How a dead star burst back to life
The scientists believe the star was similar to our Sun, but had already ended nuclear burning and begun its journey towards becoming a white dwarf – the hot, dense core left behind after an ordinary star dies. It underwent a rare event known as a “very late thermal pulse”, when a layer of helium deep inside the dead star suddenly reignites.
The event caused the star to rapidly expand, cool and eject large amounts of material into space, temporarily returning to an earlier stage of its life, leading astronomers to describe it as a “born-again” star.
Only two stars have ever been directly observed undergoing this type of dramatic rebirth: Sakurai’s Object and V605 Aquilae.
Following its outburst, Sakurai’s Object became hidden behind thick clouds of gas and dust released during the eruption, making it difficult to study directly.
To investigate its current state, the team analysed light collected by the Very Large Telescope and compared it with sophisticated computer models that simulate the atmospheres and powerful winds of Wolf-Rayet stars.
The observations revealed distinctive signatures of carbon and helium, allowing the researchers to find its temperature, chemical composition and the characteristics of its stellar wind.
Their analysis suggests the star’s surface temperature is currently between around 27,000 and 36,000 degrees Kelvin, showing that it is reheating following its dramatic eruption nearly three decades ago.
