How stars are formed is still one of biggest mysteries in astrophysics. While we know what stars are made of – mostly hydrogen and helium, which produce light and heat – we haven’t yet figured out how exactly these gaseous elements of a galaxy come together.
New findings from teams at the University of Bath and the National Astronomical Observatory (NAO) in Madrid, however, may have brought us one step closer. Published in the Journal of Astronomy and Astrophysics, they shed some light on how stars might have formed during the early days of the universe, AKA the Big Bang. During this time, star and galaxy formation happened more frequently than it does now.
Prof Carole Mundell, head of astrophysics at the University of Bath and a co-author of the paper, explained the research process. She said: “The little galaxy we’ve been studying was born in a violent, gas-rich galactic collision and offers us a unique laboratory to study the physics of star formation in extreme environments.”
That “little galaxy” is a tidal dwarf galaxy, one that would have formed from the debris after two older galaxies collided with force. These smaller galaxies are commonly used by scientists to learn more about the formation of larger ones, such as the Milky Way.
To examine the small galaxy, the researchers employed a mega telescope based in Chile called the Atacama Large Millimeter Array (ALMA). ALMA made it possible to view even the smallest details of the tidal dwarf galaxy, they said, despite its distance of around 50m light years from Earth.
Using ALMA, they learned that the molecular clouds in a tidal dwarf galaxy are similar in size and content to those in the Milky Way, a much older galaxy thought to be more than 13bn years old. The researchers believe this suggests that the same star-formation process might be occurring all across the universe.
A new question raised for star formation
However, the researchers also noted that the tidal dwarf galaxy – called TDG J1023+1952 – was emitting large amounts of dispersed gas. While gas is a common feature of larger galaxies like the Milky Way, it appears as clouds that act as “star-forming factories”, they said.
“ALMA’s observations were made with great precision so we can say with confidence that the contribution of diffuse gas is much higher in the tidal dwarf galaxy we studied than typically found in normal galaxies,” explained Dr Miguel Querejeta, who works at the OAN and was the lead author of the study.
“This likely means most of the molecular gas in this tidal dwarf galaxy is not involved in forming stars, which questions popular assumptions about star formation.”
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