EPoS Contribution
EPoS Contribution
Evolution of Hubble Wedges in Episodic Protostellar Outflows

Paul Rohde
PH1, Cologne, DE
The "Hubble-law" and mass-velocity relation exhibit features of individual outflow bullets which suggest that protostellar outflows are episodic. In order to study these "Hubble wedges" and jumps in the position-velocity relation it is necessary to follow their evolution. For this reason, we present our new episodic outflow model for the SPH code GANDALF that mimics the accretion and ejection behaviour of FU Orion type stars. We tested our new model and found that it behaves in a self-regulated manner and that we achieve good results even for low resolutions. Using this model, we find that a recently ejected outflow bullet marks a "Hubble wedge" in the position-velocity relation. As soon as this bullet hits the leading shock front it decelerates and aligns with older bullets to the "Hubble-law" relation. At this point we can identify this bullet as a jump in the mass-velocity relation close to the break point of the broken power-law.
Caption: MV- (left) and PV-diagram (right) for the right hand side lobe of an outflow, with a turbulent Bonnor--Ebert sphere as initial conditions, at four different simulation times. The individual bullets are labelled from A to F.
Left Panels: Double logarithmic MV-diagram with the mass in Msol per velocity bin on the y-axis against the velocity in km s-1 on the x-axis. The relations show the expected broken power-law behaviour with the turn over point at high velocities. The jumps indicate the velocity of individual outflow bullets. The slope of the low- velocity part varies between γl = 1.43 and γl = 1.53, whereas the slope of the high-velocity part depends strongly on the ejection history and varies between γh = 5.41 and γh = 32.49.
Right panels: PV-diagram with velocity in km s-1 on the y-axis against the distance from the source in pc on the x-axis. The colour-bar illustrates the mass in a given pixel in 10-6 Msol. The time evolution shows the dynamics of the individual outflow bullets and their alignment to a Hubble-law like relation after decelerating at the leading shock front.
Collaborators:
S. Walch, PH1, DE
D. Seifried, PH1, DE
S.D. Clarke, PH1, DE
 Suggested Session: Cores