Science Highlights
Multiple Shells Driven by Disk Winds: ALMA Observations in the HH 30 Outflow
Left panel: The 12CO (J = 2–1) molecular line emission at 2.3 km s−1 with respect to the systemic velocity of the monopolar outflow associated with the protostellar system HH 30. Right panel: Schematic representation of the different components of the source, assuming that the outflow is driven by disk winds. The molecular outflow exhibits an internal cavity and multiple outflowing shell structures. These multiple shells may result from episodic ejections of material from the accretion disk, corresponding to three different epochs with dynamical ages of 497 ± 15 yr, 310 ± 9 yr, and 262 ± 11 yr for the first (red line), second (blue line), and third (green line) shells, respectively. The ages of the shells are consistent with episodic outburst in the collimated jet, observed at optical wavelengths, suggesting that the episodic nature seen in both the jet and the outflow may originate from the same outburst event. Through kinematic analysis, the positions of the shells (red, blue, and green dots on right panel) are identified, with all three shells expanding at constant velocity and presenting signatures of the rotation. These shells can be explained by magnetocentrifugal disk wind with launching radii Rlaunch . 4 au, as illustrated in the accompanying diagram.
J. A. López-Vázquez et al. (2024), ApJ, 962, 28