Will Earth 'Be Wiped Out' by a Supernova?
It's very easy to get worried when you hear that a star could explode "with the force of 20 billion billion billion megatons of TNT" and the explosion is going to detonate so close to us that it "could strip away the Earth's ozone layer."
However, when the news source also states this supernova could happen "soon," we suddenly have an imminent doomsday event in the offing! Stock your lead-lined bunker now! Buy as many cans of baked beans as you can carry!
As with many astronomical meetings, the American Astronomical Society (AAS) conference currently underway in Washington D.C. is presenting some astonishing, cutting-edge research from the world's best scientists. However, often this research can sound a bit scary. For example, the energies associated with supernovae and gamma-ray bursts will do more than simply singe your eyebrows off, these events can decimate entire star systems.
Enter the U.K.'s Telegraph, with an article entitled, "Earth 'to be wiped out' by supernova explosion." One would think that by making such a statement, the journalist must have found a fairly compelling piece of evidence that suggests global doom?
Not so much.
The article is referring to research presented at the AAS by Edward M. Sion and his team from Villanova University, Philadelphia. Their research suggests that a binary star called T Pyxidis is acting rather strange.
Up until 1967, T Pyxidis was exploding as a recurrent nova every 20 years or so. This nova was being caused by a white dwarf sucking gas from its companion star. As the quantity of gas reached a certain limit, it would detonate as a nova (a stellar explosion that leaves the star intact). However, for the last 40 years, the repeating novae have stopped.
Naturally, this excites astronomers and Sion's team has reached the conclusion that T Pyxidis is about to go supernova (in this case, it would be a Type 1a supernova, destroying both stars).
The thing is, T Pyxidis is only 3,260 light-years from us, prompting the researchers to also postulate that the resulting supernova could damage Earth.
This fact alone was the trigger for the Telegraph's scary headline (although it's not clear where the quote 'to be wiped out' came from - damage to the ozone layer is one thing, wiping out Earth is quite another!).
Interested in what was going on, I contacted my colleague Ray Villard who is currently attending the conference in D.C. and he confirmed that the Telegraph article is 90 percent hype.
During Sion's presentation, he was challenged by one of his peers in the audience, Prof. Alex Fillipenko from Berkeley Astronomy Department. Apparently Sion had possibly miscalculated the damage that could be caused by a T Pyxidis supernova.
It seems that Sion had used data for a far more deadly gamma-ray burst (GRB) exploding 3,260 light-years from Earth, not a supernova. T Pyxidis certainly isn't expected to produce a GRB. (Gamma-ray bursts are thought to only be generated by a massive star that has reached the end of its life as a Wolf-Rayet star collapsing under its own gravitational attraction.)
"A supernova would have to be 10 times closer [to Earth] to do the damage described," Ray informed me via email.
The scientists at the meeting were also highly dubious about Sion's estimate that the star could explode imminently. In fact, the Telegraph article even closes with a quote from Robin Scagell, vice-president of the UK's Society for Popular Astronomy: "The star may certainly became a supernova soon - but soon could still be a long way off so don't have nightmares."
In summary, T Pyxidis is too far away to cause the Earth any harm and there's doubt that the star will even explode "soon."
So, where's the panic? That's right, there isn't any. I'm sure the Telegraph took Sion's pre-conference press release at face-value and didn't have the good fortune to have a correspondent at the AAS to confirm Sion's claims. But, publishing an article indicating a global catastrophe is imminent strikes me as a little irresponsible.
Meetings like the AAS are key to the scientific process where theories are aired and results are open to academic scrutiny, sometimes it's better to wait until after the conference before reaching any conclusions.