Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple Outflow Episodes from Protostars:3-D Models of Intermittent
  Jets   Short abstract: We present fully 3-D simulations of supersonic, radiatively
cooling intermittent jets with intermediate and long variability periods (that
is, periods of the order of or longer than, the dynamical time scale of the
jet). Variations of intermediate period elucidate the formation and evolution
of chains of internal regularly spaced radiative shocks, which in this work are
identified with the observed emission knots of protostellar jets. Variations of
long period elucidate the formation of multiple bow shock structures separated
by long trails of diffuse gas, which resemble those observed in systems like
HH111 and HH46/47. The time variability of the outflow is probably associated
with observed irruptive events in the accretion process around the protostars.
In our simulations, the outflow variations are produced by periodically turning
on the outflow with a highly supersonic velocity and periodically turning off
it to a low velocity regime. In the case of velocity variations of intermediate
period, we find, as in previous work, that the shock structures form a train of
regularly spaced emitting features which move away from the source with a
velocity close to that of the outflow, have high radial motions, and produce
low intensity spectra, as required by the observations. As they propagate
downstream, the shocks widen and dissipate due to the expulsion of material
sideways to the cocoon by the high pressure gradients of the postshock gas.
This fading explains the most frequent occurence of knots closer to the driving
source. In the case of the long period velocity variability, our simulations
have produced a pair of bow-shock-like structures separated by a trail almost

37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph