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Looks like 2013 now! :)

John Matese (University of Louisiana at Lafayette) thinks the gravitational influence of a solar companion is disrupting that part of the cloud, scattering comets in its wake. His calculations suggest Nemesis is between 3 to 5 times the mass of Jupiter, rather than the 13 Jupiter masses or greater that some scientists think is a necessary quality of a brown dwarf. Even at this smaller mass, however, many astronomers would still classify it as a low mass star rather than a planet, since the circumstances of birth for stars and planets differ.

Richard Muller of the University of California Berkeley first suggested the Nemesis theory, and even wrote a popular science book on the topic. He thinks Nemesis is a red dwarf star 1.5 light years away.

Binary star systems are common in the galaxy. It is estimated that one-third of the stars in the Milky Way are either binary or part of a multiple-star system.

Part of the WISE mission is to search for brown dwarfs, and NASA expects it could find one thousand of the dim stellar objects within 25 light years of our solar system.

Ned Wright, professor of astronomy and physics at UCLA and the principal investigator for the WISE mission, said that WISE will easily see an object with a mass a few times that of Jupiter and located 25,000 AU away, as suggested by Matese.

We may not have an answer to the Nemesis question until mid-2013. WISE needs to scan the sky twice in order to generate the time-lapsed images astronomers use to detect objects in the outer solar system. The change in location of an object between the time of the first scan and the second tells astronomers about the object’s location and orbit. Then comes the long task of analyzing the data.

“I don’t suspect we’ll have completed the search for candidate objects until mid-2012, and then we may need up to a year of time to complete telescopic follow-up of those objects,” said Kirkpatrick.

So they are speculating on the size of a failed, unlit [companion] star, before it's even found?

Sedna, is more like a large asteroid type of thing, smaller than Pluto, at 800-1100 miles diameter. That's the object in the strange, 12,000 yr. orbit mentioned in the article, right?

I'm getting the idea that the Sedna discovery helped lead to the "size" speculation of this yet-to-be-found but expected to exist dark companion star?