New Insight into the Early Galaxies of the Universe Revealed

The early galaxies of the universe were far different than today's - a fact scientists have been aware of for some time. What has not always been clear, however, is just how they differed. Now, through the help of the ESO's Very Large Telescope (VLT) and the Hubble Space Telescope, scientists have studied an early galaxy in unprecedented detail, according to a new study published in the journal Monthly Notices of the Royal Astronomical Society.

In all, the researchers were able to determine a number of the galaxy's important properties, including size, mass, content of elements and how quickly it creates new stars.

In order to achieve this, the researchers studied a galaxy located approximately 11 billion years back in time and in front of a quasar, a space body brighter than a galaxy. For this reason, many of the outer regions of the galaxy were illuminated, allowing scientists a chance to see into it. Furthermore, active star formation within the galaxy also meant some of the gas was lit up, allowing scientists to observe it directly.

With the Hubble Space Telescope, they could also see the recently formed stars in the galaxy and calculate how many stars there were in relation to the total mass, which is comprised of both stars and gas. They could then see that the relative proportion of heavier elements was the same in the center of the galaxy as in the outer parts, showing that the stars that were formed earlier in the center of the galaxy enrich the stars in the outer parts with heavier elements.

"By combining the observations from both methods - absorption and emission - we have discovered that the stars have an oxygen content equivalent to approximately one-third of the Sun's oxygen content," explained authors Johan Fynbo of the University of Copenhagen and Jens-Kristian Krogager of the Niels Bohr Institute. "This means that earlier generations of stars in the galaxy had already built up elements that made it possible to form planets like Earth 11 billion years ago."