homehome Home chatchat Notifications


Astronomers discover micronova explosions

The Universe is a dynamic place teeming with unknowns -- but step by step, we're learning new things about it.

Jordan Strickler
April 20, 2022 @ 7:00 pm

share Share

Image credits: NASA.

With the help of the European Southern Observatory’s (ESO) Very Large Telescope (VLT), a team of astronomers have observed a new type of stellar explosion they’ve coined ‘micronova’. While the event is a smaller cousin of the general nova, they still pack quite a punch and can burn through around 3.5 billion Great Pyramids of Giza of stellar material in only a few hours.

In a classical nova, the accreting white dwarf builds a layer of fresh hydrogen that covers its entire surface. Once this layer reaches high enough temperatures and pressures, the whole layer ignites thermonuclearly. This makes the entire system a lot brighter for weeks or months.

Meanwhile, this micronova explosion is created in a close binary star system consisting of a white dwarf and either a main sequencesubgiant, or red giant star. Micronovae are similar explosions but smaller in scale and faster, lasting just a few hours. These smaller explosions occur on some white dwarfs with strong magnetic fields, which funnel material towards the star’s magnetic poles.

“Classical novae are somewhat similar to micronovae,” Simone Scaringi, assistant professor in the Centre for Extragalactic Astronomy at Durham University who led the study on the explosions, told ZME Science. “In micronovae, because of the strong white dwarf magnetic field, we think the accretion is restricted to the magnetic poles of the white dwarf only. This allows the fresh hydrogen to reach high enough temperature and pressure to ignite thermonuclearly much faster. These events burn through about one million times less mass than classical novae, and consequently are about one million times less bright than classical novae.”

The team first came across these mysterious micro-explosions when analyzing data from NASA’s Transiting Exoplanet Survey Satellite (TESS). In their research, they found something startling, a bright flash of optical light lasting for a few hours. They ended up viewing three micronova in all with TESS, two of which originated from white dwarfs, however, the third required further observations with the X-shooter instrument on ESO’s VLT to confirm its white dwarf status.

Although they’ve only been discovered now, researchers suspect micronovae are a common occurrence in our great Universe.

“We think they may be quite common in an accreting magnetic white dwarf, and possibly a phenomenon observe on those which have relatively high white dwarf masses,” Scaringi said. “They are just very difficult to catch in action: you need to be looking at the right place and at the right time or you’ll miss them entirely!”

The discovery of micronovae adds to the repertoire of known stellar explosions. The team now wants to capture more of these elusive events, requiring large-scale surveys and quick follow-up measurements.

“We already have a follow-up paper detailing the theoretical model we have to trigger micronovae. Now that we know, more or less, what to look for, the challenge will be to find more and use these new observations to test and refine our current models,” Scaringi said. “I think this goes to show just how dynamic the Universe is. These micronova are fast flashes of light, that may be quite common out there. It also goes to show that thermonuclear explosions can occur on localized areas (as opposed to the entire surface) of white dwarfs, something that was unexpected and surprising.”

The discovery was published in Nature.

share Share

How Hot is the Moon? A New NASA Mission is About to Find Out

Understanding how heat moves through the lunar regolith can help scientists understand how the Moon's interior formed.

A Huge, Lazy Black Hole Is Redefining the Early Universe

Astronomers using the James Webb Space Telescope have discovered a massive, dormant black hole from just 800 million years after the Big Bang.

Should we treat Mars as a space archaeology museum? This researcher believes so

Mars isn’t just a cold, barren rock. Anthropologists argue that the tracks of rovers and broken probes are archaeological treasures.

Proba-3: The Budget Mission That Creates Solar Eclipses on Demand

Now scientists won't have to travel from one place to another to observe solar eclipses. They can create their own eclipses lasting for hours.

This Supermassive Black Hole Shot Out a Jet of Energy Unlike Anything We've Seen Before

A gamma-ray flare from a black hole 6.5 billion times the Sun’s mass leaves scientists stunned.

Astronauts will be making sake on the ISS — and a cosmic bottle will cost $650,000

Astronauts aboard the ISS are brewing more than just discoveries — they’re testing how sake ferments in space.

Superflares on Sun-Like Stars Are Much More Common Than We Thought

Sun-like stars release massive quantities of radiation into space more often than previously believed.

Astronomers Just Found Stars That Mimic Pulsars -- And This May Explain Mysterious Radio Pulses in Space

A white dwarf/M dwarf binary could be the secret.

These Satellites Are About to Create Artificial Solar Eclipses — And Unlock the Sun's Secrets

Two spacecraft will create artificial eclipses to study the Sun’s corona.

Mars Dust Storms Can Engulf Entire Planet, Shutting Down Rovers and Endangering Astronauts — Now We Know Why

Warm days may ignite the Red Planet’s huge dust storms.