Table Of ContentRef. p. 131 4.1 Physical parameters of the stars 1
4 The stars
4.1 Physical parameters of the stars
4. I .O General remarks
The physical parameters given here are integral values which characterize the physical properties of a star
as a whole, especially mass, luminosity, radius, effective surface temperature, age, spectral type, color, absolute
magnitude, surface gravity, equatorial rotational velocity. Characteristic diagrams such as the luminosity-tempera-
ture (Hertzsprung-Russell) diagram enable us to describe the evolution of stars.
4.1.1 Classification of stellar spectra ‘)
4.1.1.1 The (improved and extended) Harvard classification
The stars can be arranged in a linear sequence according to the general appearance of their line spectra.
The essential parameter is the ionisation temperature of the stellar atmosphere. As the color temperature decreases
from 0 to M, the stars become redder.
-7
55 @K 25 11 6.0 5.1 3.6
=c carbon stars 1.0 I I I I I
iG
secondary series
P 1
I / 7
W-O-B-A-F-G-K-M main series
A 03 BO A0 FO GO KO MO
early inter- late types SP-
Fig. 1. The relative intensities Ire, of the most important
mediate
lines in the spectra of the main series O,..M (illustrated
schematically).
99.95 % of the stars brighter than 8?‘0 (completeness limit of the Henry Draper Catalogue) belong to the main
series 0 to M.
The spectral classes SP are given as decimals (e.g. 09,09.5,09.7, BO, Bl, . . .). Agreement is about f0.6 of a sub-
division [l]. The classification is made either based upon a summary description, or by determining the intensity
ratios between certain (neighbouring) lines, or by comparison with the spectra of standard stars. The classification
criteria may vary for spectra of different dispersions and wavelength regions.
Detailed descriptions of the line spectra of selected stars are referenced, e.g. in [2, 3, 41. A selected list is given
in Table 10, p. 7.
Table 1. Spectral classification of stars with predominant emission lines (hot stars) [S].
SP Standards Spectral characteristics
P NGC7027, Planetaries or planetary nebulae (see 5.4): many emission lines of very high
NGC6720 excitation, including forbidden lines
Q GK Per 1901 Novae (see 5.1.3.2) p
DQ Her 1934
W y2Vel (WC7 -t- 07) Wolf-Rayet stars (=WR stars; see 5.2.1.2): very broad, intensive emission
lines of H, He I, He 11 are superposed on a continuum which is especially
intensive in the blue-UV region
WN HD 192 163 (WN6) a) nitrogen sequence WN5...8 with strong emission lines of N III, IV, V
WC HD 192 103 (WC7) b) carbon sequence WC5...8 with strong emission lines of C II, III,
IV, 0 III.. .o VI
Details of subclasses of WR stars are given in Table 2, page 3.
See also 4.1.1.3, Table 9a.
‘) In the following tables all wavelengths are given in [A], if not stated otherwise.
Schmidt-Kaler
2 4.1 Physical parameterso f the stars [Ref. p. 13
For Tahlc 2. seen ext page.
Table 3. Spectral types with predominant absorption lines (main series O...M).
For any two lines a and b in the third column:
a>b line a stronger than lint b
a=b lines a and b have the samei ntensity
a: max lint a has maximum intensity at this spectral type
arOS<AO> lint a has half the intensity of the same lint in spectral type A0
az0.1 H6 line a has one tenth of the intensity of the line H6
a%20 line a has twice the intensity as the same line in the solar spectrum
SP Standards Spectral characteristics
0 Intensive (blue) continuum, predominant absorption lines of He II,
additionally of C III, N 111S, i IV [S]. If N III 4634/40/41a ppears
in emission the star is called Of (see5 .2.1.1),if He II 4686,
it is Onfp. See [8].
03 HDE 3033 08 He 14471/He 114541= O.l
04f HD 190429A =0.2
05 0-l HD 15558 =0.3
06 fp h’ Cep =0.6
07 HD 190864 =0.9
08 h Ori =1.3
09 1 Ori = 1.8
BO T Sco, E Ori He I > He II; C III 4650 and Si IV 4089/4116:m ax;
H6 = 1.5 He I 4026.
B3 x4 Ori He I: max: H (Balmcr lines) z0.5<AO> ; 0 II and Si IV very weak.
B5 cpV el Si114128/4131>He14121.
BS j3 Per HeI4471=Mg114481; H6=15HeI4026;
metal lines appear.
A0 CLC Ma Balmer series dominating (H: max); Mg II 4481 most conspicuous
after Balmer lines: K (Ca II 3934) x0.1 H6; Si II: max: depression
of UV continuum by continuous Balmer absorption.
A5 j3T ri, ci Pit Ca II (K)=0.9 (Ca II (H)+HE} and >H6;
Fe 14299/4303a nd Ti II 4303 strong.
FO 6 Gem, a Car Balmer series x0.5<AO> ; Ca II (K)=Ca II (H)+Hc=3 H6;
many metal lines: G-band 4307 (Fc, Ti, Ca) appearing.
F5 CLC Mi, Q Pup Balmer lines 220; Ca 14227=0.5 Hy; G-band = 0.6 Hy.
GO u Aur. j3 Hyi Solar-type spectrum (sun: G 2 or somewhat later); very intense metal
lines: Ca I 4227= H6; G-band = 2 Hy = 3 Fe I 4325.
KO 01B oo, u Phc Metal lines further enhanced,B almer lines further weakened;
CaI4227=2Fe114172=3FeI4383; Fe14325=2Hy;
Ca II (H, K): max.
K5 u Tau Similar to sunspot spectrum; Ca I and II dominating: G-band
dissolved in lines: green TiO-bands appearing.
MO... 2 (Ma) PA nd (MO), TiO-bands dominating (esp. 4762...4956, 5168...5445);
u Ori (M2) Ca I4227 strongest line.
M3... 5 (Mb) I[ Aur (M3) Subclassificationb y increasing intensity of the green and red
M6,..10 (MC) c~P er (M6) (665I , 7054,7589)b and systems.
MOc...MlOe (Md) 0 Cet (M6c) Balmcr lines (at least Ha) in emission.
Schmidt-Kaler
Ref. p. 131 4.1 Physical parameters of the stars 3
Table 2. The subclasses of the Wolf-Rayet stars
(according to the intensity ratio He II 5441/He 15875)
CT6 1.
He II 5441
SP Intensity ratio
He1 5875
WN5 0.1 N V4605...22/He II 4686=0.2
WN6 0.5
WN7 1.5 N III 4640jHe II 4686 =0.5
WN8 5.0 =1.5
WC6 0.5 C III 5696/C II 5812 =0.3
WC7 1.5 =0.7
WC8 = 3.0
The WR stars are divided into a narrow-line (HD 93 131
WN6-A) and a broad-line (HD 191765W N6-B)
sequence[ 7].
Table 4. Spectral classification of special late type-stars (seea lso 5.2.3).
SP Standards Spectral characteristics
S d Gru Strong bands of ZrO and YO, Lao, TiO; subclassification by strength of TiO
R Gem and ZrO bands; Ca II (H, K), Ca 14227, Ba II 4554. Very rare type;
RAnd transitions to class M.
R BD 10” 5057 (RO) Strong bands of CN and CO instead of TiO in classM ; subclassificationb y
HD 52432( R5) strength of bands.
N 19 Psc (NO) Swan bands of C,, Na I (D), Ca I 4227,f or the rest similar to R; subclassification
(=Na) by strength of bands.
The “carbon series” CO..C7, corresponding to classesR , N, branches off the main seriesa t G5, running parallel
to the oxygen-rich G5...M4 main series.
Table 5. Pecularities not covered by the classification criteria and expressedb y prefixes or suffixes.
Prefixes Suffixes
especially sharp lines, characteristic of supergiants, n, nn (=nebulous) diffuse lines ‘)
C
aCyg:cA2 sharp lines
S
g features typical for normal giants, c1A ur: gG0 e, em emission lines
d features typical for dwarf stars, CIC Ma: dA0 p CYg emission lines with a violet absorption
sd featurest ypical for subdwarfs component (expandingg aseouse nvelope)
w featurest ypical for white dwarfs P, pet peculiar line intensities
m metal
AP peculiar A stars, see5 .2.2.1
Arn...Frn metallic-line stars, see5 .2.2.2
con purely continuous spectrum (often class 0)
camp composite spectrum
v, var variable spectrum
k interstellar Ca II (K) absorption line
‘) Diffuse lines (n, nn) are often observedi n rapidly rotating stars seene quator-on.
