The closest cluster of stars to the Sun, the Hyades , is being disturbed by the gravitational influence of a massive, albeit invisible, structure in our galaxy, astronomers have discovered, who believe that this structure located about 150 light years away from us, have been crushed by a powerful cloud of dark matter with a force equivalent to 10 million solar masses.
From our perspective here on Earth, the stars of the Hyades cluster (which number about 80) are very bright and form a striking V that outlines the head of the bull, along with the even brighter red giant Aldebaran, in the constellation Taurus. , occupying about 60 light years in diameter.
Now, a team of astronomers from the European Space Agency (ESA) has discovered, thanks to data from ESA’s Gaia star mapping satellite, the aftermath of a hit-and-run in our own galactic neighborhood . While studying the cluster they discovered that it could have been ripped apart by the gravitational influence of a massive but invisible structure in our galaxy, possibly dark matter. If true, this could provide evidence of a suspicious population of “dark matter subhalos”, invisible clouds of particles believed to represent true relics of the formation of the Milky Way and are now scattered throughout the galaxy , forming a An invisible substructure that exerts a considerable gravitational influence on any object that gets too close.
Star clusters naturally lose their stars as they move within the open structure and are influenced by their own gravitational pulls. These jerks can move some of the stars to the edge of the cluster and these are dragged again by the gravitational force of the galaxy, which forms long tails, which are known as tidal tails (since one follows the star cluster and another comes forward).
The star cluster is dissolving
Trying to quantify how many stars each of the Hyades’ tidal tails counted with data from Gaia, whose survey tracks the distance and movements of 1.8 billion stars in our galaxy, researchers from ESA and the European Southern Observatory developed a model. which simulates the motion of stars as they escape from the cluster, during the cluster’s lifetime of 600 to 700 million years. When these simulations were compared with the Gaia data, they found that the Hyades’ tidal tails were much longer than expected.
What had happened? The tails included thousands of stars spread over thousands of light years. Also, one of the queues seemed to have fewer stars than it should.
Adjusting the simulations to try to explain this enigma, an intriguing possibility appeared before his eyes: a collision with a group of matter with a mass of approximately 10 million suns appeared to have caused the effect.
“There must have been a close interaction with this really massive group, and the Hyades were just crushed,” explains Tereza Jerabkova, leader of the work that publishes the journal Astronomy & Astrophysics .
Given that there are no visible gas clouds or other star clusters around, what could have caused this disintegration?
Scientists attribute this event to dark matter, that elusive and mysterious component that is believed to permeate the universe and that interacts through its amazing gravity.
“And with these discoveries, we will be able to map the substructures (dark matter) of the Milky Way much better than ever,” he says.
Referencia: Tereza Jerabkova et al. The 800 pc long tidal tails of the Hyades star cluster, Astronomy & Astrophysics (2021). DOI: 10.1051/0004-6361/202039949
