Astronomers Discover 'Micronova', The Universe's Least Powerful Star Explosion

The discovery of a new type of stellar explosion called a "micronova" has shook astronauts. The explosion was noted through thermonuclear blasts that were discovered on the polar regions of a white dwarf, a kind of burned-out star that swallows material from a companion star.

This micronova is the least powerful type of star explosion assessed by scientists so far. It has less energy than a blast called a nova wherein a white dwarf's "entire surface blows up." This explosion is small compared to a supernova that takes place when some giant stars are in the process of dying.

Reuters

Only third micronova to be noted

From Earth, micronovae are observed as bursts of light that last for about 10 hours. So far, they've been seen on three white dwarfs, Reuters reported. The first one was seen on a white dwarf situated 1,680 light years away from Earth, another 3,720 light years away, and the last one situated 4,900 light years away. For the uninitiated, a light year is the distance light travels in a year - 9.5 trillion kilometres (or 5.9 trillion miles).

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Reuters

"The discovery was an unexpected surprise. It goes to show just how dynamic the universe is. These events are fast and sporadic. Finding them requires looking at the right place at the right time," said Simone Scaringi, an astronomer from Durham University in England, who is also lead author of the study published in the journal Nature.

What even are white dwarfs?

Simply put, white dwarfs are some of the densest objects in the universe that come into being after a dying star's core collapses. White dwarfs are peculiar, for they have the mass of similar to our Sun, but diameter similar to that of Earth. Even our central star, the Sun will die in a similar fashion.

Micronovae usually happen in specific binary systems, wherein a white dwarf is in orbit with another star. For micronovae to take place, a white dwarf needs a strong magnetic field and a low-mass normal companion star.

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Owing to the white dwarf's gravitational pull, the companion star keeps losing hydrogen. This hydrogen runs across the white dwarf's magnetic poles that are somewhat similar to the process that causes auroras on Earth.

Representative image

How does a micronova blast occur?

Scientists say owing to accumulating columns of gas at the white dwarf's poles, pressure and temperature are driven upward - creating conditions for a thermonuclear fusion to take place. At this stage, hydrogen is converted into helium... and bam! A thermonuclear bomb then goes off!

Even then, the explosion is localised, i.e., it does not lead to the destruction of a white dwarf, but instead keeps repeating itself. According to Scaringi, each micronova event burns through material that is equal to one large asteroid, or over a millionth of Earth's mass.

NASA

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Micronova may be benign explosions in the larger scheme of universe. With regular nova explosions, more mass is burnt and the impact is felt across the white dwarf. But in micronovae, stolen energy from a companion star is distributed only in polar regions.

This micronovae was discovered by scientists who were assessing data from NASA's TESS space telescope. For this purpose, scientists used the European Southern Observatory's Chile-based Very Large Telescope. What do you think about the discovery of this new stellar explosion? Let us know in the comments below. For more in the world of technology and science, keep reading Indiatimes.com.

References

Dunham, W. (2022, April 20). Surprised astronomers find new type of star explosion - a micronova. Reuters.