SPECTROSCOPIC OBSERVATIONS OF MIRA CETI, 1934tT952 Alfred H. Joy 1954ApJS....1...39J Mount Wilson and Palomar Observatories Carnegie Institution or Washington California Institute of Technology Received August 7,1953 ABSTRACT The use of coudé spectrograms with dispersions up to 2.3 A/mm permits a more critical study of the spectroscopic behavior of Mira Ceti than was possible with lower dispersions. Eighty-eight spectrograms were measured for velocity. Absorption lines.—Radial velocities deduced from 70 selected lines, representing 16 cycles of the star’s variation, indicate fluctuations from cycle to cycle in amounts comparable with the range within a single cycle. In each cycle, maximum velocity of recession usually occurred shortly after maximum light, but the observations near mimmum light are too few to permit conclusions with regard to their application to the pulsation theory. Different elements yield slightly different velocities. The displacements of the Fe lines are correlated with the excitation potential. Emission lines.—The intensity of the emission varies in different cycles, and the incidence of various lines of different elements and different multiplets is peculiar. In general, the velocities from the bright lines are more regular than those of the absorption lines. The velocities of recession of the metallic lines increase with phase, but the hydrogen velocities show approach until phase +65 days and then join the curve of the metals. With respect to the reversing layer, the velocities are always outward. Bright-line velocities are also correlated with excitation potential. Certain lines are greatly enhanced by fluorescent effects. The visual companion.—Variations in the relative intensity of the spectrum of the visual companion indicate that the period of light-fluctuation may be about 12-14 years. The sharp reversal in the bright H and K lines shows a velocity of +52.3 km/sec, which may be the velocity of the star. No other absorp- tion lines occur except the strong P Cygni absorption accompanying the hydrogen lines. Discussion.—Velocity variations within the cycle are confirmed, but the evidence for volume pulsa- tion of the whole star is open to question. Since 1926, when an extended report1 on low-dispersion spectroscopic observations of Mira Ceti was issued, many coudé spectrograms of the star have been obtained at Mount Wilson by P. W* Merrill, W. S. Adams, and A. H. Joy for various investigations and for recording the variations in different cycles. While these observations have not been systematic or exhaustive, the use of considerably higher dispersion makes possible a more precise examination of many details than has heretofore been possible. At the coudé spectrograph of the 100-inch telescope a dispersion of 10.3 A/mm was used to good advantage at all phases except near minimum light. At phases of greatest brightness the dispersion was, at times, increased to 2.9 A/mm. In 1950 a few spectrograms with dis- persions of 2.3 and 9.1 A/mm were obtained by I. S. Bowen at the 200-inch Hale tele- scope. In addition, 117 spectrograms with dispersions of 36 and 75 A/mm, exposed at the 60- and 100-inch reflectors, were used for checking and comparison. In Table 1 the coudé spectrograms measured for velocity are listed, together with the velocity results from absorption and emission lines. The number of lines used in deter- mining the velocity from each plate appears in parentheses. The dispersion of the spectro- grams is in the last column. The phases from maximum light, in the fourth column, are computed from the maxima of Table 2. The measurement has been shared by Miss Sylvia Burd. The mean systematic difference in our measures is less than 0.1 km/sec, and our accidental errors are nearly identical in amount. Because of the accuracy attained in 1 A. H. Joy, Mt. W. Contr., No. 311; Ap. 63, 281, 1926. 