Astronomers have observed the formation of a young galaxy in the Leo constellation, a phenomenon that is unfolding at the end of the longest tidal tail ever recorded.
According to scientists from India and the United Kingdom, the galaxy is in its nascent stages and is forming at the end of a tidal tail associated with NGC 3785, a galaxy situated approximately 435 million light-years away from Earth.
Nascent galaxy discovered in formation at the end of the longest tidal tail of NGC 3785 galaxy
NGC 3785 galaxy is known to possess the longest tidal tail discovered so far. The tail extends from the galaxy and is formed due to gravitational forces (“tidal forces”) when two… pic.twitter.com/1664WozUME
— PIB India (@PIB_India) January 6, 2025
The groundbreaking discovery has been credited to researchers from the Indian Institute of Astrophysics (IIA) in Bengaluru, the National Centre for Radio Astrophysics (NCRA) in Pune, Pondicherry University, and the SKA Observatory in the United Kingdom.
As per the findings, gravitational interactions between NGC 3785 and a neighboring galaxy have led to the creation of the tidal tail—a stream of stars and gas extending an astonishing 1.27 million light-years. The Department of Science and Technology noted, “The discovery centers on galaxy NGC 3785, which features a massive tidal tail stretching through space.”
This gravitational force caused matter to stretch into a long tail, which eventually facilitated the birth of the new galaxy.
Chandan Watts, the first author of the research paper, explained that galaxy interactions fall into two categories: mergers, where galaxies collide and combine, and flybys, where galaxies pass close to one another, pulling matter from one galaxy to another. He noted that the tidal tail of NGC 3785 resulted from a flyby interaction.
Ultra-diffuse galaxies, such as the one forming at the end of the tidal tail, are challenging to detect because of their low luminosity and faint surface brightness, making them nearly invisible compared to galaxies like the Milky Way.
Omkar Bait, a co-author of the study, revealed that he initially noticed the tidal tail several years ago while conducting research at NCRA in Pune. “We decided to examine this extraordinary galaxy and its massive tidal tail in detail,” Bait told Deccan Herald. The team plans to continue their research to uncover more insights into the evolution of galaxies.
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