- Thanks to the Gaia satellite, scientists were able to find the tidal tails of the Hyade star cluster
- The real surprise for the astronomers was that stars appeared to be missing in the cluster’s tidal tail
- These disturbances, astronomers say, could be an indication that there is a “dark matter podhalo” nearby
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These disturbances, astronomers say, could be an indication that a “dark matter podhalo” is nearby. According to scientists, these may be invisible clouds of particles that are left over from the formation of the Milky Way. They are scattered throughout the galaxy, creating an invisible substructure that exerts a noticeable gravitational effect on anything that comes too close.
Tereza Jerabkova of the European Space Agency and colleagues made this discovery while studying how a nearby star cluster blends into the overall background of stars in our galaxy. The Hyades cluster was chosen because it is the closest star cluster to the Sun. The distance is 153 light years.
In fact, the disruption of star clusters by gravitational forces is inevitable. A star cluster is, as its name suggests, a tight, dense cluster of stars. Even inside the cluster, gravitational forces can be quite violent.
In the process, some of the stars may be moved to the edges of the cluster and then swept away by the galaxy’s gravitational pull, creating two long tails. One that follows the cluster and the other moves ahead of it. They are called tidal tails.
Thanks to the Gaia satellite, scientists were able to find the tidal tails of the Hyade star cluster. Hundreds of stars related to the Hyade have been found. The central cluster is about 60 light years in diameter, and its tidal tails extend thousands of light years.
The real surprise for the astronomers was that stars appeared to be missing from the tidal tail. This could indicate that something more violent is happening there than simply “dissolving the stars.” The simulations showed that the data provided by Gaia could be reconstructed if the tail collided with a cloud of matter containing about 10 million solar masses.
The observations, however, show no such massive gas cloud or star cluster nearby. Tereza Jerabkova suggests that this unknown object may be a podhalo of dark matter.
Scientists have calculated that about 80 percent. all matter in the universe is dark matter. It is believed to be an essential part of the galaxy formation process – large clusters of galaxies in the early universe collected and shaped normal matter into the galaxies we see today.
These clusters of dark matter can still be found today in extended “dark halo” around galaxies. There is one in the Milky Way, estimated to be 1.9 million light years in diameter. Astronomers predict that inside these halos there are denser lumps, called dark matter podhas, that simply drift.
Source: Science Alert / Urania.edu.pl
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