Resumen de Episodic molecular outflow in the very young protostellar cluster Serpens South
Adele L. Plunkett, Héctor G. Arce, Diego Mardones, Pieter G. van Dokkum, Michael M. Dunham, Manuel Fernández López, José Gallardo, Stuartt A. Corder
The loss of mass from protostars, in the form of a jet or outflow, is a necessary counterpart to protostellar mass accretion1,2. Outflow ejection events probably vary in their velocity and/or in the rate of mass loss. Such ‘episodic’ ejection events3 have been observed during the class 0 protostellar phase (the early accretion stage)4,5,6,7,8,9,10, and continue during the subsequent class I phase that marks the first one million years of star formation11,12,13,14. Previously observed episodic-ejection sources were relatively isolated; however, the most common sites of star formation are clusters15. Outflows link protostars with their environment and provide a viable source of the turbulence that is necessary for regulating star formation in clusters3, but it is not known how an accretion-driven jet or outflow in a clustered environment manifests itself in its earliest stage. This early stage is important in establishing the initial conditions for momentum and energy transfer to the environment as the protostar and cluster evolve. Here we report that an outflow from a young, class 0 protostar, at the hub of the very active and filamentary Serpens South protostellar cluster16,17,18, shows unambiguous episodic events. The 12C16O (J=2-1) emission from the protostar reveals 22 distinct features of outflow ejecta, the most recent having the highest velocity. The outflow forms bipolar lobes—one of the first detectable signs of star formation—which originate from the peak of 1-mm continuum emission. Emission from the surrounding C18O envelope shows kinematics consistent with rotation and an infall of material onto the protostar. The data suggest that episodic, accretion-driven outflow begins in the earliest phase of protostellar evolution, and that the outflow remains intact in a very clustered environment, probably providing efficient momentum transfer for driving turbulence.
