Astronomers spot weird star that is travelling faster than any like it

A quick flash and wobbly explosion on a small star could help scientists understand how planets like ours come to exist

Jon Kelvey
Wednesday 15 June 2022 22:27
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<p>An artist’s conception of a bright stellar explosion</p>

An artist’s conception of a bright stellar explosion

Astronomers have now observed the fastest fading nova ever recorded, a stellar explosion that led  researchers to an array of bizarre traits that could help them better understand the death process of stars and its connection to interstellar chemistry.

A nova is a massive explosion that results when a small, but very dense and gravitationally powerful white dwarfstar siphons so much material from a nearby companion star that the star stuff ignites in an uncontrolled thermonuclear reaction on the white dwarf’s surface. Such explosions can be incredibly bright, and typically take many days to weeks to fade.

But V1674 Hercules, a nova observed on 12 June 2021, flashed bright enough to be seen by the naked eye on Earth, and then faded in a matter of hours. The researchers used the Large Binocular Telescope Observatory, an optical telescope in the Pinaleno Mountains of southeastern Arizona, to make their observations.

“It was only about one day,” Arizona State University astrophysicist and one of the authors of a paper published Tuesday in the Research Notes of the American Astronomical Society, said in a statement. “The previous fastest nova was one we studied back in 1991, V838 Herculis, which declined in about two or three days.”

But the strangeness of V1674 Hercules doesn’t end with how fast it faded in brightness. Astronomers also observed the explosion wobble. A pulsation in visible light and X-rays every 501 seconds persists a year after the initial explosion.

“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,” Mark Wagner, a research scientist in astronomy at Ohio State University and a co-author of the study said in a statement.

“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.”

Novae are important to the cycle of matter in the cosmos, as white dwarfs siphon, transform, and then expel matter during nova explosions, seeding space with material that can eventually form into other star systems and planets.

Understanding the bizarre behavior of  V1674 Hercules, and whether it is more or less typical of the average novae in the cosmos, may help scientists not only understand the life cycles of stars, but how those stars contribute to planets with a wide array of matter suitable for the evolution of life. Planets like ours.

“We’re always trying to figure out how the solar system formed, where the chemical elements in the solar system came from,” Dr Starrfield said in a statement.

“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.”

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