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Astronomers have captured for the first time in real time the dramatic end of a star’s life before collapsing into a type II supernova.
Using two telescopes in Hawaii, the University of Hawaii’s Pan-STARRS Institute for Astronomy, in Haleakalā, Maui, and the WM Keck Observatory, in Maunakea, on the island of Hawaii, scientists began to observe the star, a red supergiant called SN 2020tlf, located about 120 million light years from Earth.
Scientists observed it for 130 days before its final violent collapse, according to a new study published in the Astrophysical Journal.
During that lead-up period, the researchers watched as the star, located in the galaxy NGC 5731 and about 10 times more massive than our own Sun, eIt erupted with brilliant flashes of light as great globs of gas exploded off the star’s surface.
There is not always “calm before the storm”
The team, who captured the moments as part of the Young Supernovae Experiment, an ongoing project trying to find stellar explosions in the night sky in their earliest stages, say this unprecedented look at one of the most fascinating and widely scale of the Universe shows that there is not always a “calm before the storm” when it comes to supernova explosions, something that challenges previous assumptions.
“This is a major advance in our understanding of what massive stars do in the moments before they die,” says Wynn Jacobson-Galán, an NSF research fellow at UC Berkeley and lead author of the study.
“Direct detection of pre-supernova activity in a red supergiant star has never been observed before in an ordinary type II supernova. For the first time, we observe the explosion of a red supergiant star,” he added.
Supernovae occur when massive stars die. or they run out of fuel and collapse in on themselves. The collapse is followed by a gigantic, super-bright explosion that sends shock waves through space, often leaving behind a dense core surrounded by a cloud of gas called a nebula. Science Alert. However, this spectacular process had never been seen in real time. Up to now.
According to the WM Keck Observatory press release, Pan-STARRS first detected the massive star in the summer of 2020 thanks to the enormous amount of light radiating from the red supergiant. A few months later, in the fall of 2020, a supernova lit up the sky.
Using the Keck Observatory’s Low Resolution Imaging Spectrometer (LRIS), the team then quickly captured the powerful flash and obtained the first spectrum of the energetic explosion, dubbed supernova 2020tlf, or SN 2020tlf.
super light emission
The data collected is already providing new insights. For example, there is direct evidence of dense circumstellar material surrounding the star at the time of its explosion, which the researchers believe is the same gas that they had detected being expelled from the red supergiant several months earlier.
“It’s like watching a time bomb. We have never confirmed such violent activity in a dying red supergiant star in which we have seen it produce such a luminous emission, then collapse and combust, until now,” said lead author Raffaella Margutti, an associate professor of astronomy at UC Berkeley.
According to the statement, the discovery challenges previous ideas about how red supergiant stars evolve just before they explode. Previously, all red supergiants did not show signs of violent eruptions or luminous emissions, as was observed before SN 2020tlf.
These observations suggest that red supergiants undergo significant changes in their internal structures, giving rise to chaotic gas explosions in their last months before collapsing.
“What excites me most are the new unknowns that have been revealed with this discovery,” says Jacobson-Galán. “Detecting more events like SN 2020tlf will have a dramatic impact on how we define the final months of stellar evolution, uniting observers and theorists in the quest to solve the mystery of how massive stars spend the last moments of their lives.”
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