Those changes might hint at whether these objects are really spinning neutron stars. Astronomers could watch how gamma rays from the candidates change over time. It would be much easier to prove the candidates found so far are not antistars, he says. He works at the Institute of Research in Astrophysics and Planetology. He’s an astrophysicist in Toulouse, France. Why? Because antistars are expected to look almost identical to normal stars, explains Simon Dupourqué. In fact, proving any object is an antistar could be nearly impossible. But in that scenario, one antistar could lurk among every 10 normal stars.Īntistars are still only hypothetical. They also should emit fewer gamma rays in this more isolated environment. There, they would have less chance to interact with normal matter. Understanding light and other forms of energy on the moveĪntistars could exist, however, outside the Milky Way’s disk. How rare? Perhaps only one antistar would exist for every 400,000 normal stars. But the researchers only found 14 candidates. That could cause them to emit lots of gamma rays. Those estimates depended on where antistars would most likely be found, if they truly existed.Īny in the disk of our galaxy would be surrounded by lots of normal matter. The team then estimated how many antistars could exist near our solar system. Researchers reported their find online April 20 in Physical Review D. That was further evidence that the sources could be antistars. Those spots did not look like other known gamma-ray sources - such as spinning neutron stars or black holes. So the team looked for those wavelengths in data from the Fermi Gamma-ray Space Telescope.įourteen spots in the sky gave off the gamma rays expected from matter-antimatter annihilation events. This type of particle annihilation gives off gamma rays with certain wavelengths. That could happen when normal matter from interstellar space falls onto an antistar. The team knew that matter and antimatter annihilate each other when they meet. Intrigued by this idea, some researchers went hunting for potential antistars. But if they are, that antimatter could have been shed by antimatter stars. One instrument might have seen bits of antihelium atoms in space. Space-station data have recently cast doubt on this idea of a practically antimatter-free universe. Now the cosmos appears to have almost no antimatter. Physicists think the universe was born with equal amounts of matter and antimatter. Where electrons have negative electric charge, positrons have positive charge. For instance, electrons have antimatter twins called positrons. ![]() But astronomers haven’t completely ruled out that some could be made of antimatter.Īntimatter is the oppositely charged alter-ego of normal matter. So we’re not likely to go warping around the galaxy in antimatter-powered ships anytime soon.All known stars are made of ordinary matter. The problem, though, is that making the stuff is extraordinarily expensive: trillions of dollars for a single gram. And it would be the most efficient power source around. Of course, the most famous use of antimatter is fictional: as a power source for starships. And research suggests that antimatter could someday be used to treat tumors. Antimatter from this type of decay is used in PET scans. There’s also evidence that positrons are produced by thunderstorms.Īntimatter is also produced by the decay of radioactive elements, like the potassium in bananas. A tiny fraction of the cosmic rays that strike Earth’s atmosphere, for example, consists of positrons and antiprotons. When matter and antimatter meet, they annihilate each other, producing pure energy.Īntimatter appears to be quite rare, but there is some. An electron, for example, has a negative charge, while a positron has a positive charge. Particles of antimatter have the opposite electric charge from normal matter. They’re no threat, though - there just aren’t enough of them. As the element decays, it produces positrons, the antimatter counterpart of electrons. ![]() That’s because a banana contains a tiny amount of a radioactive form of potassium. A banana is a good source of fiber, vitamin C, manganese, and a host of other goodies.
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