A three-dimensional map of the Milky Way using classical Cepheid variable stars

The Milky Wayis a barred spiral galaxy, with physical properties inferred from various tracers informed by the extrapolation of structures seen in other galaxies. However, the distances of these tracers are measured indirectly and are model-dependent. We constructed a map of the Milky Wayin three dimensions, based on the positions and distances of thousands of classical Cepheid variablestars. This map shows the structure of our Galaxy’s young stellar populationand allows us to constrain the warped shape of the MilkyWay’s disk. A simple model of star formation in the spiral arms reproduces the observed distribution of Cepheids.