Parsec but in globular clusters the stellar density could be from 100 to 1000 per cubic parsec. Parsec The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System. A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond, which corresponds to astronomical units. One parsec is equal to about 3.26 light-years (30 trillion km or 19 trillion miles) in length. The nearest star, Proxima Centauri, is about from the Sun. Most of the stars visible to the unaided eye in the night
Unit distance graph be a congruence; that is, for the infinite unit distance graph whose vertices are all the points in the plane, any graph automorphism must be an isometry . The definition of a unit distance graph may naturally be generalized to any higher-dimensional Euclidean space. Any graph may be embedded as a set of points in a sufficiently high dimension; show that the dimension necessary to embed a graph in this way may be bounded by twice its maximum degree. The dimension needed to embed a graph so that all edges have unit distance, and the dimension needed to embed a