Despite its small size, a galaxy 11.5 billion light-years from Earth was once a powerhouse of star formation, a new study suggests. The distant galaxy, known as SDP.81, forged the equivalent of 315 of our suns each year in an era when star formation was at its maximum in the universe. This compares with just three new sun-sized stars per year in today’s Milky Way, the diameter of which is about 15 to 20 times that of SDP.81. Researchers estimated the rate of star formation by measuring far-infrared wavelengths of light emanating from the distant galaxy. Through a process called “gravitational lensing,” the image of the distant galaxy, which appears as a smudged ring of light, is magnified about 17 times the size it would normally appear from Earth. A massive galaxy that lies in between SDP.81 and Earth is what creates the lensing effect, but it doesn’t appear in the image because it isn’t bright in far-infrared wavelengths. Researchers then used computer software to unwarp SPD.81’s smudge and, for the first time for such a distant galaxy, discern small areas of intense star formation, some less than 150 light-years across. SPD.81 contains three regions of enhanced star formation (depicted in red and orange), according to researchers, who will present their findings in an upcoming article in the Monthly Notices of the Royal Astronomical Society. SPD.81 may be a rotating disk of stars seen edge on, the team suggests, or it could be the result of the merger of two smaller galaxies.
(Credit for linked PDF: Rybak et al., MNRAS )