Feb. 1 () –
A study from Embry-Riddle Aeronautical University describes a high-mass, X-ray-luminous twin star system with an oddly circular orbit, a rarity among binaries.
This system appears to have formed when an exploding or supernova star faded without the usual explosion, as published in the journal ‘Nature’.
After processing a mountain of astronomical data, Clarissa Pavao, a student at Embry-Riddle Aeronautical University, presented her preliminary analysis to her mentor about this strange binary star system with unusual features.
The round orbit of the binary was a key clue that helped researchers identify the second star in the binary system. as a depleted or “ultra-exploded” supernova.
Normally, when a star uses up all its nuclear fuel, its core collapses before exploding into space as a supernova. In this case, according to Richardson, “the star was so depleted that the explosion did not even have enough energy to give the orbit the more typical elliptical shape seen in similar binaries.”
The researchers estimate that there are currently only about 10 such star systems in the Galaxy. By studying it, they are unraveling new clues about our early beginnings, like stardust.
“When we look at these objects, we look back in time,” Pavao explains. it’s a statement–. We get to know more about the origins of the universe, which will tell us where our solar system is headed. As humans, we started with the same elements as these stars.”
Richardson adds that without binary systems like CPD-29 2176, life on Earth would be very different. “Systems like this are likely to evolve into binary neutron stars, which eventually merge and form heavy elements that are spewed out into the universe,” he notes.
“Those heavy elements allow us to live the way we do,” he adds. “For example, most of the gold was created by stars similar to the relic supernova or neutron star in the binary system we studied. Astronomy deepens our understanding of the world and our place in it.”
The project began when Pavao stopped by the office of Dr. Noel D. Richardson, Associate Professor of Physics and Astronomy at Embry-Riddle and co-author of the study, hoping to score a research experience.
“I told him: ‘Please, give me any research.’ It turns out that he had data, captured by the 1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile, of a bright star known as a Be-type star,” he recalls. –.The star Be was located in the same place in the sky as another that had produced a large X-ray flare. That flare, possibly something called a ‘soft gamma repeater’, had caught the attention of astronomersprompting Richardson and others to request the telescope data.”
Pavao plotted the spectra of the star Be, but first had to clean up the data so it was less noisy. “The telescope looks at a star and captures all the light so that you can see the elements that make it up,” he says, “but Be stars tend to have disks of matter around them. It’s hard to see straight through all that stuff.”
Pavao was able to learn more about data processing and computer coding to be able to analyze stellar spectra. She and Richardson found a single line that came from the star and was not influenced by the surrounding disk.
She thought her graph was a scatterplot, but Richardson thought otherwise, that it was an orbit. After quickly entering Pavao’s data into a special computer program, realized they had found an orbit for the star, but that it was different than expected. Analysis of the data revealed that one star circled the other about every 60 days. Pavao remembers that Richardson told him that it was not a simple binary system.
Jan J. Eldridge, from the University of Auckland (Australia), co-author of the article and one of the leading experts on binary star systems and their evolution. At Richardson’s request, Eldridge reviewed thousands of binary star models and found only two analogs to the one he and Pavao were studying.
Next, Eldridge and his colleagues diagrammed the life cycle of the two stars in the binary system, explaining how the supernova relic had swelled and dumped mass onto the Be star until it began accreting, too. As a last resort, the supernova became a low-mass helium star that exploded, leaving behind a neutron star, but had already transferred so much mass to the Be star that the explosion was dull.
“Basically, we found out how the ultra-exploded supernova interacts with the star Be, and how it goes through these strange phases of the life cycle,” Pavao explains. “At some point in the future, that star Be will also be a supernova neutron star as it the cycle continues. It will become a binary system with two neutron stars, millions of years from now.”
