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E-class asteroid





Steins
2867 Šteins
A rare category of asteroid, slightly red in color and spectrally similar to M-class asteroids and P-class asteroids, but of higher albedo (in the range 0.25–0.60). E-class asteroids dominate the Hungaria group of the main belt, though some, including the two largest, 44 Nysa (see Nysa-Polana family and 64 Angelina, are found scattered further out. Their flat reflectance spectra in the 0.3 to 1.0 micron region and high albedos suggest a connection with the aubrite (otherwise known as enstatite achondrite, hence the "E") category of meteorite. However, this link is problematic because aubrites are clearly of igneous origin, whereas some E-class asteroids (including Nysa) show an absorption feature at 3 microns that points to water- and/or hydroxyl-bearing minerals and a non-igneous history.

The Rosetta spacecraft achieved the first fly-by of an E-class asteroid when it passed within 800 km of the main belt asteroid 2867 Šteins on Sep. 5, 2008. Šteins has dimensions of 6.67 × 5.81 × 4.47 km and a mean distance from the Sun of about 2.4 AU.


Related category

   • ASTEROIDS AND OTHER MINOR PLANETS: TYPES AND GROUPS