3-Methoxy-1-propanol Rotational Spectroscopy and Radio Astronomical Search toward NGC 6334I

Abstract

The methoxy functionalized alcohol species methoxymethanol and 2-methoxyethanol have recently been identified toward the MM1 protostellar source in the NGC 6334I massive star-forming region. Here we report measurements of portions of the centimeter, millimeter, and sub-millimeter regions of the rotational spectrum of the most stable conformer of 3-methoxy-1-propanol in order to probe the presence of even larger methoxylated alcohols toward the source. The experimental rotational parameters determined from these spectra were used to simulate the rotational spectrum of 3-methoxy-1-propanol under the physical conditions of the MM1 source and compared to the same ALMA observational dataset of the source in which 2-methoxyethanol was first discovered. No 3-methoxy-1-propanol transitions are identified in the data, and an upper limit on its column density toward the source was determined to be $7.5 \cdot 10^{15} \text{ cm}^{-2}$. When considering the series of these three methoxy alcohols, the decrease in column density going from 2-methoxyethanol to 3-methoxy-1-propanol is consistent with how the column density of 2-methoxyethanol decreases compared to methoxymethanol.