The Hyades cluster is losing mass at an accelerated rate and has entered its twilight years. Hyades is the closest open cluster to Earth, located only 150 light-years away. For comparison, the galactic centre of the Milky Way is about 26,000 light-years away – 152,844,260,000,000,000 miles.
In a paper published on the Cornell University preprint server arXiv.org, astronomers have predicted when the cluster will disappear.
The paper has been titled Kinematic modelling of clusters with Gaia: the Death Throes of the Hyades.
Dr Semyeong Oh, an astronomer at the University of Cambridge said: “We find that there’s only something like 30 million years left for the cluster to lose its mass completely.”
The astronomers used data collected by the European Space Agency’s (ESA’s) Gaia spacecraft to determine the velocities of stars in the cluster.
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Dr Oh said: “Compared to the Hyades’ age, that’s very short.”
The Hyades star cluster is estimated to have formed about 680 million years ago.
Hyades is visible from Earth and appears to sit in the constellation Taurus.
The cluster’s brightest stars form a distinct V shape together with the star Aldebaran, which is only about 65 light-years away.
Clusters like Hyades are prone to losing stars and rarely reach an age of one billion years or more.
Hyades was born holding about 1,200 times more mass than our Sun but the cluster now only holds about 300 solar masses.
According to Science News, astronomers first caught a glimpse of trouble brewing in Hyades in 2018.
Then, stars were caught escaping the cluster through two distinct tails streaming into out into space.
The two tails were found to contain more stars than the cluster itself.
In turn, the fewer stars are present within the cluster, the weaker the gravity binding them together.
At the current rate of mass loss, the astronomers estimate Hyades will disintegrate in the next 30 million years – a very short time on the cosmic scale.
The astronomers wrote in their study: “We estimate that less than 30 Myr is left until the final dissolution; the Hyades is in its death throes.”
However, Siegfried Röser, an astronomer from Heidelberg University in Germany who led one of the teams that discovered the cluster’s tails, is not certain about the accuracy of the prognosis.
The expert said: “That seems to be a little bit risky to say.”
Instead, the astronomer proposed running computer simulations to paint a better picture of how the cluster will behave in the future.
In the 2018 study, the astronomers wrote: “The Milky Way galaxy exerts tidal forces onto its gravitationally bound stellar sub-systems with the effect that these sub-systems continuously lose members.
“Once the members are no longer gravitationally bound, they might still remain in co-moving tidal tails that lead and trail their home sub-system.
“The tidal tails of stellar clusters are an important piece of information on the clusters’ kinematic evolution, the process of dissolution, and the impact of the Galactic gravitational field onto a sub-system.”