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Tyche is the nickname given to a possible gas giant located in the outer Oort cloud of the solar system. Astronomers John Matese and Daniel Whitmire of the University of Louisiana at Lafayette[1][2] claimed in 2011 that evidence of this object would be detectable in the archive of data that was collected by NASA's Wide-field Infrared Survey Explorer (WISE) telescope,[3] but the two have said that more analysis of the WISE data is required to determine if such a world exists or not
History
Matese and Whitmire first proposed the existence of this planet in 1999,[5] based on a perceived bias in the points of origin for long-period comets. Rather than arriving from random points across the sky as is commonly thought, Matese and Whitmire concluded that they were in fact clustered in a band inclined to the ecliptic. Such clustering could be explained if they were disturbed by an unseen object at least as large as Jupiter, possibly a brown dwarf. The hypothetical planet—or companion of the Sun—would be located in the outer part of the Oort cloud.[6][7] They suggest that such an object might also explain Sedna's peculiar orbit.[8] However, their sample size was small and the results were inconclusive.[4]
[edit] Orbit
The orbit of the possible new planet is speculated to lie at approximately 500 times Neptune's distance; equivalent to 15,000 AU (2.2×1012 km; 1.4×1012 mi) from the Sun, a little over one-fourth of a light year. This is still well within the Oort cloud, whose boundary is estimated to be beyond 50,000 AU. It would have an orbital period of roughly 1.8 million years.[9]
[edit] Mass
The discoverers speculate that Tyche could be up to four times the mass of Jupiter and have a relatively high temperature of approximately 200 Kelvin[3] (-73°C), due to residual heat from its formation.[10] With a mass of four times the mass of Jupiter, it would still be too small to be a brown dwarf, the ignition of which requires an astronomical object to possess a mass of at least 13 Jupiter masses.
[edit] Origin of name
In ancient Greek city cults, Tyche (Τύχη, meaning "fortune" or "luck" in Greek) was the presiding tutelary deity that governed the fortune and prosperity of a city, its destiny (Roman equivalent: Fortuna). The use of the name "Tyche" for the planet may also be a reference to an earlier theory of the Solar System's structure that involved the Sun having a dim companion named Nemesis as it was proposed as a cause for mass-extinctions on Earth. Tyche was the name of the sister of Nemesis. |
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