The Cartwheel Galaxy ESO 350-40

The Cartwheel Galaxy also known as ESO 350-40 firstly discovered by Fritz Zwicky in 1941. An estimation of the galaxy's span resulted in a conclusion of 150,000 light years, which is slightly larger than the Milky Way. Cartwheel Galaxy is a lenticular galaxy 496 million light-years away in the constellation Sculptor It is 153,261 light-years across. The estimated mass is 2.9–4.8 × 109 solar masses, and it is rotating at 217 km/s.

The Cartwheel galaxy in different light spectra (X-ray, ultraviolet, visible, and infrared). The image combines data from four different space-based observatories: the Chandra X-ray Observatory (purple), the Galaxy Evolution Explorer (ultraviolet/blue), the Hubble Space Telescope (visible/green), and the Spitzer Space Telescope (infrared/red).

The Cartwheel galaxy is one of the brightest ultraviolet energy sources in the local universe. In some visible-light images, it appears to have spokes. Appleton is presenting his finding today at the 207th meeting of the American Astronomical Society in Washington. His research collaborators included Armando Gil de Paz of Universidad Complutense, Madrid, Spain; and Barry Madore of The Observatories of the Carnegie Institution of Washington, Pasadena, Calif.

Most galaxies have only one or two bright X-ray sources, usually associated with gas falling onto a black hole from a companion star. The Cartwheel has a dozen. Appleton said that makes sense, because black holes thrive in areas where massive stars are forming and dying fast.

The Cartwheel's rim is an immense ring-like structure 100,000 light years in diameter composed of newly formed, extremely bright, massive stars. When galaxies collide, they pass through each other -- their individual stars rarely come into contact. The galaxies' gravitational fields, however, may be greatly distorted by the collision. In fact, the ring-like shape is the result of the gravitational disruption caused by a small intruder galaxy passing through a large one, compressing the interstellar gas and dust, and causing a wave of star formation wave to move out from the impact point like a ripple across the surface of a pond. In this case, the large galaxy may have originally been a spiral, not unlike our own Milky Way Galaxy, transformed by the collision.