A multinational team of scientists has discovered and identified a sort of star explosion that has never previously been witnessed, which they have termed micronovae.
Researchers describe a little but strong cousin of the ordinary nova, or stellar outburst, in which the surface of certain dead stars, known as white dwarfs, explodes. The article was published on Wednesday in the journal Nature. The previously unknown explosions reported in this new research, in contrast to novae, are smaller and quicker, consuming the equivalent of around 3.5 billion Great Pyramids of Giza‘s worth of stellar material in only a few hours.
It was headed by Simone Scaringi, an astronomer and assistant professor at Durham University in the United Kingdom, who was quoted as saying, “For the first time, we have detected and recognized what we are calling a micronova.” According to Scaringi, the discovery questions the present understanding of how cosmic explosions occur in certain stars and how they are caused.
“We were under the impression that we understood what we were talking about, but this finding suggests a whole new technique to produce them,” Scaringi said of stellar explosions. “It only goes to illustrate how dynamic the cosmos is,” says the researcher.
Researchers analyzed data from NASA‘s Transiting Exoplanet Survey Satellite. They discovered quick bursts of energy originating from a white dwarf – a tiny, dense remnant of sun-like stars that have burnt up all of their fuel and are no longer producing light. The surge of lights lasted just ten hours before everything was over and forgotten.
They discovered two incidents that were quite similar after doing more research. A new kind of nova, occurring in some regions of white dwarfs, was found using the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert. The scientists verified this by using the telescope’s Very Large Telescope.
White dwarfs with magnetic fields strong enough to pull in material from a nearby star to their poles are thought to be responsible for these mini versions of energetic nova.
Binary systems — that is, systems in which two stars are gravitationally bound to each other — are thought to be responsible for these mini-novae. In contrast to a full-fledged nova, which causes thermonuclear flares to envelop the whole white dwarf, minor, localized explosions are triggered by this process.
If two stars are near enough to one other, a white dwarf in a two-star system may take material from its partner star, which is primarily hydrogen in composition. As this gas descends upon the white dwarf star’s very hot surface, it causes the hydrogen atoms to fuse together explosively, resulting in the formation of helium.
These thermonuclear explosions take place throughout the whole stellar surface in novae (new stars). Nathalie Degenaar, an astronomer at Amsterdam’s University of Amsterdam, adds that “such detonations cause the whole surface of the white dwarf to burn and light brilliantly for many weeks,” as co-author Nathalie Degenaar explains.
Micronovae are comparable explosions, but they are smaller in magnitude and occur more quickly, lasting just a few hours instead of many days. Occasionally, they may be found on white dwarfs with high magnetic fields, which funnel material towards the star’s magnetic poles as it rotates.
“We have now shown for the first time that hydrogen fusion may occur in a confined manner. It is possible for certain white dwarfs to have their hydrogen fuel trapped at the base of their magnetic poles, which would result in fusion occurring exclusively at these magnetic poles,” explains Paul Groot, an astronomer at Radboud University in the Netherlands and co-author of the research.
“This results in the detonation of micro-fusion bombs, which have roughly one millionth the power of a nova explosion, thus the term micronova,” Groot explains. Although the term “micro” implies that these occurrences are little, do not be fooled: just one of these outbursts has the potential to burn through around 20,000,000 trillion kg of material, or almost 3.5 billion Great Pyramids of Giza.
This video depicts an animation of a micronova explosion in space and time. The material, predominantly hydrogen, that makes up the blue disc revolving around the brilliant white dwarf in the center of the photograph was taken from its partner star and used to create the disc.
The white dwarf, which is located at the core of the disc, utilizes its powerful magnetic fields to funnel hydrogen towards its poles. A micronova explosion occurs when the material falls on the heated surface of the star, which is confined by magnetic fields at one of the white dwarf’s poles when it descends on the star. Credit: ESO/L. Calçada and M. Kornmesser.
When the researchers used TESS, they discovered three micronovae: two were from known white dwarfs, while the third needed further observations with the X-shooter instrument on ESO’s VLT telescope before it could be confirmed as a white dwarf.
“With the assistance of the European Southern Observatory’s Very Large Telescope, we discovered that all of these optical flashes were generated by white dwarfs,” Degenaar explains. In Scaringi’s opinion, “this finding was critical in understanding our result and in the discovery of micronovae.”
According to the experts, although Novas may be seen shining brilliantly for many weeks, micronovas can only be seen for a few hours. These modest pyrotechnic displays, according to the study’s authors, might be found in large numbers across the cosmos.
Our galaxy’s micronovae and other elusive cosmic events will be discovered and studied in the future. According to Scaringi, the large-scale surveys, which will be conducted in the net they move so quickly makes it impossible to capture them in action, according to Scaringi.
Editor: Kiran Maharana
Published By: Akshaj Joshi
