series of neutral helium, the most persistent lines of the element, and this is significant in view of the extremely low pressure that is assigned to the atmosphere of the star on the basis of absolute magnitude.
THE C-STARS
The c-characteristic was first used by Miss Maury[471] to designate stars, found in several spectral classes, that have marked spectral peculiarities. The intensities of some of the metallic lines, chiefly those of ionized atoms, are greatly strengthened for the class, and other lines, chiefly those of the neutral atom, are weakened. The
band becomes markedly discontinuous, and heavy blends at 4072, 4077, become conspicuous. The spectrum of a c-star is unmistakable in appearance.
[TABLE XXVI]
| Wave Lenght | Wave Lenght | Atom | Series | Wave Lenght | Wave Lenght | Atom | Series |
|---|---|---|---|---|---|---|---|
| 3758.8 | 3757.68 | Ti+ | 4325.2 | 4314.98 | Ti+ | ||
| 3759.30 | Ti+ | 4321.1 | Ti+ | ||||
| 3856.2 | 4337.6 | 4337.92 | Ti+ | ||||
| 3863.2 | 4374.7 | Ti+? | |||||
| 3900.7 | 3900.53 | Ti+ | 4395.3 | 4395.04 | Ti+ | ||
| 3913.6 | 3913.45 | Ti+ | 4400.2 | 4399.77 | Ti+ | ||
| 4003.0 | 4002.09 | Fe+ | 4417.9 | 4417.71 | Ti+ | ||
| 4009.4 | 4444.0 | 4443.80 | Ti+ | ||||
| 4012.6 | 4012.40 | Ti+ | 4450.6 | 4450.49 | Ti+ | ||
| 4024.8 | 4025.13 | Ti+ | 4469.5 | 4468.14 | Ti+ | ||
| 4028.5 | 4028.35 | Ti+ | 4471.8 | 4472.93 | Fe+ | ||
| 4030.8 | 4409.6 | 4489.21 | Fe+ | ||||
| 4053.8 | 4053.84 | Ti+ | 4491.6 | 4491.41 | Fe+ | ||
| 4077.9 | 4077.71 | Sr+ | 4501.5 | 4501.27 | Ti+ | ||
| 4122.8 | 4122.64 | Fe+ | 4508.5 | 4508.29 | Fe+ | ||
| 4128.1 | 4128. | Si+ | 4515.4 | 4515.34 | Fe+ | ||
| 4131.4 | 4131. | Si+ | 4520.3 | 4520.24 | Fe+ | ||
| 4143.9 | 4522.9 | 4522.64 | Fe+ | ||||
| 4173.6 | 4173.47 | Fe+ | 4534.2 | 4533.97 | Ti+ | ||
| 4179.5 | 4178.87 | Fe+ | 4534.17 | Fe+ | |||
| 4l87.6 | 4556.0 | 4555.90 | Fe+ | ||||
| 4215.7 | 4215.52 | Sr+ | 4558.9 | ||||
| 4233.6 | 4233.16 | Fe+ | 4564.0 | 4563.77 | Ti+ | ||
| 4271.7 | Fe+? | 4584.0 | 4583.84 | Fe+ | |||
| 4288.1 | 4287.88 | Ti+ | 4586. | ||||
| 4294.3 | 4294.10 | Ti+ | 4619.2 | 4620.52 | Fe+ | ||
| 4297.1 | 4296.56 | Fe+ | 4629.9 | 4629.33 | Fe+ | ||
| 4314.4 | 4312.88? | Ti+ | 4657.0 |
The foregoing tabulation contains a list of the lines that are strongly enhanced in the spectra of the c-stars. Successive columns give the approximate wave-length, taken from Miss Maury’s original list, the laboratory wave-length of the line with which the stellar line is identified, the atom, and the series relations.
The preponderating characteristic lines are clearly those of ionized iron and ionized titanium.[472] All the strong lines of these atoms are found in the c-star spectrum, and they are there stronger than in any other class. It is found that spectra possessing the c-character have in general unusually sharp and narrow lines. It is probable that the lines in the spectrum of a c-star are actually stronger, as well as sharper, than the corresponding lines in a star of the same class and lower luminosity.[473]
