There is irresistible observational evidence that binary systems of compact
objects with at least one neutron star are progenitors of short gamma-ray
bursts, as well as a production site for r-process elements, at least when some
matter is ejected by the merger and an accretion disk is formed. The recent
observations of gravitational waves in conjunction with electromagnetic
counterparts fuel the need for models predicting the outcome of a given merger
and the properties of the associated matter outflows as a function of the
initial parameters of the binary. In this manuscript, we provide updated
fitting formulae that estimate the disk mass for double neutron star binaries
and ejecta masses for black hole-neutron star and double neutron star binaries,
fitted to the results of numerical simulations. Our proposed fitting formulae
improve on existing models by aiming for analytical simplicity, by covering a
larger region of parameter space, and by accounting for regions of parameter
space not covered by numerical simulations but with physically manifest merger
outcomes.
