Abstract:
The density distribution of globular clusters in the Galaxy derived from the Kukarkin catalog obeys the R^1/4 law in projection on the YZ plane: logσ(R)=3.303-2.587R^1/4 over the whole range of distances (R <50 kpc), with a standard deviation Є(logσ)=0.145 (or 3.3% of the 4.4 range in logσ), consistent with the counts statistics. The effective radius of the system is R_e=2.75±0.34 kpc, with its centroid at R_0=7.0 kpc from the sun. There is no evidence for a significant flattening of the cluster system as a whole. The apparent density distribution of globular clusters in Messier 31 derived from the recent list of Sargent et aI. also obeys the R^1/4 law outside the radius of severe bulge and disk interference (R < 16'): logσ(R)=2.222-1.616R^1/4(15' ≤ R ≤ 120'), with a standard deviation Є(logσ)=0.072, consistent
with the counts statistics. The effective radius of the system is R_e =18'.0=3.4 kpc if the distance is Δ=650 kpc. It is in close agreement with the effective radius R_e =17'.3 of the luminosity distribution in the spheroidal component which obeys also closely the R^1/4 law: μ_B =14.65 + 1.45(r")^1/4. We conclude that the observed density distribution of
globular clusters may be used to infer the effective radius of the spheroidal (bulge) component of the Galaxy.
