Astronomers may have discovered a new kind of stellar explosion

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A new study suggests astronomers have discovered a new kind of stellar explosion called a "micronova."

According to research published in the journal Nature on Wednesday, a micronova is a kind of thermonuclear blast, or an outburst that happens on the surface of certain stars. The team of researchers said it could burn through stellar material the size of 3.5 billion Great Pyramids of Giza, and that it occurs so quickly – over the course of just a few hours – that it is difficult for researchers to observe.

The team first came across the unusual explosion when they noticed a bright flash of light lasting for a short time while analysing data from NASA’s Transiting Exoplanet Survey Satellite (TESS). Using TESS, the researchers said they observed the phenomenon in three white dwarfs – dense dead stars with a mass similar to our Sun, but similar in size to Earth.

White dwarfs can, when close enough to a companion star, can steal stellar materials from that star. When they steal the material – usually mostly hydrogen – the hydrogen fuses together when it hits the hot surface of the white dwarf to become helium, causing an explosion.

In other thermonuclear explosions, or novae, this reaction occurs over the entire surface of the star, causing a bright light that lasts for weeks.

This new study suggests that micronovae are similar, but smaller in scale and occurring much more quickly.

"This leads to micro-fusion-bombs going off, which have the strength of about one millionth of a nova explosion, hence the name 'micronova,'" study co-author Paul Groot of Radboud University said in a press release on Wednesday.

The team now hopes to observe and study more of these stellar events to determine how often this kind of reaction happens in the universe.

"The phenomenon challenges our understanding of how thermonuclear explosions in stars occur," lead author Simone Scaringi of Durham University, said in the press release. "We thought we knew this, but this discovery proposes a totally new way to achieve them. It just goes to show how dynamic the Universe is. These events may actually be quite common, but because they are so fast they are difficult to catch in action.”