R-type asteroids are moderately bright, relatively uncommon inner-belt

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...

s that are spectrally intermediate between the V and A-type asteroids. The spectrum shows distinct

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers qui ...

and

pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

features at 1 and 2

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of ...

s, with a possibility of

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

. Shortwards of 0.7 μm the spectrum is very reddish. The IRAS mission has classified

4 Vesta Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, th ...

246 Asporina Asporina (minor planet designation: 246 Asporina) is a sizeable main-belt asteroid. It is classified as one of the few A-type asteroids. It was discovered by A. Borrelly on 6 March 1885 in Marseilles and was named after Asporina, a goddess wor ...

349 Dembowska Dembowska (minor planet designation: 349 Dembowska) is a large asteroid of the main belt, discovered on 9 December 1892, by the French astronomer Auguste Charlois while working at the observatory in Nice, France. It is named in honor of the Baron ...

, 571 Dulcinea and 937 Bethgea as type R; however, the re-classification of Vesta, the V archetype, is debatable. Of these bodies, only

is recognized as being type R when all wavelengths are taken into account.

List

As of February 2019, at least 5 asteroids have been classified as R-type:

List

References

See also