APOGEE strings: a fossil record of the gas kinematic structure
  We compare APOGEE radial velocities (RVs) of young stars in the Orion A cloud
with CO line gas emission and find a correlation between the two at
large-scales, in agreement with previous studies. However, at smaller scales we
find evidence for the presence of substructure in the stellar velocity field.
Using a Friends-of-Friends approach we identify 37 stellar groups with almost
identical RVs. These groups are not randomly distributed but form elongated
chains or strings of stars with five or more members with low velocity
dispersion, across lengths of 1-1.5~pc. The similarity between the kinematic
properties of the APOGEE strings and the internal velocity field of the chains
of dense cores and fibers recently identified in the dense ISM is striking and
suggests that for most of the Orion A cloud, young stars keep memory of the
parental gas substructure where they originated.
