Astronomers trace mystery behind the formation of a star from dwarf galaxy

A team of Indian astronomers from Aryabhatta Research Institute of Observational Sciences (ARIES) have claimed to trace the mystery behind dwarf galaxy aberrations of massive star formation.

To understand the nature of star formation in dwarf galaxies ARIES astronomers Dr. Amitesh Omar and his former student Dr. Sumit Jaiswal observed several dwarf galaxies using two Indian telescopes — 1.3-meter Devasthal Fast Optical Telescope (DFOT) and the Giant Meter wave Radio Telescope (GMRT).

The Indian astronomers said, amidst the billions of galaxies in the universe, a large number are tiny ones 100 times less massive than our own Milky-way galaxy. While most of these tiny tots called dwarf galaxies form stars at a much slower rate than the massive ones, some dwarf galaxies are seen forming new stars at a mass-normalized rate 10-100 times more than that of the Milky-way galaxy.

Star formation at a high rate requires very high density of Hydrogen in the galaxies. According to the study conducted by the ARIES team, the 1420.40 MHz images of several intense star-forming dwarf galaxies indicated that hydrogen in these galaxies is very disturbed.

While one expects a nearly symmetric distribution of hydrogen in well-defined orbits in galaxies, hydrogen in these dwarf galaxies is found to be irregular and sometimes not moving in well-defined orbits.

Some hydrogen around these galaxies is also detected in forms of isolated clouds, plumes, and tails as if some other galaxy recently has collided or brushed away with these galaxies, and gas is scattered as debris around the galaxies.

The optical morphologies sometimes revealed multiple nuclei and high concentration of ionized hydrogen in the central region. Although galaxy-galaxy collision was not directly detected, various signatures of it were revealed through radio, and optical imaging, and these are helping to build up a story. The research, therefore, suggests that recent collisions between two galaxies trigger intense star formation in these galaxies.

The findings of this research with detailed images of 13 galaxies will be appearing in the forthcoming issue of Monthly Notices of Royal Astronomical Society (MNRAS) Journal published by the Royal Astronomical Society, the UK.