The discovery was made at India's first dedicated multi-wavelength space observatory UltraViolet Imaging Telescope (UVIT) onboard AstroSat.
As science moves forward, several long standing mysteries about the universe are being answered. Why dwarf galaxies have active star formations, is one such latest puzzle for which a team led by Indian astrophysicists has found out a crucial piece.
A recent study comprising scientists from India, US and France discovered formation of newer stars by such galaxies beyond their visible boundaries. It traced how star-forming complexes or clumps which consist of young stars migrate towards the inner regions of the galaxies and gradually make the stellar content.
What is a dwarf galaxy?
A small galaxy, called a dwarf galaxy, would be much smaller than galaxies like our Milky Way. They are usually characterized by concentrated star formation at their centre. They hold from around 1000 to some tens of billion stars compared to 200-400 billion stars of the Milky Way. One such example sometimes classified as a dwarf galaxy is the Large Magellanic Cloud with over 30 billion stars.
What did the research find out?
The team observed signals from the outskirts of a galaxy not more than 150 million years old indicating the formation of stars outside visible boundaries. The discovery was made at India's first dedicated multi-wavelength space observatory UltraViolet Imaging Telescope (UVIT) onboard AstroSat.
Scientists detected faint emission of Far UltraViolet (FUV) light on the outskirts of distant Blue Compact Dwarf (BCD) galaxies at a distance of approximately 1.5 - 3.9 billion light-years away. The discovery is a significant step towards tracing the mysteries of galaxy formation, said a PIB press release.
The study was conceived by Prof. Kanak Saha of Inter University Center for Astronomy and Astrophysics (IUCAA), Pune and the lead author of the article published in the journal Nature is Anshuman Borgohain, a recipient of the INSPIRE Fellowship of the Department of Science and Technology (DST) and researcher at Tezpur University.
“The resolving power of UVIT and UV deep field imaging techniques has been the key to spotting these very young, large star-forming clumps. Due to their large distances from us, it was a challenging task to establish the detection of these faint, extremely blue star-forming clumps with million solar masses,” said Prof. Kanak Saha, highlighting that it helped witnessing the 'live' formation of these far-way dwarf galaxies.
Principal research staff in the IBM Research Division, USA, Dr. Bruce Elmegreen, who contributed to the study, said, “It has been a mystery how some small galaxies like these can have such active star formation. These observations suggest that accreting gas in the far outer parts can be forced to move inward through torques exerted by giant gas and stellar complexes. This migration builds up the central density over the galaxy's lifetime.”
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