The Interaction Between Infall and Winds
in Young Stellar Objects
Guy Delamarter, Adam Frank, and Lee Hartmann
Submitted to ApJ
Abstract
We present simulations of the interaction between a collapsing sheet density
distribution with a central spherically symmetric wind as might be found
around a young stellar object (YSO). We investigate how the morphology
and velocity structure of the resulting outflows change as we vary the
ratio (denoted f') of the inflow mass flux to the wind mass flux.
In addition to elucidating the behavior around YSOs of different wind strengths,
this serves in part as a preliminary survey of the effect of time dependent
winds from a single object on the resulting outflow.
We find that relatively strong winds can carve out wide, conical outflow
cavities and that relatively weak winds can be strongly collimated into
jet-like structures. If the winds become weak enough, they can be
cut off entirely by the infalling environment.
Learn more about
the collapsing sheet environment used in these simulations.
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| Comparison between outflows at times of similar
axial extent. The density of the f'=10,20,30,40, and 50 (left to right
- strong wind to weak wind) cases are shown at their full heights at 100,
200, 220, 240, and 220 years, respectively. Note the increased focusing
of the bubbles as the wind becomes weaker. |
Compare these shapes to those in some observational
images of outflows.
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f '=10 (180 y)
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f' =30 (220 y)
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f' =50 (220y)
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| Density, pressure, temperature,
velocity snapshots for three representative simulations. |
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f' =10
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f' =50
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| Density and velocity
animations for two cases. Frames are taken 20 years apart.
The color scale corresponds to that used in the still frames shown earlier. |
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| Mass vs. velocity curves over time for each
simulation. The left-hand shallow portion has a power law dependence
of about -1.5, while the steeper portion has a dependence of -10 or steeper.
Note, however, the bottom f'=50 case where, as time passes, the steeper
portion flattens. This is likely due to the stong focusing in this
case (see density snapshots above) accelerating more mass at high velocities
than in the other cases. |
Compare these plots to those made from observational
data |
