التصنيف النجمي

(تم التحويل من تصنيف النجوم)

تصنيف مورگان كينان الطيفي Morgan-Keenan spectral classification هو طريقة أو أسلوب في التصنيف، تصنف فيه النجوم السماوية على وفق نمطها الطيفي وطبقة تألقها.


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مراتب سـِكي

الترتيب Temperature[1]
(كلڤن)
اللون المعتاد Apparent color[2]خطأ استشهاد: إغلاق </ref> مفقود لوسم <ref>[3][4] Mass[1]
(الكتل الشمسية)
نق[1]
(أنصاف الأقطار الشمسية)
التألق[1]
(bolometric)
خطوط
الهيدروجين
جزء من كل
main sequence stars[5]
O ≥ 30,000 K blue blue ≥ 16 M ≥ 6.6 R ≥ 30,000 L ضعيف ~0.00003%
B 10,000–30,000 K أزرق إلى أزرق أبيض أزرق أبيض 2.1–16 M 1.8–6.6 R 25–30,000 L متوسط 0.13%
A 7,500–10,000 K white أبيض إلى أزرق أبيض 1.4–2.1 M 1.4–1.8 R 5–25 L Strong 0.6%
F 6,000–7,500 K أبيض مصفر أبيض 1.04–1.4 M 1.15–1.4 R 1.5–5 L Medium 3%
G 5,200–6,000 K yellow yellowish white 0.8–1.04 M 0.96–1.15 R 0.6–1.5 L Weak 7.6%
K 3,700–5,200 K orange yellow orange 0.45–0.8 M 0.7–0.96 R 0.08–0.6 L Very weak 12.1%
M ≤ 3,700 K red orange red ≤ 0.45 M ≤ 0.7 R ≤ 0.08 L Very weak 76.45%

The mass, radius, and luminosity listed for each class are appropriate only for stars on the main sequence portion of their lives and so are not appropriate for red giants. A popular mnemonic for remembering the order is "Oh Be A Fine Girl/Guy, Kiss Me" (there are many variants of this mnemonic). The spectral classes O through M are subdivided by Arabic numerals (0–9). For example, A0 denotes the hottest stars in the A class and A9 denotes the coolest ones. The Sun is classified as G2.

Classifications in the Draper Catalogue of Stellar Spectra[6][7]
سكي دريپر تعليق
I A, B, C, D Hydrogen lines dominant.
II E, F, G, H, I, K, L
III M
IV N لم تظهر في الفهرس.
  O Wolf-Rayet spectra with bright lines.
  P Planetary nebulae.
  Q أطياف أخرى.



الألوان المعتادة والظاهرة


تصنيف يركس الطيفي


A number of different luminosity classes are distinguished:

  • 0 hypergiants
  • I supergiants
    • Ia-0 (hypergiants or extremely luminous supergiants (later addition)), Example: Eta Carinae (spectrum-peculiar)
    • Ia (luminous supergiants), Example: Deneb (spectrum is A2Ia)
    • Iab (intermediate luminous supergiants)
    • Ib (less luminous supergiants), Example: Betelgeuse (spectrum is M2Ib)
  • II bright giants
    • IIa, Example: β Scuti (HD 173764) (spectrum is G4 IIa)
    • IIab Example: HR 8752 (spectrum is G0Iab:)
    • IIb, Example: HR 6902 (spectrum is G9 IIb)
  • III normal giants
    • IIIa, Example: ρ Persei (spectrum is M4 IIIa)
    • IIIab Example: δ Reticuli (spectrum is M2 IIIab)
    • IIIb, Example: Pollux (spectrum is K2 IIIb)
  • IV subgiants
    • IVa, Example: ε Reticuli (spectrum is K1-2 IVa-III)
    • IVb, Example: HR 672 A (spectrum is G0.5 IVb)
  • V main sequence stars (dwarfs)
    • Va, Example: AD Leonis (spectrum M4Vae)
    • Vab[8]
    • Vb, Example: 85 Pegasi A (spectrum G5 Vb)
    • "Vz", Example: LH10 : 3102 (spectrum O7 Vz), located in the Large Magellanic Cloud.[9]
  • VI subdwarfs (rarely used). Subdwarf are general represented with a prescript of sd or esd (extreme subdwarf) in front of the spectra.
    • sd, Example: SSSPM J1930-4311 (spectrum sdM7)
    • esd, Example: APMPM J0559-2903 (spectrum esdM7)
  • VII white dwarfs (rarely used)

Marginal cases are allowed; for instance a star classified as Ia0-Ia would be a very luminous supergiant, verging on hypergiant. Examples are below. The spectral type of the star is not a factor.

الرموز الجانبية مثال شرح
- G2 I-II The star is between super giant and bright giant.
+ O9.5 Ia+ The star is a hypergiant star.
/ M2 IV/V The star is either a subgiant or a dwarf star.

