Resolved ALMA observations of water in the inner astronomical units of the HL Tau disk.

The water molecule is a key ingredient in the formation of planetary systems, with the water snowline being a favourable location for the growth of massive planetary cores. Here we present Atacama Large Millimeter/submillimeter Array data of the ringed protoplanetary disk orbiting the young star HL Tauri that show centrally peaked, bright emission arising from three distinct transitions of the main water isotopologue ( ). The spatially and spectrally resolved water content probes gas in a thermal range down to the water sublimation temperature.