T-type asteroids are rare inner-belt
asteroids of unknown composition with dark, featureless and moderately
red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
spectra, and a moderate absorption feature shortwards of 0.85 μm. No direct
meteorite analog has been found to date. Thought to be
anhydrous, they are considered to be related to
P-types or
D-types, or possibly a highly altered
C-type.
Examples of T-type asteroids include
96 Aegle
Aegle ( minor planet designation: 96 Aegle) is a carbonaceous asteroid and the namesake of the Aegle family located in the outer regions of the asteroid belt, approximately in diameter. It was discovered on 17 February 1868, by French astronom ...
,
114 Kassandra
Kassandra ( minor planet designation: 114 Kassandra) is a large and dark main-belt asteroid. It belongs to the rare class T. It was discovered by C. H. F. Peters on July 23, 1871, and is named after Cassandra, the prophetess in the tales of th ...
,
233 Asterope
Asterope ( minor planet designation: 233 Asterope) is a large main-belt asteroid that was discovered on 11 May 1883, by French astronomer Alphonse Borrelly at Marseille Observatory in Marseille, France. The asteroid was named after Asterope (or ...
, and
308 Polyxo
Polyxo ( minor planet designation: 308 Polyxo) is a main-belt asteroid that was discovered by A. Borrelly on March 31, 1891, in Marseilles. It is orbiting the Sun at a distance of with a low orbital eccentricity (ovalness) of 0.04 and a perio ...
. The infrared spectrum of the first three are similar to the mineral
troilite
Troilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron-rich endmember of the pyrrhotite group. Pyrrhotite has the formula Fe(1-x)S (x = 0 to 0.2) which is iron deficient. As troilite lacks the iron deficiency whic ...
, while 308 Polyxo is modified with hydration features.
[
In 2010, the asteroid ]596 Scheila
Scheila ( minor planet designation: 596 Scheila) is a main-belt asteroid and main-belt comet
orbiting the Sun. It was discovered on 21 February 1906 by August Kopff from Heidelberg. Kopff named the asteroid after a female English student with w ...
was impacted by a projectile. The impact changed its spectrum from T-type to D-type, likely by exposing fresh material that was not weathered.
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 differentiated ...
References
Asteroid spectral classes
*
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