65 lines
3.3 KiB
Plaintext
65 lines
3.3 KiB
Plaintext
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TAXONOMIC CLASSIFICATIONS OF ASTEROIDS
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David J. Tholen
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Institute for Astronomy
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2680 Woodlawn Drive
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Honolulu, HI 96822
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Since the last Asteroids book was published, there have been two taxonomic
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classification schemes developed and applied to the body of available color
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and albedo data (Tholen, 1984; Barucci et al., 1987). Asteroid taxonomic
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classifications according to these schemes are reproduced in the table. The
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Barucci et al. classifications have been copied directly from the paper they
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published in Icarus. Their classifications are based on a combination of
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eight-color photometry and IRAS albedos. The Tholen classifications are
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essentially the same as those supplied to the IRAS Asteroid Advisory Group
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in November, 1983, and as such, are not based on the IRAS albedos. This list
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consists of the classifications tabulated in Tholen (1984), but extended by a
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rigorous application of the classification scheme to those objects with UBV
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colors (Bowell et al., 1979), and a non-rigorous application to those objects
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with 24-color spectra (Chapman and Gaffey, 1979). A few of the classifications
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given here disagree with the ones given by Tholen (1984). These discrepancies
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are flagged in the Notes column. In some cases, the classifications of objects
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in the X and C spectral classes are based on unpublished albedos provided by
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Tedesco and Gradie. Although IRAS albedos are available that would permit the
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elimination of some classification ambiguities, caution is advised when
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applying IRAS albedos, because in many cases the IRAS fluxes have been
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overestimated, resulting in underestimated albedos.
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Two differences between Tholen's 1984 list and this list are apparent. The
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letter X has been used to stand for E or M or P. Tholen (1984) used EMP,
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which could be misinterpreted as meaning E is most likely, M is next most
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likely, and P is least likely. Note that the E, M, and P classes are
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spectrally degenerate, so in the absence of albedo information, their similar
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spectra can be represented by a single letter. Also, the letter I has been
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introduced to stand for Inconsistent data. In Tholen (1984), 515 Athalia was
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given a stand-alone U classification, due to its S-type spectrum but uniquely
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low albedo. However, because of the desire to use U as only a suffix, the
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letter I was introduced.
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The following notation appears in the classifications:
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U suffix indicating an unusual spectrum; falls far from cluster center
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: suffix indicating noisy data
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:: suffix indicating very noisy data
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--- indicates data that are too noisy to permit classification
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(essentially all types would be allowed)
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Due to popular demand, orbital group designations have been included in this
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table. The 2- or 3-letter abbreviations stand for the following groups:
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ATE Aten
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APO Apollo
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AMO Amor
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MC Mars crosser
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HUN Hungaria
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PHO Phocaea
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GRI Griqua
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CYB Cybele
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HIL Hilda
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TRO Trojan
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Explanatory notes and references are given in file TAXONOMY.NOT. This list
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was revised as of 1988 March 20 and therefore supercedes earlier tabulations.
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