Oh those irrepresible Mayans. Not only did they foretell our doom, they may have foretold just how we’ll go. The cosmic bullet that’s going to get us is known as WR 104, a star located 8,000 light years from Earth in the constellation Sagittarius, and it’s time you got familiar with it.
Why is WR 104 so dangerous? Because it’s what’s known as a Wolf Rayet star — a particular type of extra-large star about 20 times the size of our sun which sheds its mass especially fast as it nears the end of its life. If a Wolf Rayet star’s spin-velocity is great enough — and WR 104’s appears to be — it could go not just supernova, but hypernova, expelling gamma rays from its poles that could fry anything in their path. Telescope images have shown that one of WR 104’s poles is pointed straight at us.
And what do the Mayans have to do with this? Uh, hello! Sagittarius is a December sign, and when did the Mayans say the world would end? Anyone? Good! December 21! See, science is easy.
OK, but before you cash out your mortgage and spend your remaining hours drinking tequila because, well, it seems kind of Mexican-y and the Mayans might look favorably on you, let’s consider some of the other things science tells us about WR 104. A terrific summary of all that smartness comes from Discover Magazine’s Phil Plait, whose wonderfully named Bad Astronomy column looked at WR 104 as long ago as 2008.
The so-called death star is actually part of a binary star system, whose partners are whipping around each other fast enough — and stirring enough enough cosmic wind in the process — that they do look like they could produce a gamma ray burst. Astronomer Phil Tuthill of the University of Sydney, created a video clip of the pole-first spin of WR 104, generated from images captured by the Keck telescope, and it fits the dead-aim profile that would make it a menace to us. And a word like menace understates it. According to Plait, a gamma ray burst pointed our way would, among other things, deplete about 30% of the Earth’s ozone and convert the nitrogen in our atmosphere into nitrogen dioxide (think muddy-colored smog), which is not what you want on a planet you plan to continue living on.
But we don’t know if either star will indeed go hypernova, we don’t know when it will happen if it does — thousands of years? Hundreds of thousand? Millions? And 8,000 light years might be more than distant enough to keep us safe. Plus, gamma-ray bursts are emitted in narrow beams, so if WR 104’s aim isn’t really truly sharp, it will miss us entirely.
And that question of aim is the key. As long ago as 2009, further studies by Keck showed that the star is actually not pointed directly at us, but inclined 30º or more away. That angle could grow even sharper if the beam were to ricochet off of the swirl of mass the two stars are shedding. Those little details aren’t making a lot of news with all the Mayan noise, but that’s OK. We’ll have plenty of time to discuss it all on the morning of December 22 — or perhaps the afternoon if you went for the tequila option the night before.