Galactic Monster Dwarfs the Milky Way

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As far as spiral galaxies go, the Milky Way is a relative pipsqueak, especially when compared to one known as NGC 6872, a barred spiral galaxy located some 212 million light-years from Earth in the constellation Pavo.

Spanning 522,000 light-years from end to end — roughly five times larger than the Milky Way — NGC 6872 has been crowned the king of spiral galaxies, based on an analysis of data gathered by NASA’s Galaxy Evolution Explorer telescope.

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Fueling the galaxy’s growth is its ongoing interaction with a small disk galaxy, known as IC 4970, which is visible only in ultraviolet light.

Computer simulations indicate the dwarf galaxy, which is about one-fifth the size of the spiral galaxy, made its closest pass by NGC 6872 about 130 million years ago. Its gravitational tugging kicked up a flurry of star formation in the process.

Analysis shows the youngest stars are located in the far end of the northwestern arm, where tidal forces from the dwarf galaxy would be strongest. Moving toward the galaxy’s center, the stars grow progressively older. A similar pattern is seen in the southwestern arm.

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In addition to GALEX, which probes ultraviolet radiation, scientists used archival data from the European Southern Observatory’s Very Large Telescope, the Two Micron All Sky Survey, and NASA’s Spitzer Space Telescope.

The research was presented last week at the American Astronomical Society conference in Long Beach, Calif.

For more information and full-resolution versions of the NGC 6872 observation, browse the NASA project pages.

Image: The giant barred spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory’s Very Large Telescope with far-ultraviolet (1,528 angstroms) data from NASA’s GALEX and 3.6-micron infrared data acquired by NASA’s Spitzer Space Telescope.

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