0.1" - 1" spatial resolution. A column density of 4(2) x $10^{18}$ cm$^{-2}$ at $T_{ex}$ = 200 K is derived toward MM1, ~34 times less abundant than methanol (CH$_3$OH), and significantly higher than predicted by astrochemical models. Probable formation and destruction pathways are discussed, primarily through the reaction of the CH$_3$OH photodissociation products, the methoxy (CH$_3$O) and hydroxymethyl (CH$_2$OH) radicals. Finally, we comment on the implications of these mechanisms on gas-phase vs grain-surface routes operative in the region, and the possibility of electron-induced dissociation of CH$_3$OH rather than photodissociation.