Nemesis not to blame for mass extinctions

We have all heard that the fossil records show a curious cycle of every 27 million years, Earth has been bombarded so heavily as to cause a mass extinction. Some scientists blamed a star dubbed Nemesis. In a recent IO9 article, Adrian Melott of the University of Kansas and Richard Bambach of Smithsonian Institution Museum of Natural History, say that the theory that every 27 million years, Nemesis would swing through the outer system bringing with it vast quantities of material from the Ort cloud. Melott and Bambach researched the fossil records and indeed found an extremely accurate record of mass extinctions every 27 million years, further back than anyone else had researched. And that accuracy it appears, is the failing point of the Nemesis as the cause. Because the occurrences are SO regular it can not be a Nemesis object, because it is SO regular!

Melott and Bambach postulate that if Sol had a binary companion, their shared orbit around a common central point would distort the regularity of each body around the system. This means that each time Nemesis swung in, its orbit would change and the occurrence would not and could not be the same as the one before and the one after. The change might be subtle but it would be enough for the regularity of the events to be wildly different instead of every 27 million.

You can read the whole article on IO9 here