Astronomers discover new kind of stellar explosion that last only a few hours

These extremely powerful events occur on some white dwarfs with strong magnetic fields, which funnel material towards the star's magnetic poles. As the material hits the star's hot surface, it produces a bright, explosive flash - a micronova.

Astronomers, using the European Southern Observatory's Very Large Telescope (VLT), have discovered a new type of stellar explosion that last only a few hours. Called micronova, the short explosion takes place on the surface of certain stars and just one of these outbursts can burn through 3.5 billion Great Pyramids of Giza's worth of material.

Micronovae are much less energetic than the currently-known stellar explosions called novae. Both types of explosions happen on white dwarfs, dead stars with a mass about that of our Sun, but as small as Earth.

According to ESO's media release, the team first came across these mysterious micro-explosions when analysing data from NASA's Transiting Exoplanet Survey Satellite (TESS). They observed three micronovae with TESS: two were from known white dwarfs, and the third required further observations with the X-shooter instrument on ESO's VLT to confirm its white dwarf status.

"We have discovered and identified for the first time what we are calling a micronova. The phenomenon challenges our understanding of how thermonuclear explosions in stars occur. We thought we knew this, but this discovery proposes a totally new way to achieve them," said Simone Scaringi, an astronomer at Durham University in the UK and the lead author of the study published in the journal Nature.

These extremely powerful events occur on some white dwarfs with strong magnetic fields, which funnel material towards the star's magnetic poles. As the material hits the star's hot surface, it produces a bright, explosive flash - a micronova.

"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," said Scaringi.

The researchers now want to capture more of these elusive events, requiring large scale surveys and quick follow-up measurements.

1/ Using our Very Large Telescope, astronomers have discovered a new phenomenon: micronovae — stellar explosions lasting only a few hours. Full story: 🔗 https://t.co/i8LVpIDpmYDetails 👇 Credit: @ESO / M. Kornmesser L. Calçada pic.twitter.com/SOIYXnxpxJ

— ESO (@ESO) April 20, 2022