In the context of the ASAI ( Astrochemical Surveys At IRAM ) project , we carried out an unbiased spectral survey in the millimeter window towards the well known low-mass Class I source SVS13-A .
The high sensitivity reached ( 3–12 mK ) allowed us to detect at least 6 HDO broad ( FWHM \sim 4–5 km s ^ { -1 } ) emission lines with upper level energies up to E _ { u } = 837 K. A non-LTE LVG analysis implies the presence of very hot ( 150–260 K ) and dense ( \geq 3 \times 10 ^ { 7 } cm ^ { -3 } ) gas inside a small radius ( \sim 25 AU ) around the star , supporting , for the first time , the occurrence of a hot corino around a Class I protostar .

The temperature is higher than expected for water molecules are sublimated from the icy dust mantles ( \sim 100 K ) .
Although we can not exclude we are observig the effects of shocks and/or winds at such small scales , this could imply that the observed HDO emission is tracing the water abundance jump expected at temperatures \sim 220–250 K , when the activation barrier of the gas phase reactions leading to the formation of water can be overcome .
We derive X ( HDO ) \sim 3 \times 10 ^ { -6 } , and a H _ { 2 } O deuteration \geq 1.5 \times 10 ^ { -2 } , suggesting that water deuteration does not decrease as the protostar evolves from the Class 0 to the Class I stage .