A submillimetre survey of the kinematics of the Perseus molecular cloud - II. Molecular outflows

TL;DR

This large-scale survey of molecular outflows in the Perseus cloud reveals differences between Class 0 and I protostars, showing outflows' role in cloud dynamics and evolution.

Contribution

It provides one of the largest and most sensitive surveys of molecular outflows in a single cloud, with detailed analysis of outflow properties and their relation to protostar evolution.

Findings

Class 0 outflows are longer, faster, more massive, and more energetic than Class I outflows.

Outflows' force decreases with age, indicating declining mass accretion rates.

Outflow energy exceeds local turbulent energy, affecting cloud evolution.

Abstract

We present a census of molecular outflows across four active regions of star formation in the Perseus molecular cloud (NGC 1333, IC348/HH211, L1448 and L1455), totalling an area of over 1000 sq arcmin. This is one of the largest surveys of outflow evolution in a single molecular cloud published to date. We analyse large-scale, sensitive CO J=3-2 datasets from the James Clerk Maxwell Telescope, including new data towards NGC 1333. Where possible we make use of our complementary 13CO and C18O data to correct for the 12CO optical depth and measure ambient cloud properties. Of the 65 submillimetre cores in our fields, we detect outflows towards 45. We compare various parameters between the outflows from Class 0 and I protostars, including their mass, momentum, energy and momentum flux. Class 0 outflows are longer, faster, more massive and have more energy than Class I outflows. The dynamical time-scales we derive from these outflows are uncorrelated to the age of the outflow driving source, computed from the protostar's bolometric temperature. We confirm the results of Bontemps et al., that outflows decrease in force as they age, suggesting a decline in the mass accretion rate. If F_rad=L_bol/c is the flux expected in radiation from the central source, then F_CO(Class I)~100F_rad and F_CO(Class 0)~1000F_rad. Finally, we note that the total energy contained in outflows in NGC 1333, L1448 and L1455 is greater than the estimated turbulent energy in the respective regions, which may have implications for the regions' evolution.