![]() In the Tholen classification, the S-type is a very broad grouping which includes all the types in the SMASS S-group except for the A, Q, and R, which have particularly strong "stony" absorption features around 1 μm. The entire "S"-assemblage of asteroids is spectrally quite distinct from the carbonaceous C-group and the often metallic X-group. Sa, Sk, Sl, Sq, and Sr-types containing transition objects between the core S-type and the A, K, L, Q, and R-types, respectively.a "core" S-type for asteroids having the most typical spectra for the S-group.In the SMASS classification, several generally "stony" types of asteroids are brought together into a wider S-group which contains the following types: P-type objects are distinguished from the spectrally similar E-type and M-type asteroids by their lower albedo (in the range 0.02 to 0.06). A survey of 11 S-type asteroids found an average density of 3.0 g/cm 3. A dark type of asteroid, commonest in the outer part of the main asteroid belt at a solar distance of about 4 AU, with a spectrum intermediate between that of C-type asteroids and D-type asteroids. The composition of these asteroids is similar to a variety of stony meteorites which share similar spectral characteristics.ĭue to their volatile-poor (rocky) composition, S-type asteroids have relatively high density. Often there is also a broad but shallow absorption feature centered near 0.63 μm. ![]() ![]() The 1 μm absorption is indicative of the presence of silicates (stony minerals). Their spectrum has a moderately steep slope at wavelengths shorter than 0.7 micrometres (μm), and has moderate to weak absorption features around 1 μm and 2 μm. These largest S-types are visible in 10x50 binoculars at most oppositions the brightest, 7 Iris, can occasionally become brighter than +7.0, which is a higher magnitude than any asteroid except the unusually reflective 4 Vesta. Now its easier to find great businesses with recommendations. The largest are 3 Juno (about 240–250 km across) and 15 Eunomia (230 km), with other large S-types being 29 Amphitrite, 532 Herculina and 7 Iris. They are dominant in the inner part of the asteroid belt within 2.2 AU, common in the central belt within about 3 AU, but become rare farther out. S-type asteroids, with an astronomical albedo of typically 0.20, are moderately bright and consist mainly of iron- and magnesium- silicates.
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