Halloween is a time of scary things like witches, ghosts and monsters. So how about a really scary monster: a Gamma Ray Burst (GRB)? I’m speaking of what could happen if the binary star WR104 were to implode in a particular type of supernova.
First, what is a Gamma Ray Burst and why should you care? Well, think of it this way, the amount of gamma ray (X ray) energy in a GRB is more energy than our sun will produce in its entire life. Gamma Ray bursts are big enough than when a star collapses and produces one, the GRB can be seen across most of the known universe. They are a special but fortunately rare type of supernova.
How GRBs would affect Earth is subject to some speculation. However, they are thought to produce both gamma rays and cosmic rays. Some believe the combination of the two would deplete the ozone layer by at least 30% with as much as 50% depletion in some areas. Additionally, atmospheric nitrogen could be turned into nitrogen dioxide producing smog.
Sounds bad, right? Breathing smog and getting skin cancer.
It could get even worse. The cosmic rays, which are really subatomic particles, could hit the air and cause the generation of other sub-atomic particles called muons. Muon behavior and impacts are even more speculative than the effects of gamma ray bursts. But that speculation does include the possibility of life extinction. At least you wouldn’t have to worry about skin cancer or breathing smoggy air.
Granted, GRBs are bad and they happen. Is there a special threat to Earth of one?
Yes, binary start WR104. Only discovered in 2000, this is a really interesting binary system. The larger sun is a Class O, being 1 million times brighter than the Sun (Class G). It appears it will follow a normal solar life cycle and have an ordinary supernova in its future. The other star is where the problem may lie. It is called a Wolf Rayet start. Currently, about 20 times larger than the Sun, it represents what is thought to be the collapse of a special type of Class O star. (Wolf Rayet’s are rare: only about 300 have been identified in the Milky Way galaxy).
Here’s where it gets really spooky. The monster lives close by.
The accepted distance to WR104 is only about 8,000 light years (with some other estimates as low at 5,000 light-years). So, we have a late-stage star thought to be able to produce a Gamma Ray Burst in the neighborhood. What’s to worry about?
The reality is that no one knows if the Wolf Rayet has exploded already, will explode next year during the 2012 festivities, or 10,000 years in the future. Beyond that, even when it collapses, there’s no certainty it would actually produce a GRB, or if it did would it hit the Earth. And we’d be safe it it was an ordinary supernova – you have to be closer than 25 light years to be at risk.
All in all, WR104 is there and could be a risk to all of us on Earth. But so could the comet or asteroid approaching Earth from the southern Hemisphere where astronomical observatories and sky searches are much fewer.
It’s just that at Halloween everyone needs a monster to be scared of – if even just a little.