Classis spectralis

Classis spectralis, in astronomia, est divisio stellarum in classes secundum temperaturam vel magnitudinem. Sunt plures classificationes, quae inter se differunt.

 Classificatio Harvardiana 
500px|right|thumb|Classificatio Harvardiana
Classificatione Harvardiana, stellae dividuntur in classes O—B—A—F—G—K—M—C—S. Plerumque communes sunt stellae classium O—B—A—F—G—K—M, quae appellantur "stellae normales," sed stellae classium C—S (olim R, N) sunt "stellae peculiares," hoc est stellae quae spectrum "peculiare" habent.

 Tabula classium 
 Classis Temperatura Color verus Coror visibilisThe Guinness book of astronomy facts & feats, Patrick Moore, 1992, 0-900424-76-1 — Explains the reason for the difference in color perception. Massa(in massis Solis) Radius(in radiis Solis) Luminsoitas  Lineae Hydrogenii % e stellis seriei capitalis O 30,000–60,000 K caeruleus caeruleus 60 M☉ 15 R☉ 1,400,000 L☉ debiles ~0.00003% B 10,000–30,000 K albus-caeruleus albus caeruleus albusque 18 M☉ 7 R☉ 20,000 L☉ medii 0.13% A 7,500–10,000 K albus albus 3.1 M☉ 2.1 R☉ 80 L☉ lucidi 0.6% F 6,000–7,500 K ochroleucus albus 1.7 M☉ 1.3 R☉ 6 L☉ medii  3% G 5,000–6,000 K flavus ochroleucus 1.1 M☉ 1.1 R☉ 1.2 L☉ debiles 8% K 3,500–5,000 K aurantius rutilus 0.8 M☉ 0.9 R☉ 0.4 L☉ admodum debiles 13% M 2,000–3,500 K ruber flammeus 0.3 M☉ 0.4 R☉ 0.04 L☉ admodum debiles >78%

 Classificatio Yerkes 
Factor supplementaruis afficiens in characterem spectri est densitas stratorum exteriorum stellae, dependens a massa et densitate stellae, hoc est a luminositate. Admodum a lumnositate SrII, BaII, FeII, TiII dependunt, propterea est differentia spectrorum stellarum gigantum et pumilionum aequalibus classibus Harvardianis.

Ha clssificatione stella habet classem luminocitatis:
 I Supergigantes
 Ia-0 hypergigantes vel lucidissimi supergigantes
 Ia lucidi supergigantes, e.g. Deneb (spectrum A2Ia)
 Iab Supergigantes mediocriter lucidi
 Ib minus lucidi gigantes, e.g. Betelgeuse (spectrum M2Ib)
 II Lucidi gigantes
 IIa, e.g.: β Scuti (HD 173764) (spectrum G4 IIa)
 IIab, e.g.: HR 8752 (spectrum G0Iab:)
 IIb, e.g.: HR 6902 (spectrum G9 IIb)
 III e.g.: gigantes
 IIIa, e.g.: ρ Persei (spectrum M4 IIIa)
 IIIab, e.g.: δ Reticuli (spectrum M2 IIIab)
 IIIb, e.g.: Pollux (spectrum K2 IIIb)
 IV subgigantes
 IVa, e.g.: ε Reticuli (spectrum K1-2 IVa-III)

 IVb, e.g.: HR 672 A (spectrum G0.5 IVb)
 V series principalis 
 Va, e.g.: AD Leonis (spectrum M4Ve)

 Vb, e.g.: 85 Pegasi A (spectrum G5 Vb)
 VI suppumiliones (rare, obsoletum)
 VII pumilio alba (rare, obsoletum)

Classificatio Harvardiana definit Abscissam diagrammatis Hertzsprung—Russell, sed Yerkes classificatio — positionem stellae in diagrammate.
Supplementaria autem praestantia huius classificationis est possibilitas definendi luminocitatem sellae (spectro cognoto), et propterea possibilitas aestimandi distantionem ad stellam.

Sol, pumilio flava, habet classem spectralem G2V.

 Exemplaria spectrorum stellarum variarum 

 Notae 

 Bibliographia 
 Hearnshaw, J. B.  The Analysis of Starlight: Two Centuries of Astronomical Spectroscopy.  Novi Eboraci:  Cambridge University Press, 2014.
 Kaler, James B.  Stars and their Spectra: An Introduction to the Spectral Sequence. Cantabridgiae:  Cambridge University Press, 2011.

Categoria:Astronomia
Categoria:Stellae