Schmidt-Kaler
4 4.1 Physical parameters of the stars [Ref. p. 13
4.1.1.2 The (Yerkes or) MK system: spectral type and luminosity class
For a given chemical composition the line spectrum of a star is essentially determined by the degree of
ionisation. i.e. not only by the temperature but also by the electron pressure.T his is taken into account in the
Yerkes system [9] by a second parameter, the luminosity class LC. Each luminosity class is subdivided into
subclassesa , ab. b in the order of decreasing luminosity; often, transition classes are also used, e.g. Ib-II.
LC Stars Examples
0 0-Ia Ia- super-supergiants GO Iaa
Ia Iab Ib supergiants Bl Jab
IJa JIab IIb bright giants KOJI
IJIa IIIab IJIb (normal) giants KO JJJa( gK0)
IVa IVab IVb subgiants K2 IV
Va Vab Vb main-sequences tars G2V (dG2)
(dwarfs)
(VI) subdwarfs (sdK3)
(VW white dwarfs (wA0, DB)
Table 6. MK classification of some bright standard stars: revised system [9].
Star SP LC Star SP LC Star SP LC
E Ori B 0 la 6 Ori 09.5 II Y Peg B2 IV
x2 Ori B2 Ia E CMa B 2 II 19 Tau B6 IV
f3 Ori B 8 Ia o Sco A 5 II y Gem A0 IV
a Cyg A 2 Ia HR 292 F 0 II FO IV
J.I Cep M2 Ia v Her F 2 JJ ;2 Gl IV
2 Aur B 5 lab E Leo G 1 II q Boo GO IV
CT Cyg B 9 Iab 0 Lyr KO’ II P Ad G8 IV
44 Cyg F 5 Iab y Aql K3 II HD 46 223 04
o’ CMa K2.5 Iab 1 Ori 09 III r PUP 05f
ci Ori Ml-2 Ia-Ib o Per B 1 III 10 Lac 09 V
‘I CMa 09 Ib rJ Tau Bl III T SC0 BO V
< Per Bl Ib tZ12T au Al III q Aur B3 V
u Lep F 0 Ib 5 Leo F 0 III 18 Tau B8 V
u Per F 5 Ib 0 Psc G8 111 u Lyr A0 V
p Cam GO Ib f3 Gem KO IIIb e Gem FO V
C Cep K 1.5 Ib u Ari K2 IIIab 78 UMa F2 V
119 Tau M2 Iab-lb u Tau KS III 0 Corn GO V
J3 And MO JJIa o Dra KO V
X Peg M2+ III 61 K5 V
(3%
HD 147379 MO V
Table 7. Apparent distribution of the bright stars
according to spectral type Sp and luminosity class LC LC SP
[S] p. 289.
0, B A,F G, K, M
I 3% 4 % 4%
II 2% 1% 6 %
III 6% 5% 25 X
IV 3% 3% 4%
V 10% 14% 1 x
w, m 5% 5%
camp
Schmidt-Kaler
Ref. p. 131 4.1 Physical parameters of the stars 5
The MK system has a physical basis, but is strictly instrumentally defined: classification is done purely phenome-
nologically by comparing to spectra of standard stars obtained with exactly the same instrument under identical
conditions. Thus the system is completely defined by its standard stars (listed in [9. s.1 11,w hich includes revisions
of earlier lists and atlases).A n atlas identifying all relevant features and useful also at low dispersions is [2]. The
criteria in Table 8 summarize the essenceo f all previous classification work. Since the MK systema pplies to about
95 % of the whole spectral domain it is generally used as a reference system for all other spectral classifications.
Classification in other spectral regions, e.g. the UV, assumesc onstant spectral types for standards in all spectral
wavelengths.
The calibration of spectral type and luminosity class in terms of physical quantities of the stellar atmospheres
(temperature or temperature equivalents like intrinsic colors; gravity or absolute magnitude; chemical composi-
tion) is treated separately from the empirical determination of spectral type and luminosity class (see 4.1.2).