الأنواع الطيفية

الرسم التالي يمثل طبقات النجوم بألوان قريبة جداً من تلك الألوان التي تشاهدهم بها العين البشرية. الأحجام النسبية هي من أجل main sequence أو النجوم "القزمة".

تصنيف مورگان-كينان الطيفي

Class O

Class L

Artists vision of an L-dwarf


Class T: methane dwarfs

Artists vision of a T-dwarf

المميزات الطيفية

Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum.[10]

Code المميزات الطيفية للنجوم
: Blending and/or uncertain spectral value
Undescribed spectral peculiarities exist
! مميزات خاصة
comp Composite spectrum
e Emission lines present
[e] "Forbidden" emission lines present
er "Reversed" center of emission lines weaker than edges
ep Emission lines with peculiarity
eq Emission lines with P Cygni profile
ev Spectral emission that exhibits variability
f NIII and HeII emission (for element name followed by roman numeral see spectral line)
f* NIV λ4058Å is stronger than the NIII λ4634Å, λ4640Å, & λ4642Å lines[11]
f+ SiIV λ4089Å & λ4116Å are emission in addition to the NIII line[11]
(f) Weak emission lines of He
((f)) Displays strong HeII absorption accompanied by weak NIII emissions[12]
((f*)) [9]
((f+)) [9]
h WR stars with emission lines due to hydrogen.[13]
ha WR stars with hydrogen emissions seen on both absorption and emission.[13]
He wk Weak He lines
k Spectra with interstellar absorption features
m Enhanced metal features
(n) [9]
[n] [9]
n Broad ("nebulous") absorption due to spinning
nn Very broad absorption features due to spinning very fast
neb A nebula's spectrum mixed in
p تميز غير محدد، نجم مميز.
pq Peculiar spectrum, similar to the spectra of novae
q Red & blue shifts line present
s Narrowly "sharp" absorption lines
ss Very narrow lines
sh Shell star features
v Variable spectral feature (also "var")
w Weak lines (also "wl" & "wk")
d Del Type A and F giants with weak calcium H and K lines, as in prototype Delta Delphini
d Sct Type A and F stars with spectra similar to that of short-period variable Delta Scuti
Code If spectrum shows enhanced metal features
Ba Abnormally strong باريوم
Ca Abnormally strong كالسيوم
Cr Abnormally strong كروم
Eu Abnormally strong اوروپيوم
He Abnormally strong هليوم
Hg Abnormally strong زئبق
Mn Abnormally strong منگنيز
Si Abnormally strong سليكون
Sr Abnormally strong سترونتيوم
Tc Abnormally strong تكنتيوم
Code Spectral peculiarities for white dwarfs
: Uncertain assigned classification
P Magnetic white dwarf with detectable polarization
E توجد خطوط إشعاع
H Magnetic white dwarf without detectable polarization
V Variable
PEC توجد مميزات طيفية

For example, Epsilon Ursae Majoris is listed as spectral type A0pCr, indicating general classification A0 with strong emission lines of the element chromium. There are several common classes of chemically peculiar stars, where the spectral lines of a number of elements appear abnormally strong.

تصنيف القياس الضوئي

انظر أيضاً

الهامش


المصادر

  1. ^ أ ب ت ث Tables VII, VIII, Empirical bolometric corrections for the main-sequence, G. M. H. J. Habets and J. R. W. Heinze, Astronomy and Astrophysics Supplement Series 46 (November 1981), pp. 193–237, قالب:Bibcode. التألقات مشتقة من Mbol figures, using Mbol(☉)=4.75.
  2. ^ The Guinness book of astronomy facts & feats, Patrick Moore, 1992, 0-900424-76-1
  3. ^ "The Colour of Stars". Australia Telescope Outreach and Education. 2004-12-21. Retrieved 2007-09-26.  Check date values in: |date= (help) — يشرح سبب الاختلاف في رؤية اللون.
  4. ^ What color are the stars?, Mitchell Charity. Accessed online March 19, 2008.
  5. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة LeDrew2001
  6. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة drapera
  7. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة draperb
  8. ^ A Low-Dispersion Luminosity Indicator for Solar-Type Dwarfs, Barry, Don C. 1970
  9. ^ أ ب ت ث ج Multiwavelength Systematics of OB Spectra, Walborn, N. R., 2008
  10. ^ SkyTonight: The Spectral Types of Stars
  11. ^ أ ب Pismis 24-1: The Stellar Upper Mass Limit Preserved, J. Maíz Apellániz et al. 2006
  12. ^ Early-type stars in the core of the young open cluster Westerlund2, G.Rauw et al. 2006
  13. ^ أ ب خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة WR

وصلات خارجية