Astronomers have used the ALMA observatory to trace the fuel for star formation – molecular hydrogen gas – in the iconic Hubble Ultra-Deep Field, one of the best-studied regions of the sky. The observations allowed a group led by Fabian Walter of the Max Planck Institute for Astronomy to track how the universe’s inventories of gas and dust have changed over time from just two billion years after the big bang to the present. Comparing their own observations with additional observational data and modern simulations, the astronomers were able to characterize and quantify the gas flows that are necessary prerequisites for the formation of stars within galaxies. The result is a broad-brush history of cosmic star formation that includes all the important pieces: the history of star production itself as well as information about the supply chain that enables stars to be produced in the first place.
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