Gaia EDR3 Reveals the Substructure and Complicated Star Formation
  History of the Greater Taurus-Auriga Star Forming Complex
  The Taurus-Auriga complex is the prototypical low-mass star forming region,
and provides a unique testbed of the star formation process, which left
observable imprints on the spatial, kinematic, and temporal structure of its
stellar population. Taurus's rich observational history has uncovered
peculiarities that suggest a complicated star forming event, such as members at
large distances from the molecular clouds and evidence of an age spread. With
Gaia, an in-depth study of the Taurus census is possible to confirm membership,
identify substructure, and reconstruct its star formation history. We have
compiled an expansive census of the greater Taurus region, identifying spatial
subgroups and confirming that Taurus is substructured across stellar density.
There are two populations of subgroups: clustered groups near the clouds and
sparse groups spread throughout the region. The sparse groups comprise Taurus's
distributed population, which is on average older than the population near the
clouds, and hosts sub-populations up to 15 Myr old. The ages of the clustered
groups increase with distance, suggesting that the current star formation was
triggered from behind. Still, the region is kinematically coherent, and its
velocity structure reflects an initial turbulent spectrum similar to Larson's
Law that has been modified by dynamical relaxation. Overall, Taurus has a
complicated star formation history, with at least two epochs of star formation
featuring both clustered and distributed modes. Given the correlations between
age and spatial distribution, Taurus might be part of a galaxy-scale star
forming event that can only begin to be understood in the Gaia era.
