Young Stellar Objects and Triggered Star Formation in the Vulpecula OB Association

TL;DR

This study uses infrared data to analyze star formation in Vulpecula OB, finding a homogeneous YSO population, a star formation efficiency of about 8%, and evidence of small-scale triggered star formation.

Contribution

It provides a detailed census of YSOs in VulOB1 and identifies small-scale triggered star formation sites, challenging the propagating star formation scenario.

Findings

Identified 856 YSO candidates in VulOB1.

Found the YSO population to be relatively homogeneous.

Discovered pillar-like structures as triggered star formation sites.

Abstract

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.