TOOELE — Amateur astronomer Patrick Wiggins last week made a stellar discovery — a Type II supernova in the famous Fireworks Galaxy.
A supernova is the catastrophic death explosion of a star, the largest blast known since the Big Bang.
For more than Scheherazade’s 1,001 nights, Wiggins — a mainstay of the Salt Lake Astronomical Society — has searched diligently for supernovas, using his home observatory.
The NASA solar system ambassador, who has received the agency’s highest award for his service, focuses his automated telescope and then starts it on a program that shifts its aim from one galaxy to another. At each, it makes a short-exposure photograph.
About 300 of these gigantic "island universes" are on his list. Every 15 or 25 photographs, he processes the digital images and compares them with their counterparts taken earlier, and then, as the telescope keeps searching, moves to the next batch.
He’s already found two supernovas — one in January 2015 and the other in June 2015. Neither was in a particularly notable or close galaxy. Now he has come upon this most spectacular supernova.
On supernova patrol the night of May 11, Wiggins — a public outreach educator for the University of Utah’s Department of Physics and Astronomy — took a view of the Fireworks Galaxy and saw nothing unusual. The next night was too cloudy for imaging. But on the night of May 13, he noticed a new dot in the picture — a bright point where no star had shown before.
What was his reaction?
"Cautious,” he said. It might have been a flaw in the photo or an asteroid.
It is in a famous spiral galaxy called NGC 6946, nicknamed the Fireworks Galaxy. Closer to Earth than most at 22 million light-years, it forms a relatively bright, large view in a modest telescope. The formation has four main arms that curve counterclockwise around a bright nucleus.
NGC 6946 is one of the more unusual and beautiful galaxies in the near vicinity. Color photographs show that the arms are mostly bluish with patches of red nebulosity and several arms that seem to split. The complex, yellow-orange nucleus shows an interesting cloud-like feature.
After the potential supernova was logged onto an official site, reports began to arrive in Wiggins’ email. They were encouraging, but not definitive until spectra could be obtained confirming it as a supernova. Wiggins waited several hours, went to bed, got up later "and there it is: somebody got spectra and, yes, it’s a Type IIP supernova, and I guess I get credit for it."
Supernovas are divided into two basic physical types.
A Type I supernova occurs when a white dwarf star sucks material away from a nearby star that is locked to it by gravity in a binary arrangement. Its mass grows so great that it blows up.
A Type II happens at the end of the life of a gigantic red star, when it has fused so much of its usable fuel that the radiation pushing outward from the core is too weak to resist the immense force of gravity pulling inward. By this time, much of the core has fused into iron. The star begins to collapse and rebounds as a supernova explosion and then continues to fall.
"In a microsecond, the core may reach temperatures of billions of degrees Celsius," according to National Geographic. Material flies out in “an enormous, superheated shock wave.”
Brian Mendez, an astronomer and educator at the Center for Science Education at the University of California’s Berkeley Space Science Laboratory, writes: “Supernovae are really bright — about 10 billion times as luminous as the sun. Supernovae rival entire galaxies in brightness for weeks.”
If the star’s remaining core isn't big enough, it will become a neutron star, a tiny object composed only of neutrons and harboring a frightful surface gravity. But if the star is more massive, with a remnant core at least two or three times the size of our sun, nothing can stop the collapse, and it forms a black hole.
Wiggins’ discovery came at a fortuitously early stage. Astronomers will have time to study it carefully as it develops and fades.
NGC 6946 has an unusually high rate of supernovas. Many galaxies average one a century. The Fireworks Galaxy now has had 10 in about 100 years.
Assuming the latest estimate of the distance to the Fireworks Galaxy is accurate, the supernova exploded 22 million years ago. Wiggins had a sobering thought about the cataclysm.
"It was like, 'OK, I’m here all happy I found this thing,' but does it mean that 22 million years ago some planet with lives on it was suddenly destroyed by my supernova?" Wiggins said.
The red giant was an old star, Wiggins mused, "so any advanced civilization would have had millions of years to notice that this was happening." If the inhabitants were advanced enough, they moved to another star system far from the cataclysm and survived, he hypothesized.