Biggest Star in Existence Explodes into Supernova
Scientists confirmed that the star labeled SN 2013cu exploded into a supernova. The star, which had 20 times the mass of the Sun, was considered by astronomers to be the biggest star in existence. It was part of the Wolf-Rayet class, which is the largest class of stars, and was located 360 million light years from Earth. Wolf-Rayet stars are of particular interest to scientists because they contain elements that will eventually become parts of planets.
Credit: Sloan digital Sky Survey and Palomar Observatory
Supernovae occur when a star essentially collapses in on itself and dies. When a star becomes supermassive, the process by which it fuses hydrogen atoms to create helium is accelerated to the point of gravitational collapse. When the fusion process slows down after the star runs out of hydrogen, heavy elements in the core begin to rise to the surface and set off powerful winds, called stellar wind. This wind carries the debris and often blocks the supernova from the view of telescopes.
Alex Filippenko, Professor of Astronomy at UC Berkeley and co-author of the study, stated, "We are gradually determining which kinds of stars explode, and why, and what kinds of elements they produce. These elements are crucial to the existence of life. In a very real sense, we are figuring out our own stellar origins."
Observation of supernovae is extremely difficult as a result of the time it takes for the light from the supernova to reach Earth. By the time the light reaches us, the supernova has already occurred. The explosion allows for scientists to study the chemistry of the star that caused the supernova, but only for a very limited time. The explosion ionizes the surrounding area, but that ionization is swept away by the force of the explosion within a day.
"When a Wolf-Rayet star goes supernova, the explosion typically overtakes the stellar wind and all information about the progenitor star is gone," said Peter Nugent, head of Berkeley Lab's Computational Cosmology Center. But in this case, scientists were able to obtain information about the progenitor star because they caught the supernova on telescopes before it overtook the stellar wind. The supernova emitted a flash of ultraviolet light, thereby heating and lighting up the stellar wind. According to the research team, the observed conditions simulated the conditions prior to the supernova. These observations indicate that there is potential for a whole new research area in astronomy: developing statistics for supernovae and their progenitor stars.