Astronomers from NASA are discovering unusual behavior in one particular star, called Nasty 1, which has been formed several decades ago. The star is rapidly aging and may represent a brief transitory stage in the evolution of giant stars.
What was previously thought to be a typical Wolf-Rayet star, a celestial body defined by a massive size that evolves quickly and it’s much wider than the sun, is now turning into a living wonder. Normally, this particular kind of star is known to lose its hydrogen filled outer layers, exposing its extremely hot and incredibly bright helium-burning core.
Nasty 1 is far from being that typical Wolf-Rayet star. If it were, it should have had twin lobes of gas flowing from its opposite sides, similar to those emanating from the Eta Carinae massive star. Instead, Nasty 1 is differently shaped and has pretty much different behavior. Its shape looks more like a pancake, with disks of gas encircling it. Those gas disks are nearly 2 trillion miles wide and are thought to have formed from an unseen companion star that snacked on the outer envelope of the new-born Wolf-Rayet.
Astronomers are excited to see the uncommon structure of Nasty1, as it may reveal considerable evidence for a Wolf-Rayet star forming from binary interaction. It seems that our galaxy offered too few examples of this process in action, as this phase is very short lived, lasting only a hundred thousand years, “while the timescale over which a resulting disk is visible could be only ten thousand years or less”, Jon Mauerhan of UC Berkley, lead author on the new Nasty 1 paper declared.
Researchers outline a hypothetical scenario in their paper, describing what is going on. Nasty 1 appears to have been swelling up as it has evolved, while its outer hydrogen layer has become looser and more vulnerable to a behavior known as gravitational stripping. This means that a nearby companion star has started to cannibalize the envelope, growing like a parasite while devouring Nasty and helping the larger star complete its transformation into Wolf-Rayet.
Seemingly, there is a Wolf-Rayet star buried inside the nebula and this very nebula is created by this huge mass-transfer process.
There is however an alternative theory on how a typical Wolf-Rayet star is formed. That is when a massive star ejects its own hydrogen envelope in a strong stellar wind, streaming with particles. The binary interaction model is now happening as astronomers have reached the conclusion that at least 70% of massive stars are members of double star systems.
Nasty 1 is something worth looking at, the more so it appears to be so surprising. Its evolutionary path is yet uncertain, with hypothesis claiming that it could evolve into another Eta-Carinae type system. We will surely keep our eyes wide open to see what future holds for this nasty celestial body.
Image Source: benchmarkreporter.com