A mysterious arc of light found behind a distant cluster of galaxies has turned out to be the biggest, brightest and hottest star-forming region ever seen in space. The so-called Lynx Arc is one million times brighter than the well-known Orion Nebula, a nearby prototypical 'starbirth' region visible with small telescopes. The newly identified super-cluster contains a million blue-white stars that are twice as hot as similar stars in our Milky Way galaxy.
Arp 227 consists of two galaxies in the constellation Pisces: the large (250,000 light-years across) lenticular galaxy NGC 474 (also known as UGC 864) located about 93 million light-years away, and the spiral galaxy NGC 470 at about 95 million light-years away. They lie at a separation of about 160,000 light-years. - Credit: NASA