COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 471 Konkoly Observatory Budapest 1970 October 8 CLASSIFICATION OF PULSATING VARIABLES BY LIGHT GRADIENTS The gradient diagrams (G_u = dU/dB, G_v= dV/dB) of cepheids, Mira-stars, semi-regular and RV Tau type variables were investigated in papers (9-11). It was found that they form two sequences elongated along the G_u axis and located one over the other. Apart from this we have for the variables RR G_u < 1.06 lower sequence CW 1.06 < G_u < 1.16 C G_u > 1.16 M, SR G_u < 1.15 upper sequence RV G_u > 1.15 This fact may be used for classification of pulsation variables. This classification was carried out for the stars given in the Table. Here, in the second and third columns the gradients obtained are given, in the fourth one the type of the variable defined by gradients, in the fifth column the type given in the new edition of GCVS (3) are included. Finally remarks on individual variables and references to papers containing series of UBV-magnitudes are given. TABLE Star GU GV Type GCVS Remarks Source DI Car 1.35: 0.79: C delta Ins 5 V 419 Cen 1.21 0.69 C delta Cep 6 V659 Cen 1.13 0.71 CW Cep 6 EP Cyg 1.26 0.72 C delta C delta 1 EU Cyg 1.03: 0.75 CW C delta 1 EX Cyg 1.31 0.70 C delta C delta 1 EZ Cyg 1.40 0.64: C delta C delta 1 GH Cyg 1.29 0.69 C delta C delta 1 GI Cyg 1.41: 0.59 C delta C delta 1 GL Cyg 1.18 0.72 C delta Cep According to gradients 1 it may be CW. Eggen (1) also assumes it may be CW IU Cyg 1.16 0.72 CW C delta Eggen (1) assumes it 1 may be CW IY Cyg 1.24 0.74: C delta C delta 1 QY Cyg 1.09 0.72 CW Cep Eggen (1) assumes it may be CW V 336 Cyg 1.43 0.63 C delta CW According to Eggen (1) it may be CW V 343 Cyg 1.30 0.63 C delta Cep Eggen (1) assumes it 1 may be CW V 383 Cyg 1.35 0.67 C delta CW? 1 V 547 Cyg 1.42 0.69 C delta 1 V 924 Cyg 1.16 0.60 C delta C delta 1 V 1025 Cyg 1.42 0.62 C delta C delta 1 BX Del 1.08 0.63 CW Cep 1,2 AT Her 1.48 1.02 RV Isb? The gradients obtained 8 by short series of UBV-magnitudes SV Mon 1.52 0.51: C delta C delta 1 SZ Mon 0.90: 1.00: SR C delta Stobie (6) assumes it 6,7 may be RV VW Mon 1.17: 0.66: C delta RRab 1 XX Mon 1.28 0.72 C delta C delta 1 YY Mon 1.31 0.76 C delta C delta 1 AC Mon 1.28 0.62 C delta C delta 1 CS Mon 1.14 0.61 C delta Cep Value of G_u such as 1 for a CW but G_v is typical for C delta CU Mon 1.37 0.70 C delta Cep 7 EK Mon 1.25 0.68 C delta C delta 1 FI Mon 1.35 0.67 C delta C delta 1 FT Mon 1.17 0.70 C delta C delta 1 V636 Sco 1.27 0.67 C delta Cep 6 AH Vel 1.13 0.68 CW Cep 6 S Vul 1.67 0.63 C delta SRd 4 Kiev, September, 1970 I.G. KOLESNIK The Main Astronomical Observatory of the Ukrainian Academy of Sciences REFERENCES (1) O.J. Eggen, Ap.J, 156, 617 (1969). [BIBCODE 1969ApJ...156..617E ] (2) B. Basu, PASP, 81, 834 (1969) [BIBCODE 1969PASP...81..834B ] (3) B.Y. Kukarkin, P.N. Kholopov, Yu.N. Efremov, N.P. Kukarkina, N.E. Kurochkin, G.I. Medvedeva, N.B. Perova, V.P. Fedorovich M.S. Frolov, General Catalogue of Variable Stars, vol.I and II. Third Edition, Moscow, 1969. [BIBCODE 1969gcvs.book.....K ] (4) J.D. Fernie, AJ, 75, 244 (1970). [BIBCODE 1970AJ.....75..244F ] (5) W. Seggewiss, AJ, 75, 345 (1970). [BIBCODE 1970AJ.....75..345S ] (6) R.S. Stobie, Mon. Not. R. Astron. Soc., 148, 1(1970). [BIBCODE 1970MNRAS.148....1S ] (7) R.I. Mitchell, B. Iriarte, D. Steinmetz, H.L. Johnson, Bol. Obs. Tonantzintla Tacubaya, 3, 153 (1964). [BIBCODE 1964BOTT....3..153M ] (8) B. Basu, PASP, 80, 616 (1968). [BIBCODE 1968PASP...80..616B ] (9) E.S. Kheilo, Inf. Bull. Var. Stars, No. 356 (1969). (10) I.G. Kolesnik, E.S. Kheilo, Perem. Zvezdy, 17, 234 (1970). [BIBCODE 1970PZ.....17..234K ] (11) I.G. Kolesnik, Inf. Bull. Var. Stars, No. 470 (1970).