The physical and dynamical structure of Serpens Two very different sub-(proto)clusters

Context. The Serpens North Cluster is a nearby low mass star forming region which is part of the Gould Belt. It contains a range of young stars thought to correspond to two different bursts of star formation and provides the opportunity to study different stages of cluster formation. Aims. This work aims to study the molecular gas in the Serpens North Cluster to probe the origin of the most recent burst of star formation in Serpens. Methods. Transitions of the C17O and C18O observed with the IRAM 30m telescope and JCMT are used to study the mass and velocity structure of the region while the physical properties of the gas are derived using LTE and non-LTE analyses of the three lowest transitions of C18O. Results. The molecular emission traces the two centres of star formation which are seen in submillimetre dust continuum emission. In the ∼40 M NW sub-cluster the gas and dust emission trace the same structures although there is evidence of some depletion of the gas phase C18O. The gas has a very uniform temperature (∼10 K) and velocity (∼8.5 kms−1) throughout the region. This is in marked contrast to the SE sub-cluster. In this region the dust and the gas trace different features, with the temperature peaking between the submillimetre continuum sources, reaching up to ∼14 K. The gas in this region has double peaked line profiles which reveal the presenc