Question

On April 9, 2010, David Morrison wrote, "Scientists today no longer think an object like Nemesis could exist. If it were real it would have been detected long ago in infrared sky surveys." However, in a 2011 response to a similar question regarding Tyche, Whitney Clavin responds, "It is too early to know whether WISE data confirms or rules out a large object in the Oort cloud. The full survey, scheduled for release in March 2012, should provide greater insight. Once the WISE data are fully processed, released and analyzed, the Tyche hypothesis will be tested." My question simply is how do we account for the apparent discrepancy in responses?

There is no discrepancy. I was discussing Nemesis, a suggested companion star to the Sun. The other response deals with Tyche, a suggested giant planet orbiting the Sun in the outer comet cloud. A star is, of course, very much more massive and brighter than a planet. Early infrared surveys such as IRAS in 1983 were sufficient to rule out the presence of a star but not a planet. The fact is that none of the surveys since IRAS has provided any support for the Tyche hypothesis. But since WISE is the most sensitive all-sky infrared survey, it seems prudent to wait until all the WISE data are available before passing final judgment on the reality of Tyche.

David Morrison
Astrobiology Senior Scientist
August 2, 2011