Table 8. Some of the most important criteria of the MK system.
SP Criteria for Sp type SP Criteria for luminosity
03...09.5 He 14471/He II 4541 0 stars Si IV 4089,4116/He 14120,4143 [S]
BO ...Bl Si III 4552/Si IV 4089 09...B3 (Si IV, He I4116...21)/He 14144
B2 . . .B8 Si II 4128,..30/He 14121 BO’ ’ .B3 N II 3995/He II 4009
B8 . . .A2 He 14471jMg II 4481, Bl . ..A5 wings of Balmer lines
He 14026/Ca II 3934 A3 . . .FO blend 4416/Mg II 4481
A2 . ..F2 Mn 14030...34/4128...32,
430014385 FO . . .F8 4172fCa I4227
F2 . ..K CH 4300 (G-Band)/Hy 4341
F5 . . .G5 Fe 14045/H6 4101, F2 ...K5 (Fe 14045,F e 14063, Ca 14227)/Sr II 4077
Ca I 4227/Hy 4341 G5...M discontinuity at 4215
G5...KO Fe 14144/H& 4101
KO...K5 Ca 14227/4325,4290/4300 K3...M 4215/4260,C a I increasing
4.1.1.3 Abundance effects in spectral classification (see also 5.2)
The revised MK system (MK 78) is defined by the two spectral atlases [lo, 111 and comprises mostly stars of
population I. The boxes are defined by spectral features observed in widened spectra of the blue region (3500)
3800...51008 , at moderate dispersions 60...13OA/mm. Localized third dimensions can only be incompletely
identified, such as strong-helium, Ap, Am stars.
In the domain of the cooler stars three composition indices are sufficient to describe even the most peculiar
spectra (Table 9). They indicate the departure from the strength of the feature in a star of solar composition and
of the same luminosity and temperature as the star considered.
Emission line stars (Be...Ae), P Cyg-, shell- and symbiotic stars (prototype AG Peg, B + M) as well as very
rapidly rotating stars (Bnn.+.Fnn) cannot be classified in the MK system with high accuracy.
Spectral group Characteristic SP Typical star
0, B, A emission line star H CI( or higher Balmer lines) Oe, Be, Ae cpP er B1.5 III-Vpe
in emission
Stars with flat absorption rapidly rotating stars Bnn...Fnn n UMa B3 Vn
profiles
All other peculiarities not fitting into the two-dimensional MK system can be attributed to abundance effects.
Thesec hemically peculiar (CP) stars [ll . ..20] are describedi n Table 9.
Schmidt-Kaler
6 4.1 Physical parameters of the stars [Ref. p. 13
Table 9a. Early-type chemically peculiar (=CP) stars (seea lso 52.1 and 52.2).
Spectral group Abundance group Typical star
WR stars (see5 .2.1.2) C, N, 0 strongly enhanced (N/He z 0.07),
H underabundant
N predominant HD 50896 WN 6
C even more enhanced (C/He g 0.8) HD 192 103 WC 8
OB subdwarfs Balmcr lines too broad for dwarfs, N IV enhanced HD 149382 sdB0
He-strong stars (see5 .2.1.6) He very enhanced HD 124448 B3 p
He-weak stars (see5 .2.1.6) Q(Sp)>Q(UBV) [see4.1.1.6] subdivisions: u Scl B4Vp
Ti-Sr-subgroup
P-Ga-subgroup
Si-subgroup
CNO stars (see5 .2.1.5) anomalies in the abundance of C, N and 0, HD 1045 65 OC9.7 la
respectively HD 1230 08 ON9.7 Iab
Ap stars Hg-Mn (see5 .2.2.1) Hg, Mn, Hg II 3984 enhanced 01A nd B9p Hg-Mn
Ap stars (magnetic stars) enhanced Si, Cr, Sr, Eu, rare earths; 56 Tau Ap Si
(see5 .2.2.1) various subgroups, partly spectrum variable BCrB Fp Sr-Cr-Eu
Am. Fm (metallic stars) weak Ca II and/or SCI I, enhanced heavy 63Tau Am
(see5 .2.2.2) metals;Sp(K)sSp(H)s Sp(M) (Ca II-K: Al ;
metals: F5)
Weak line stars H/metals larger than normal hBoo AOp
HD 161817 sdA2
6 Set stars (see5 .1.2.4) Ca II-K too weak for type 6 Set F3 III-IV
Table 9b. Late-type CP stars (seea lso 5.2.3).
