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THE term ‘nova’ in astronomy comes from the Latin nova stella or new star, referring to occasional brilliant stars that flare up in the sky and then disappear.

The brightest of these events is the supernova, which is caused by a giant star collapsing inward at the end of its life, when all its fuel has burned out.

The most famous such super new star was first spotted by Chinese astronomers in 1054 and remained visible until 1056.

This supernova formed the Crab Nebula, visible today through binoculars as an expanding crab-shaped cloud of gas. Helping to drive this expansion are radiations from the Crab Pulsar, which is a neutron star in the middle of the nebula, the extremely dense remains of the original star that collapsed to cause the supernova.

On a smaller scale, we get the “nova”, which occurs on white dwarf stars. These dwarfs are also collapsed stars, but are not as dense and compressed as neutron

stars.

As dust accumulates on these white dwarfs, the entire surface of the star can ignite, burning for days and sometimes for years.

Novas can happen repetitively on one white dwarf.

However, an announcement by the European Southern Observatory in April 2022 presented a whole new class of nova, detected on three separate occasions.

“We have discovered and identified for the first time what we are calling a micronova,” said Simone Scaringi, an astronomer at Durham University in the UK who led the study on these explosions.

CHALLENGES

“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.”

Micronovas occur on white dwarf planets that have strong magnetic fields.

They also have a companion star, from which they accumulate dust in the form of hydrogen atoms.

Because of the magnetic field, this dust is channeled to the poles of the white dwarf.

This is like the solar wind on earth being channeled to the poles, causing the auroras seen in polar regions.

Because the explosion is localised at the poles, it emits less light than a nova,

when the whole surface of the white dwarf ignites.

These micronova explosions last about 10 hours. Three have been spotted so far. As their name indicates, they are the smallest type of nova yet observed; but they have been making a big bang in astronomy.

Making another big bang in space news was a statement on Wednesday by American congressman Michael Turner, who is chairperson of the House Intelligence Committee.

He spoke very vaguely about a major security threat to the USA and called on the Biden government to declassify this information.

No one was quite sure what he was talking about, but two sources told ABC News that it concerned Russia planning to put a nuclear weapon into space, stressing that this had not yet happened and therefore there was no imminent danger.

If the story is true, it would indicate that Russia is planning to abandon the Outer Space Treaty of 1967, which bans all orbital nuclear weapons.

This was one of the first arms control treaties negotiated between the US and the Soviet Union, and is one of the last to remain in place.

The planned Russian nuclear craft is believed to be a satellite destroyer, critical at a time when vast amounts of battlefield data are carried via space links.