The astronomical popularization magazineAstronomy, one of the most widely read in the Anglo-Saxon world, has placed the Spanish research that led to the discovery of the origin of the brightest stellar event in history, a 1006 supernova, in second place in its annual ranking. The list of findings is headed by the discovery of the Higgs Boson and includes other milestones such as the studies around the asteroid Vesta, the discovery of the comet ISON, the adventures ofCuriosityby Mars or the latest findings in the field of exoplanets.
Last September, the magazineNaturededicated its cover to a Spanish investigation, led by the researcher of the Institute of Astrophysics (IAC) of the Canary Islands Jonay González Hernández, who had found an explanation for the most brilliant event in the history of mankind:the SN1006 supernova that exploded in the spring of 1006 and which, according to Chinese astronomers, was visible on Earth for three years. An Egyptian astronomer made the most accurate description known: it was a phenomenon three times brighter than Venus as it emitted light in an amount equivalent to almost a quarter of the brightness of the Moon. The conclusion of this work suggested that the supernovaoriginated from the merger of two white dwarf stars.
As González explains, the team of researchers carried out an exhaustive exploration in the place where it occurred and found no trace of a companion star. “TheSN1006It invites us to think that this event was produced by a collision and merger of two white dwarf stars of similar mass ”, says the IAC researcher.
How do you arrive at this deduction? What astronomers observed in 1006 was a supernova, an explosion of stars that occur in the last stage of their lives: they emit a lot of energy and eject huge amounts of material at high speed into the interstellar medium. Specific,SN1006 belongs to the type of supernovae that occur in binary systems, those made up of two astronomical objects linked together by their gravitational force. These systems can be formed by a white dwarf and a “normal” companion star that provides the necessary matter to reach a critical mass of 1.4 times the mass of the Sun, the so-called Chandrasekhar limit mass. The white dwarf increases its density and temperature and, once it reaches this mass, it explodes as a supernova. Another option is that the system is made up of two white dwarfs that end up merging in a supernova.
The final clue that led the researchers to conclude that in this case the merger of two white dwarfs had occurred was that this supernova, some 7,000 light years from Earth, does not have a companion star to the parent white dwarf. The explosion produced by the merger of two white dwarfs, in fact, does not leave any trace, except for the supernova remnant that can be studied until centuries later, as in the case of the supernova of 1006, one of the only four historical supernovae of this type occurred in the Milky Way.
