Apohele asteroid

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Apohele asteroids, or alternatively Interior-Earth Objects (IEOs) or Atira asteroids, are a class of near-Earth asteroids.[1] They have not only their perihelion within Earth's orbit, but also their aphelion; that is, their entire orbit is within Earth's (which has a perihelion of 0.983 AU).

The first suspected Apohele was 1998 DK36, and the first confirmed was 163693 Atira in 2003. As of February 2014, there are 13 suspected Apoheles, of which eight have well-known orbits,[2] of which two have been determined with sufficient precision to receive a permanent number (see list below); 28 more objects have aphelia shorter than the Earth's aphelion (1.017 AU). The Near Earth Object Surveillance Satellite is intended to find more.

In great part because of the search methods used to look for asteroids, there are currently no known asteroids with orbits contained within Venus or Mercury's (e.g. vulcanoids).

There is no standard name for the class. The name Apohele was proposed by the discoverers of 1998 DK36,[3] and is the Hawaiian word for orbit; it was chosen partially because of its similarity to the words aphelion (apoapsis) and helios.[4] Other authors adopted the designation Inner Earth Objects (IEOs).[5] Still others, following the general practice to name a new class of asteroids for the first recognized member of that class,[6][7] use the designation Atira asteroids.[1]

Atiras do not cross Earth's orbit and are not immediate impact threats, but their orbits may be perturbed outward by a close approach to either Mercury or Venus and become Earth-crossing asteroids in the future.

List of known and suspected Apoheles as of February 2014[2][8]
Name Perihelion
(AU)
Semi-major axis
(AU)
Aphelion
(AU)
Eccentricity Inclination
(°)
# of oppositions
(Observation arc)
(H) Diameter
(m)
(163693) Atira 0.502 0.741 0.980 0.322 25.6   9 16.3 2,300
(164294) 2004 XZ130 0.337 0.618 0.898 0.454 3.0 3 20.4 250
1998 DK36 0.405 0.692 0.980 0.416 2.0 1 (1 day) 25.0 30
2004 JG6 0.298 0.635 0.973 0.531 18.9   2 18.9 550
2005 TG45 0.428 0.681 0.935 0.372 23.3   4 17.6 1,000
2006 KZ39 ( 2013 JX28) 0.292 0.616 0.939 0.525 9.4 2 20.1 330
2006 WE4 0.641 0.785 0.928 0.183 24.8   3 18.8 600
2007 EB26 0.116 0.550 0.980 0.783 8.4 1 (6 days) 19.6 400
2008 EA32 0.428 0.616 0.804 0.305 28.3   2 16.5 1,500
2008 UL90 0.431 0.695 0.959 0.380 24.3   4 18.6 650
2010 XB11 0.288 0.618 0.948 0.534 24.8   1 (43 days) 19.9 350
2012 VE46 0.454 0.712 0.971 0.362 6.7 1 (37 days) 20.3 300
2013 TQ5 0.653 0.773 0.894 0.155 16.3   1 (23 days) 19.8 380

See also[edit]

References[edit]

  1. ^ a b "Near-Earth Object Groups". NASA. Archived from the original on 25 March 2010. Retrieved 2010-04-03. 
  2. ^ a b "JPL Small-Body Database Search Engine: Q < 0.983 (AU)". JPL Solar System Dynamics. Retrieved 2014-02-14. 
  3. ^ Tholen D. J. and Whiteley R. J. (1998). "Results from NEO searches at small solar elongations". Bulletin of the American Astronomical Society 30: 1041. 
  4. ^ http://abob.libs.uga.edu/bobk/ccc/cc070998.html
  5. ^ Michel P., Zappalà V., Cellino A., and Tanga P. (2000). "Estimated abundances of Atens and asteroids on orbits between Earth and Sun". Icarus 143 (2): 421–424. Bibcode:2000Icar..143..421M. doi:10.1006/icar.1999.6282. 
  6. ^ Wm. Robert Johnston. "Names of Solar System objects and features". Archived from the original on 12 April 2010. Retrieved 2010-04-03. 
  7. ^ Shoemaker E M (1983). "Asteroid and Comet Bombardment of the Earth". Annual Review of Earth and Planetary Sciences 11: 461–494. Bibcode:1983AREPS..11..461S. doi:10.1146/annurev.ea.11.050183.002333. 
  8. ^ "List Of Aten Minor Planets". Minor Planet Center. 02/04/2010. Retrieved 2010-10-25.