(ORDO NEWS) — Astronomers from the University of Arizona, USA, have identified five examples of a new class of star systems. These objects are not full-fledged galaxies and exist only in seclusion.
These new star systems contain only young, blue stars, randomly distributed, and exist in surprising seclusion from any possible host galaxy.
These star systems, which look like “blue spots” in observations and are close in size to dwarf galaxies, are located in the boundaries of the Virgo Cluster of galaxies, located relatively close to us. These five systems are separated from any possible host galaxies by more than 300,000 light-years, making it difficult to determine their origin.
Astronomers discovered these new systems after another team of researchers had previously cataloged nearby gas clouds that could be the birthplace of new galaxies.
Following the publication of this catalog, several research teams, including the team of Michael Jones at the University of Arizona, who is the lead author of the new study, began observing stars that could be associated with these clouds of gas.
It was assumed that these gas clouds belonged to the Milky Way, but after observing the first of the systems, called SECCO1, it was discovered that the system is located in the Virgo cluster of galaxies, which is much further from us.
In the work, the team used the Hubble Space Telescope, Very Large Array (USA) and Very Large Telescope (Chile) observatories.
In their work on the mysterious “blue spots,” the two teams joined forces and found that most of the stars in each system are very young and blue, and the systems contain very little atomic hydrogen gas.
This fact is of great importance for understanding the dynamics of star formation in the system, since the formation of new stars usually begins with atomic hydrogen in the form of gas, which eventually evolves into dense clouds of molecular hydrogen, from which stars are subsequently born.
The increased metallicity of the matter of the stars that make up these systems, registered as a result of observations, helped astronomers put forward hypotheses about their origin. There are two main pathways for the formation of gas clouds from which young blue stars are formed.
The first mechanism is called tidal stripping, and it occurs in the gravitational interaction between the material of two massive galaxies passing by each other.
The second mechanism is called ram pressure stripping, and can be likened to belly-falling into water when a fast-moving galaxy crashes into a cluster of galaxies, leaving a large amount of its gas behind. According to Jones’ team, it is the second of these mechanisms that occurs in the case of blue spots.
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