Precursors of the RNA-world in space: Detection of ($Z$)-1,2-ethenediol in the interstellar medium, a key intermediate in sugar formation

Abstract

We present the first detection of ($Z$)-1,2-ethenediol, (CHOH)${}_2$, the enol form of glycolaldehyde, in the interstellar medium towards the G+0.693-0.027 molecular cloud located in the Galactic Center. We have derived a column density of (1.8$\pm$0.1)$\times$10${}^{13}$ cm${}^{-2}$, which translates into a molecular abundance with respect to molecular hydrogen of 1.3$\times$10${}^{-10}$. The abundance ratio between glycolaldehyde and ($Z$)-1,2-ethenediol is $\sim$5.2. We discuss several viable formation routes through chemical reactions from precursors such as HCO, H${}_2$CO, CHOH or CH${}_2$CHOH. We also propose that this species might be an important precursor in the formation of glyceraldehyde (HOCH${}_2$CHOHCHO) in the interstellar medium through combination with the hydroxymethylene (CHOH) radical.

Accepted for publication in The Astrophysical Journal Letters