Proper Motions in the Local Group

Abstract

In this thesis, the proper motions of two Local Group galaxies, namely M33 and IC10. The proper motions were measured by phase-referencing Very Long Baseline Interferometry (VLBI) observations of water vapour masers in the galaxies with respect to nearby background quasars. These results can be used to constrain kinematic models of the Local Group.<br /> Also, a geometric distance to M33 could be measured. The method is to measure the relative proper motions of maser sources on opposite sides of M33. The measured angular rotation rate, coupled with other measurements of the inclination and rotation speed of the galaxy, yields a direct distance measurement.