Chuck Bednar for redOrbit.com – @BednarChuck
NASA’s Chandra X-ray Observatory has for the first time captured a detailed time-lapse image of a “mini supernova” that they believe could reveal new information about the dynamics of far larger stellar explosions, the US space agency announced earlier this week. Here’s a video to get you in the explosion mood.
Dai Takei of the RIKEN SPring-8 Center in Japan and his colleagues used Chandra to observe GK Persei, an object discovered in 1901 that appeared as one of the brightest stars in the sky for only a few days before it started gradually becoming increasingly dimmer. Today, experts know that GK Persei is an example of what is known as a “classical nova.”
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A classical nova, NASA explained, is an outburst created by a thermonuclear explosion that occurs on the surface of a white dwarf star, the dense remnant of a Sun-like star. They take place when a white dwarf’s powerful gravity pulls in enough hydrogen gas and other materials from an orbiting companion star to cause nuclear fusion reactions to occur and intensify.
If enough material accumulates, it can result in a “cosmic-sized hydrogen bomb blast,” blowing away the other layers of the white dwarf and producing a nova outburst that can be observed for a period of at least several months. These classical novas are essentially small-scale versions of supernova explosions, which are far brighter and result in the destruction of an entire star.
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There is a tremendous amount of interest in supernovas, which inject tremendous amounts of energy into interstellar gas. They are responsible for disperses iron, calcium, oxygen, and other elements into space, where they may one day become part of the next generation of planets and stars. However, because these phenomena only last long, they have been difficult to study.
UNTIL NOW…
Because of the enormous amount of time during which that stellar explosions take place, experts have traditionally turned to both computer simulations and different supernovas believed to be in different stages of evolution. Now, however, Takei and his fellow investigators hope to use their observations of GK Persei to learn more about the expansion of gases in the universe.
“I wanted to understand how these explosions unfold, but there were many obstacles,” Takei said in a statement. “We thus took on the challenge of… studying the expansion of a classical nova explosion, since this process is expected to develop within approximately a human lifetime. The GK Persei nova… provided the perfect model for our study.”
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Since the classical nova’s development is fairly rapid in comparison to supernovas, his team used X-ray snapshots collected by Chandra in 2000 and 2013 and compared the emissions created due to the expanding gases heat the interstellar medium into plasma during that time frame.
They discovered that, while the nova remnant expanded by approximately 90 billion kilometers during that 14-year span, the temperature of the plasma remained at a nearly constant one million degrees Celsius. The light was fading but the energy of the dominant photons had not changed, suggesting that the nova remnant was expanding into a region of lower density.
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“For the first time, we have a detailed image of how the nova propagates through space,” Takei said. “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.”
Their findings appear in the April 2015 edition of The Astrophysical Journal.
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