Trans-ethyl methyl ether in space - A new look at a complex molecule in selected hot core regions

TL;DR

This study searches for trans-ethyl methyl ether in various hot core regions, confirming its presence in W51e2 and providing new abundance ratios, thereby enhancing understanding of complex molecule chemistry in space.

Contribution

It provides the first confirmed detection of trans-ethyl methyl ether in W51e2 and offers new abundance ratios, improving knowledge of complex molecules in hot core regions.

Findings

Confirmed trans-ethyl methyl ether in W51e2 with a column density of 2x10^14 cm-2.

Did not confirm previous Orion KL detection within the stated limits.

Provided new upper limits for the molecule's abundance in other regions.

Abstract

An extensive search for the complex molecule trans-ethyl methyl ether towards several hot core regions has been performed. Using the IRAM 30m telescope and the SEST 15m we looked at several frequencies where trans-ethyl methyl ether has strong transitions, as well as lines which are particularly sensitive to the physical conditions in which the molecule can be found. We included G34.26, NGC6334(I), Orion KL, and W51e2 which have previously been proven to have a rich chemistry of complex molecules. Our observations cannot confirm the tentative Orion KL detection made by Charnley et al. (2001) within their stated column density limits, but we confirm the existence of the trans-ethyl methyl ether towards W51e2 with a column density of 2x10^14 cm-2. The dimethyl ether/methanol ratio of 0.6 as well as the newly found ethyl methyl ether/ethanol ratio of 0.13 indicate relative high abundances of ethers toward W51e2. Furthermore, the observation of ethyl methyl ether also confirms the importance of ethanol as a grain mantle constituent. We present new upper limits of around 8x10^13 cm-2 for the column densities of the molecule toward Orion KL, G34.26, NGC6334(I) and estimate the column density towards SgrB2(N) to be of the same order. The W51e2 observations are discussed in more detail.