[link to www.ucs.louisiana.edu]

A wide-binary solar companion as a possible origin of Sedna-like objects
John J. Matese1, Daniel P. Whitmire1 and Jack J. Lissauer2
1Department of Physics, University of Louisiana, 2006

Abstract. Sedna is the first inner Oort cloud object to be discovered. Its dynamical origin remains unclear, and a possible mechanism is considered here. We investigate the parameter space of a hypothetical solar companion...
...
A Jupiter mass or larger object on a highly inclined orbit in the inner Oort cloud would most likely have formed as a small, distant binary-star like companion, e.g., by fragmentation during collapse or capture. We conclude that a model of a hypothetical wide-binary solar companion of mass ¼ 3 ¡ 10MJ orbiting at distances of ¼ 10; 000 AU is no less cosmogonically plausible than is the stellar impulse scenario.

[link to www.binaryresearchinstitute.org]

...the remaining signal was far larger than anyone expected. In fact, it is so large it either means there is some unforeseen problem with the gyros or that our sun is part of a binary star system.

Yes, that’s right, if the data is correct our solar system is curving through space (carrying the earth and spacecraft with it of course) so rapidly that the only way to explain it is if our sun is gravitationally bound to another nearby star. When I met with the GP-B team at Stanford last fall they were still in the early process of analysing the data but openly discussed the idea of an unknown companion to our sun, including the possibility of a not too distant blackhole.

[link to ultoday.com]

Could this be the planet that was hypothesized to cause the periodic mass extinctions we have seen on Earth, and which may have killed off the dinosaurs?

No, that was the Nemesis conjecture. 28 years or so ago there was the conjecture of an even larger object, further out, but that data is not connected to ours. The evidence was that the larger one created comet storms that crashed into the Earth. That topic is still being debated.
...
Would this be the first new planet in the Solar System in some years?

The International Astronomical Union (IAU) would decide what to call Tyche. We have never found in any stellar systems a Jupiter mass object that rotates out at that distance from the central star, they've never seen a wide binary object of that size. From its size, the IAU may call it a planet. Or because of the formation and distance from the Sun, they may decide to call it something like an ultracool dwarf

If it exists, would Tyche interest the Nobel committee?

No, not even close. We probably wouldn't even get credit for the discovery. We have data that suggests it's out there, what its mass is and what its path is, but we can't tell where it is on the path.