Lonely Dwarf Galaxy Shatters Cosmic Rules, Scientists Left Stunned

Last Updated:November 19, 2025, 17:19 IST

A blue compact dwarf galaxy in the Local Void, defies star formation theories by rapidly creating stars without collisions or gas accretion, puzzling astronomers

Astronomers from Spain, led by Ignacio Trujillo of the University of La Laguna, used the Two-Meter Twin Telescope (TTT3) to capture deep optical images of NGC 6789.

A small, isolated galaxy on the outskirts of the universe is challenging conventional understanding of how stars are born. NGC 6789, a dwarf galaxy residing in the vast emptiness of the ‘Local Void’, is forming new stars at a remarkable rate, despite showing no signs of galactic collisions or gas accretion, processes traditionally considered essential for star formation.

Astronomers from Spain, led by Ignacio Trujillo of the University of La Laguna, used the Two-Meter Twin Telescope (TTT3) to capture deep optical images of NGC 6789. Their findings, shared on November 10 via the arXiv preprint server, reveal that the galaxy’s star-forming activity is concentrated at its core, while its outer regions retain a pristine, red elliptical structure.

The outer regions of NGC 6789 show no tidal features or evidence of past mergers, the researchers wrote, noting that the galaxy appears remarkably undisturbed. This contradicts the standard notion that new stars primarily emerge when galaxies collide or draw in external gas.

Discovered in 1883 and situated approximately 12 million light-years from Earth, NGC 6789 is classified as a blue compact dwarf (BCD) galaxy. Its striking blue hue stems from the abundance of hot, newly formed stars. Previous studies suggested that roughly four percent of its stellar mass, equivalent to nearly 100 million suns, was generated over the past 600 million years.

The Spanish team went further, calculating the maximum possible stellar mass that could have been added by a disrupted satellite galaxy, finding it to be only around 2,00,000 solar masses, far too little to account for the 4 million solar masses of stars now forming in the core.

“The recent central star formation was either built from in-situ leftover gas or from the accretion of pure external gas linked to minor merger activity," the study concluded. In other words, NGC 6789 appears to be producing stars independently, without the usual cosmic interactions that fuel such activity.

This discovery challenges prevailing theories of galactic evolution and star formation, offering a rare glimpse into how galaxies may thrive even in extreme isolation. Scientists are now grappling with a new question: where does NGC 6789 source the gas necessary to forge these stars?

News world Lonely Dwarf Galaxy Shatters Cosmic Rules, Scientists Left Stunned

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