6. B2
The blend near 4072 is weaker than at B1. Si II 4128-4130 is fainter than in class B3. The luminosity classes were determined from the ratios 3995: 4009, 4121: 4144, 4387: 4552 and from the appearance of the wings of the hydrogen lines. The stars Peg and Cas are located between classes B2 and B3.
Star | MKK | a | m | HD | Notes | |
Peg...... | B2.5 IV | 0:08 | +14°38' | 2.9 | B2 | |
Cas..... | B2.5 IV | 0:31 | +53 21 | 3.7 | B3 | |
Ori...... | B2 IV | 5:19 | + 6 16 | 1.7 | B2 | |
2 Ori..... | B2 I | 5:58 | +20 8 | 4.7 | B2p | |
Sco...... | B2 IV | 15:52 | -25 50 | 3.0 | B2 | |
Oph...... | B2 V | 16:19 | -23 13 | 5.2 | B5 | 1 |
Oph...... | B2 IV | 17:15 | -24 54 | 3.4 | B3 | |
Sco...... | B2 IV | 17:26 | -37 2 | 1.7 | B2 | |
9 Cep...... | B2 I | 21:35 | +61 38 | 4.9 | B2p | 2 |
12 Lac..... | B2 III | 22:37 | +39 42 | 5.2 | B2 | |
1. The He I lines are as strong as in other B2 stars and are considerably stronger than at class B5. The H lines are strong and broad; this has been taken to be an effect of low luminosity in a B2 spectrum rather than a reason for classifying the star as B5. The H lines are somewhat weaker than in UMa (B3). All spectral lines are very broad. | ||||||
2. The star 9 Cep is a pronounced supergiant but spectroscopic evidence ( 3995: 4009, 4387: 4552, intensity of H lines) indicates that it is definitely less luminous than Ori. |
The luminosity effects are so well marked at B2 that there is no ambiguity in the location of any of the stars in the five luminosity classes used.
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