Why Are Stars Declining In Our Universe? Indian Astronomers Have the Answer

There is evidence to suggest that the early universe had a dense star formation as compared to the present-day universe. Researchers from Pune and Bengaluru seem to have found the ‘why’ behind this change.

From the 8-billion-year-old epoch, the astronomers have found obscure impressions of hydrogen gas. India’s biggest radio telescope — Giant Metrewave Radio Telescope (GMRT) — was used for the discovery, reported Deccan Herald.

Studying 7,653 galaxies, astronomers found that the hydrogen present in them, billions of years after the Big Bang, was 2.5 times more than the hydrogen found presently in them.

The lead author of this research — published in the reputed Science journal Nature — Aditya Chowdhury explained that the atomic gasses would be consumed in one to two billion years, given the fact that star formation happened at a higher intensity in early galaxies.

He said that the decline in the star formation can be explained by the fact that atomic hydrogen was exhausted.

Nissim Kanekar, another team member at the NCRA, said that almost half the stars seen in the night sky were from that period, which roughly means eight to ten billion years ago.

Jayaram Chengalur, a scientist involved in this research said that stars have been studied extensively in the context of evolution of galaxies but there is hardly any knowledge on atomic gases as they are hard to detect.

Speaking to Deccan Herald, he said, “The measurement of atomic hydrogen will now provide a complete picture on the evolution of the galaxies.” Jayaram is a scientist at Pune’s National Centre for Radio Astrophysics (NCRA).

Astronomer from National Radio Astronomy Observatory, New Mexico, Chris Carilli called it a “watershed moment” in the understanding of how galaxies use baryonic matter. The scientist is not associated with the study.

This discovery has been made possible after the 1990s GMR telescope was upgraded to make it sensitive enough to catch faint signals.