Wolf-Rayet stars are massive stars that have completely lost their outer hydrogen and are fusing helium or heavier elements in the core. Therefore a supernova (explosion) of Wolf-Rayet stars previously unseen.
Prof. Avishay Gal-Yam from the Weizmann Institute and colleagues recently identified the first-time-ever Wolf-Rayet Stars Supernova. Their findings appear today in Nature.
Every star’s core is powered by nuclear fusion when lighter elements’ nuclei combine to generate heavier elements. Four hydrogen nuclei fused together make helium, while numerous helium nuclei united form carbon, oxygen, and so on.
The most stable atomic nucleus, iron, is the final element to naturally originate by nuclear fusion. In normal conditions, the star’s core produces high temperatures that cause gaseous stuff to expand, keeping the star’s mass in balance with gravity.
So, when a star runs out of materials to fuse and ceases producing energy, this equilibrium is upset, resulting in either an eruptive spiral black hole at the star’s core or the star exploding, releasing the heavy elements fused during evolution into the universe. The entire procedure is lengthy.
Massive stars Gal-Yam research have life spans of only a few million years. The Sun, on the other hand, has a 10-billion-year lifespan. Massive stars stratify as a result of succeeding nuclear fusion events, with heavy components concentrating at the core and lighter elements composing the outer layers.
Wolf-Rayet stars are huge stars that lack one or more of their lighter outer layers. Instead of hydrogen, the star’s surface contains helium, carbon, and heavier elements. Strong winds caused by high pressure near the star’s envelope may disperse its outermost layer, causing the star to lose layers over several hundred thousand years.
Observing these stars without the lighter elements in their envelopes is like taking a still snapshot of a long-winded process. Despite their short lives and state of disintegration, a Wolf-Rayet supernova explosion has yet to be confirmed.
If Wolf-Rayet stars explode, we would have seen one by now, based on the increasing frequency of supernova findings.
The Weizmann group and their international team of partners recently discovered a supernova emanating from this type of star, shattering this idea. Spectroscopic study of the light generated by the explosion revealed spectrum fingerprints associated with distinct components.
The researchers were able to prove that the explosion comprised carbon, oxygen, and neon atoms, the latter of which has never been seen in a supernova. The researchers also discovered that the materials emitted by the exploding star did not participate in the blast but rather came from the surrounding vacuum. This bolstered their case for strong winds shredding the star’s outer envelope.
Because this is the first of its kind, Gal-Yam believes it is premature to predict the fate of all similar stars. “At this point, we can’t determine whether all Wolf-Rayet stars die violently. He believes that some of them do quietly sink into a black hole.
The star that exploded had a mass at least ten times bigger than the Sun. So where did the mass go?
So, once nuclear fusion runs out in the star’s core, an explosion occurs, blasting some of the material into space while the rest collapses in on itself to form a black hole. “This is not the ‘silent’ collapse,” argues Gal-Yam.
Since this discovery, another identical explosion of a Wolf-Rayet star has been discovered, indicating that this phenomena is not unique. This form of explosion, which is currently rare and exotic, may become more prevalent as our detection and monitoring technologies improve.
Supernovae may appear to be massive phenomena that have little direct impact on our life. But, in actuality, they are the essence of life. These cosmic explosions send the components created at the star’s core to the galaxy’s outer reaches, where they serve as the foundations for fresh star formation. This resulted in the Earth and all its lifeforms (including us, Homo sapiens).
“We look for answers for many of the physical occurrences we take for granted,” says Gal-Yam. “I am personally curious about the origins of everything, and I want to be able to answer this question as correctly as possible.”