Astronomers claim to have isolated the remains of an absolutely colossal supernova less than 4000 light years from Earth. In terms of apparent size, imagine an expanding cloud of gas and dust nearly a hundred times the size of a full moon.
A supernova is a dying star. There are two main mechanisms that can produce this type of event. The first results from the thermonuclear explosion of a corpse of a star called a white dwarf initiated by the capture of material spilled by a close companion (thermonuclear supernova). This process therefore involves two objects contained in a binary system. The second results from the implosion of a massive star. This is called a heart failure supernova).
Whether it is one or the other, the result is the same: a cataclysmic explosion releasing an expanding shell of the star’s outer material which, for a time, can shine brighter than an entire galaxy.
Note that these events play a major role in the evolution of the cosmos. It is indeed during these explosions that the heaviest elements are formed which seed the universe.
A gigantic afterglow
A team of astronomers led by Werner Becker, from the Max Planck Institute in Germany, announce that they have isolated the remains of one of those stellar explosions. Named Hoinga, after the medieval name of its hometown, it is the largest supernova remnant ever to be found.
“In terms of apparent size, imagine an expanding cloud of dust and gas about 90 times the size of a full moon.“, Underlines the researcher.
But then, how is it that we have been missing it all this time? In reality, these remains are only visible in x-rays and only under the eye of one of the most powerful x-ray telescopes built to date: eROSITA. Launched in 2019, you will find it on board the Russian-German satellite SRG.
“The eROSITA telescope is twenty-five times more sensitive than its predecessor ROSAT. Also, we expected to discover new supernova remnants in the years to come, but we were pleasantly surprised to see one so quickly.“Said astronomer Natasha Hurley-Walker of the International Radio Astronomical Research Center in Australia.
Other remains awaiting discovery
Based on this radio data, the team calculated that these remains have between 21,000 and 150,000 years. In addition, they evolve relatively close to the Earth, at between 1470 and 3915 light years.
The location of this supernova is also surprising. These remains have indeed been isolated far from the galactic plane where most of the stars of the Milky Way (and therefore supernova remains) reside. After analysis of past data, available on the server arXiv, it also appeared that this supernova was already present (weakly, but present) in the data of the ROSAT telescope taken thirty years ago.
“Supernova remnants are not generally expected to be found in high galactic latitudes, so these areas are usually not the focus of investigation, which means there may be even more of these neglected remains on the shelf. to be discovered“, Note Werner Becker.