α Comae Berenicis


Alpha Comae Berenicis is a multiple star system. There is a very close companion with an orbit of 25.9 years, seen perfectly edge-on: 4.8, 55; 12º, 0.6". The second companion is a binocular binary: 5.2, 10.2; 346º, 87.2º.

Alpha Comae is quickly found west of Arcturus (alpha Boötis). Centre Arcturus in your glasses and move four binocular fields west: binoculars.

This star is the size of our Sun and is 47 light years away.

M53, one degree northeast of alpha, is a globular star cluster about 65,000 light years away. It has an apparent magnitude of 7.6 and, as with all the Messier objects in Coma, it's best seen in large telescopes. It contains about a half million stars, and is considered to be about 12.7 billion years old.


Most of Coma's binaries and clusters are within a two binocular field of alpha-northwest to west, culminating in the wonderful 'Coma Star Cluster' two fields northwest.

First, however, stop for a while to examine a lovely optical binary two degrees west of 36 Com (in your current field of view). Place this star on the eastern edge of your viewing field, and you'll have 32-33 Com centred: an easy binocular binary: 6.5' 6.9; 51º, 196".

Another full binocular field west will give you a lovely colour-contrasting binary. Click on 24 Com on the map for further details.

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