Asteroid pair

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A asteroid Pair ( German translation asteroid pair) are two asteroid with nearly identical track members and the same mineralogical composition without gravitational binding . Due to non-gravitational effects, their lifespan is limited to a few hundred thousand years.

In contrast to the asteroid pair, one speaks of a double asteroid when there is a gravitational bond.

Life cycle

The asteroid pairs have almost identical heliocentric osculating orbital elements and with a back integration, a point in time can be determined at which the two asteroids were at a mutual distance smaller than the Hill radius . The color index and the spectrum of the two minor planets are indistinguishable.

The following hypotheses have been put forward regarding the development:

  • The breakup of an asteroid by a meteoroid impact
  • Fission of an asteroid by increasing its rotation due to the YORP effect
  • Splitting of a double asteroid through gravitational and non-gravitational forces such as scattering through a passage close to a planet or the YORP effect

Some young asteroid pairs show at times during their period of rotation a surface that has only slightly aged due to space erosion , while this cannot be observed in others. The former was probably caused by the breaking up of an asteroid, in which the internal cohesive forces of the rubble pile were no longer sufficient. Today it is assumed that the asteroid pairs are formed by the cleavage of a double asteroid, while by a Meteoroideneinschlag Although Asteroid families can arise and groups, but an asteroid pair diverge, the resulting orbital elements too strong.

The lifespan of the asteroid pairs is limited by the gravitational interaction with planets and the YORP effect. After a few hundred thousand years, the orbital elements differ so much that the two asteroids can no longer be perceived as a pair (in contrast to asteroid families whose age can be estimated to be several billion years).

Examples

literature

  • Seth A. Jacobson: Asteroid Systems: Binaries, Triples, and Pairs . In: Astrophysics. Solar and Stellar Astrophysics . 2015, arxiv : 1511.00566v1 .
  • Jean-Luc Margot, Petr Pravec, Patrick Taylor, Benoît Carry, Seth Jacobson: Multiple origins of asteroid pairs . In: Astrophysics. Solar and Stellar Astrophysics . 2015, arxiv : 1504.00034v3 .
  • David Polishook: Spin Axes and Shape Models of Asteroid Pairs: Fingerprints of YORP and a Path to the Density of Rubble Piles . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1406.3359v1 .
  • David Polishook et al .: Observations of "Fresh" and Weathered Surfaces on Asteroid Pairs and Their Implications on the Rotational-Fission Mechanism . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1401.4465v1 .
  • P. Pravec: Formation of asteroid pairs by rotational fission . In: Astrophysics. Solar and Stellar Astrophysics . 2010, arxiv : 1009.2770v1 .

Individual evidence

  1. ^ Adrián Galád: Effect of main belt perturbers on asteroid-pair age estimation . Astronomy and Astrophysics 548, A25 2012, pages 1f, 4 and 7 ( PDF , English)