HD 106906 b

Source: Wikipedia, the free encyclopedia.

billion km)[4]
>3,000 years[5]
StarHD 106906
Physical characteristics
Mass11±2 MJup[2]
Temperature≈1,800 K (1,500 °C; 2,800 °F)[2]

HD 106906 b is a directly imaged planetary-mass companion

in-situ formation from a protoplanetary disk.[6]

Description

HD 106906 b is the only known companion orbiting

projected separation from the star is much larger, about 738 AU (110 billion km; 69 billion mi),[2][a] giving it one of the widest orbits of any currently known planetary-mass companions.[2]

The measurements obtained thus far are not adequate to evaluate its orbital properties. If its

periastron. In such a case, the outer extent of the debris disk would be truncated at the inner edge of HD 106906 b's Hill sphere at periastron.[2]

The discovery team evaluated the possibility that HD 106906 b is not gravitationally bound to HD 106906, but is seen close to it along our line of sight and moving in the same direction by chance. The odds of such a coincidence were found to be less than 0.01%.[2]

Discovery

Observation of star HD 106906 began in 2005, utilizing the

The Astrophysical Journal Letters.[2]

Possible formation mechanism

The discovery team and astronomers worldwide were puzzled by HD 106906 b's extreme separation from its host star, because it is not considered possible that a star's protoplanetary disk could be extensive enough to permit formation of gas giants at such a distance. To account for the separation, it is theorized that the companion formed independently from its star as part of a binary system. This proposal is somewhat problematic in that the mass ratio of ~140:1 is not in the range expected from this process; binary stars typically do not exceed a ratio of 10:1.[6][9] This is still considered preferable, however, to the alternate theory that the companion formed closer to its primary and then was scattered to its present distance by gravitational interaction with another orbital object. This second companion would need to have a mass greater than that of HD 106906 b, and the discovery team found no such object beyond 35 AU from the primary. Additionally, the scattering process would have likely disrupted the protoplanetary disk.[2]

Subsequently, astronomer

apastron. An analysis of the motions of 461 nearby stars using Gaia observations revealed two (HIP 59716 and HIP 59721, a possible loosely bound binary system) that passed within 1 pc (3.3 ly) of HD 106906 between 2 and 3 million years ago.[4]

Public reaction

A petition had been launched asking the International Astronomical Union (IAU) to name the companion Gallifrey, after the homeworld of The Doctor on the British science fiction series Doctor Who. The petition gathered over 139,000 signatures. In January 2014, however, it was agreed by the IAU not to accept the petition's goal to name it Gallifrey, as the petition did not follow the public policy of the IAU that a discussion between the public and IAU should be started before naming any spatial entity, and that this policy was not respected.[10][11]

In 2009, IAU stated that it had no plans to assign names to extrasolar planets, considering it impractical.[12] However, in August 2013 the IAU changed its stance, inviting members of the public to suggest names for exoplanets.[13]

Recent observations made by the Hubble Space Telescope "pinned" down that the planet had a somewhat unusual orbit that perturbed it from its host star's debris disk. With NASA and several news outlets comparing it to the so-called hypothetical Planet Nine.[14][15]

See also

  • DT Virginis, a planetary mass object which orbits a binary star, it has the farthest known orbit of a known circumbinary object
  • GU Piscium b, an exoplanet orbiting GU Piscium at a distance of 2000 AU and period of 80,000 years in the AB Doradus moving group
  • WD 0806-661
    , a planetary mass object with the widest discovered orbit

Notes

  1. aphelion
    .

References

  1. ^ a b Morin, Monte (December 5, 2013). "Giant alien world discovered where it should not exist". Los Angeles Times. Retrieved December 8, 2013.
  2. ^
    S2CID 119113709
    .
  3. ^ "Planet HD 106906 b". Extrasolar Planets Encyclopaedia. Archived from the original on October 31, 2019. Retrieved December 8, 2013.
  4. ^
    S2CID 119191779
    .
  5. ^
    S2CID 119424481
    .
  6. ^ a b Osborne, Hannah (December 6, 2013). "Mystery Planet 'That Shouldn't Exist' Baffles Astronomers". International Business Times. Archived from the original on December 13, 2013. Retrieved December 8, 2013.
  7. ^
    S2CID 59575201
    .
  8. S2CID 4812512
    .
  9. ^ Chow, Denise (December 6, 2013). "Giant Alien Planet Discovered in Most Distant Orbit Ever Seen". Space.com. Retrieved December 8, 2013.
  10. ^ "Gallifrey Petition". The Mighty Challenge. Retrieved February 20, 2014.
  11. ^ Quinn, Karl (December 11, 2013). "Doctor Who fan in online petition to name newly found planet". The Sydney Morning Herald. Retrieved December 10, 2013.
  12. ^ "Planets around other stars". International Astronomical Union. Archived from the original on January 1, 2010. Retrieved December 6, 2009.
  13. ^ "Public Naming of Planets and Planetary Satellites: Reaching Out for Worldwide Recognition with the Help of the IAU" (PDF). International Astronomical Union. August 13, 2013. Retrieved August 19, 2013.
  14. ^ Jenner, Lynn (December 9, 2020). "Hubble Pins Down Weird Exoplanet with Far-Flung Orbit". NASA.
  15. ^ "Hubble Discovers a Strange Exoplanet That Resembles the Long-Sought "Planet Nine"". December 11, 2020.
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