Early giant galaxy discovered
By combining data from the Hubble and Spitzer Space Telescopes, astronomers have identified a distant galaxy that is significantly larger and more massive than current theory suggests - because the light from galaxy HUDF-JD2 is about 13 billion years on its way to earth. This means that the star system cannot be older than around 800 million years.
HUDF-JD2 is barely visible in Hubble visible-light images. It only appears in infrared images - the longer the wavelength, the stronger it is. The scientists from the European space agency Esa and the Space Telescope Science Institute recognize this as a consequence of the red shift: Because the universe is expanding, the light rays it contains are also stretched and therefore redder. A red shift as pronounced as in HUDF-JD2 therefore indicates an age otherwise only known from quasars and baby galaxies that are still forming.
The brightness of the galaxy in the images taken by the Spitzer telescope in the long-wave infrared range is surprising. According to this, HUDF-JD2 is a huge and, importantly, massive galaxy even by today's standards. According to current theory, star systems formed gradually in the early universe through the slow accumulation of matter. This is obviously not the case with HUDF-JD2. The researchers suspect that at least some galaxies were formed by an as yet unknown, faster mechanism.
