COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 702 Konkoly Observatory Budapest 1972 July 31 SPECTRAL CLASS AND METAL-ABUNDANCE INDEX DETERMINATION FOR 20 RR LYRAE STARS AT LIGHT MAXIMUM The spectral classes of 20 RR Lyrae type stars determined according to hydrogen as well as K(Ca II) lines are given in the Table. The observations were performed with the 70 cm meniscus telescope (dispersion 166 A/mm near H_gamma) of the Abastumani observatory. The stars were photographed on A-500 film with the aid of a spectral camera. The classification was made visually, using the MK standards for AV and FV stars, When classifying, much attention was given to the identity of blackening and quality of the spectra of the stars in question and the standards. The determination of the spectra of the variables was made at their light maxima, since in other phases and especially at minima they were not within the reach of our devices. The analysis of our data shows that during 1 hour near light maximum the change of the spectra is almost unnoticeable. Since, our data are reliable in the sense of coverage of the light curve peaks. These conditions are not kept only for TW Lyn. The phases are computed relative to the elements, given in (1), involving refinements on some occasions. Except BB Vir, we have had several negatives for each star. Only the best negatives were used for classification. For SZ Lyn we give the determinations of the spectra not only for the maxima, but also for other phases, in order to state the constancy of the index DeltaS within the accuracy of the spectral type estimation. We also give extreme values of RR Lyrae spectra obtained in the course of the same night. In this case the variation of DeltaS was observed. In terms of the present and our earlier papers (2,3) we can state that when DeltaS varies with the phase it is always less near to maximum and attains the highest value at light minimum. Therefore in such cases the use of mean values of DeltaS which are met in references, seems to be incorrect. ---------------------------------------------------------------- Star Hel. J.D. Phase Exp. Spectrum H CaII DeltaS ---------------------------------------------------------------- RZ CVn 2441392.387 0.872 20m A8 A1 7 409 0.902 20 A9 A1 8 459 0.999 15 A9 A2 7 41396.392 0.930 15 A9 A1 8 41421.346 0.908 15 A8 A2 6 357 0.928 15 A8 A1 7 369 0.949 15 A9 A2 7 AA CMi 41007.198 0.012 10 A7 A1 6 207 0.030 15 A7 A0 7 RV CrB 41134.455 0.958 15 F0 A2 8 467 0.989 15 F0 A2 8 478 0.023 15 F0 A2 8 41157.341 0.965 15 A9 A1 8 41485.398 0.203 20 F0 A2 8 TV CrB 41418.421 0.062 26 A8 A1 7 41473.377 0.067 26 A9 A1 8 BK Dra 41187.418 0.008 15 A8 A0 8 430 0.028 15 A8 A0 8 BT Dra 41418.360 0.042 30 A8 A1 7 41421.407 0.009 25 A8 A1 7 422 0.038 12 A8 A1 7 SZ Gem 41007.355 0.991 10 A5 A0 5 372 0.025 10 A5 A0 5 DL Her 41187.248 0.000 20 A6 A0 6 263 0.025 20 A7 A0 7 SZ Hya 41412.261 0.007 20 A7 A1 6 V LMi 41396.431 0.696 20 A8 A1 7 439 0.710 20 A8 A2 6 SZ Lyn 41009.250 0.845 10 F1 A9 2 258 0.911 10 A8 A7 1 266 0.978 10 A8 A7 1 274 0.044 10 A9 A9 0 282 0.110 10 F1 F0 1 289 0.168 10 F1 F0 1 41061.230 0.090 10 A7 A7 0 308 0.737 10 A9 A9 0 TV Lyn 41007.232 0.952 10 A7 A3 4 239 0.981 10 A7 A3 4 247 0.014 9 A7 A3 4 256 0.051 15 A8 A4 4 TW Lyn 41417.229 0.202 30 F6 A6 10 RR Lyr 41213.216 0.801 6.2 F7 A7 10 224 0.815 6.2 F7 A7 10 329 0.000 2.5 A8 A2 6 VY Ser 41425.430 0.996 10 F1 A3 8 448 0.007 10 F0 A3 7 457 0.020 13 F1 A4 7 AV Ser 41159.272 0.024 20 F0 A2 8 287 0.055 20 F1 A1 10 ST Vir 41061.354 0.047 10 A6 A1 5 362 0.066 10 A7 A2 5 A8 A2 6 AF Vir 41418.393 0.018 16 A7 A0 7 AT Vir 41412.309 0.932 20 A8 A1 7 323 0.959 20 A8 A1 7 338 0.988 20 A8 A0 8 351 0.012 20 A9 A2 7 41442.308 0.981 15 A7 A0 7 320 0.010 20 A8 A2 6 BD Vir 41412.388 0.009 15 A8 A1 7 References (1.) Roczn.astr.obs.Krakow, 1970, N42. (2.) Alania I.F., Abastumansk.astrofiz.obs.Bjull. 1968, 36, 17. (3.) Alania I.F., Abastumansk.astrofiz.obs.Bjull. 1969, 37, 39. [BIBCODE 1969AbaOB..37...39A ] June, 1972 I.F. ALANIA Abastumani Astrophysical Observatory Georgia, USSR.