Tyche (hypothetical planet)

Source: Wikipedia, the free encyclopedia.
Not to be confused with the hypothetical planet Planet Nine, the hypothetical star Nemesis, or other hypothesized planets beyond Neptune.
This article is about the hypothetical planet. For the asteroid, see 258 Tyche.
An artist's rendering of the Oort cloud and the Kuiper belt (inset)

Tyche

long-period comets. More recently, Matese[3] and Whitmire[4] re-evaluated the comet data and noted that Tyche, if it existed, would be detectable in the archive of data that was collected by NASA's Wide-field Infrared Survey Explorer (WISE) telescope.[5] In 2014, NASA announced that the WISE survey had ruled out any object with Tyche's characteristics, indicating that Tyche as hypothesized by Matese, Whitman, and Whitmire does not exist.[6][7][8]

History

Matese, Whitmire and their colleague Patrick Whitman first proposed the existence of this planet in 1999,[9] based on observations of the orbits of long-period comets. Most astronomers agree that long-period comets (those with orbits of thousands to millions of years) have a roughly isotropic distribution; that is, they arrive at random from every point in the sky.[10] Because comets are volatile and dissipate over time, astronomers suspect that they must be held in a spherical cloud tens of thousands of AU distant (known as the Oort cloud) for most of their existence.[10] However, Matese and Whitmire claimed that rather than arriving from random points across the sky as is commonly thought, comet orbits were in fact clustered in a band inclined to the orbital plane of the planets. Such clustering could be explained if they were disturbed by an unseen object at least as large as Jupiter, possibly a brown dwarf, located in the outer part of the Oort cloud.[11][12] They also suggested that such an object might explain the trans-Neptunian object Sedna's peculiar orbit.[13] However, the sample size of Oort comets was small and the results were inconclusive.[14]

Orbit

Whitmire and Matese speculated that Tyche's orbit would lie at approximately 500 times

light year. This is 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.[15] A failed search of older IRAS data suggests that an object of 5 MJ would need to have a distance greater than 10,000 AU.[7] Such a planet would orbit in a plane different from the ecliptic,[16] and would probably have been in a wide-binary orbit at the time of its formation.[7] Wide binaries may form through capture during the dissolution of a star's birth cluster.[7]

Mass

size comparison between the Sun, a low-mass star, a brown dwarf, and the planets Jupiter and Earth

In 2011, Whitmire and Matese speculated that the hypothesized planet could be up to four times the mass of

degenerate pressure causes massive gas giants to increase only in density, not in size, relative to their mass.[a] If Tyche was to be found, it was expected to be found by the end of 2013 and only be 1–2 Jupiter masses.[19]

Origin of name

Nemesis.[7] This name was first used for an outer Oort cloud object by J. Davy Kirkpatrick at the Infrared Processing and Analysis Center of the California Institute of Technology.[20]

WISE mission

The Wide-field Infrared Survey Explorer (WISE) space telescope has completed an all-sky infrared survey that includes areas where Whitmire and Matese anticipate that Tyche may be found.[7] On March 14, 2012, the first-pass all-sky survey catalog of the WISE mission was released.[21] The co-added (AllWISE) post-cryo second survey of the sky was released at the end of 2013.[22] On March 7, 2014, NASA reported that the WISE telescope had ruled out the possibility of a Saturn-sized object out to 10,000 AU, and a Jupiter-sized or larger object out to 26,000 AU (0.4 light-years).[6][23]

See also

Notes

  1. billion years of cooling, large gas giants are all very nearly Jupiter's radius, but more massive objects are slightly smaller.[18]

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. ^ "Astrophysics Homepage of John J. Matese". Ucs.louisiana.edu. September 21, 2011. Retrieved April 1, 2013.
  4. ^ "Daniel P. Whitmire". Ucs.louisiana.edu. Retrieved April 1, 2013.
  5. ^ Whitney Clavin (February 18, 2011). "Can WISE Find the Hypothetical 'Tyche'?". NASA/JPL. Retrieved February 19, 2011.
  6. ^ a b Clavin, Whitney; Harrington, J.D. (March 7, 2014). "NASA's WISE Survey Finds Thousands of New Stars, But No 'Planet X'". NASA. Retrieved March 7, 2014.
  7. ^
    S2CID 44204219
    .
  8. ^ Helhoski, Anna. "News 02/16/11 Does the Solar System Have Giant New Planet?". The Norwalk Daily Voice. Retrieved July 10, 2012.
  9. Bibcode:2002ESASP.500..309M
    . Retrieved March 21, 2008.
  10. ^ a b Harold F. Levison; Luke Donnes (2007). "Comet Populations and Cometary Dynamics". In Lucy Ann Adams McFadden; Lucy-Ann Adams; Paul Robert Weissman; Torrence V. Johnson (eds.). Encyclopedia of the Solar System (2nd ed.). Amsterdam; Boston:
    ISBN 978-0-12-088589-3
    .
  11. doi:10.1046/j.1365-8711.1999.02806.x
    .
  12. doi:10.1006/icar.1999.6177
    .
  13. S2CID 13647204
    .
  14. ^ Plait, Phil (February 14, 2011). "No, there's no proof of a giant planet in the outer Solar System". Discovery Magazine. Archived from the original on April 16, 2016. Retrieved February 15, 2011.
  15. ^ "Orbital period of a planet at a distance of 15000 AU with a circular orbit". Retrieved February 15, 2011.
  16. ^ "Have UL Physicists Identified a New Planet?". University of Louisiana. February 14, 2011. Archived from the original on August 1, 2015. Retrieved February 16, 2011.
  17. ^
    S2CID 8369390. The reference states 500 ME (1.6 MJ). Jupiter is 318 times
    more massive than Earth.
  18. S2CID 118513110
    .
  19. ^ Bruce Dorminey (March 31, 2013). "Sun May Still Have Low-Mass Solar Companion, Say Astrophysicists Searching NASA WISE Mission Data". Forbes. Retrieved April 1, 2013.
  20. ArsTechnica
    . Retrieved March 21, 2011.
  21. ^ "NASA Releases New WISE Mission Catalog of Entire Infrared Sky". NASA/JPL. March 14, 2012. Archived from the original on June 4, 2012. Retrieved March 15, 2012.
  22. ^ Wide-field Infrared Survey Explorer
  23. S2CID 122930471
    .
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