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.
The subject of this NASA/ESA Hubble Space Telescope image is known as NGC 3597. It is the product of a collision between two good-sized galaxies, and is slowly evolving to become a giant elliptical galaxy. This type of galaxy has grown more and more common as the universe has evolved, with initially small galaxies merging and progressively building up into larger galactic structures over time.
Using the Atacama Large Millimetre/submillimetre Array (ALMA), a team of astronomers has delved remarkably deep into the heart of a nearby elliptical galaxy to study the motion of a disc of gas encircling the supermassive black hole at its centre. These observations provide one of the most accurate mass measurements to date for a black hole outside of our galaxy.