WR 104 is a Wolf-Rayet star discovered in 1998, located 8,000 light years from Earth. It is a binary star with a class OB companion. The stars have an orbital period of 220 days and the interaction between their stellar winds produce a spiral "pinwheel" outflow pattern over 200 astronomical units long. The spiral is composed of dust that would normally be prevented from forming by WR 104's intense radiation were it not for the star's companion. The region where the stellar wind from the two massive stars interacts compresses the material enough for the dust to form, and the rotation of the system causes the spiral-shaped pattern.
Some optical measurements indicate that WR 104's rotational axis is aligned within 16° of Earth. This could have potential implications to the effects of WR 104's eventual supernova, since these explosions often produce jets from their rotational poles. It is possible that WR 104 may even produce a gamma-ray burst, though it is not possible to predict with certainty at this time. Newer spectroscopic data suggest that WR 104's rotational axis is more likely angled 30–40° from Earth.
Hypothetical effects of gamma-ray bursts in the past
GRBs close enough to affect life in some way might occur once every five million years or so – around a thousand times since life on Earth began.
The major Ordovician-Silurian extinction event of 450 million years ago may have been caused by a GRB. The late Ordovician species of trilobite that spent some of its life in the plankton layer near the ocean surface was much harder hit than deep-water dwellers, which tended to stay put within quite restricted areas. Usually it is the more widely spread species that fare better in extinction, and hence this unusual pattern could be explained by a GRB, which would probably devastate creatures living on land and near the ocean surface, but leave deep-sea creatures relatively unharmed.
 Hypothetical effects of gamma-ray bursts in future
The real danger comes from Wolf–Rayet stars, regarded by astronomers as ticking bombs. When such stars transition to supernovas, they may emit intense beams of gamma rays, and if Earth were to lie in the beam zone, devastating effects may occur. Gamma rays would not penetrate Earth's atmosphere to impact the surface directly, but they would chemically damage the stratosphere.
For example, if WR 104 were to hit Earth with a burst of 10 seconds duration, its gamma rays could deplete about 25 percent of the world's ozone layer. This would result in mass extinction, food chain depletion, and starvation. The side of Earth facing the GRB would receive potentially lethal radiation exposure, which can cause radiation sickness in the short term, and in the long term result in serious impacts to life due to ozone layer depletion.
 Effects after exposure to the gamma-ray burst on Earth's atmosphere
Longer-term, gamma ray energy may cause chemical reactions involving oxygen and nitrogen molecules which may create nitrogen oxide then nitrogen dioxide gas, causing photochemical smog. The GRB may produce enough of the gas to cover the sky and darken it. Gas would prevent sunlight from reaching Earth's surface, producing a cosmic winter effect, and may even further deplete the ozone layer, thus exposing the whole of the Earth to all types of cosmic radiation.
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