Astronomers watched a giant star explode in a fiery supernova for the first time ever in an unexpectedly majestic sight.
Scientists began viewing the star, a red giant named SN 2020tlf located about 120 million light-years from Earth, more than 100 days before its final violent collapse, according to a new study published Jan. 6 in The Astrophysical Journal. During that previous period, researchers saw the star explode with bright flashes of light as huge balls of gas exploded from the star’s surface.
The researchers said that these fiery radiation, which existed before the supernova, was a great surprise, as previous observations of red giants about to explode their tops did not show any traces of violent emissions.
The study’s lead author, Wayne Jacobson Gallan, a researcher at the University of California, Berkeley, said: statment: “This is a breakthrough in our understanding of what massive stars do moments before they die. For the first time, we’ve seen a red giant star explode!”
The red giant planets are the largest stars in the universe in terms of size, with a radius of hundreds or sometimes more than a thousand times. (Although they may be massive, red giant stars are not the brightest or most massive stars out there.)
Like our sun, these massive stars generate energy through the nuclear fusion of elements in their cores. But because they are so large, the red giant planets can form elements much heavier than the hydrogen and helium that our sun burns. And when giants burn more massive elements, their cores get hotter and more compact. Eventually, by the time the iron and nickel fusion begins, these stars run out of energy, and the cores collapse, releasing the gaseous outer atmosphere into space in a violent Type II supernova explosion.
Scientists have observed red giants before they transform into a supernova, and studied the ramifications of these cosmic explosions – however, they haven’t seen the whole process work in real time yet.
The authors of the new study began observing SN 2020tlf in the summer of 2020, when the star flashed a bright flash of radiation that the team later interpreted as gas erupting from the star’s surface. Using two telescopes in Hawaii – the University of Hawaii Institute for Astronomy’s Pan-STARRS1 telescope and the WM Keck Observatory in Mauna Kea – the researchers monitored the eccentric star for 130 days. Finally, at the end of that period, the star went to boom.
The researchers said the team saw evidence of a dense cloud of gas surrounding the star at the time of its explosion – likely the same gas the star had released in previous months. This indicates that the star began experiencing violent outbursts long before its heart collapsed in the fall of 2020.
“We’ve never confirmed such violent activity in a dying red giant star that we see it produce such a luminous emission, then collapse and burn, until now,” said study co-author Raffaella Margotti, an astrophysicist at the University of California, Berkeley.
The team concluded that these observations indicate that the red giant planets underwent significant changes in their internal structures, resulting in chaotic explosions of gas in the final months before the collapse.
Source: Live Science