A strange star produced the fastest nova on record

Astronomers are buzzing after observing the fastest nova on record. The unusual event drew scientists’ attention to an even more unusual star. By studying it, they can find answers not only to the many puzzling traits of nova, but also to larger 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 of Arizona State Regents University, Professor Charles Woodward of the University of Minnesota and research scientist Mark Wagner of Ohio State University, co-authored a published report today in the American Astronomical Society Research Notes.

A nova is a sudden burst of bright light from a two-star system. Each nova is created by a white dwarf – the very dense remaining core of a star – and a nearby companion star. Over time, the white dwarf draws matter from its companion, which falls on the white dwarf. The white dwarf heats up this material, causing an uncontrolled reaction that releases a burst of energy. The explosion throws the material at high speed, which we observe in the form of visible light.

Bright nova usually fades in a few weeks or more. On June 12, 2021, nova V1674 Hercules erupted so hard it was visible to the naked eye – but in just over a day it faded away again. It was like someone turning a flashlight on and off.

Nova events at this level of speed are rare, making this nova a valuable subject of study.

“It was only about a day, and the previous fastest nova was the one we studied in 1991, V838 Herculis, which decayed in about two or three days,” says Starrfield, an astrophysicist at the School of Science. Earth and Space Exploration of ASU.

As the astronomy world watched V1674 Hercules, other researchers discovered that its speed wasn’t its only unusual trait. The light and energy it sends out also pulsates like the sound of a reverberating bell.

Every 501 seconds there is an oscillation that observers can see in both visible light waves and X-rays. A year after its explosion, the nova is still showing this oscillation, and it appears to have been going on for even longer. long time. Starrfield and his colleagues continued to study this oddity.

“The most unusual thing is that this wobble was observed before the explosion, but it was also evident when the nova was about 10 magnitudes brighter,” says Wagner, who is also the science chief at the observatory of the large binocular telescope used to observe the nova. “One mystery that people are trying to wrestle with is what drives this periodicity at which you would see it over this range of brightness in the system.”

The team also noticed something strange while monitoring the material ejected by the nova explosion – some kind of wind, which may depend on the positions of the white dwarf and its companion star, shapes the flow of material in the nova explosion. space surrounding the system.

Although the fastest nova is (literally) flashy, the reason it deserves further study is that novae can give us important information about our solar system and even the universe as a whole.

A white dwarf collects and modifies matter, then seasons the surrounding space with new material in a nova explosion. It is an important part of the cycle of matter in space. The materials ejected by the novae will eventually form new star systems. Such events also contributed to the formation of our solar system, ensuring that the Earth is more than a lump of carbon.

“We’re still trying to figure out how the solar system formed, where the chemical elements of the solar system came from,” Starrfield says. “One of the things that we will learn from this nova is, for example, the amount of lithium that was produced by this explosion. We are pretty sure now that a significant fraction of the lithium we have on Earth was produced by these types of explosions.

Sometimes a white dwarf star does not lose all of its collected matter in a nova explosion, so with each cycle it gains mass. This would eventually make it unstable and the white dwarf could generate a type 1a supernova, which is one of the brightest events in the universe. Each type 1a supernova reaches the same level of brightness, so they are called standard candles.

“Standard candles are so bright that we can see them from great distances across the universe. By examining how the brightness of light changes, we can ask questions about how the universe is accelerating or about the three-dimensional structure overall picture of the universe,” Woodward explains. “That’s one of the interesting reasons we’re studying some of these systems.”

Additionally, novae can tell us more about how stars in binary systems evolve until they die, a process that is not well understood. They also act as living laboratories where scientists can see nuclear physics in action and test theoretical concepts.

The nova took the world of astronomy by surprise. It wasn’t on scientists’ radar until an amateur astronomer from Japan, Seidji Ueda, discovered it and reported it.

Citizen scientists are playing an increasingly important role in the field of astronomy, as is modern technology. Although it is now too faint for other types of telescopes to see it, the team is still able to monitor the nova thanks to the large aperture of the Large Binocular Telescope and other equipment at its observatory, including its pair of double multi-object spectrographs and its exceptional PEPSI high-resolution spectrograph.

They plan to investigate the cause of the explosion and the processes that led to it, the reason for its record decline, the forces behind the observed wind, and the cause of its pulsating brightness.

Reference:

  1. CE Woodward, R. Mark Wagner, Sumner Starrfield. V1674 Hercules: A wind is blowing. AAS Research Notes, 2022; 6(6):124 DOI: 10.3847/2515-5172/ac779d
/Public release. This material from the original organization/authors may be ad hoc in nature, edited for clarity, style and length. The views and opinions expressed are those of the author or authors.View Full here.

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