History of galaxies unravelled for the first time

A team of international scientists has shown for the first time that galaxies can change their structure over the course of their lifetime.

Using data from the NASA's Hubble telescope and European Space Agency's Herschel Space Observatory, the team showed that a large proportion of galaxies have undergone a major "metamorphosis" since they were initially formed after the Big Bang.

"Galaxies are the basic building blocks of the Universe so this metamorphosis really does represent one of the most significant changes in its appearance and properties in the last eight billion years," said lead study author professor Steve Eales from Cardiff University's school of physics and astronomy.

Many people have claimed before that this metamorphosis has occurred.

"We have for the first time been able to accurately measure the extent of this transformation," he added.

The team observed around 10,000 galaxies currently present in the universe.

They classified the galaxies into the two main types: flat, rotating, disc-shaped galaxies (much like our own galaxy, the Milky Way); and large, oval-shaped galaxies with a swarm of disordered stars.

The team showed that 83 percent of all the stars formed since the Big Bang were initially located in a disc-shaped galaxy.

However, only 49 percent of stars that exist in the universe today are located in these disc-shaped galaxies - the remainder are located in oval-shaped galaxies.

The results suggest a massive transformation in which disc-shaped galaxies became oval-shaped galaxies.

By providing the first direct evidence of the extent of this transformation, the team hope to shed light on the processes that caused these dramatic changes.

It will help scientists gain a greater understanding of the appearance and properties of the universe as we know it today.

The study appeared in the journal Monthly Notices of the Royal Astronomical Society.