When a dying star explodes as a supernova, it usually releases a chaotic web of dust and gas. But new images of the supernova remnant look quite different, as if its central star had set off a cosmic fireworks display. It’s the most unusual remnant researchers have found so far, and may indicate a rare type of supernova that astronomers have long struggled to explain.
“I’ve been working on supernova remnants for 30 years and I’ve never seen anything like this,” says astronomer Robert Fesen of Dartmouth College in Hanover, New Hampshire. He reported his findings at his Jan. 12 meeting of the American Astronomical Society, and submitted the as-yet-unpeer-reviewed paper the same day.
Fireworks 850 years ago
In 2013, amateur astronomer Dana Pachik discovered the object in archived images from NASA’s Widefield Infrared Survey Explorer. Over the next decade, several teams studied the wreckage known as Pa 30, with increasingly puzzling results.
Vasilii Gvaramadze, an astronomer at Lomonosov Moscow State University in Russia, and his colleagues discovered a very rare star at Pa 30 dead center in 2019. Kilometers per second – about 5% of the speed of light. “The star doesn’t have 16,000 kilometers per second wind,” Fesen says. Speeds of 4,000 kilometers per second aren’t unheard of, he says, but 16,000 kilometers is wild.
Pa 30 has been the subject of a conspiracy again in 2021. Andreas Ritter, an astronomer at the University of Hong Kong, and his colleagues have proposed that the remnants are the aftermath of a supernova that lit up the sky in his 1181, 850 years before him. Chinese and Japanese astronomers observed the object for about six months before it disappeared.
While investigating Pa 30, Ritter and his colleagues noticed that the wreckage’s emission spectrum contained certain lines related to elemental sulfur. Intrigued, Fesen’s group then used his 2.4-meter Hirtner telescope at the Michigan-Dartmouth-MIT Observatory in Kitt, Arizona. I took a picture of the wreckage.
The data they collected not only helped confirm that Pa 30 was indeed the remnant of the supernova observed in 1181, but also produced a unique image of the remnant. It contains hundreds of fine filaments that radiate outward. Researchers usually expect supernova remnants to look like the Crab Nebula. It resembles an anemone more than a crab, with an oval mass of tentacle-like filaments with a smooth area in the center. They also usually look like Tycho supernovae, which look like jumbled knotted spheres.
But Saurabh Jha, an astronomer at Rutgers University in Piscataway, New Jersey, says Pa 30 is a relatively “just amazing image.” “I’ve never seen anything like it before. It’s really amazing.
cheating death
What caused such a wreckage? In 2021, Ritter and his colleagues speculated that it was a rare supernova explosion classified as Type Iax.
A normal type Ia supernova occurs when a white dwarf siphons matter from its companion, eventually becoming too massive to support the extra weight, and being blown apart and its interior dispersed throughout the galaxy. . But in a type Iax supernova, the star somehow survives. “We often call these zombie stars,” Jah says.
Theorists have developed many possible mechanisms to explain Type Iax supernovae, but Ritter and his colleagues believe that two white dwarfs collided to produce the Pa 30 fireworks. increase. This is evidenced by the amount of sulfur in the debris, a byproduct of white dwarf explosions, and the lack of light elements found in more massive stars.
Anthony Pirro, an astronomer at the Carnegie Observatory in Pasadena, California, believes these findings embody at least one of the pathways by which Type Iax forms. But it differs from the previously favored scenario of white dwarfs siphoning matter from their mates. This idea he developed in 2014. Astronomers were able to identify the stars involved in the Iax explosion by examining archived images before the event occurred.
Thus, the discovery of Pa 30 “definitely extends what may have led to Type Iax supernovae, in my opinion,” says Jha.
These rare explosions tend to occur in distant galaxies, making them difficult to study. But the distance to Pa 30 (if that’s really her Iax type) is only 2.3 kiloparsecs. That means future observations will reveal more of this unusual type of supernova.
Fesen has already applied for time observations with both the Hubble Space Telescope and the new James Webb Space Telescope (JWST). “I think the optical image taken only gives a hint of what it actually looks like,” he says. “But the JWST images will be amazing.”
This article is reproduced with permission and was first published on January 26, 2022.
