  We fit an isothermal oscillatory density model to the outer disk of TW Hya in
which planets have presumably already formed and they are orbiting within four
observed dark gaps. At first sight, this 52 AU small disk does not appear to be
similar to our solar nebula; it shows several physical properties comparable to
those in HL Tau (size $R_{\rm max}=102$ AU) and very few similarities to AS 209
($R_{\rm max}=144$ AU). We find a power-law density profile with index $k=-0.2$
(radial densities $\rho(R) \propto R^{-1.2}$) and centrifugal support against
self-gravity so small that it virtually guarantees dynamical stability for
millions of years of evolution to come. Compared to HL Tau, the scale length
$R_0$ and the core size $R_1$ of TW Hya are smaller only by factors of $\sim$2,
reflecting the disk's half size. On the opposite end, the Jeans frequency
$\Omega_J$ and the angular velocity $\Omega_0$ of the smaller core of TW Hya
are larger only by factors of $\sim$2. The only striking difference is that the
central density ($\rho_0$) of TW Hya is 5.7 times larger than that of HL Tau,
which is understood because the core of TW Hya is only half the size ($R_1$) of
HL Tau and about twice as heavy ($\Omega_J$). In the end, we compare the
protostellar disks that we have modeled so far.
