Copyright by Athena Ranice Stacy 2011 - The University of Texas at ...

sink tform [yr] Mfinal [M⊙] rinit [AU] rfinal [AU]
1 0 43 0 0
2 300 13 60 700
3 3700 1.3 930 1110
4 3750 0.8 740 890
5 4400 1.1 270 240
Table 2.1: Formation times, final masses, and distances from the main sink.
We include all sinks still present at the end of the simulation.
angular momentum outward through gravitational torques, allowing some of
the inner gas to accrete onto the sinks (see Krumholz et al. 2007). By 1000 yr
after initial sink formation, several new fragments have formed, represented
by new sink particles (shown in Fig. 2.5). Some of these fragments eventually
merge with other more massive sinks, but by the end of our simulation we have
5 sink particles throughout the disk, described in Table 1. The two largest
sinks are 700 AU apart, have a mass ratio of ∼ 1/3, and form 300 yr apart
(see Chapter 2.4.2.4 and Fig. 2.9). This is not unsimilar to the two fragments
found in Turk et al. (2009), which had a separation of 800 AU, a mass ratio of
∼ 3/5, and formed ∼ 60 yr apart. The three smallest sinks in our calculation
are all around 1 M⊙ and formed after approximately 4000 yr. Compared to
the two largest sinks, these smaller sinks are quite low-mass and have been
present in the simulation for only a short time. The two largest sinks seem to
be the only long-term sinks in the simulation.
Analytical estimates concerning massive disk fragmentation by Kratter
and Matzner (2006) showed interesting similarity to our results. They find
that protostellar disks hosting massive stars (O and B stars) are prone to
fragmenation for disk radii larger than 150 AU, and they predict that many
low-mass companions will form in the disks around these stars at initial sep-
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