Detection of antifreeze molecule ethylene glycol in the hot molecular core G358.93–0.03 MM1

Abstract

The identification of complex prebiotic molecules using millimeter and submillimeter telescopes allows us to understand how the basic building blocks of life are formed in the universe. In the interstellar medium (ISM), ethylene glycol ((CH2OH)2) is the simplest sugar alcohol molecule, and it is the reduced alcohol of the simplest sugar-like molecule, glycolaldehyde (CH2OHCHO). We present the first detection of the rotational emission lines of aGg′ conformer of ethylene glycol ((CH2OH)2) towards the hot molecular core G358.93–0.03 MM1 using the Atacama Large Millimeter/Submillimeter Array (ALMA). The estimated column density of aGg′-(CH2OH)2 towards the G358.93–0.03 MM1 is (4.5±0.1) × 1016 cm−2 with an excitation temperature of 155±35 K. The abundance of aGg′-(CH2OH)2 with respect to H2 is (1.4±0.5) × 10−8. Similarly, the abundances of aGg′-(CH2OH)2 with respect to CH2OHCHO and CH3OH are 3.1±0.5 and (6.1±0.3) × 10−3. We compare the estimated abundance of aGg′-(CH2OH)2 with the existing three-phase warm-up chemical model abundance of (CH2OH)2, and we notice the observed abundance and modelled abundance are nearly similar. We discuss the possible formation pathways of aGg′-(CH2OH)2 towards the hot molecular cores, and we find that aGg′-(CH2OH)2 is probably created via the recombination of two CH2OH radicals on the grain surface of G358.93–0.03 MM1.