Article · Wikipedia archive · Last revised Jul 30, 2026

A-type asteroid

A-type asteroids are relatively uncommon inner-belt asteroids that have a strong, broad 1 μm olivine feature and a very reddish spectrum shortwards of 0.7 μm. They are thought to come from the completely differentiated mantle of an asteroid, and appear to have a high density. One survey found that 7 similar A-, V- and X-type asteroids had an average density of 3.6 g/cm3. A-type asteroids were once thought to be rare, but a 2026 study of data from the Gaia spacecraft showed that they were quite common among members of the Flora and Vesta asteroid families, with an overall abundance among all main belt asteroids of about 2%, significantly higher than earlier estimates.

Last revised
Jul 30, 2026
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A-type asteroids are relatively uncommon inner-belt asteroids that have a strong, broad 1 μm olivine feature and a very reddish spectrum shortwards of 0.7 μm. They are thought to come from the completely differentiated mantle of an asteroid, and appear to have a high density. One survey found that 7 similar A-, V- and X-type asteroids had an average density of 3.6 g/cm3.1

List

A-type asteroids are so rare that as of August 2024, only 17 had been discovered:2

Designation Class Diam. Refs
246 Asporina main-belt 50.891 km MPC · JPL
289 Nenetta main-belt 37.586 km MPC · JPL
446 Aeternitas main-belt 53.562 km MPC · JPL
863 Benkoela main-belt 38.724 km MPC · JPL
1126 Otero main-belt 10.974 km MPC · JPL
1600 Vyssotsky main-belt 7.413 km MPC · JPL
1951 Lick Mars-crossing 5.57 km MPC · JPL
2234 Schmadel main-belt 9.473 km MPC · JPL
2423 Ibarruri Mars-crossing 4.899 km MPC · JPL
2501 Lohja main-belt 10.218 km MPC · JPL
2715 Mielikki main-belt 13.252 km MPC · JPL
2732 Witt main-belt 11.001 km MPC · JPL
3352 McAuliffe Amor 2.1 km MPC · JPL
4142 Dersu-Uzala Mars-crossing 7.1 km MPC · JPL
4713 Steel main-belt 6.286 km MPC · JPL
4982 Bartini main-belt 7.975 km MPC · JPL
5641 McCleese Mars-crossing 5.68 km MPC · JPL
Diameter: averaged estimates only; may change over time
See also

See also

References

References

  1. P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  2. "JPL Small-Body Database Search Engine: spec. type = A (SMASSII)". JPL Solar System Dynamics. Retrieved 2024-08-15.
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