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Tyche (hypothetical planet)

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For the asteroid, see 258 Tyche.

Tyche is the nickname given to a possible gas giant located in the outer Oort cloud of the solar system. Astronomers John Matese, Greg Jennings, 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.[4]

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]

Orbit

The orbit of the possible new planet is speculated to lie at approximately 500 times Neptune's distance; equivalent to 15,000 AU, (1,400,000,000,000 miles / 2,250,000,000,000 km) 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 at 50,000 AU. It would have an orbital period of roughly 1.8 million years.[9]

Mass

The discoverers speculate that Tyche could be up to four times the mass of Jupiter and have a relatively high surface temperature of approximately -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.

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.

See also

References

  1. ^ Rodgers, Paul (February 13, 2011). "Up telescope! Search begins for giant new planet". The Independent. Retrieved February 14, 2011.
  2. ^ Wolchover, Natalie (February 15, 2011). "Article: Astronomers Doubt Giant Planet 'Tyche' Exists in Our Solar System". Space.com. Retrieved February 15, 2011.
  3. ^ Matese, John J.; Whitmire, Daniel P. (2011). "Persistent evidence of a jovian mass solar companion in the Oort cloud" (PDF). Icarus. 211 (2): 926–938. doi:10.1016/j.icarus.2010.11.009. arXiv:1004.4584.
  4. ^ a b Plait, Phil (February 14, 2011). "No, there's no proof of a giant planet in the outer Solar System". Discovery Magazine. Retrieved February 15, 2011.
  5. ^ Matese, John J.; Lissauer, Jack J. (May 6, 2002). "Continuing Evidence of an Impulsive Component of Oort Cloud Cometary Flux" (PDF). University of Louisiana at Lafayette, and NASA Ames Research Center. Retrieved March 21, 2008.
  6. ^ Murray, John B. (1999). "Arguments for the Presence of a Distant Large Undiscovered Solar System Planet". Monthly Notices of the Royal Astronomical Society. 309 (1): 31–34. doi:10.1046/j.1365-8711.1999.02806.x. {{cite journal}}: Unknown parameter |laydate= ignored (help); Unknown parameter |laysource= ignored (help); Unknown parameter |laysummary= ignored (help)CS1 maint: unflagged free DOI (link)
  7. ^ Matese, John J.; Whitman, Patrick G.; Whitmire, Daniel P . (1999). "Cometary Evidence of a Massive Body in the Outer Oort Clouds". Icarus. 141: 354. doi:10.1006/icar.1999.6177.
  8. ^ Matese, John J.; Whitmire, Daniel P.; Lissauer, Jack J. (2006). "A Widebinary Solar Companion as a Possible Origin of Sedna-like Objects". Earth, Moon, and Planets. 97 (3–4): 459–470. doi:10.1007/s11038-006-9078-6. Retrieved August 17, 2010.
  9. ^ "Orbital period of a planet (distance of 15000 AU and mass of 1300 Earths)". Retrieved February 15, 2011.
  10. ^ "Search on for Tyche, believed to be largest planet in the Solar System". Daily Mail. Daily Mail. February 14, 2011. Retrieved February 14, 2011.
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