Most people are familiar with supernovae, spectacular stellar explosions that occur at the end of a huge star’s life and often end up in a black hole or neutron star. On the other hand, nova’s are much less well known to the general public, although they occur much more frequently than supernovae, perhaps because they are usually less dramatic. Nova is a sudden, short-lived, dramatic glow of a star. Usually, the star fades slowly to its original brightness for several weeks or many months. Although the specific causes of a nova can vary depending on the circumstances, they always involve white dwarf stars in narrow binary systems – two stars orbiting each other, bound by gravity. Now, astronomers are buzzing after observing the fastest nova ever recorded. The unusual event caught the attention of scientists on an even more unusual star. As they study it, they can find answers not only to the many confusing features of nova, but also to bigger questions about the chemistry of our solar system, the death of stars, and the evolution of the universe. The research team, led by Professor Sumner Starrfield, Professor Regents of Arizona State University, Professor Charles Woodward of the University of Minnesota, and researcher Mark Wagner of The Ohio State University, wrote a report published today (June 14, 2022). ) in the Research Notes of the American Astronomical Society. The nova is a sudden burst of glare from a two-star system. Each nova is created by a white dwarf – the very dense nucleus of a remaining star – and a nearby companion star. Over time, the white dwarf draws matter from his mate, which falls on the white dwarf. The white dwarf heats this material, causing an uncontrollable reaction that releases an explosion of energy. The explosion throws matter away at high speeds, which we observe as visible light. The bright nova usually fades after a few weeks or more. On June 12, 2021, the nova V1674 Hercules exploded so brightly that it was visible to the naked eye – but in just over a day, it was dim again. It was like turning on and off a flashlight. Nova events at this speed level are rare, making this nova a valuable object of study. “It was only one day, and the previous fastest nova was the one we studied in 1991, the V838 Herculis, which dropped to about two or three days,” said Starrfield, an astrophysicist at ASU’s School of Earth and Space Exploration. As the world of astronomy watched the V1674 Hercules, other researchers found that its speed was not its only unusual feature. The light and energy it emits also vibrates like the sound of a ringing bell. Every 501 seconds, there is an oscillation that observers can see in both visible light waves and X-rays. A year after its eruption, the nova still shows this oscillation and seems to continue for even longer. Starrfield and his colleagues continued to study this peculiarity. “The most unusual thing is that this oscillation was seen before the eruption, but it was also evident when the nova was about 10 sizes brighter,” said Wagner, who also heads science at the Large Binocular Telescope Observatory used for observation. the nova. “A mystery that people are struggling with is what drives this periodicity that you would see in this range of brightness in the system.” The team also noticed something strange as they watched the material ejected by the nova explosion – a kind of wind, which may depend on the positions of the white dwarf and the star companion, regulates the flow of material around the system. Although the fastest nova is (literally) fancy, the reason it’s worth further study is that novae can tell us important information about our solar system and even the universe as a whole. A white dwarf collects and alters matter and then seasons the surrounding area with new material during a nova explosion. It is an important part of the cycle of matter in space. The materials launched by the novae will eventually form new stellar systems. Such events have helped shape our solar system as well, ensuring that the Earth is more than just a piece of carbon. “We’re always trying to figure out how the solar system came to be, where the chemical elements in the solar system came from,” says Starrfield. “One of the things we will learn from this nova is, for example, how much lithium was produced by this explosion. “We are quite confident now that a significant fraction of the lithium we have on Earth was produced by these kinds of explosions.” Sometimes a white dwarf star does not lose all of its collected material during a nova explosion, so with each cycle, it gains mass. This would eventually make it unstable and the white dwarf could create a type 1a supernova, which is one of the brightest events in the universe. Each type 1a supernova reaches the same brightness level, hence they are known as standard candles. “Typical candles are so bright that we can see them at great distances throughout the universe. “By looking at how the brightness of light changes, we can ask questions about how the universe is accelerating or about the overall three-dimensional structure of the universe.” “That’s one of the interesting reasons we’re studying some of these systems.” In addition, novae can tell us more about how stars in binary systems evolve to death, a process that is not well understood. They also function as living laboratories where scientists can see nuclear physics in action and test theoretical concepts. Nova surprised the world of astronomy. It was not on the radar of scientists until an amateur astronomer from Japan, Seidji Ueda, discovered it and reported it. Citizen scientists are playing an increasingly important role in astronomy, as is modern technology. Although it is now very faint for other types of telescopes, the team is still able to monitor the nova thanks to the wide aperture of the Large Binocular Telescope and other observatory equipment, including a pair of high-resolution, dual-spectrum PE and high-resolution spectroscopes. . They intend to investigate the cause of the outbreak and the processes that led to it, the reason for its record-breaking fall, the forces behind the observed wind and the cause of its pulsating brightness. Reference: June 14, 2022, Research Notes by the American Astronomical Society. DOI: 10.3847 / 2515-5172 / ac779d
