NGC 4473

NGC 4473 is an elliptical galaxy roughly 50 million light-years from Earth in the constellation Coma Berenices. It belongs to Markarian's Chain, a string of galaxies that forms part of the larger Virgo Cluster. William Herschel first spotted it on April 8, 1784. The galaxy is tilted at an inclination of about 71°.

Inside NGC 4473, astronomers estimate there are 376 ± 97 globular clusters. These clusters might have come from several small mergers that helped build the galaxy’s outer regions. The galaxy also contains two stellar discs in its inner area that rotate in opposite directions. These counter-rotating discs could have formed either from gas pulled in from outside or from mergers of gas-rich galaxies.

At the center, observations from the Hubble Space Telescope and ground-based spectroscopy—led by Douglas Richstone and colleagues at the University of Michigan—reveal a supermassive black hole. By tracking the motions of stars near the core, they estimate its mass at roughly 100 million times that of the Sun. Its diameter is about 4.459 AU, or 669 million kilometers.