Observed Classification Abundance Remarks Typical star
feature symbols group
Balmer H6 hydrogen Balmer lines much HD 49500
lines stronger or weaker K2- III CN-2 CH-1 Hl
than normal
Ca II 4226 Ca or Na light alkali R Set KO Iab-Ib Ca-1
NaID elements
Fe 4263,427 1, Fe iron-peak “strong-line” or HD 221170
4325.4383, elements “weak-line” stars KO II CN-4 Fe-3
Cr 4254
CN 4216,3883 CN C and/or N, determine temperature ‘pzO ri KO IIIb CN-2
(set 5.2.3.1.2) or total metal type from neutral
atoms of the same
abundance group only
CH G-band CH C and/or H HR 6791
(see5 .2.3.1.1) G8 III CH-3 CN-1
C, Swan bands: Spectral C/H carbon stars, originally X Cnc C 5.4
4737,5165, type c types R and N
etc. (see5 .2.3.2)
continued
Schmidt-Kaler
Ref. p. 131 4.1 Physical parameters of the stars 7
Table 9b, continued
Observed Classification Abundance Remarks Typical star
feature symbols group
4744 12c 13C
4735 12C 12C
13C ratio of isotopes observedo nly in YCVnC5.5 13C3
6260 ’ 3C 14N
12C/13C carbon stars
6206 “C 14N I
Ba II 4554 Ba s-process types G, K HD 199939K l III Ba 4
Sr 114077 (see5 .2.3.1.2) elements
ZrO 4620,464l Zr s-process type S (see5 .2.3.3) U Cas S6eZ r3 Ti 5
elements
Li 6708 Li lithium primarily in types WZ Cas C7 Li 5
C or S; occasionally
in types K or M
A multi-dimensional classification schemef or late spectral types is given in [S] p. 293, Fig. 3.
Table 10, supplementing Table 5 in [S] p. 457 by the literature published since 1964, gives a list of carefully
studied stellar spectra.
Table 10. Line spectra of selecteds tars.
Type Star 1 PI Ref.
WC8+09 I y2 Vel 946... 3 182 Johnson, H.M.: Astrophys. J. Suppl. 36 (1978)2 17
04 If 6 Pup 3150... 8600 Baschek,B.,Scholz,M.: Astron. Astrophys. 15(1971)285
907... 3 196 Morton, DC., Underhill, A.B.: Astron. J. Suppl. 33
(1977)8 3
BOV 7 SC0 3323... 8598 Scholz, M.T.: Abhandl. Hamburger Sternw. 7 (1965)3 19
949... 1560 Rogerson, J.B.,j r., Upson II, W.L.: Astrophys. J. Suppl.
35 (1977)3 7
BOI a E Ori 3 554... 6735 Lamers, H.J.: Astron. Astrophys. Suppl. 7 (1972) 113
953... 3 166 Stalio, R., Selvelli, P.L.: Astron. Astrophys. Suppl. 21
(1975)2 41
Bi Ia- C’ SC0 3437... 6678 Sterken, C., Wolf, B.: Astron. Astrophys. Suppl. 35
(1978)6 9
1230... 3105 Appenzeller, I., Wolf, B.: Astron. Astrophys. Suppl. 38
(1979)5 1
B2 IV Y Peg 3090... 6700 Peters,G .J.: Astrophys. J. Suppl. 30 (1976)5 51
B3V t Her 3586... 6583 Kodaira, K., Scholz, M.: Astron. Astrophys. 6 (1970)9 3
3589... 6644 Peters,G .J., Aller, L.H.: Astrophys. J. 159 (1970)5 25
999... 1467 Upson, II, W.L., Rogerson,J .B.,j r.: Astrophys. J. Suppl.
