How organics deuteration changes during the formation of a Sun-like star

Abstract

Deuterated molecules have been detected towards the early stages of Sun-like star formation (prestellar cores, Class 0 objects) as well as towards the Solar System; they are a powerful diagnostic tool for studying physical conditions at the moment of the organics formation. However, observations in intermediate stages (Class I/II objects) are still missing. In the framework of the ASAI-IRAM Large Program, we report here the formaldehyde and methanol deuteration as measured in the Class I object SVS13-A. The deuterium fractionation is found to be 9 × 10<SUP>-2</SUP> for HDCO, 5 × 10<SUP>-3</SUP> For D<SUB>2</SUB>CO, and 4 × 10<SUP>-3</SUP> for CH_2DOH, up to one order of magnitude lower than the value measured in Class 0 sources. The present measurements of organics deuteration towards the Class I object SVS13-A contribute to fill in the gap between prestellar cores and protoplanetary disks in the context of deuterium fractionation measurements (see \citet{bia17}).