Astronomers Find The Largest Known Spiral Galaxy

Based on information from the GALEX program, astronomers have crowned spiral galaxy NGC 6872 the largest known spiral galaxy in the universe.



200 million light years from Earth is the galaxy NGC 6872, which astronomers have now confirmed as being the largest known spiral galaxy in the Universe. Tip to tip, the galaxy spans over 522,000 light years, making it five times bigger than the Milky Way.

Part of the reason for the galaxy’s size is its interaction with nearby galaxy, IC 4970 which interacted with NGC 6872 hundreds of millions of years ago. That interaction increased the size of NGC 6872, and also produced new star forming regions where stars much younger than the other stars in the two galaxies are now being born.

Determining the length of the galaxy took years of research from the astronomers, and combined observations from a number of different instruments. Those include NASA’s Galaxy Evolution Explorer (GALEX), which helped confirm the new findings.

“Without GALEX’s ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system,” said lead scientist Rafael Eufrasio in a press release.

NGC 6872 may not hold this title forever, though. As a result of its interaction with IC 4970, one of the arms of NGC 6872 looks likes it may be spinning off to form its own dwarf galaxy.

“The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems,” said team member Duilia de Mello.

(Image credit: NASA’s Goddard Space Flight Center/ESO/JPL-Caltech/DSS)

Astronomers Find The Largest Known Spiral Galaxy - Forbes