The distance to the Galactic Center

Abstract

One of the Milky Way's fundamental parameters is the distance of the Sun from the Galactic Center, R 0 . This article reviews the various ways of estimating R 0 , placing special emphasis on methods that have become possible recently. In particular, we focus on the geometric distance estimate made possible thanks to observations of individual stellar orbits around the massive black hole at the center of the Galaxy. The specific issues of concern there are the degeneracies with other parameters, most importantly the mass of the black hole and the definition of the reference frame. The current uncertainty is nevertheless only a few percent, with error bars shrinking every year.