Messier 79


Messier 79 is a globular cluster in the constellation Lepus. It was discovered by Pierre Méchain in 1780 and is at a distance of about 42,000 light years away from Earth and 60,000 light years away from the Galactic Center.
Like Messier 54, it is thought that M79 is not native to the Milky Way galaxy at all, but instead to the putative Canis Major Dwarf Galaxy, which is currently experiencing a very close encounter with the Milky Way. This is, however, a contentious subject as astronomers are still debating the nature of the Canis Major dwarf galaxy itself.

Color-magnitude diagram

This color-magnitude diagram was made using infrared images of Messier 79 in J and K bands. J-band magnitude is plotted along the y-axis and J-K color is plotted along the x-axis. The diagram was created using DAOPHOT, Peter Stetson's code for crowded-field photometry.
Based on the diagram, it is evident that most of the bright stars in this cluster are red giants. The elongated branch is the red giant branch. Some of the stars in the diagram, including those extending outward from the red giant branch toward the upper left, are actually foreground stars that are not members of the cluster.
Altogether three regions of the Hertzsprung-Russell diagram are present here: the low-mass end of the main sequence, the complete red giant branch and the horizontal branch. Compared to optical bands, in infrared bands the lower main sequence is shallower and the horizontal branch is steeper.