  We study quasi-static atmospheres of accreting protoplanetary cores for
different opacity behaviors and realistic planetesimal accretion rates in
various parts of protoplanetary nebula. Atmospheres segregate into those having
outer convective zone which smoothly merges with the nebular gas, and those
having almost isothermal outer radiative region decoupling atmospheric interior
from the nebula. Specific type of atmosphere depends only on the relations
between the Bondi radius of the core, photon mean free path in the nebular gas,
and the luminosity radius (roughly the size of the sphere which can radiate
luminosity of the core at effective temperature equal to the nebular
temperature). Cores in the inner parts of protoplanetary disk (within roughly
0.3 AU from the Sun) have large luminosity radii resulting in the atmospheres
of the first type, while cores in the giant planet region (beyond several AU)
have small luminosity radii and always accumulate massive atmospheres of the
second type. Critical core mass for nucleated instability is found to vary as a
function of distance from the Sun. It is 5-20 M_Earth at 0.1-1 AU which is too
large to permit the formation of ``hot Jupiters'' by nucleated instability near
the cores that have grown in situ. In the region of giant planets critical mass
is 20-60 M_Earth (for opacity 0.1 cm^2/g) if planetesimal accretion was fast
enough for protoplanetary cores to form prior to the nebular gas dissipation.
This might indicate that giant planets in the Solar System have gained their
atmospheres by nucleated instability only after their cores have accumulated
most of the mass in solids during the epoch of oligarchic growth, subsequent to
which planetesimal accretion slowed down and cores became supercritical.
