This bright spiral galaxy is known as NGC 2441, located in the northern constellation of Camelopardalis (The Giraffe). However, NGC 2441 is not the only subject of this new Hubble image; the galaxy contains an intriguing supernova named SN1995E, visible as a small dot at the approximate center of this image. File Photo by UPI/Kevin Dietsch | License Photo
CARDIFF, Wales, Aug. 30 (UPI) -- A team of international scientists, led by astronomers from Cardiff University in Wales, have unraveled the history of galaxies -- providing first direct evidence of galaxy "metamorphosis."
For the study, published in the Monthly Notices of the Royal Astronomical Society, researchers observed about 10,000 galaxies in the universe. The scientists classified the galaxies into the two main types: flat, rotating, disc-shaped galaxies, such as our own -- the Milky Way -- and large, spherical galaxies with hordes of disordered stars.
"By observing the sky as it is today, and peering back in time using the Hubble and Herschel telescopes, the team have shown that a large proportion of galaxies have undergone a major 'metamorphosis' since they were initially formed after the Big Bang," Cardiff University said in a statement.
The team found that discovered galaxies can change their structure over the course of their lifetime.
The team also discovered that 83 percent of all stars formed since the Big Bang were initially in disc-shaped galaxies, but now there are only 49 percent -- with the rest belonging to spherical-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, and therefore gain a greater understanding of the appearance and properties of the universe as we know it today," Cardiff University added. "The results suggest a massive transformation in which disc-shaped galaxies became spherical-shaped galaxies."
Popular theories suggest that galaxy "metamorphosis" is caused by cosmic catastrophes, where two disk-dominated galaxies that are too close to each other are forced by gravity to merge into a single galaxy -- causing the destruction of disks and the production of a huge accumulation of stars.
Another theory suggests that galaxy "metamorphosis" is a gentler process, where stars formed in a disk gradually move to the center of the disk and create a central compilation of stars.
"Many people have claimed before that this metamorphosis has occurred, but by combining Herschel and Hubble, we have for the first time been able to accurately measure the extent of this transformation," professor Steve Eales, lead author of the study from Cardiff University's School of Physics and Astronomy, said in a statement. "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 8 billion years."