Alpheratz system

Alpheratz is a binary star system. The two binary components Alpheratz A and B have an close and eccentric 96.7 day orbit about their common center of gravity. Alpheratz A is a bluish spectral type B subgiant star, with an unusually high amount of mercury, manganese, and certain other metals in its photosphere. This is likely due to its slow rotation and radiation pressure from within rather than due to an intrinsically high amount of these metals. Alpheratz B is a spectral type A main sequence star which is cooler and less bluish in color than its larger binary partner.

Trivia

Alpheratz is one of the four star systems that comprise the Great Square of Pegasus for Earth astronomers.