The true shapes of the globular clusters in M 31

نویسنده

  • A. Staneva
چکیده

The true shapes of the globular clusters (GCs) in M 31 have been derived from observed ellipticities. The nonparametric kernel estimates for the axis ratios distributions in the case of oblate or prolate spheroid hypothesis and the parametric estimates in the case of triaxial ellipsoid hypothesis have been used. The cluster shapes are inconsistent with the oblate/prolate hypothesis and only the shapes of the GCs situated beyond the outermost visible limit of M 31 disk (so called “halo” clusters) are consistent with that hypothesis. We conclude that the GCs in the M 31 are most likely triaxial ellipsoids. The distributions of intrinsic axis ratios derived on the base of triaxial ellipsoid hypothesis have been compared with results published earlier. It has been found out that the clusters in M 31 are more spherical than those in the LMC and in the SMC while the GCs in the Galaxy are rounder than those in M 31.

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تاریخ انتشار 1996