The artist rendering above shows two massive stars getting a bit too cozy. The pair are located in the middle of the planetary nebula, Henize 2-428. The two stars are expected to slowly get closer to one another. Keyword here is slowly. They are not expected to merge together for another 700 million years. But, when they do – look out. The pair of stars will have enough material to cause an impressive supernova explosion.
Miguel Santander-Garcia led a team of astronomers in the discovery of the two white dwarf stars. The discovery was actually a bit of an accident. Miguel’s team was trying to figure out how some stars create weirdly shaped nebulae. One of the nebulae they observed was Henize 2-428.
“When we looked at this object’s central star with ESO’s Very Large Telescope, we found not just one but a pair of stars at the heart of this strangely lopsided glowing cloud,” says co-author Henri Boffin from ESO.
Follow up observations with telescopes in the Canary Islands showed the two white dwarf stars will ultimately merge and cause a massive supernova explosion.
Each of the white dwarfs has a mass slightly less than our own Sun. Mass is key here for the inevitable supernova explosion. According to the Chandrasekhar limit, a white dwarf star’s mass cannot exceed about 1.4 times the mass of the Sun. Anything higher than that and the star cannot support itself against gravitational collapse.
Once the two white dwarf stars merge, its mass will exceed the 1.4 times figure. After that the star will start to contract, causing massive spikes in temperature and nuclear reactions. This ends with a massive explosion that blows the star apart.
Check out the video below to see what it will look like when the two stars merge.
“Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical,” explains David Jones, another study coauthor. “The pair of stars in Henize 2-428 is the real thing!”