History | 7 August 2015Hypernovas and Gamma-Ray Bursts Share article facebook twitter google pinterest Have you ever wondered how the ray guns from your favorite science fiction books and movies work? Here’s a description of how gamma rays occur in space from Christopher Cooper’s Our Sun. Recently, scientists have classified a specific type of core collapse called a hypernova. Usually, a supernova is characterized by a star exploding as a result of thermal runaway or core collapse. But for stars with masses about 15 times that of our Sun, the outward burst of energy created by collapsing matter in the star’s core is insufficient to blow the outer layers beyond the pull of gravity. Instead of exploding heavy elements into the universe, most of the star’s mass collapses in on itself, forming a black hole. Only some of the mass is able to escape as jets of high-energy particles called gamma-ray bursts. These bursts are the brightest electromagnetic events known to occur in the universe. Because they are usually short-lived, focused beams, gamma-ray bursts are extremely powerful. So far, astronomers have only observed them (about one a day) emanating from distant galaxies. If a gamma-ray burst were to occur in the Milky Way and the Earth was in its path, the results would be catastrophic. The planet would be bathed in so much ultraviolet radiation that even the Earth’s protective magnetosphere could not prevent most organisms from being killed. In fact, some scientists speculate that exposure to a gamma-ray burst is precisely what triggered the Ordovician-Silurian mass extinction event some 450 million years ago. More about the star in all our lives… Our Sun: Biography of a Star Author: Christopher Cooper Our sun is one star among 50 billion in the galaxy. Our galaxy is only one among 50 billion in the universe. With a vastness this incomprehensible, it is easy to feel like we are mere specks of sand on an endless shore. But our sun is special. Though roughly 150 million kilometers separate us, we could not be more connected. Literally, everything you see comes from the sun. The words you are reading now are really photons that left the sun about 8 minutes ago only to bounce off this page and into your eyes. We owe our very existence to our sun. It provides just enough heat to keep our fragile bodies from freezing to ice or burning to a crisp. Every bite of food we eat we owe to the sun, whose energy is converted into plants that provide sustenance for everything up the food chain. We have understood the sun’s importance for millennia. The earliest humans, awestruck by its blazing splendor, left drawings of the sun on cave walls. Nearly every civilization, no matter where it sprang up on the planet, has revered the sun. Myths about the sun were the basis of the earliest deities of ancient Sumerian, Hindu, Egyptian, Chinese, and Meso-American cultures. Before Apollo, the ancient Greeks worshiped the sun-god Helios. Before Zeus, the ancient Romans worshiped Sol. Throughout our history, the sun has been central to humanity’s quest for meaning in the universe. But our history has been a brief moment in our sun’s 4.5 billion year life. Only recently, through advances in science and technology, have we begun to understand our sun – where it came from, how it functions, how it affects our lives and how it eventually will destroy our planet. Our Sun is a comprehensive, easy-to-understand guide to everything we know about our closest star. Illustrated with stunning pictures from NASA’s newly-launched Solar Dynamics Observatory, Our Sun will reveal the science behind the sun, trace its impact on human history, and reveal its growing importance to our future way of life. Buy from an Online Retailer In North America: In The UK: Share article facebook twitter google pinterest If you have any comments on this article please contact us or get in touch via social media.