Astronomers Think They've Spotted a Rare Kind of Supernova Only Predicted to Exist

This is a color composite image showing SN 2018zd (the bright dot in the center) and NGC 2146 (the host galaxy at left). Image courtesy NASA/STScI/J. DePasquale, Las Cumbres ObservatoryAstronomers found a supernova that they believe was formed when the stars electrons were consumed in its core. This would make the supernova an "electron-capture supernova", a type of starburst first proposed 40 years back. Researchers say that this may not be the first time these rare explosions have been documented by humans. The Chinese astronomers recorded the famous supernova on July 4, 1054 and it may have also been an electron-capture Supernova.AdvertisementWe only see two types of supernovae. This will be the third type of supernovae that has been observed, if this observation is correct. Type Ia is when a star orbiting another star becomes too small, cool, dense, and explodes. Type II occurs when a huge star runs out fuel and collides with itself. In a paper published in Nature Astronomy today, the research team describes SN 2018zd, a supernova that occurred recently. Its conditions are similar to the other two types of supernovae. This makes it the third most likely type.This kind of explosion could only be produced by the star being just right in size. Lead author Daichi Hiramatsu (an astronomer at Santa Barbara University) said that the mass was not large enough to cause the outer envelope to collapse and create a white dwarf. It is also too heavy to fuse to iron in its core and explode as an iron core-collapse supernova. It is perfectly normal for the neon to capture electrons to transform their protons into neutrons. This reduces the core pressure and induces an electron-capture Supernova.A X-ray image taken by the Chandra X-ray Observatory, the European Space Agencys XMM-Newton. It was released in 2014. Image courtesy NASA/CXC/IAFE/G.Dubner et. al & ESA/XMM–NewtonSN 2018zd also had a Goldilocks-type star mass that spelled it particular doom. Astronomers expect electron capture supernovae to possess six attributes. SN 2018zd has six. These features include characteristics such as chemistry, mass and radioactivity. Las Cumbres Observatory was part of the Global Supernova Project that aims to study hundreds more supernovae by 2023.It is possible that this supernova with electron-capture supernova was not the first one to be observed by humans. Chinese astronomers discovered a bright star in the sky on July 4, 1054 that could be seen for three weeks during daylight hours. These scientists witnessed the birth of the Crab Nebula. It is the remnant of a supernova that occurred over 6,500 light years from Earth. Hiramatsu stated that other researchers suggested that the Crab Nebula might be an electron-capture Supernova based on unusual characteristics of the supernova remnant. These include its inability to eject much energy, low mass, and dense gas that shrouds it.This composite 2018 image of the Crab Nebula was created using data from the Chandra X-ray Observatory and the Hubble Space Telescope. Image: Xray: NASA/CXC/SAO, Optical NASA/STScI, Infrared NASA-JPL–CaltechAdvertisementRosetta Stone is too often used as an analogy to describe a new astrophysical object when it's discovered, stated Andrew Howell, co-author and UCSB astronomer. In this instance, I believe it is appropriate. The supernova literally helps us to decode thousands-year-old records from all cultures around the globe. It is also teaching us fundamental physics, such as how neutron stars are made, how extreme stars live, and how elements are created and scattered throughout the universe.I'm very happy that the electron-capture supernova, which my colleagues and me predicted would exist and have a link to the Crab Nebula 40 years back, was finally discovered. Ken Nomoto, a researcher from the Kavli Institute for the Physics and Mathematics of the University, who first suggested this type of supernova should be found, made the announcement in the same release. These observations were made possible by a lot of hard work. This is a great example of the combination theory and observations.AdvertisementSN 2018zd is not likely to be the last supernova that captures electrons. Scientists at the SupernovaeKey Project continue to study these residual structures, and they are certain to discover more quirks in stars to come.Continue reading: Astronomers Find the Brightest Neutron Star Ever Observed