Although Betelgeuse, a famous star on Orion's shoulder, may die out in the next few days, years, hundreds of thousands of years or even a million years, scientists insist that Betelgeuse's dimming is caused by the pulsation of stars, which is relatively common in red Supergiant star, and Betelgeuse has been considered to belong to this category for decades.
Coincidentally, researchers at the University of California, Santa Barbara, have predicted the brightness of supernovae when stars like Betelgeuse pulsate and explode. Jared Goldberger, a graduate student in physics, published a study with Lars Bilston, director of the Cuffley Institute of Theoretical Physics (KITP), a professor of physics at Gluck, and bill paxton, a senior researcher at KITP.
How the stellar pulsation will affect the subsequent supernova explosion is described in detail, and its research results are published in the journal Astrophysics. Goldberger, a graduate researcher at the National Science Foundation, said: We want to know what it would be like if a star pulsed and exploded at different stages.
Early models were simple because they didn't consider the time-dependent effect of pulsation. When the Betelgeuse-sized star finally runs out of fusion material in its center, it loses the external pressure to prevent it from collapsing under its own huge weight. The resulting core collapse occurs in half a second, much faster than the speed of the star's surface and outer layer.
when the iron core collapses, atoms dissociate into electrons and protons. These combine to form neutrons, and in the process release high-energy particles called neutrinos. Under normal circumstances, neutrinos hardly interact with other substances, but for example, trillions of neutrinos pass through your body and the earth every second without a collision. In other words, supernova hugging is one of the most powerful phenomena in the universe. The number and energy of neutrinos produced in the core collapse are so huge that even a small part of them collide with the star material, which is usually enough to send out a shock wave that can make the star explode.
The resulting explosion hits the outer layer of the star with amazing energy, which can briefly eclipse the whole galaxy. The explosion remains bright for about 1 days, because radiation can escape only when ionized hydrogen recombines with lost electrons to become neutral. This means that over time, astronomers can see deeper inside the supernova until the light from the center finally escapes. At this point, all that remains is the dim light of radioactive dust, which may last for years.
the characteristics of supernovae vary with the star mass, total explosion energy and, more importantly, its radius, which means that the star pulsation of Betelgeuse makes it quite complicated to predict how it will explode. The researchers found that if the whole star is pulsating in unison, the supernova behaves like Betelgeuse is a static star with a given radius. However, different layers of a star can oscillate in opposite directions: the outer layer expands, the middle contracts, and vice versa. For the simple pulsation case, the team model produces similar results as the model without considering the stellar pulsation.
at different positions of the star pulse, it looks like a supernova from a larger star or a smaller star. When we start to consider more complex pulsations, that is, when substances move in and out, the research models do have obvious differences. In these cases, the researchers found that when the light leaked from the deeper layer of the explosion, the emission looked like the result of a supernova from stars of different sizes. The light emitted by the compressed part of the star is weak, just as we expect it to be denser and without stellar pulsation.
at the same time, the light from the expanding star at that time will appear brighter, just like it comes from a bigger star without pulse. Together with Andy Howell, a professor of physics, and Evan Bauer, a postdoctoral researcher at KITP, Goldberger plans to submit a report to the research notes of the American Astronomical Society, summarizing the results of their simulation specially run on Betelgeuse. Goldberg also cooperated with Benny Chan, a postdoctoral fellow at KITP, to compare different radiation transmission technologies of supernovae, and cooperated with Songfreshman, a physics researcher, to compare the theoretical explosion model with supernova observation.