Ionized strontium is represented in stellar spectra by the and the series. The former contains the important absolute magnitude lines 4215, 4077, which are first seen at about , and reach a maximum[330] near . They appear to have “abnormal” intensities in certain stars,[331] and in the stars are often the finest and sharpest lines in the spectrum. This behavior suggests a high-level origin, but “stationary Strontium,” [Pg 82] although suggested by Plaskett[332] as likely to occur, has not yet been observed. YTTRIUM (39) Numerous lines of yttrium[333] are found in the solar spectrum. The lines of the ionized atom are somewhat stronger than the lines of the neutral atom. The lines of the neutral element which can be identified in the solar spectrum are contained in the following table. TABLE XV Series Wave-Lenght Int. Attribution Int. Wave-Lenght 3620.94 20 Y? 00 3621.110 3592.91 10 Y 0 3593.040 3552.69 3 - - 4128.32 30 00 4128.46 4039.83 5 Y 00 4040.013 4047.65 8 Y 4047.823 4102.38 20 Y 0 4102.541 4167.52 10 00 4167.737 4077.39 20 La, Y ? 4077.498 The multiplets at 4174, etc., and at 4674, etc., and the multiplets, do not appear in the solar spectrum. None of the above lines is strong enough to be seen in the spectra of the stars. IONIZED YTTRIUM [Pg 83] Four of the multiplets attributed to ionized yttrium[334] are satisfactorily identified in the solar spectrum. The wave-lengths and identifications are contained in Table XVI, p. 83. The arrangement is as in Table XI. TABLE XVI Series Wave-Lenght Int. Attribution Int. Wave-Lenght * 3710.30 100 Y 3 3710.431 3832.87 20 3833.026 * 3774.33 50 Y 3 3774.473 3878.27 4 1 3878.334 3818.37 10 Y 1 3818.487 * 3788.69 30 2 3788.839 3600.72 50 Y 3 3600.880 3548.99 20 Y? 2 3549.151 3664.59 20 Y 2 3664.760 3611.05 30 Y, Mg? 2 3611.189 3584.51 10 Y 2 3584.660 3628.70 10 Y, Mg? 2 3628.847 3601.91 20 Y 1 3602.060 4309.61 20 1 4309.792 4235.71 6 0 4235.894 4199.283 3 00 4199.434 4398.03 15 In zircon * 1 4398.178 4358.72 8 Y-Zr 0 4358.879 4422.60 10 Fe, Y 3 4422.741 5087.42 10 Y? 1 5087.601 4982.12 3 000 4982.319 5320.77 1 - - 5205.71 10 Y 0 5205.897 5119.10 3 00 5119.292 5289.81 2 000 5289.988 5200.41 8 V 0 5200.590 * But not Zr. ZIRCONIUM (40) The ultimate lines of the zirconium atom[335] are all found in the solar spectrum, far into the ultra-violet.