The mass of these stars ranged from 500 to 1000 solar masses, and their lifetime was only 5-10 million years. Although these stars are very far away, bright flares from their explosions can be observed today. To observe this phenomenon, the telescope can be pointed at any part of the sky by tuning it to the appropriate range of the spectrum. There is no preferential direction for finding them. Any direction for a stargazer is a look into the past. By now, all these stars have turned into medium-mass black holes as a result of supernova explosions. The reason for the accelerated expansion, according to cosmologists, is a mysterious dark energy, which is prescribed about 74% of the density of the Universe (in the mass-energy balance). The nature of this mysterious substance is the subject of fierce debate in the scientific community.
But one thing is certain - dark energy acts as a kind of anti-gravity, and creates negative pressure, forcing space-time to stretch faster and faster.