  The possibility that long tidal tails formed during compact object mergers
may power optical transients through the decay of freshly synthesized r-process
material is investigated. Precise modeling of the merger dynamics allows for a
realistic determination of the thermodynamic conditions in the ejected debris.
The results of hydrodynamic and full nuclear network calculations are combined
to calculate the resultant r-process abundances and the heating of the material
by their decays. The subsequent homologous structure is mapped into a radiative
transfer code to synthesize emergent model light curves and determine how their
properties (variability and color evolution) depend on the mass ratio and
orientation of the merging binary. The radiation emanating from the ejected
debris, though less spectacular than a typical supernova, should be observable
in transient surveys and we estimate the associated detection rates. The case
for (or against) compact object mergers as the progenitors of short gamma-ray
bursts can be tested if such electromagnetic transients are detected (or not)
in coincidence with some bursts, although they may be obscured by on-axis
afterglows.
