First detection of glycolaldehyde outside the Galactic Center

Glycolaldehyde is the simplest of the monosaccharide sugars and is directly linked to the origin of life. We report on the detection of glycolaldehyde (CH2OHCHO) towards the hot molecular core G31.41+0.31 through IRAM PdBI observations at 1.4, 2.1, and 2.9 mm. The CH2OHCHO emission comes from the hottest (≥ 300 K) and densest (≥2×10 cm) region closest (≤ 10 AU) to the (proto)stars. The comparison of data with gas-grain chemical models of hot cores suggests for G31.41+0.31 an age of a few 10 yr. We also show that only small amounts of CO need to be processed on grains in order for existing hot core gas-grain chemical models to reproduce the observed column densities of glycolaldehyde, making surface reactions the most feasible route to its formation. Subject headings: ISM: individual objects: G31.41+0.31 — ISM: molecules — stars: formation