Thanks to a worldwide network of 18 robotic telescopes, researchers led by the University of California Santa Barbara (UCSB) were able to catch a brief blue glow in the sky which, they say, was the result of a different kind of supernova explosion. The find reveals surprising information about the companion star next to the white dwarf that sparked the spectacle.
The giant cosmic explosions known as supernovae take place in one of two ways in our universe. They can happen at the end of a star's life cycle, when it runs out of fuel in its core and it begins collapsing in on itself. When enough material gathers at the center of the star, the core collapses and explodes.
The second method of supernova generation happens when a white dwarf, the core of a dead star, starts gathering in matter from another nearby star. Again, when the dwarf grabs enough material from its companion star, it gets too heavy and explodes. The most-recent popular theory of this kind of supernova event is that the two stars involved are both white dwarfs. However, the UCSB-led study shows that in the case of a supernova known as SN 2017cbv, that wasn't the case.
When David Sand, an associate professor at the University of Arizona spotted the supernova on March 10, he noticed the brief blue glow. That's because it's believed that he was seeing the light from the supernova event just hours, or at most a day, after it happened. Minutes later, he activated the 18 robotic telescopes that are part of the Las Cumbres Observatory (LCO) network so that the supernova could be constantly monitored.
"With LCO's ability to monitor the supernova every few hours, we were able to see the full extent of the rise and fall of the blue glow for the first time," said lead author Griffin Hosseinzadeh, a UCSB graduate student. "Conventional telescopes would have had only a data point or two and missed it."
After analyzing the blue light in a the UCSB-led study, the researchers concluded that the white dwarf at the center of the event had been grabbing matter from a star that was about 20 times bigger than our own sun – not from a white dwarf, as expected. When the dwarf got enough matter to go supernova, it slammed into the nearby giant star, shocking it and leading to the blue glow, which was rich with ultraviolet light. UCSB says that such a shock would not have been possible if the companion star was another white dwarf.
"The universe is crazier than science fiction authors have dared to imagine," said Andy Howell, a staff scientist at LCO. "Supernovae can wreck nearby stars, too, releasing unbelievable amounts of energy in the process."
Howell also points to the power of a multi-point telescope system.
"These capabilities were just a dream a few years ago," he said. "But now we're living the dream and unlocking the origins of supernovae in the process."
The research describing the find has been published in the Astrophysical Journal Letters.