July 3, 2013
Details Of Early Galaxy Revealed
Lee Rannals for redOrbit.com - Your Universe Online
Researchers have published details, including size, mass and content of elements, of an early galaxy in the scientific journal Monthly Notices of the Royal Astronomical Society.
Galaxies from the early universe were much different than those found today. The team's new detailed study using the European Space Observatory's Very Large Telescope (VLT) and NASA's Hubble Space Telescope allows scientists to peer into one of the ancient worlds.
"Galaxies are deeply fascinating objects. The seeds of galaxies are quantum fluctuations in the very early universe and thus, understanding of galaxies links the largest scales in the universe with the smallest. It is only within galaxies that gas can become cold and dense enough to form stars, and galaxies are therefore the cradles of starbirth," explains Johan Fynbo, professor at the Dark Cosmology Center at the Niels Bohr Institute at the University of Copenhagen.
Galaxies in the early universe were formed from large clouds of gas and dark matter. Gas is used by the universe as material for the formation of stars. Inside galaxies, the gas can cool down to become very dense. The gas can become so compact that it collapses into a ball where the gravitational compression heats up the matter to create a star.
The early stars contained only a thousandth of the elements found in the Sun today. Scientists believe that each generation of stars becomes richer and richer in heavy elements. In today's galaxies you can find lots of stars and less gas, whereas the early galaxies contained a lot of gas and fewer stars.
"We want to understand this cosmic evolutionary history better by studying very early galaxies. We want to measure how large they are, what they weigh and how quickly stars and heavy elements are formed," explains Fynbo, who has led the research together with Jens-Kristian Krogager, PhD student at the Dark Cosmology Center at the Niels Bohr Institute.
The team studied a galaxy located about 11 billion light years away. The large amount of gas in the young galaxy absorbed a massive amount of the light from a quasar that lies behind it. Scientists could see the other parts of the galaxy, as well as active star formation.
They used the Hubble observatory to see the recently formed stars in the galaxy and calculate how many stars there were in relation to the total mass. The team was able to determine that the relative proportion of heavier elements is the same in the center of the galaxy as in the outer parts.
"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. 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," concluded Fynbo and Krogager.