Galaxies Don't Need Collisions to Form New Stars

New data collected by the European Space Agency's (ESA) Herschel Space Observatory indicate that galaxies can start producing new stars at a frantic pace regardless of whether they collide with other galaxies. This was previously thought to be the main mechanism that reignited the process.

At this time, Herschel is the most advanced telescope in Earth's orbit. Its infrared detectors can make sense of structures hiding behind massive dust and gas clouds, such as for example stars smothered in their protective cocoons and extremely distant galaxies.

Thanks to its most recent study, astronomers now have a better understanding of how galaxies form and grow. This is very important to know, since thus far the collision theory could not be used to explain all instances of sudden stellar formation researchers noticed during their studies.

During its newest observation sessions, Herschel looked at a collection of galaxies located at various distances from our solar system. Together, the galaxies covered an estimated 80 percent of the age of the entire Universe.

Astronomers paid special attention to galaxies located some 10 billion years ago, because that was the time when stellar formation peaked for most of these structures. During those tumultuous times, galaxies were forming stars at rates that were tens or hundreds of times higher than today.

Until now, astronomers believed that galactic collisions were the main causes of such intense bouts of stellar formation, but Herschel demonstrates that that is not the case. While some galaxies were put into action by collisions, this was not a general rule.

The new investigation was conducted by expert David Elbaz, from CEA Saclay, France. He and his team explain that galaxies appeared to be capable of producing this many stars all on their own.

“It's only in those galaxies that do not already have a lot of gas that collisions are needed to provide the gas and trigger high rates of star formation,” he explains. The amount of molecular hydrogen gas in a galaxy is therefore the most important aspect to consider when analyzing its performances.

“Herschel was conceived to study the history of star formation across cosmic time. These new observations now change our perception of the history of the Universe,” explains Herschel project scientist Göran Pilbratt.

The new study definitely gave the international scientific community something to consider. The manner in which galaxies evolved – and the processes this included – are of extreme importance to a large number of theories seeking to explain the nature of the Universe.