There are about 125 Billion galaxies in the nearby observable universe according to the Hubble Deep Field. It’s been a remarkable journey by the scientists to reach this position to identify, classify, and analyze these giant gravitationally bound systems of matter. Also, a major portion of these galaxies consists of stars. According to the theories, stars are formed in molecular clouds. The dust and other elements together at a particular temperature and pressure are responsible for the birth of a Protostar. But the mystery of the process by which different elements are combined is still left unanswered.
Scientists across the globe tried to find an answer to the process of star formation. And guess what, there is a small chance of finding an answer to it. An international team of scientists and astrophysicists from the University of Bath in the UK and the National Astronomical Observatory (OAN) in Madrid, Spain took an important step towards this mystery. Furthermore, they observed molecular clouds in the tidal galaxies.
For their study, researchers used ALMA (Atacama Large Millimeter Array). It is the Chile-based giant network of small radio telescopes combined. The team had observed a type of galaxy called a Tidal Dwarf Galaxy (TDG). The TDG named in the study as TDG J1023+1952. The TDG is located around 50 million light-years this is very far from the Earth. Because of the vast distance, individual molecular gas clouds appear as tiny regions in the sky when viewed through the naked eye. However, ALMA has the power to distinguish the smallest details. These observations were of the highest resolution till now of molecular gas in a TDG.
When two galaxies collide together with a great force, the debris remainings are responsible for TDG formation. Stars form actively in these systems due to the collisions. In our milky way galaxy, molecular clouds are responsible for star formation. The observations of the TDG were unexpected it also displayed a profusion of dispersed gas.
This TDG is a pristine environment for scientists trying to connect the early days of other galaxies, including our Milky Way galaxy. Their study might shed light on the time when there was chaos in the universe at the starting stage and during the collapsing of galaxies. Because star formation was at a greater rate than the normal situations in these cases.
Professor Carole Mundell(co-author of the article ) is the head of Astrophysics at the University of Bath. According to him,” 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”.
“The fact that molecular gas appears in both cloud form and as diffuse gas was a surprise”.” We have managed to identify clouds with an apparent size as small as observing a coin placed several kilometers away from us,” said Professor Mundell, He added that “It’s remarkable that we can now study stars and the gas clouds from which they are formed in a violent extragalactic collision with the same details that we can study from those forming in the calm environment of our own Milky Way.”
To conclude, their findings highlight the sophisticated organization of molecular gas in a TDG, with a large pool of diffuse molecular gas and many clouds that are not forming stars. The Giant Magellenic Clouds(GMC) in this system is similar in mass distribution and sizes as observed in other galaxies. But they show departures from the scaling relations involving velocity dispersion. On the other hand, the south of the TDG suggests that once the clouds begin to form stars, the process of star formation and subsequent feedback proceeds in a very similar fashion as in other galaxies. This process might be assisted by a mechanism such as stochastic self-propagating star formation.
Like the rooms of a building left unexplored when we are stuck in a single room in the basement. We still have to do further studies. It’s true that a lot is known to us, but it is also true that there are more spaces yet to uncover.
REFERENCE: M. Querejeta et al, ALMA resolves giant molecular clouds in a tidal dwarf galaxy, Astronomy & Astrophysics (2020). DOI: 10.1051/0004-6361/202038955
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