An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) The act of specifying.
2) A particular item, aspect, calculation, etc., in such a description.
3) Something specified, as in a bill of particulars; a specified particular, item, or article (Dictionary.com).

Verbal noun of → specify.

A system that assigns a → spectral type to a star according to characteristics of its spectrum. The earliest attempt to divide stars on the basis of their spectra was the → Secchi classification in the 1860s. This scheme paved the way for the → Harvard classification that led to the current → Morgan-Keenan classification of spectral types. In the Harvard system stars were originally thought to follow an evolutionary sequence from the "early" O and B types to the "late" K and M types. Although this is now known to be wrong, the terms → early-type star and → late-type star are still in use. In the Morgan-Keenan system stars are classified as type O, B, A, F, G, K, or M in order of decreasing → effective temperature, and each type further subdivided into subclasses from 0 (hottest, except for → O-type stars) to 9 (coolest). They are also accompanied by a → luminosity class. In the late 1990s, spectral types L and T were added to the sequence to accommodate the coolest stars and → brown dwarfs (with class Y reserved for the coolest brown dwarfs of all, as yet unobserved).

→ spectral; → classification.

A layered structure of sedimentary rocks in which the individual layers can be traced a considerable distance. The layers can be caused by many differences which include materials of different composition, color, grain size or orientation.

Strati-, from → stratum + -fication from L. -ficare "to do, make."

Ciné, → stratum + bandi, from bastan "to bind, shut; to contract, get, acquire; to coagulate," (Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind, → band).

A fundamental system for the classification of → asteroids based on → albedo and → spectral characteristics. The Tholen scheme includes 14 types with the majority of asteroids falling into one of three broad categories, and several smaller types. → C-type asteroid, → M-type asteroid, → S-type asteroid.

David J. Tholen (1984) Ph.D. thesis, University of Arizona; → classification.

The assignment of telescope time by an expert panel to proposals after evaluating the merits of the observation projects.

→ time; → allocation.

The act or process of truncating, as → disk truncation.

Verbal noun from → truncate.

1) The process of unifying or uniting; union.
2) The state or condition of being unified (Dictionary.com).

Verbal noun of → unify.

The act of verifying. The state of being verified.
The process of research and examination required to establish correctness, authenticity, or validity.

Verbal noun of → verify.