R-type asteroids are moderately bright, relatively uncommon inner-belt
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
s that are spectrally intermediate between the
V and
A-type asteroid A-type asteroids are relatively uncommon inner-belt asteroids that have a strong, broad 1 micrometre, μm olivine feature and a very reddish spectrum shortwards of 0.7 μm. They are thought to come from the completely differentiated Mantle (geo ...
s. 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 quickl ...
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 Unit ...
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 prope ...
. Shortwards of 0.7 μm the spectrum is very reddish.
The
IRAS
The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...
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, the ...
,
246 Asporina,
349 Dembowska,
571 Dulcinea
Dulcinea (minor planet designation: 571 Dulcinea) is an asteroid orbiting in the inner main belt. It was named after Dulcinea, a character from Miguel de Cervantes' novel ''Don Quixote''. This is classified as a stony S-type asteroid and it is the ...
and
937 Bethgea
937 Bethgea is a background asteroid from the inner region of the asteroid belt. It was discovered on 12 September 1920 by German astronomer Karl Wilhelm Reinmuth, from Heidelberg
Heidelberg (; Palatine German language, Palatine German: ''He ...
as type R; however, the re-classification of Vesta, the V archetype, is debatable. Of these bodies, only
349 Dembowska 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:
References
See also
*
Asteroid spectral types
An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiate ...
Asteroid spectral classes
R-type asteroids
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