SIMBAD references

The projected radial distribution of 88 red giant spectroscopic binaries has been compared to that of 260 single giants in 14 intermediate-age and old open clusters. The radial extension of the available data is of crucial importance, and the clusters have been partitioned in two groups. In the first group, with most complete data, only one cluster (M67) shows a statistically significant concentration of spectroscopic binaries towards the inner regions relative to single giants. Central concentration of binaries is observed, without statistical significance, for three younger clusters. The segregation does not depend on the period of the binaries, but qualitatively seems to depend on the total mass of the binary. For the 7 clusters of the second group, no effect is visible. These clusters are either not old enough (8.45 < logt < 9.25) or, more probably, the radial extension of the existing photometric studies is too small. Simulation with real data tends to favour the latter explanation.