42 (1980)1 75
B3 Ia o2 CMa 3530... 8863 van Helden, R. : Astron. Astrophys. Suppl. 7 (1972)3 11
B4 Vp 3CenA 3721... 8665 Jugaku, J., Sargent,W .L.W., Greenstein,J .L.:
Astrophys. J. 134 (1961)7 83
B5 Ia q CMa 3 187... 6678 Underhill, A.B., Fahey, R.P.: Astrophys. J. Suppl. 25
(1973)4 63
B8p (Si) HD 1687 33 3457... 6600 Little, S.J.,A ller, L.H.: Astrophys. J. Suppl. 22(1970)1 57
B8 Ia j3 Ori 3670... 4340 Svolopoulos, S.N.: Ann. d’Astrophys.2 9 (1966)2 9
lOlO... 1450 Selvelli, P.L., Crivellari, L., Stalio, R.: Astron. Astrophys.
1765... 3215 Suppl. 27 (1977)1
B9p UW 53 Tau 3677... 4755 Aller, L.H., Bidelman, W.P.: Astrophys. J. 139( 1964)1 71
B9p (Cr-Eu) HR 465 3850... 4707 Aller, M.F.: Astron. Astrophys. 19 (1972)2 48
continued
Schmidt-Kaler
8 4.1 Physical parameters of the stars [Ref. p. 13
Table 10,c ontinued
Type Star 1.[ Al Ref.
AOV CLL yr 1 loo... 1470 Faraggiana, R., Hack, M., Leckrone, D.S.: Astrophys. J.
2000... 3000 Suppl. 32 (1976)5 01
AOP( Cr) E UMa 1100... 1500 Mallama, A.D., Molnar, M.R.: Astrophys. J. Suppl.
1900... 3000 33(1977) 1
AOp (Si) HD 34452 3442... 6678 Tomley, L.J., Wallerstein, G., Wolff, S.C.:
Astron. Astrophys. 9 (1970)3 80
AOp (Si, Eu, Hg) a’ CVn 3850... 4740 Burbidgc, G.R., Burbidge, E.M.: Astrophys. J. Suppl. 1
(1955)431
5000... 6700 Cohen, J.G., Deutsch, A.J., Greenstein,J .L.:
Astrophys. J. 156 (1969)6 29
Al V u CMa 3530... 4417 Kurucz, R.L., Furcnlid, I.: Smithsonian Astrophys. Obs.
Special Report 387 (1979)
A2 VI HD 161817 3350... 6563 Kodaira, K.: Z. Astrophys. 59 (1964)1 39
A2 la QzC YE 1798... 2550 Barbicr, R., Swings, J.P., Delcroix, A., Homack, P.,
Rogcrson,J .B.: Astron. Astrophys. Suppl. 32(1978)69
A7: BD + 39’4926 3748... 6792 Kodaira, K., Greenstein,J .L., Oke, J.B.:
(metal poor) Astrophys. J. 159 (1970)4 85
FSV p Vir 3905,.. 6772 Baschek, B., Holweger. H., Namba, O., Traving, G.:
Z. Astrophys. 65 (1967)4 18
Gov/Kov u Cen A/B 4200... 6855 French, V.A., Powell, A.L.T.: R. Obs. Bull. 173 (1971)
GO Ib p Per ’
G2 Ib uAqr
G5 Ib 9 Peg
G8 Ib &Gem * 5000... 6650 van Paradijs, J.: Astron. Astrophys. Suppl. 11 (1973)2 5
K2 Ib E Peg
K3 lb 3 Cet
K5 lb 5CYiz ’
G5 0-Ia HR 8752 5400... 6800 Luck, R.E.: Astrophys. J. 202 (1975)7 43
G7 IV 11C ep
G8 111 6 Tau 3986,.. 4812 Gratton, L., Natali, G., Nesci, R.: Spectrophotometric
G9 III y Tau \ Atlas, Univ. Roma, Frascati (1975)
G8 III E Vir 4300,.. 6800 Cayrel, G., Cayrcl, R.: Astrophys. J. 137 (1963)431
KO 111 p Gem 3 130... 8700 Ruland, F., Griffin, R., Griffin, R., Biehl, D.,
Holwcgcr, H.: Astron. Astrophys.Suppl.42(1980)391
Kl Illp 37 Corn
KO III x UMa 3700... 6700 Yamashita, Y.: Publ. Dom. Astrophys. Obs. Victoria 12
Kl 111 $ UMa 1 (1967)455
K2 IIIp ct Boo 3600... 8825 Griffin, R.F.: Photometric Atlas ofthe Spectrum of
Arcturus, Cambridge, Phil. Sot. (1968)
11400~~~25100 Montgomery, E.F., Connes, P., Connes,J .,
Edmonds, F.N., jr.: Astrophys. J. Suppl. 19 (1969) 1
