YSO jets in the Galactic Plane from UWISH2: III - Jets and Outflows in Cassiopeia and Auriga

TL;DR

This study analyzes 98 new molecular hydrogen outflows in Cassiopeia and Auriga, revealing their orientations, source types, and properties, and providing insights into star formation and outflow characteristics in these regions.

Contribution

First comprehensive survey of H2 outflows in Cassiopeia and Auriga, identifying new objects, sources, and star clusters, and analyzing their physical and statistical properties.

Findings

98 new MHOs identified, mostly bipolar outflows

Outflow orientations are randomly distributed

Outflow properties suggest episodic ejections not caused by FU-Ori eruptions

Abstract

We present the analysis of 35.5 square degrees of images in the 1-0S(1) line of H2 from the UK Widefield Infrared Survey for H2 (UWISH2) towards Cassiopeia and Auriga. We have identified 98 Molecular Hydrogen emission-line Objects (MHOs) driven by Young Stellar Objects, 60% of which are bipolar outflows and all are new discoveries. We estimate that the UWISH2 extended emission object catalogue contains fewer than % false positives and is complete at the 95% level for jets and outflows brighter than the UWISH2 detection limit. We identified reliable driving source candidates for three quarters of the detected outflows, 40% of which are associated with groups and clusters of stars. The driving source candidates are 20% protostars, the remainder are CTTSs. We also identified 15 new star cluster candidates near MHOs in the survey area. We find that the typical outflow identified in the sample has the following characteristics: the position angles are randomly orientated; bipolar outflows are straight within a few degrees; the two lobes are slightly asymmetrical in length and brightness; the length and brightness of the lobes are not correlated; typical time gaps between major ejections of material are 1-3kyr, hence FU-Ori or EX-Ori eruptions are most likely not the cause of these, but we suggest MNors as a possible source. Furthermore, we find that outflow lobe length distributions are statistically different from the widely used total length distributions. There are a larger than expected number of bright outflows indicating that the flux distribution does not follow a power law.