Supernovas, the dramatic stellar explosions that occur at the conclusion of a big star's existence and frequently culminate in a black hole or neutron star, are well-known to most people. Novas, on the other hand, are significantly less widely known among the general public, despite the fact that they occur far more frequently than supernovas, maybe due to the fact that they are not nearly as spectacular.
A nova is a quick, spectacular brightening of a star that lasts only a few minutes. Over several weeks or months, the star usually declines to its previous brilliance. Although the origins of novas vary depending on the conditions, they usually include white dwarf stars in tight binary systems – two stars orbiting each other and linked by gravity.
Astronomers are excited right now after witnessing the quickest nova yet seen. The strange occurrence led astronomers' attention to an even stranger star. They may uncover answers to not just the nova's many perplexing characteristics, but also to wider concerns about the chemistry of our solar system, star death, and the development of the cosmos as they study it.
Professor Sumner Starrfield of Arizona State University, Professor Charles Woodward of the University of Minnesota, and Research Scientist Mark Wagner of The Ohio State University co-authored a study that was published today (June 14, 2022) in the American Astronomical Society's Research Notes.
A nova is a two-star system's abrupt eruption of brilliant light. A white dwarf - a star's dense residual core — and a neighboring partner star are responsible for every nova. The white dwarf takes matter from its partner throughout time, which eventually falls upon the white dwarf. This substance is heated by the white dwarf, resulting in an uncontrolled reaction that unleashes a burst of energy. The substance is sent out at great speeds by the explosion, which we see as visible light.
Over the course of a few weeks or more, the dazzling nova normally fades. The nova V1674 Hercules exploded bright enough to be seen with the naked eye on June 12, 2021, but it faded away in just over a day. It seemed as if someone had turned on and off a spotlight.
This nova is a valuable research topic since nova occurrences at this speed are uncommon.
“It was only about one day, and the previous fastest nova was one we studied back in 1991, V838 Herculis, which declined in about two or three days,” says Starrfield, an astronomer from ASU's School of Earth and Space Exploration.
While the astronomical community was watching V1674 Hercules, other researchers discovered that its speed wasn't its only unique feature. It also emits pulsating light and energy, similar to the sound of a resounding bell.
Observers can spot a wobble in both visible light waves and X-rays every 501 seconds. The nova is still wobbling a year after it exploded, and it appears to have been going on for even longer. Starrfield and his colleagues have continued to look at this strange phenomenon.
“The most unusual thing is that this oscillation was seen before the outburst, but it was also evident when the nova was some 10 magnitudes brighter,” adds Wagner, who is also the chief of science at the Large Binocular Telescope Observatory that is observing the nova. “A mystery that people are trying to wrestle with is what’s driving this periodicity that you would see it over that range of brightness in the system.”
While monitoring the matter expelled by the nova explosion, the scientists found something strange: some form of wind is influencing the flow of material into space surrounding the system, which may be based on the locations of the white dwarf and its partner star.
Though the fastest nova is (literally) showy, it's worth studying because novae can reveal significant details about our solar system and potentially the entire cosmos.
During a nova explosion, a white dwarf accumulates and modifies stuff, then seasons the surrounding space with new material. It's a crucial aspect of the matter-in-space cycle. Novae expel elements that will ultimately create new star systems. Such catastrophes also aided in the formation of our solar system, ensuring that Earth is more than a carbon blob.
“We’re always trying to figure out how the solar system formed, where the chemical elements in the solar system came from,” Starrfield adds. “One of the things that we’re going to learn from this nova is, for example, how much lithium was produced by this explosion. We’re fairly sure now that a significant fraction of the lithium that we have on the Earth was produced by these kinds of explosions.”
Because a white dwarf star doesn't always lose all of its accumulated materials after a nova explosion, it accumulates mass with each cycle. The white dwarf would become unstable as a result, and a type 1a supernova, one of the brightest explosions in the cosmos, might result. Because each type 1a supernova achieves the same brightness, they are referred to as standard candles.
“Standard candles are so bright that we can see them at great distances across 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,” Woodward adds. “This is one of the interesting reasons that we study some of these systems.”
Furthermore, novae can reveal more about how stars in binary systems die, a process that is yet poorly understood. They also serve as live labs, allowing scientists to see nuclear physics in action while also putting theoretical notions to the test.
The nova astounded the astronomical community. It wasn't noticed by scientists until Seidji Ueda, a Japanese amateur astronomer, spotted and reported it.
Citizen scientists, like contemporary technology, are becoming increasingly significant in the study of astronomy. The team is still able to monitor the nova thanks to the Large Binocular Telescope's wide aperture and other observatory equipment, including its pair of multi-object double spectrographs and exceptional PEPSI high resolution spectrograph, even though it is now too faint for other types of telescopes to see.
They intend to look into the source of the outburst and the processes that led to it, as well as the explanation for the outburst's record-breaking decrease, the forces that caused the observed wind, and the cause of the pulsating brilliance.
