The unusual nova, which died out in less than a day, could lead us to answer some big questions about the formation of our solar system and the evolution of the universe.

About a year ago, a Japanese amateur astronomer spotted a bright nova in the night sky. Named V1674 Hercules, this nova was so bright that it was visible to the naked eye from Earth. But as quickly as V1674 Hercules had come, he was gone again. Now, a year later, this fierce nova still haunts people. Because not only does it turn out to be the fastest ever discovered, the nova also appears to have some other peculiar properties.

More about novas
A nova is actually a sudden, momentary but dramatic brightening of a star. A classic nova differs from the more famous supernova because the former always occurs in binary systems. Each nova is created by a white dwarf (the compact, leftover core of a star) and a nearby companion star. Over time, the white dwarf dismantles more and more matter from its companion and heats it up. Ultimately, an uncontrolled reaction occurs, in which an enormous amount of energy is released. In addition, the explosion causes matter to shoot away at high speed. And we perceive that as visible light.

Normally, novas fade to their original brightness over a period of a few weeks or months. But V1674 Hercules is an odd one out. Not only did this nova shine so brightly that anyone could see it in the night sky with only binoculars, it also faded out in just over a day, as if someone blinked a flashlight.

Record-breaking fast

The light from the nova was thus attenuated in just over a day. And that is unprecedented. Never before have astronomers spotted such a fast nova. “The previous record holder was a nova we studied in 1991; V838 Herculis,” said study researcher Sumner Starrfield. This nova faded in just under three days, making V838 Herculis one of the fastest novas ever recorded. But now it has been knocked off the throne by an even faster one.

Pulsating

The enormous speed with which V1674 gave Hercules an appearance was not the only remarkable thing. The emitted light and energy turned out to pulsate, similar to the sound of a reverberating bell. Every 501 seconds, there was a fluctuation in visible light waves and X-rays. And now, a year after the explosion, this fluctuation can still be seen. “The strange thing is that this oscillation was already seen before the eruption,” said researcher Mark Wagner. “But it was also clearly recognizable when the nova was about 10 magnitudes brighter. One mystery we grapple with is what exactly causes this periodicity.”

Wind

The team also noticed something strange when they tracked the matter ejected from the nova explosion. Some kind of wind, which may depend on the positions of the white dwarf and its companion star, appears to direct the flow of matter into space around the system.

Solar system

The record-breaking fast nova still keeps people busy. And so research into V1674 Hercules continues. Not least because novas can also provide us with very important information about our solar system and even the universe. That’s because during nova explosions matter is thrown into space, eventually forming new stellar systems. Such events, for example, also contributed to the formation of our solar system, making the Earth more than a lump of carbon. “We’re always trying to figure out how the solar system came to be and where the chemical elements in the solar system come from,” Starrfield says. “One of the things we’re going to learn from the new nova, for example, is how much lithium was produced by this explosion. We are now pretty sure that a significant portion of the lithium we find on Earth was produced by nova explosions.”

All in all, a year after V1674 Hercules emerged, many questions still remain unanswered. The researchers therefore plan to better study the cause of the eruption and the processes that led to it. And eventually, they hope to answer some pressing questions, including the reason for the record-breaking speed at which the nova appeared, the forces behind the observed wind and the cause of the pulsating brightness. And that could potentially tell us a lot more about the formation of our solar system and the evolution of the universe as a whole.