Italian amateur astronomer discovers 5 dwarf galaxies that are now named after him

An Italian amateur astronomer, Giuseppe Donatiello, has discovered five new dwarf galaxies orbiting a distant spiral galaxy, one of the largest galaxies visible from Earth. The new galaxies, named Donatiello V, VI, VII, VIII, and IX, add to the growing list of celestial bodies bearing his name.

"Out of eleven discoveries, nine galaxies bear my name. To my knowledge, I am the first and only amateur astronomer to have galaxies named after them," Donatiello told Space.com. His journey began in 2016 with the discovery of Donatiello I, and since then, he has been consistently identifying new celestial bodies.

These newly discovered satellite galaxies orbit the Sculptor galaxy, also known as NGC 253. Their detection is significant due to their ultrafaint nature and distance of approximately 11.5 million light-years from Earth. These galaxies could provide insights into the oldest stars in the universe, the distribution of dark matter, and could potentially influence current cosmological models.

"Dwarf galaxies are objects that exhibit very low luminosity," Donatiello explained. "Many satellites of the Milky Way are difficult to detect because they are well-camouflaged in the star fields. This becomes increasingly difficult for external galaxies."

The trio of dwarf galaxies discovered in 2021 and the latest five join a total of 18 known galaxies in the Sculptor galactic group. The significance of these findings extends beyond mere discovery; they challenge existing models of cosmology, particularly the Lambda Cold Dark Matter (LCDM) model. This model predicts a much higher number of satellite galaxies around major galaxies than currently observed. For instance, while simulations suggest our neighboring galaxy, Andromeda, should host 500 to 1,000 satellite galaxies, only 39 have been identified so far.

"This discrepancy has become known as the 'missing satellite problem,'" Donatiello noted. "Even with the discovery of ultrafaint galaxies, the number remains markedly low. Where are they all?"

This question prompts further investigation into the nature of dark matter and the processes governing galaxy formation and evolution. Donatiello and his team utilized archival data from the Dark Energy Spectroscopic Instrument (DESI) on the 4-meter Mayall telescope at Kitt Peak National Observatory. Their study revealed the new dwarf galaxies around NGC 253, helping to paint a clearer picture of the Sculptor galactic group.

Despite the significant contributions these findings make to astronomy, Donatiello remains focused on the thrill of discovery. "How does it feel having galaxies named after me?" he reflected. "It's a nice feeling, but I've gotten used to it a bit, too!"

The team's findings are detailed in a pre-peer-reviewed paper available on arXiv.