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After the dissociation is completed, the exponent becomes
.
This gas forms a second core composed of atomic hydrogen, which is called the second core
(points number 7-8 of Figure 4.13).
Since the accretion rate [eq.(4.75)] is proportional to
or
,
the accretion rates onto the second core
is larger than that of the first core
as
![\begin{displaymath}
\frac{\dot{M}_{\rm 2nd}}{\dot{M}_{\rm 1st}}
\simeq 5\times ...
...10^{3.5}{\rm K}\right)^{3/2}}{\left(T/10{\rm K}\right)^{3/2}}.
\end{displaymath}](img1245.png) |
(4.97) |
Thus, the first core disappears quickly and after that the gas begins to accrete onto the second core,
which will be a protostar.
However, this is the case of non-rotating, spherical symmetric cloud collapse.
As previously seen, the angular momentum plays a crucial role and forms a disk.
The evolution must be different completely for such a case.
Kohji Tomisaka
2007-07-08