Visible and Ultra-Violet image from the ASTRO-1 Shuttle mission. Messier 79 is a globular cluster of typical size and mass, located in the constellation of Lepus (the Hare), which is an unusual location for a globular; these objects typically accumulate around the galactic center. M79 contains approximately 90,000 stars, many of which are like the Sun in mass, temperature, and color. It also contains many larger, cooler stars known as red giants. These commonly occurring stars radiate most of their energy at visible wavelengths; therefore, the visible-light image shows many more stars than the UV image. The UIT/UV image reveals those few stars which are finished with their red giant phase and are in the process of becoming white dwarfs --- some by way of a second giant phase. This important transitional period in a star's life is most easily studied at ultraviolet wavelengths, where stars of this type are radiating most of their luminous energy.
Last Modification: June 20, 1999