Young Stellar Objects and Triggered Star Formation in the Vulpecula OB
  Association
  The Vulpecula OB association, VulOB1, is a region of active star formation
located in the Galactic plane at 2.3 kpc from the Sun. Previous studies suggest
that sequential star formation is propagating along this 100 pc long molecular
complex. In this paper, we use Spitzer MIPSGAL and GLIMPSE data to reconstruct
the star formation history of VulOB1, and search for signatures of past
triggering events. We make a census of Young Stellar Objects (YSO) in VulOB1
based on IR color and magnitude criteria, and we rely on the properties and
nature of these YSOs to trace recent episodes of massive star formation. We
find 856 YSO candidates, and show that the evolutionary stage of the YSO
population in VulOB1 is rather homogeneous - ruling out the scenario of
propagating star formation. We estimate the current star formation efficiency
to be ~8 %. We also report the discovery of a dozen pillar-like structures,
which are confirmed to be sites of small scale triggered star formation.
