EPoS Contribution

Dense gas flows and feedback in the Serpens South protocluster Rachel Friesen UToronto, Toronto, CA
Star-forming groups and clusters are largely found in filamentary systems, where hubs of dense gas may be fed by mass accretion along molecular filaments, which themselves fragment and form stars. Analysis of the dense gas kinematics is required to confirm the existence of gas flows, and to assess the impact of the current star formation on the material actively involved in forming the next generation of stars. I will present high resolution (VLA) ammonia observations of the hub-filament Serpens South cluster-forming system. We find that the majority of dense cores in the region are super-virial, with gravitationally bound cores located primarily in the filaments as expected from continuum surveys. Gas temperatures and non-thermal linewidths both increase towards the centre of the young stellar cluster, in the dense gas generally and in the cores specifically. As a result, cores near the protocluster are more likely to be super-virial, with increased virial parameters driven primarily by the increased non-thermal velocity dispersions. We additionally find a strong correlation between the non-thermal velocity dispersion and the gas temperature, and argue that both are increasing near the cluster centre primarily via mechanical heating and interaction between the protocluster-driven outflows and the dense gas. Filament-led accretion may also contribute to the increased velocity dispersions. Assuming a constant fraction of core mass ends up in the young stars, and that the cluster cores accrete material from the observed filamentary flows, feedback from low-mass stars will thus shift future star formation in the cluster to higher masses by a factor ~2.

Caption: Left: Line-of-sight velocity (v_LSR) of dense gas traced by NH3 towards the Serpens South protocluster and filaments (with inset IR image; Gutermuth et al. 2008), with contours highlighting the integrated NH3 intensity. Right: Kernel Density Estimations of the v_LSR (top), non-thermal velocity dispersion (middle), and gas temperature (bottom) as a function of distance from the YSO cluster centre, revealing the correlated increase in gas temperature and non-thermal velocity dispersion in the dense gas toward the protocluster.
Collaborators: E. Jarvis, UToronto, CA	Relevant topic(s): Clustered SF Cores Feedback
Relevant Big Question: What is the impact of feedback from low mass star-forming clusters on future star formation?