All the stars we can see are actually inside the Milky Way. Unless there is a sudden change in the brightness of a stellar explosion (such as a nova or supernova), the brightest supernovae are visible beyond 10 billion light years. For a star that has not experienced an explosion, the majority of the galaxies beyond the Milky Way are too dim, and they are a hundred times darker than the limit of astronomical observations and cannot be individually detected.
This time, two U.S. research teams used the Hubble Space Telescope to repeatedly observe the sky area containing a large number of open clusters. Their results benefited from the gravitational lensing effect of the open star cluster between the two stars and us—the clusters The powerful gravitational field produced is like a lens that can amplify the light emitted by stars behind the cluster. It is enough to allow scientists to observe the two stars. They could not be observed on Earth because of their distance. One of them is 140 miles away. The billion-year-old star was magnified by more than 2000 times.
Among them, scientists at the University of South Carolina, Steven Rodney, and colleagues observed 'flashing' stars because the surface of the star is exploding, and scientists from the University of California, Berkeley, Padreco Carey and colleagues observed another. The 'flashing' of a star is due to the relative motion between the star and the open cluster.
By studying these 'flickering', astronomers can not only reveal the physical properties of the star itself, but more importantly, it can reveal the distribution of dark matter in the open cluster of lenses. Dark matter cannot be directly observed, but it is generally believed that the quality of dark matter can be Explain the observed galaxy internal movement.