Time Lapse Image of Century-Old Explosion Sheds Light on Supernovae

Scientists have created a time lapse image of a classical nova explosion that occurred over a century ago in the hopes of shedding some light on supernovae phenomena, according to a new study.

The GK Persei nova is a binary star system located 1,500 light-years away that underwent a nova explosion in 1901. It is believed to contain a dead white dwarf star (meaning it's at the end of its thermonuclear phase) and a red dwarf companion with hydrogen still burning on its surface. On occasion, as seen about 100 years ago, hydrogen gas from the companion builds up on the surface of the white dwarf, and reaches a certain critical point where thermonuclear runaway starts. This process causes gases to expand and the white dwarf to explode out into the Universe.

While supernovae gain the most attention as some of the most powerful events in the entire Universe, able to outshine a whole galaxy, they are difficult to understand. These kinds of stellar explosions occur over thousands, perhaps millions of years - such as over the entire written history of humankind - so studying the entire gas expansion process is impossible.

That's where classic nova explosions come in, which unlike supernovae, reportedly develop within approximately a human lifetime.

"I wanted to understand how these explosions unfold, but there were many obstacles. We thus took on the challenge of, instead of looking at supernovae, studying the expansion of a classical nova explosion," lead researcher Dai Takei, of the RIKEN SPring-8 Center in Japan, said in a news release.

Although classical novae and supernovae are completely different processes, their basic mechanism is about the same.

Using NASA's space-based Chandra observatory, the research team examined two X-ray snapshots of the nova taken in 2000 and 2013 and compared them. The images were created as the expanding gases heated the interstellar medium into a plasma.

What they found was that although the nova remnant had expanded by approximately 90 billion kilometers during the 14 years, the temperature of the plasma remained relatively constant at a staggering 1 million degrees Celsius. What's more, observations showed that the light from the explosion was fading, but the energy of the dominant photons had not changed. This means that the nova remnant is expanding into a region of lower density.

"For the first time," Takei said, "we have a detailed image of how the nova propagates through space. Through this kind of study, we hope to be able to understand exactly how these powerful explosions expand into interstellar space, and it may ultimately give us new insights into the history of the cosmos."

The results were published in The Astrophysical Journal.

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