We investigate Hoyle-Lyttleton accretion for the case where the central
source is a luminous accretion disk. %In classical Hoyle-Lyttleton accretion
onto a ``spherical'' source, accretion takes place in an axially symmetric
manner around a so-called accretion axis. The accretion rate of the classical
Hoyle-Lyttleton accretion onto a non-luminous object and Ξ the
luminosity of the central object normalized by the Eddington luminosity. %If
the central object is a compact star with a luminous accretion disk, the
radiation field becomes ``non-spherical''. %Although the gravitional field
remains spherical. In such a case the axial symmetry around the accretion axis
breaks down; the accretion radius Raccβ generally depends on an inclination
angle i between the accretion axis and the symmetry axis of the disk and the
azimuthal angle Ο around the accretion axis. %That is, the cross section
of accretion changes its shape. Hence, the accretion rate MΛ, which is
obtained by integrating Raccβ around Ο, depends on i. % as well as
M, Ξ, and vββ. %In the case of an edge-on accretion
(i=90β), The accretion rate is larger than that of the spherical case
and approximately expressed as MΛβΌMΛHLβ(1βΞ) for
Ξβ€0.65 and MΛβΌMΛHLβ(2βΞ)2/5 for Ξβ₯0.65. %Once the accretion disk forms and the anisotropic radiation fields
are produced around the central object,the accretion plane will be maintained
automatically (the direction of jets associated with the disk is also
maintained). %Thus, the anisotropic radiation field of accretion disks
drastically changes the accretion nature, that gives a clue to the formation of
accretion disks around an isolated black hole.Comment: 5 figure