  Approximately 70 percent of the nearby white dwarfs appear to be single
stars, with the remainder being members of binary or multiple star systems. The
most numerous and most easily identifiable systems are those in which the main
sequence companion is an M star, since even if the systems are unresolved the
white dwarf either dominates or is at least competitive with the luminosity of
the companion at optical wavelengths. Harder to identify are systems where the
non-degenerate component has a spectral type earlier than M0 and the white
dwarf becomes the less luminous component. Taking Sirius as the prototype,
these latter systems are referred to here as Sirius-Like. There are currently
98 known Sirius-Like systems. Studies of the local white dwarf population
within 20 parsecs indicate that approximately 8 per cent of all white dwarfs
are members of Sirius-Like systems, yet beyond 20 parsecs the frequency of
known Sirius-Like systems declines to between 1 and 2 per cent, indicating that
many more of these systems remain to be found. Estimates are provided for the
local space density of Sirius- Like systems and their relative frequency among
both the local white dwarf population and the local population of A to K main
sequence stars. The great majority of currently unidentified Sirius-Like
systems will likely turn out to be closely separated and unresolved binaries.
Ways to observationally detect and study these systems are discussed.
