Hubble Sees G1, the Brightest Globular in M31 -

Hubble Spies Extragalactic Globular Cluster G1, in the Andromeda Galaxy M31

Hubble Space Telescope has captured a view of a globular cluster called

G1, a large, bright ball of light in the center of the photograph

consisting of at least 300,000 old stars.

G1, also known as Mayall II, orbits the Andromeda galaxy (M31), the

nearest major spiral galaxy to our Milky Way.

Located 130,000 light-years from Andromeda’s nucleus, G1 is the brightest

globular cluster in the Local Group of galaxies.

At a distance of 2.2 million light years, it shines at 13.7 mag visual

magnitude, and is thus visible as tiny patch in large amateur telescopes.

The crisp image is comparable to ground-based telescope views of

similar clusters orbiting the Milky Way. The Andromeda cluster,

however, is nearly 100 times farther away (and thus 10,000 times fainter).

A glimpse into the cluster’s finer details allow astronomers to see its

fainter helium-burning stars whose temperatures and brightnesses show

that this cluster in Andromeda and the oldest Milky Way clusters have

approximately the same age. These clusters probably were formed

shortly after the beginning of the universe, providing astronomers with

a record of the earliest era of galaxy formation.

During the next two years, astronomers will use Hubble to study about

20 more globular clusters in Andromeda.

The color picture was assembled from separate images taken in visible

and near-infrared wavelengths taken in July of 1994.

Credit: Michael Rich, Kenneth Mighell, and James D. Neill (Columbia

University), and Wendy Freedman (Carnegie Observatories), and NASA

Of this image, high resolution (300 dpi) JPEG images are available

More HST images of M31:

Last Modification: 3 Jul 1999, 00:25 MET