K2 Ib Peg 5600... 6300 Warren, P.R., Peat, D.W.: Astron. Astrophys. 17
E
(1972)450
K5 111 CLT au 4540... 6533 van Paradijs, J.: Astron. Astrophys. Suppl. 18(1974)447
Ml lb CLS C0 3600,.. 6600 Davis, D.N.: Astrophys. J. 89 (1939)4 1
M2 lb a Ori 29000~~~38500 Beer, R., Hutchinson, R.B., Norton, R.H., Lambert,
D.L.: Astrophys. J. 172 (1972)8 9
c5.3 UU Aur 15400~~~24000 Querci, M., Querci, F.: Astron. Astrophys. 42 (1975)
329
c5.4 Y CVn 5 170... 6790 Fujita, Y., Tsuji, T.: Publ. Dom. Astrophys. Obs.
Victoria 12 (1965)3 39
Schmidt-Kaler
Ref. p. 131 4.1 Physical parameters of the stars 9
4.1.1.4 Other spectral classification systems
The correlations between previous spectral classification systems and the HD and MK systems are given in
[S] p. 294.
Additional systems and special criteria for spectral type and/or luminosity class, metallicity etc. are described in
[c, 5,22, 231.
The most-important intermediate- and narrow-band systems are summarized in Table 11. See also 4.2.5.
Table 11. Multi-dimensional spectrophotometric systems’).
System Characteristic wavelength Designations
passbands (and half-widths) [A]
Striimgren four-color system 3500 (380) 4100 (200),4 700 (200),5 550 (200) UvbP
(see4 .2.5.4) plus H(3 (150/30)
Geneva seven-color system UBV systemp lus 4020 (170),4 480 (165), UBVB,B,V;G
(see4 .2.5.7) 5400 (200), 5810 (210)
Vilnius seven-color system 3450 (400), 3740 (260),4 050 (220),4 660 (260), UPXYZVS
(see4 .2.5.10) 5160 (210), 5440 (260),6 550 (200)
Vil-Gen system UPB,B,ZVS
BCD/Paris classification wavelength and value of the Balmer AD%
discontinuity, blue gradient, see [S] p. 291
Walraven system ‘) 5400 (710),4 300 (540), 3820 (430), VBLUW
(see4 .2.5.14) 3620 (230), 3250 (140)
Copenhagen system see [S] p. 290 gnkmf
Washington system 3, 3910 (1 loo), 5085 (1050) 6330 (800) CMT, T,
8050 (1500)
DDO five-color system 3, 4886 (186),4517 (76),4257 (73),4166 (83), C (4142), C (4245)
(see4 .2.5.3) additional: 3815 (330), 3460 (383) C (4548)
Eight-color-infrared 3, interference filter bands of 55A:
7120,7540,7810,8120,10395 = 1(104),
10540,10810,10975
‘) The calibrations of the quantities used in the various systems in astrophysical terms and some applications
including the RGU color system, are given in [23].
‘) Early-type stars only.
3, Late-type stars only.
Assuming a general law of interstellar extinction A, (see 4.1.2.2), suitable reddening-free color indices can be
obtained (“Q-method”, see 4.1.1.6) which are used to find effective temperature Teff, surface gravity g, chemical
composition C (and/or microturbulent velocity) etc. Alternatively, the reddening is determined explicitly by
shifting the measured points in a two-color diagram to an unreddened locus. From the five-band photometry
VBLUU: e.g., four color-indices are formed and reduced to three reddening-free indices, and correlated to Krr,
g, C [32, 331. The most commonly used system is uvbyfl; for a photometric bibliography, see [30].
