Thesupernova or stellar explosion that occurred between April 30 and May 1, 1006. Not in vain was it observed by different communities of scientists around the world, including Chinese astronomers who narrated that the astronomical event was visible for three years. The most explicit record, made by an Egyptian astronomer, indicates that the phenomenonit was about three times brighter than Venusor that it emitted light in an amount equivalent to almost a quarter of the Moon’s brightness.
Now, an international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) and the University of Barcelona (UB) has just shown thatit was probably caused by the merger of two white dwarf stars. White dwarfs are stars that are in the last stage of their life and that, when they run out of fuel, they cool very slowly.
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.
Supernovae arestarbursts that occur in the later stages of their lives, emit a lot of energy and eject huge amounts of material at high speed into the interstellar medium. In particular, the type of supernova that occurred in 1006 was probably produced by a thermonuclear explosion of the white dwarf upon reaching the Chandrasekhar limit mass due to merging with the other white dwarf of the binary system.
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.
