This NASA/ESA Hubble Space Telescope image shows the globular star cluster Messier 79.
The stars in the globular star cluster Messier 79 look a lot like a blizzard in a snow globe in this Hubble image. Image credit: NASA / ESA / S. Djorgovski, Caltech / F. Ferraro, University of Bologna.
Messier 79, otherwise known as NGC 1904, is located 41,000 light-years from Earth in the constellation Lepus.
The cluster was discovered by the French astronomer Pierre Méchain on October 26, 1780.
Méchain reported the finding to the French astronomer Charles Messier, who included it in his catalog of non-cometary objects.
About four years later, using a larger telescope than Charles Messier’s, the British astronomer William Herschel resolved the stars in Messier 79, and described it as a ‘globular star cluster.’
Messier 79 is approximately 11.7 billion years old.
It contains about 150,000 stars packed into an area measuring only 118 light-years across.
It lies in an unusual location, about 60,000 light years from the Milky Way Galactic center, in the hemisphere opposite the Galactic center.
One idea for the cluster’s location is that its neighborhood may contain a higher-than-average density of stars, which fueled its formation.
Another possibility is that Messier 79 may have formed in an unusual dwarf galaxy that is merging with the Milky Way.
In the Hubble image, Sun-like stars appear yellow.
The reddish stars are bright giants that represent the final stages of a star’s life.
Most of the blue stars sprinkled throughout the cluster are aging ‘helium-burning’ stars.
These bright blue stars have exhausted their hydrogen fuel and are now fusing helium in their cores.
A scattering of fainter blue stars are ‘blue stragglers.’
These unusual stars glow in blue light, mimicking the appearance of hot, young stars.
Blue stragglers form either by the merger of stars in a binary system or by the collision of two unrelated stars in Messier 79’s crowded core.
