Doomed for an end 700 million years in the making, a pair of white dwarf stars will inevitably merge and meet their doom and researchers are saying that the violent fate is unlike any that they've seen before.
In the study published this week in the journal Nature, a team of Spanish researchers working with the European Southern Observatory (ESO) revealed the heavy pair of white dwarf stars when looking into the strange shapes taken form by planetary nebulae. Looking to the beautiful wonders of the galaxy such as the Cat's Eye Nebula and the Helix Nebula as the basis for their study, the researchers wanted to learn why the aging stars create such diverse, multicolored structures in the night sky.
"The planetary nebula stage is the ultimate fate of stars with masses one to eight times that of the sun" the study's coauthors say. "Although several mechanisms involving binary interaction have been proposed, the origin of their complex morphologies is poorly understood."
But in looking for the origins of the odd shapes, the researchers found something far more interesting. Utilizing the Very Large Telescope to examine the nebulae, Henize 2-428, the researchers discovered not one, but two stars spinning at the center of the beautiful mass. Together with a combined mass of nearly 1.8 that of our sun, the binary pair are roughly the same size and each orbits the other.
And that's not the only thing that they found.
In a follow-up analysis using telescopes in the Canary Islands, the researchers found that not only were the two stars orbiting one another, but also that they are closer than they would have ever expected. Their orbital period is only a mere 4.2 hours, meaning that they'er spinning abnormally quickly and far too close to sustain their own distinct masses. In fact, at such a close distance, the researchers estimate that the stars' gravity will pull the pair together within 700 million years, resulting in a catastrophic merger for the stars and the nebula.
According to the Chandrasekhar limit, a theory that defines the maximum mass of a stable white dwarf star, the combined stars will be far too large to withstand their own mass, and the stellar pair will degenerate in a type Ia supernova blast that will illuminate the sky. Though the double-degenerate pathway has until now merely been a hypothesis theorized by astronomers, the odd pair of Henize 2-428 supports the hypothesis - that is, if the supernova takes place some 700 million years down the line.
Co-author of the study, Dr. David Jones says that while there is still much to be learned about the strange nebula, the revelation of the twin stars will undoubtedly add greatly to astronomers' understandings of the origins of such supernovae blasts.
"Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical" Jones says. "The pair of stars in Henize 2-428, however, is the real thing!"
