|Our Local Grouup
spans a region nearly 10 Million Light Years (Mly)
in diameter. This diagram shows some of the main members.
There are 45 members in all. With the exception of M31, the Milky Way, and M33, the remaining members are dwarf ellipticals or small irregular galaxies. New galaxies are still being found! A list is kept on http://www.seds.org/messier/more/local.html. Nearly all these dwarf and irregular galaxies would be undetected far from the Local Group.
Some important members of our Local Group include:
NGC 6822. |
Irregular galaxy about 1.7 Mly away. This galaxy shows a lot of recent bursting of young massive stars (blue stars and red nebular areas).
This dwarf galaxy is about 4 Mly away. It is 1/12th the size of the Milky Way.
The Small Magellanic Cloud.
This irregular galaxy is very near, just 0.2 Mly away and has lots of massive stars.
This is a dwarf elliptical galaxy 0.6 Mly away. It is a very diffuse grouping of stars and not easily found.
Our Local Group of galaxies is on the outskirts of a much larger extended cluster of
galaxies called the Virgo Cluster.
The Virgo Cluster is a cluster of galaxies at a distance of 60 Mly away in the direction
of the constellation Virgo. Comprising
about 1300 (and possibly up to 2000) member galaxies, the cluster forms the
heart of the
larger Local Supercluster, of which our Local Group is an outlying member. It is
estimated to weigh 1.2 x 1015 solar masses.