It is a disturbing fact of astronomy that no one receives a personal invitation to watch the breathing of a dying star. Detecting a star at the critical moment of its death is a matter of chance, making it a rare find. Using a conveniently located cluster of galaxies, an international team of researchers measured the luminosity emitted by a distant supernova star at three different times. This data will allow them to test theories about what it can tell us about the size of a dying star’s light.

The star itself is too far away for any telescope to see it in detail. It is so far away that it took about 11.5 billion years for its light to travel through this void and reach our door, mingling with the bright glow of countless other stars in its galaxy. But we can observe changes in the star’s brightness, and these reveal some truth about how it died. And they lived. Here and there, a swarm of starlight accidentally passed through the Abell 370 galaxy cluster, a knot of several hundred galaxies about 4 billion light-years away.

Having so many galaxies so close together inevitably creates a large dent in the cosmic landscape, causing the starlight to bend slightly as it slides. The impact was something like a giant galaxy-sized telescope with a lens deformed, scratched and wrinkled by the uneven gravitational force. The original light, smeared in a configuration called the Einstein cross, was magnified and copied, creating slightly different versions of the distant galaxy as it appeared at different points in time.

Researchers discovered the gravitational lensing halo during an examination of stars by the Hubble Space Telescope in 2010. With clever modeling, the team turned the light into something smart, revealing three of the four points of the cross (the fourth point was too weak to detect).

Analysis of the light in each speck revealed the exploding star’s swell glow somewhere in it, on an eight-day pattern. One showed light just six hours after the first flash. In general, the three light blurs provide details of a supernova that has slowly cooled over a week, down to 10,000 K, much colder than 100,000 degrees Kelvin. Dying stars of a certain size do not quietly enter the night. . They don’t have enough nuclear fuel to start a fire, they cool enough for their cores to collapse in a fury that leads to the mother of all nuclear explosions.

Researchers are slowly working to know when exactly the star will explode. While the gas and light envelopes emitted by supernova explosions are not difficult to find, catching a star at the time of death requires great luck. Here, astronomers not only got the characteristic glow of a dying star in a galaxy far, far away, but also got important details about how its light changes over a short period of time.

This information helps validate models of how the material surrounding stars interacts with a burst of radiation from within, warming up just before it cools rapidly again, and allowing it to work backwards to determine its initial size based on how the star cooled.

Based on what they learned from this event, the team is confident that the star they witnessed at the time of death was 530 times the radius of our own Sun. The work not only confirms theoretical models of the evolution of supernovas and the stars that gave rise to them, but also leads to the analysis of an entirely new population of stars in the early universe. And this is an invitation to a star’s final moments in flight, as close as we’ll ever get to an invitation. Source