  We report on the realization of a transversely loaded two-dimensional
magneto-optical trap serving as a source for cold strontium atoms. We analyze
the dependence of the source's properties on various parameters, in particular
the intensity of a pushing beam accelerating the atoms out of the source. An
atomic flux exceeding $10^9\,\mathrm{atoms/s}$ at a rather moderate oven
temperature of $500\,^\circ\mathrm{C}$ is achieved. The longitudinal velocity
of the atomic beam can be tuned over several tens of m/s by adjusting the power
of the pushing laser beam. The beam divergence is around $60$ mrad, determined
by the transverse velocity distribution of the cold atoms. The slow atom source
is used to load a three-dimensional magneto-optical trap realizing loading
rates up to $10^9\,\mathrm{atoms/s}$ without indication of saturation of the
loading rate for increasing oven temperature. The compact setup avoids
undesired effects found in alternative sources like, e.g., Zeeman slowers, such
as vacuum contamination and black-body radiation due to the hot strontium oven.
