M79, a globular cluster about 41,000 light years from Earth in the constellation Lepus, is a gravitationally bound group of about 150,000 stars that was discovered in 1780 by Pierre Méchain and added to Charles Messier’s famous catalog. William Herschel, using a more powerful telescope, first called it a “globular star cluster.” Globular clusters typically orbit the core of the Milky Way and can contain more than a million stars. M79 may have a more unusual history than most given its location in the opposite direction from the core. It may be a captured cluster from a dwarf galaxy in the process of merging with the Milky Way or it may have simply formed in a region with a higher density of stars. Either way, the Hubble Space Telescope provides a stunning view.
This NASA/ESA Hubble Space Telescope image reveals a delicate blue group of stars — actually an irregular galaxy named IC 3583 — that sits some 30 million light-years away in the constellation of Virgo. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90.
Astronomers have used NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton X-ray observatory to discover an extremely luminous, variable X-ray source located outside the centre of its parent galaxy. This peculiar object could be a wandering black hole that came from a small galaxy falling into a larger one.
When our galaxy was born, around 13,000 million years ago, a plethora of clusters containing millions of stars emerged. But over time, they have been disappearing. However, hidden behind younger stars that formed later, some old and dying star clusters remain, such as the so-called E 3. European astronomers have now studied this testimony to the beginnings of our galaxy.