A rare isolated group of five dwarf galaxies will aid in understanding the evolution of small systems.

Small galaxies with masses significantly lower than those of galaxies like the Milky Way are referred to as dwarf galaxies. Observing such objects in practice is challenging, which is why researchers from Yonsei University in South Korea analyzed data from various astronomical studies. As a result, they discovered an isolated group of five dwarf galaxies located approximately 117 million light-years away from Earth. This discovery will aid astronomers in gaining a better understanding of the evolutionary processes of small systems.

2024-11-27 10:01:07https://naked-science.ru/article/astronomy/redkaya_gruppa_galactic

In low-luminosity and low-mass star systems—dwarf galaxies—there are typically several billion stars. Such objects are rare, and the standard cosmological model suggests that they possess structure and satellites. However, less than five percent of dwarf galaxies can "boast" of having satellites, and the likelihood of them being part of a group containing at least four such objects is less than 0.004 percent.

Nevertheless, the authors of a new study, published in the journal Astrophysical Journal Letters, made an impressive discovery by identifying an isolated group of five dwarf galaxies that are actively forming stars—the blue color of these objects indicates the presence of young stars.

“We identified a distinct group of five dwarf galaxies located along a straight line in the celestial plane. Notably, three of them share a common rotation direction—the northern parts of these galaxies are shifted towards the red end of the spectrum, while the southern parts are shifted towards the blue,” noted the scientists.

The team analyzed data from astronomical surveys, including the Sloan Digital Sky Survey (SDSS), and designated the observed objects as D1, D2, D3, D4, and D5. The images presented in the study show that all galaxies are aligned in a straight line (spanning 154 kiloparsecs) and form a thin, flat structure.

The most massive in this small group turned out to be galaxy D2: its stellar mass is approximately 275 million solar masses, equivalent to about half the mass of the Small Magellanic Cloud—a dwarf galaxy that is a satellite of the Milky Way. The least massive was galaxy D4: its stellar mass amounted to just 14.7 million solar masses, while the total stellar mass of the entire group is approximately 598 million solar masses.

Calculations also indicated that all five galaxies are gravitationally bound, and objects D3 and D4 show signs of mutual tidal interaction. Furthermore, the same rotation direction of three out of the five galaxies, according to astronomers, may indicate their shared dynamic history.

This rare group of dwarf galaxies serves as a unique cosmic laboratory for studying processes that are incredibly difficult to observe elsewhere in the universe. Further observations, especially using radio telescopes, will allow for the confirmation of individual characteristics of the galaxies (particularly their rotation) and enhance our understanding of how such systems form and evolve.

The results of the new study also challenge certain aspects of the standard cosmological model (ΛCDM) and, according to astronomers, may lead to significant discoveries in the field of cosmology.