E-type asteroid

Last updated • 1 min readFrom Wikipedia, The Free Encyclopedia
E-Type asteroid 2867 Steins 2867 Steins by Rosetta (reprocessed).png
E-Type asteroid 2867 Šteins

E-type (enstatite achondritetype) asteroids are asteroids thought to have enstatite (MgSiO3) achondrite surfaces. They form a large proportion of asteroids inward of the asteroid belt known as Hungaria asteroids, [1] but rapidly become very rare as the asteroid belt proper is entered. Some are quite far from the inner edge of the asteroid belt, such as 64 Angelina. They are thought to have originated from the highly reduced mantle of a differentiated asteroid.

Contents

Description

E-type asteroids have a high albedo (0.3 or higher), which distinguishes them from the more common M-type asteroids. Their spectrum is featureless flat to reddish. Probably because they originated from the edge of a larger parent body rather than a core, E-types are all small, with only three (44 Nysa, 55 Pandora, 64 Angelina) having diameters above 50 kilometres and no others above 25 kilometers (the biggest three also orbit atypically far, c. 3 AU, from the Sun). Aubrites (enstatite achondrite meteorites) are believed to come from E-type asteroids, [2] because Aubrites could be linked to the E-type asteroid 3103 Eger. [3]

This grouping may be related to the Xe-type of the SMASS classification.

E-Belt

The E-type asteroids of the Hungaria family are thought to be the remains of the hypothetical E-belt asteroid population. [4] The dispersal of most of that hypothetical E-Belt might have been caused by the outward migration of the gas giants of the Solar System according to simulations done under the Nice model – and these dispersed E-Belt asteroids might in turn have been the impactors of the Late Heavy Bombardment.

Exploration

On September 5, 2008, ESA's robotic spaceprobe Rosetta visited the E-type asteroid 2867 Šteins. [5] Spectral data from the spacecraft confirmed the asteroid was composed mainly of iron-poor minerals such as enstatite (magnesium-rich pyroxene), forsterite (magnesium-rich olivine) and feldspar.

See also

Related Research Articles

<span class="mw-page-title-main">Asteroid belt</span> Region between the orbits of Mars and Jupiter

The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System.

A V-type (volcanic-type) asteroid, or Vestoid, is an asteroid whose spectral type is that of 4 Vesta. Approximately 6% of main-belt asteroids are vestoids, with Vesta being by far the largest of them. They are relatively bright, and rather similar to the more common S-type asteroid, which are also made up of stony irons and ordinary chondrites, with V-types containing more pyroxene than S-types.

<span class="mw-page-title-main">Meteorite classification</span> Systems of grouping meteorites based on shared characteristics

In meteoritics, a meteorite classification system attempts to group similar meteorites and allows scientists to communicate with a standardized terminology when discussing them. Meteorites are classified according to a variety of characteristics, especially mineralogical, petrological, chemical, and isotopic properties.

<span class="mw-page-title-main">M-type asteroid</span> Asteroid spectral type

M-type asteroids are a spectral class of asteroids which appear to contain higher concentrations of metal phases than other asteroid classes, and are widely thought to be the source of iron meteorites.

<span class="mw-page-title-main">2867 Šteins</span> Main-belt asteroid

2867 Šteins is an irregular, diamond-shaped background asteroid from the inner regions of the asteroid belt, approximately 5 kilometers in diameter. It was discovered on 4 November 1969 by Soviet astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnij on the Crimean peninsula. In September 2008, ESA's spacecraft Rosetta flew by Šteins, making it one of few minor planets ever visited by a spacecraft. The bright E-type asteroid features 23 named craters and has a rotation period of 6.05 hours. It was named for Soviet Latvian astronomer Kārlis Šteins.

<span class="mw-page-title-main">44 Nysa</span> Main-belt asteroid

44 Nysa is a large and very bright main-belt asteroid, and the brightest member of the Nysian asteroid family. It is classified as a rare class E asteroid and is probably the largest of this type.

<span class="mw-page-title-main">Achondrite</span> Stony meteorite that does not contain chondrules

An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies. As a result, achondrites have distinct textures and mineralogies indicative of igneous processes.

<span class="mw-page-title-main">Enstatite</span> Pyroxene: magnesium-iron silicate with MgSiO3 and FeSiO3 end-members

Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) – ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, (Mg,Fe)SiO
3
, has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En80Fs20).

