Such an explosion would be able to destroy all traces of life on Earth in less than a day.
When a star dies, there are several possible scenarios. If the latter hadn’t exploded in a supernova, it will collapse in on itself after fusing its hydrogen into helium.
With the increase in pressure and temperature caused by the collapse, the star begins to fuse its helium into (mostly) carbon, causing the star to puff up and become a red giant. Once the helium is depleted, the giant collapses again, but the resulting energy is insufficient to start carbon fusion.
At this point, the outer layers are flung out into space as a planetary nebula, leaving only the very dense core (the Sun’s mass condenses to the size of Earth), known as a white dwarf.
Ultraviolet surface explosions
White dwarfs are therefore extremely dense masses and in a binary system they tend to attract the lightest elements of their binomial such as hydrogen. In such systems, scientists have discovered a previously unknown phenomenon.
Using the TESS, a space telescope launched in 2018, astronomers detected unusual flashes of light. The TESS is an instrument specifically designed to track stellar luminosity fluctuations, detecting the fall in luminosity as a planet periodically passes its star.
These mysterious outbursts of about ten hours would ultimately be thermonuclear explosions similar to novas (when all the hydrogen layer on the surface explodes at once, leaving the white dwarf behind), but in a less powerful and more localized way, hence the term “micronova”. .
A mechanism similar to the Aurora Borealis
These phenomena, which have not been explained for a long time, occur in white dwarfs, whose magnetic field is particularly high. According to the scientists, the hydrogen stolen by the white dwarf eventually accumulates at the poles. On Earth we find an equivalent phenomenon with the Sun’s charged particles being deflected by our magnetosphere, forming the Aurora Borealis.
In the case of hydrogen, the reaction is much more spectacular as it leads to a thermonuclear explosion. While remaining 1 million times fainter than a classic nova, this explosion consumes an enormous amount of matter (more than 100,000 times the mass of Everest).
The energy released could destroy everything we know in less than a day. Of course, since this is a recent discovery, there are still many unknowns such as the exact triggering mechanism or the frequency with which the phenomenon repeats itself.