soon after the fragmentation occurs, when the binary or multiple protostellar system contains only a small fraction of the total mass of the original cloud [@Boss86; @BonBat94b]. However, because much of the gas contained in the original cloud still has to fall on to the system and be accreted, the final properties of the stellar system are unknown. Following the calculation significantly beyond the point at which fragmentation occurs is extremely computationally intensive. Thus, it is impossible to perform the number of calculations that are required to predict the statistical properties of binary stellar systems – even if we knew the distribution of the initial conditions. On the other hand, if we can overcome this second difficulty, we can make theoretical predictions about the properties of binary stars and, by comparing these predictions to the observed properties of binary systems, we may be able to better constrain the initial conditions for star formation.

The Effects of Accretion on a Protobinary System
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Using SPH, Bate & Bonnell [@BatBon97] studied and quantified how the properties of a binary system are affected by the accretion of a small amount of gas from an infalling gaseous envelope. They found that the effects depend 