<span class="mw-page-title-main">434 Hungaria</span> Main-belt asteroid

434 Hungaria is a relatively small asteroid orbiting in the inner asteroid belt. It is an E-type (high-albedo) asteroid. It is the namesake of the Hungaria asteroids, which orbit the Sun on the inside of the 1:4 Kirkwood gap, standing out of the core of the asteroid belt.

<span class="mw-page-title-main">Asteroid spectral types</span> Classification type of a class of astronomical objects

An asteroid spectral type is assigned to asteroids based on their reflectance 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, the surface and internal compositions are presumably similar, while large bodies such as Ceres and Vesta are known to have internal structure. Over the years, there has been a number of surveys that resulted in a set of different taxonomic systems such as the Tholen, SMASS and Bus–DeMeo classifications.

The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions.

<span class="mw-page-title-main">HED meteorite</span> Group of achondrite meteorites

HED meteorites are a clan (subgroup) of achondrite meteorites. HED stands for "howardite–eucrite–diogenite". These achondrites came from a differentiated parent body and experienced extensive igneous processing not much different from the magmatic rocks found on Earth and for this reason they closely resemble terrestrial igneous rocks.

<span class="mw-page-title-main">3103 Eger</span> Apollo asteroid

3103 Eger is an Apollo and Mars-crosser asteroid that was discovered in 1982, by Miklós Lovas. It was named after the city of Eger, Hungary. It has an albedo of 0.64, making it a highly reflective asteroid.

The Hungaria asteroids, also known as the Hungaria group, are a dynamical group of asteroids in the asteroid belt which orbit the Sun with a semi-major axis between 1.78 and 2.00 astronomical units (AU). They are the innermost dense concentration of asteroids in the Solar System—the near-Earth asteroids are much more sparse—and derive their name from their largest member 434 Hungaria. The Hungaria group includes the Hungaria family, a collisional asteroid family which dominates its population.

<span class="mw-page-title-main">Aubrite</span> Group of meteorites

Aubrites are a group of meteorites named for Aubres, a small achondrite meteorite that fell in 1836 in Aubres near Nyons, France. They are primarily composed of the orthopyroxene enstatite and are often called enstatite achondrites. Their igneous origin separates them from primitive enstatite achondrites and means they originated in an asteroid.

<span class="mw-page-title-main">Enstatite chondrite</span> Rare type of meteorite

Enstatite chondrites are a rare form of meteorite, rich in the mineral enstatite. Only about 200 E-Type chondrites are currently known, comprising about 2% of the chondrites that fall on Earth. There are two main subtypes: EH and EL, classified based on their iron content.

<span class="mw-page-title-main">Zaklodzie meteorite</span> Meteorite found in Poland

The Zakłodzie meteorite is a stony-iron meteorite found in Poland in 1998. Its mass is 8.68 kilograms (19.1 lb). It is composed predominantly from enstatite and meteoric iron. Currently classified as an ungrouped enstatite achondrite its classification is still an ongoing scientific debate.

The Itqiy meteorite is an enstatite-rich stony-iron meteorite. It is classified as an enstatite chondrite of the EH group that was nearly melted and is therefore very unusual for that group. Other classifications have been proposed and are an ongoing scientific debate.

This is a glossary of terms used in meteoritics, the science of meteorites.

<span class="mw-page-title-main">E-belt asteroids</span> Hypothetical extension of the asteroid belt

The E-belt asteroids were the population of a hypothetical extension of the primordial asteroid belt proposed as the source of most of the basin-forming lunar impacts during the Late Heavy Bombardment.

References

  1. McSween, Harry Y. (1999). Meteorites and their parent planets. Cambridge, UK: Cambridge University Press. p. 168. ISBN   978-0-521-58751-8.
  2. Zellner, B.; et al. (1977). "The E asteroids and the origin of enstatite achondrites". Geochim. Cosmochim. Acta. 41 (12): 1759–67. Bibcode:1977GeCoA..41.1759Z. doi:10.1016/0016-7037(77)90208-3.
  3. Gaffey, Michael J.; Reed, Kevin L.; Kelley, Michael S. (November 1992). "Relationship of E-type Apollo asteroid 3103 (1982 BB) to the enstatite achondrite meteorites and the Hungaria asteroids". Icarus. 100 (1): 95–109. Bibcode:1992Icar..100...95G. doi:10.1016/0019-1035(92)90021-X.
  4. Late, Late Heavy Bombardment - Bill Bottke (SETI Talks) – Youtube.com
  5. H. U. Keller, et al. - E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta - Science 8 January 2010: Vol. 327. no. 5962, pp. 190 - 193 doi : 10.1126/science.1179559