2001 QR322

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2001 QR322
Discovery
Discovered by Deep Ecliptic Survey
Discovery date 21 August 2001[1]
Designations
MPO157352
Minor planet category Trojan asteroid
Orbital characteristics[1][2]
Epoch 2011-Aug-27.0 (JD 2455800.5)
Aphelion 31.326 AU
Perihelion 29.468 AU
30.397 AU
Eccentricity 0.0306
167.59 yr (61212 d)
56.8°
Inclination 1.3213°
151.55°
168.1°
Physical characteristics
Dimensions 60–160 km[3]
8.2

2001 QR322 (also written 2001 QR322) was the first Neptune trojan discovered, in 2001 by the Deep Ecliptic Survey. It orbits ahead of Neptune at its L4 Lagrangian point.[2][4]

With an absolute magnitude of 7.8[1] to 8.2,[2] it has a diameter in the range of 60 to 160 km.[3]

Other Neptune trojans have been discovered since. A study by Scott S. Sheppard and Chad Trujillo from the Carnegie Institution suggests that Neptune could possibly have twenty times more trojans than Jupiter.[5]

Dynamical stability[edit]

Early studies of the dynamical stability of 2001 QR322, which used a small number of test particles spread over the uncertainties of just a few orbital parameters that were derived from a limited observation arc, suggested that 2001 QR322 is on a remarkably stable orbit, because most test particles remained on trojan orbits for 5 Gyr.[6] Thereafter, the stability of Neptune trojans was simply assumed.[6]

A more recent study, which used a very large number of test particles spread over the 3σ uncertainties in all six orbital parameters derived from a longer observational arc, has indicated that 2001 QR322 is far less dynamically stable than previously thought.[6] The test particles were lost exponentially with a half life of 553 Myr.[6] Further observations can determine whether 2001 QR322's orbit is actually within the dynamically stable or within the unstable part.[6]

The stability is strongly dependent on semi-major axis, with a≥30.30 AU being far less stable, but only very weakly dependent on the other orbital parameters.[6] This is because those with larger semi-major axes have larger libration amplitudes, with amplitudes ~70° and above being destabilized by secondary resonances between the trojan motion and the dynamics of at least Saturn, Uranus, and Neptune.[6] Secular resonances were found not to contribute to the dynamical stability of 2001 QR322.[6]

References[edit]

  1. ^ a b c "JPL Small-Body Database Browser: (2001 QR322)". 2008-07-21 last obs. Retrieved 2009-09-04. 
  2. ^ a b c "List Of Neptune Trojans". Minor Planet Center. Retrieved 2011-05-08. 
  3. ^ a b "Absolute Magnitude (H)". Archived from the original on 14 May 2008. Retrieved 2008-05-08. 
  4. ^ Marc W. Buie (2008-07-21 using 26 of 26 observations). "Orbit Fit and Astrometric record for 01QR322". SwRI (Space Science Department). Retrieved 2009-09-03. 
  5. ^ "Neptune May Have Thousands of Escorts". Space.com. 30 January 2007. Retrieved 2009-09-04. 
  6. ^ a b c d e f g h Horner, J.; Lykawka, P. S. (June 2010). "2001 QR322: a dynamically unstable Neptune Trojan?" (pdf). Monthly Notices of the Royal Astronomical Society 405 (1): 49–56. arXiv:1002.4699. Bibcode:2010MNRAS.405...49H. doi:10.1111/j.1365-2966.2010.16441.x. Retrieved 2012-03-20. 

External links[edit]