Spectral classification at very low dispersions
Spectral type and, to a certain extent, luminosity classification is possible even at rather low dispersions. Earlier
work is summarized in [S, 241, recent work described in [2,3,25.. .28].
Schmidt-Kaler
10 4.1 Physical parameters of the stars [Ref. p. 13
4.1.1.5 Spectral catalogues and surveys
Spectral classifications up to 1964 arc listed in [S] p. 295. Many catalogues are available on microfiche or
magnetic tape at the Centrc de Don&es Stellaircs, 11 rue de I’UniversitC,S trasbourg. France.
1. Generalc atalogues
Houk. N.: Michigan Catalogue of Two-Dimensional Spectral Types for the HD stars, Vol. I, II etc., Ann. Arbor
(1975,1 978f.3.
Nicolet, B.: Astron. Astrophys. Suppl. 34 (1979) 1: 53845 stars, qualified photoelectric UBV data on homo-
geneouss ystem.
Jaschek.C ., Conde, H., de Sierra, A.: La Plats Obs. XXVIII (2) (1964): Compilation of MK types.
Buscombc, W.: MK Spectral classifications, Third Catalogue, Evanston (1977), Fourth Catalogue, Evanston
(19SO):C ompilation of MK types. supplcmcnting Jaschck et al. (1964).
Kennedy, P.M., Buscombc,W .: MK Spectral Classifications published sinceJ aschck’sC atalogue, Evanston (1974).
2. Catalogueso f special types of stars
OB stars in the MK system:
Hiltner. W.A., Garrison, R.F., Schild, R.E.: Astrophys. J. 157 (1969) 313.
Lesh. J.R.: Astrophys. J. Suppl. 17 (1968)3 71.
Garrison. R.F., Hiltncr, W.A., Schild, R.E.: Astrophys. J. Suppl. 35 (1977) 111.
Walbom. N.R.: Astrophys. J. 161 (1970) L149; 164 (1971) L67; 167 (1972) L31.
0 stars:
Gay, G.: Astron. Astrophys. Suppl. 12 (1973)2 77; 42 (1980)9 1.
Supergiants and 0 stars:
Humphreys, R.M.: Astrophys. J. Suppl. 38 (1978)3 09.
Emission line stars:
Wackerling. L.R.: Mem. R. Astron. Sot. 73 (1970) 153: 5326 early-type emission-line stars.
Jaschck.C ., Ferrer, L., Jaschek,M .: La Plats Obs. XXXVII (1971):C atalogue and Bibliography ofB-typeemission
line stars.
Stephenson,C .B., Sanduleak. N.: Astrophys. J. Suppl. 33 (1977)4 59 and Publ. Warner and SwaseyO bs. 1 No. 1
(1971).
Henize, K.G.: Astrophys. J. Suppl. 30 (1976)4 91.
Carbon stars:
Yamashita. L.: Ann. Tokyo Obs. Ser. 2, 13, No. 3 (1972) 169.
Ap stars:
Bcrtaud. Ch.: Journal Obscrvateurs 42 (1959)4 5: 43 (1960) 129; 48 (1965)2 11; Bidclman, W.P., McConnell. D.J.:
Astron. J. 78 (1973)6 87.
Am stars:
Hauck. B.: Astron. Astrophys. Suppl. 10 (1973)3 85.
Further lists of cataloguesc an be found in
Jaschck. C.: Int. Astron. Union Symp. 50 (1973)2 75.
Golay, M.: Introduction to Astron. Photometry, Reidel, Dordrccht (1974) p. 342.
Reports of Commiss. 45 (Spectral Classification and Multi-Band Colour Indices), Trans. Int. Astron. Union.
Astron. Astrophys. Abstracts., Astron. Rechcninst. Heidelberg (annual).
4.1.1.6 Spectral classification and interstellar extinction from wide-band photometry
The color index (see4 .2.2.5)i s in gcncral a mcasurc of the tcmpcraturc and thus the spectral type of the star.
but it is at the same time changed by interstellar extinction (color excess).S ince the extinction law Ai [29] i\
remarkably uniform over the sky the influence of interstellar reddening can bc eliminated by use of suitable color
Schmidt-Kaler
