Researchers saw massive stars’ rapid self-destruction and final death before collapsing into a supernova
Researchers were able to see the death by explosion of a giant red star in real-time using ground-based telescopes. The scientists said that the star was ten times more massive than the Sun before it exploded. The star’s unusual activity was first detected by astronomers 130 days before it exploded. It was located 120 million light-years away from Earth.
Till now, it was believed that red supergiants were relatively quiet before their deaths – with no evidence of violent eruptions or luminous emissions. This discovery defies previous ideas.
The new observations detected bright radiation from a red supergiant before exploding. It suggests that at least some of these stars must undergo significant changes in their internal structure, resulting in the tumultuous ejection of gas moments before they collapse.
The discovery was published in The Astrophysical Journal. It is a significant milestone in the study of the death of stars.
Life Cycle of a Star
However, how the star dies depends on what type of star it is. Massive stars transform into supernovae, neutron stars and black holes while average stars like the Sun end life as a white dwarf surrounded by a disappearing planetary nebula.
Main Sequence – In this process, the hydrogen protons are converted into helium atoms.
Stars like the Sun
When the core runs out of hydrogen fuel, it will shrink due to gravity. As the core contracts, it heats up. It raises the temperature of the upper layers, causing them to expand. As the outer layers grow, the star’s radius will increase, becoming a red giant. The radius of the red giant will be just beyond Earth’s orbit. At some point after that, the core will become hot enough for the helium to fuse into carbon. When the helium fuel runs out, the core expands and cools. The upper layers will expand and eject material, forming a planetary nebula around the dying star. Eventually, the core will cool down into a white dwarf and finally into a black dwarf. This whole process will take a few billion years.
Stars bigger than the Sun
When their cores run out of hydrogen, these stars, like the Sun, fuse helium into carbon. However, after the helium is gone, its mass is enough to fuse carbon into heavier elements like iron. Once the core has turned to iron, it can no longer burn. The star collapses by its own gravity, and the iron core heats up. The core becomes so tightly packed that protons and electrons merge to form neutrons. In less than a second, the iron core, which is roughly the size of Earth, shrinks to a neutron core with a radius of about 10 kilometres. The star’s outer layers fall inside the neutron core, crushing it further. The core heats up to billions of degrees and explodes (supernova), releasing large amounts of energy and material into Space. Shock waves from supernovas can trigger the birth of other stars. The rest of the core can form a neutron star or a black hole depending on the mass of the original star.