Astronomers believe they have discovered a rare type of supernova that is only expected to exist

Color composite image of SN 2018zd, the bright dot in the center right, and host galaxy NGC 2146 on the left.

Color composite image of SN 2018zd, the bright dot in the center right, and host galaxy NGC 2146 on the left.
picture: NASA/STScI/J. Dipascual. Las Cumbres Observatory

A team of astronomers has discovered a supernova they believe formed after other elements in its core consumed the star’s electrons. This would make the supernova an electron-capturing supernova, a hypothesized type of starburst that was first proposed 40 years ago. It may not be the first of such rare explosions that humans have documented, though the famous supernova recorded by Chinese astronomers on July 4, 1054 may also have been an electron-capturing supernova, researchers say.

Supernovae are the wonderful consequences of the death of stars, and we observe only two types. If this last observation is correct, it would be the first time a third species has been documented. The two popular types of supernovae are Type Ia, when a small, cold, and very dense star orbiting another star reaches the end of its life and explodes, and Type II, when a massive star runs out of fuel and collapses on itself. The research team described in a research paper a recent supernova, SN 2018zd published Today in Nature Astronomy, he said his conditions lie between the two previously known types of supernovae, making them the third theoretical type.

The star was just the right size – neither too big nor too small – to produce this kind of explosion. Lead author Daiichi Hiramatsu, an astronomer at the University of California, Santa Barbara, said in an email. “It is well suited for neon and magnesium to capture electrons to convert their protons into neutrons, which lowers the basic pressure and stimulates supernova electron capture.”

In other words, SN 2018zd had a Goldilocks star cluster showing its own doom. Astronomers expect electron-capturing supernovae to have six special features; SN 2018zd has all six. These features include certain properties of the supernova’s chemistry, mass, and radioactivity. The research was carried out in part at the Las Cumbres Observatory as part of global supernova project, which aims to study hundreds of supernovae up to 2023.

More importantly, it’s not the first time humans have observed such an electron-capturing supernova. On 4 July 1054, Chinese astronomers documented a guest star in the sky that was so bright that it could be seen during the day for more than three weeks. These scientists were witnessing the birth of what we now call the Crab Nebula, the remnant of a massive supernova 6,500 light-years from Earth. Other researchers have suggested that the Crab Nebula is an electron-capturing supernova, Hiramatsu said, based on some unusual properties of a supernova remnant: it’s not very energetic, it doesn’t emit much mass, it has an unusual chemical composition, and density. Gas obscuring supernova ejector – all features are same as SN 2018zd.

A 2018 composite image of the Crab Nebula, made from data from the Chandra X-ray Observatory, the Hubble Space Telescope, and the Spitzer Space Telescope.

A 2018 composite image of the Crab Nebula, made from data from the Chandra X-ray Observatory, the Hubble Space Telescope, and the Spitzer Space Telescope.
picture: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech

“The term Rosetta Stone is used a lot as a measurement when we find a new astrophysical object,” said co-author Andrew Howell, an astronomer at UCLA at UCLA. press release. “But in this case I think it’s appropriate. This supernova literally helps us decipher the millennia-old records from cultures around the world… In the process, we’ve learned about basic physics: how some neutron stars form, and how stars live extreme and die, and how the elements we made create and spread throughout the universe.”

Ken Nomoto, a researcher at the University’s Kavli Institute for Physics and Mathematics who first said this type of supernova should exist, said in the same version. “I greatly appreciate the great effort that went into obtaining these observations. This is a wonderful case of combining observations and theory.”

SN 2018zd is likely not the last supernova to be discovered by electron capture. Scientists on the Supernovae Key Project continue their work studying these remaining structures and are sure to find more quirks in the next stars.

MORE: Astronomers have discovered the brightest neutron star ever recorded

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