May 26, 2022

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Astronomers discover a small but mighty 'micronova' starburst

Astronomers discover a small but mighty ‘micronova’ starburst

Each micronova can burn through “about 3.5 billion Great Pyramids of Giza” of material (or 20,000,000 trillion kilograms) in a few hours, according to the researchers.

These extremely powerful explosions can occur on the surface of white dwarfs, or dead stars roughly the size of our planet, based on observations by a team of astronomers using the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert.

“We have detected and identified for the first time what we call a micronova,” senior study author Simon Scaringi, an astronomer and assistant professor at Durham University in the United Kingdom, said in a statement. “This phenomenon challenges our understanding of how thermonuclear explosions occur in stars. We thought we knew, but this discovery suggests an entirely new way to achieve them.”

A detailed study of the findings, published Wednesday in the journal temper nature.

strong magnetic fields

White dwarf stars found paired with other stars derive hydrogen from their companions, like zombies that feed on other stars. When the gas encounters the hot surface of the tubes of the white dwarf, the hydrogen atoms fuse into the helium, causing an explosion. These events are known as novae.

“Such explosions cause the entire surface of the white dwarf to burn and sparkle brilliantly for several weeks,” Natalie Degenar, an astronomer and assistant professor at the University of Amsterdam, said in a statement.

Micronovae are smaller than typical supernovae and only last for a few hours.

Micronovae explosions occur on white dwarfs that have strong magnetic fields, which send material toward the star’s poles. This pathway causes hydrogen fusion reactions to occur in more localized regions of the magnetic poles.

This illustration shows a two star system.  A blue disk of material can be seen orbiting a white dwarf as it pulls material away from the companion star.

“This results in the explosion of micronova bombs, which have approximately one million parts of the force of a nova explosion, hence the name Micronova,” study co-author Paul Grote, an astronomer and professor at Radboud University in the Netherlands, said in a statement. .

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Track intense but short events

The research team discovered the tiny eruptions after looking at data collected by NASA’s Transiting Exoplanet Survey Satellite, or TESS mission. The satellite is used to search for exoplanets, but it also scans nearby stars to look for planets around them.

This premature supernova starred from a dead star

“Looking at the astronomical data collected by NASA’s TESS, we discovered something unusual: a bright flash of optical light lasting a few hours. With additional research, we found several similar signals,” DeGeneres said.

Two of the macronovas fell on white dwarfs, and the third astronomers followed up with the Very Large Telescope to make sure it was also a white dwarf. This allowed the researchers to announce their observations of the discovery of something new.

Now that micronovae are their own class of starburst, the research team hopes to monitor more of them to see how common they are — particularly as it challenges current understanding of starbursts.

“It just shows how dynamic the universe is,” Scaringi said. “These events might actually be very common, but because they’re so fast it’s hard to pick up in action.”