39 © American Astronomical Society • Provided by the NASA Astrophysics Data System TABLE 1 Velocity Observations of Mira Ceti 1954ApJS....1...39J Velocities (Km/Sec) Phase Disp. Plate JD from Coudé Date 2400000 + Max. (A/ Neutral Bright Bright Mu) (Days) Absorption Bright Hôy Fe n 885. 1935 Jan. 24 27827 + 24 +67.1 (7) +48.3 (6) +48.6(1) +47.7(1) 7.9 890. Jan. 25 7828 + 24 +63.4(16) +45.8 (9) +42.4(2) +54.0 (2) 7.9 975. 1935 Dec. 6 8143 - 7 +42.6 (1) 2.3 987. Dec. 12 8180 + 30 +57.2 (51) +42.7 (3) +40.8 (1) 7.9 1208. 1936 Oct. 25 8467 - 14 +45.0 (1) 3.1 1209. Oct. 26 8468 - 13 +68.3 (20) +45.2 (1) 7.9 1286. Dec. 23 8526 + 45 +45.9 (6) +53.0 (1) 3.1 1287. Dec. 23 8526 + 45 +63.7(20) +46.4 (9) +50.5 (2) 2.5 1290. Dec. 29 8532 + 51 +62.4(31) +46.3 (17) +47.2 (2) +53.9 (3) 10.3 1298. 1937 Jan. 4 8538 + 57 +44.4 (6) +50.6(1) 3.1 1315. Jan. 31 8565 + 84 +43.5 (1) +40.8(1) 3.1 1319. Feb. 1 8566 + 85 +59.7(50) +47.8 (11) +46.9 (1) +51.4(1) 10.3 1472. 1937 Sept. 15 8792 - 38 +56.6(11) +43.7 (1) 20.0 1513. Oct. 18 8825 - 5 +58.2 (30) +43.1 (1) +49.8(1) 10.3 1518. Oct. 19 8826 - 4 +45.7 (1) +47.7(1) 10.3 1524. Oct. 20 8827 - 3 +48.6(1) 10.3 1540. Nov. 13 8851 + 21 +57.9(27) +44.2 (2) +46.3(2) 10.3 1774. 1938 Sept. 9145 - 14 +45.1 (1) 3.1 1775. Sept. 9145 - 14 +44.6 (1) 3.1 1785. Sept. 9151 - 8 +57.0 (37) +43.6(1) 10.3 1801. Oct. 9180 + 21 +45.1 (3) +56.5 (2) 3.1 1843. Dec. 9236 + 77 +61.2 (10) +51.0 (5) +61.0(1) 10.3 1868. Dec. 29 9262 +103 +52.5 (1) 3.1 1870. Dec. 30 9263 +104 +62.4(25) +52.6(10) +51.6(1) +57.8(3) 10.3 2114. 1939 Sept. 4 9511 + 30 +49.3 (5) +55.8 (1) 2.9 2115. Sept. 4 9511 + 30 +64.4(24) +48.0 (7) +52.6(1) 2.9 2118. Sept. 21 9528 + 47 +48.8(12) +56.9 (2) 2.9 2119. Sept. 21 9528 + 47 +63.5 (8) +50.1 (11) +56.4(2) 2.9 2120. Sept. 21 9528 + 47 +49.2 (4) 2.9 2133. Sept. 29 9536 -l- 55 +63 ! 2 (66) +48.4(15) +55.3 (3) 2.9 2140. Oct. 21 9558 + 77 +50.1 (6) +56.0(4) 2.9 2141. Oct. 21 9558 + 77 +47.8(10) +54.1(3) 2.9 2173. Nov. 29 9597 +116 +51.0 (6) +53.6(3) 2.9 2423. 1940 Sept. 22 9895 + 75 +61.6(11) +50.2 (5) +54.6(1) 2.9 2426. Oct. 11 9914 + 94 +49.2 (10) +52.3 (3) 2.9 3216. 1943 Sept. 22 30990 +170 +53.2 (19) +49.9 (9) +45.2 (2) +50.1 (3) 10.3 3279. Nov. 12 1041 +221 +53.4 (3) 10.3 3686. 1945 Jan. 1 1457 - 27 +59.9(61) +50.2 (1) 10.3 3695. Jan. 3 1459 - 25 +60.3 (56) 2.9 3703. Jan. 26 1482 - 2 +61.9(21) 2.9 40 © American Astronomical Society • Provided by the NASA Astrophysics Data System TABLE 1—Continued Phase Velocities (Km/Sec) 1954ApJS....1...39J Plate Disp. Date JD FROM Coudé 2400000 + Max. (A/ (Days) Absorption Neutral Bright Bright Mm) Bright Hôy Feu 4042. 1945 Oct. 25 301754 69 +57.5 (30) +46.1 (2) 10.3 4047. Nov. 13 1773 50 +59.2 (39) +43.5 (1) +53.0(1) 10.3 4057. Nov. 20 1780 43 +57.9 (42) +44.2 (1) +53.3 (1) 10.3 4077. Nov. 29 1789 34 +59.8 (43) +43.8 (1) 10.3 4078. Dec. 11 1801 22 +58.1 (51) +44.0 (1) +50.9 (1) 10.3 4079. Dec. 11 1801 22 +57.9 (22) +44.2 (1) 10.3 4102. Dec. 23 1813 10 +57.3 (32) +44.4 (3) +46.7(1) +55.5 (1) 10.3 4103. Dec. 23 1813 10 +57.9 (59) +43.2 (1) +49.6(2) 10.3 4104. Dec. 23 1813 10 +58.5 (34) +42.6 (1) 10.3 4108. Dec. 28 1818 5 +58.8 (40) +45.8 (2) +50.4(2) 10.3 4109. 1946 Jan. 10 1831 + 8 +59.8 (32) +46.7 (3) +47.1(1) +55.2 (2) 10.3 4127. Jan. 15 1836 + 13 +59.0 (35) +48.1 (2) +47.7(1) +54.9(2) 10.3 4138. Jan. 18 1839 + 16 +58.7 (46) +46.4 (3) +46.0(1) +52.5 (2) 10.3 4141. Feb. 5 1857 -F 34 +60.1 (32) +46.8 (3) +49.3(1) +55.2 (3) 10.3 4170. Feb. 14 1866 + 43 +59.9 (32) +46.9 (5) +54.8(3) 10.3 4180. Feb. 17 1869 + 46 +60.5 (93) +48.6 (3) +49.4(2) +54.0(3) 10.3 4457. 1946 Oct. 11 2105 59 +61.8(40) +45.1 (1) +58.3 (1) 10.3 4464. Oct. 13 2107 57 +61.5 (33) +43.6 (1) +56.3 (1) 10.3 4476. Nov. 8 2133 31 +62.3 (37) +44.5 (1) 10.3 4502. Dec. 13 2168 + 4 +61.7 (34) +46.7 (5) +56.7 (2) 10.3 4547.