COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1545 Konkoly Observatory Budapest 1979 February 5 PHOTOELECTRIC OBSERVATIONS OF 53 Cam The peculiar star 53 Cam (=AX Cam=HR3109=HD 63339), classified as an A2p Sr-Cr-Eu star by Bidelman and Bohm (1955) shows strong magnetic field varying with a period of about 8 days. The variability of the line intensities (Faraggiana 1973) tends to follow the 8d period, whereas radial velocities appear to fit at least two different periods: i) a shorter one lying probably in the range 1-8 days; ii) a longer one (on the order of several years) suggesting for 53 Cam a binary nature. The light variations (Jarzebowski 1960a, 1960b, Rakos 1962, 1968; Preston and Stepien 1968; Wolff and Wolff 1971; Schoneich et al. 1976) evidence a period of about 8 days, in fairly close agreement with what has been derived from magnetic observations. Moreover, Rakos (1968, see also Faraggiana 1973) argued that a period of about 1 day better fitted his own observations than a Longer one of about 8 days. 53 Cam was observed by us during 13 nights in 1970, 9 nights in 1971, 11 nights in 1972 and one night in 1974. The observations were mostly carried out with the 30-cm Cassegrain reflector of the Astronomical Observatory of Trieste, equipped with a single beam photoelectric photometer using UBV filters. The 50-cm Newtonian telescope of the Observatory, equipped with a three- channel simultaneous photoelectric photometer, was used only in some nights. Corrections were allowed for differential extinction and the measures were transformed to the standard UBV system. Table 1 -------------------------------------------------------- Comparison star V B-V U-B -------------------------------------------------------- HD 62522 7.012+-.005 0.573+-.005 0.021+-.011 HD 62976 6.778+-.010 0.100+-.004 0.137+-.011 HD 65429 6.858+-.006 0.376+-.006 -0.010+-.005 HD 66286 6.693+-.006 0.091+-.008 0.162+-.008 HD 68457 6.420+-.009 0.199+-.010 0.189+-.009 -------------------------------------------------------- Table 2 ------------------------------------------------------------------------------------------------------- JD V sigma N JD B sigma N JD U-B sigma N 2440000+ 2440000+ 2440000+ ------------------------------------------------------------------------------------------------------- 655.3174 6.048 .003 6 656.3178 6.172 .008 6 656.3178 0.096 .011 4 666.3434 6.030 .009 7 666.3431 6.168 .012 7 666.3362 0.065 .005 6 688.3543 6.033 .013 5 688.3555 6.158 .013 5 688.3561 0.089 .009 5 689.3532 6.032 .007 5 689.3550 6.174 .311 5 689.3558 0.059 .011 5 695.3714 6.044 .004 2 695.3725 6.181 .005 2 695.3729 0.065 .011 2 701.4044 6.017 .000 4 701.4058 6.167 .018 4 701.4064 0.096 .007 4 709.3585 6.023 .034 7 709.3542 6.148 .010 6 709.3598 0.084 .013 7 711.4182 6.023 .015 5 711.4235 6.176 .019 6 711.4198 0.063 .031 5 715.3843 6.033 .020 4 715.3853 6.176 .004 4 715.3854 0.065 .024 5 726.3708 6.032 .015 5 726.3648 6.175 .014 4 726.3653 0.080 .011 4 730.3819 6.030 .006 3 730.3833 6.151 .008 3 730.3840 0.072 .035 3 731.3635 6.016 .007 4 731.3652 6.155 .011 4 731.3588 0.084 .001 2 735.3773 6.025 .006 3 735.3773 6.167 .012 3 735.3798 0.066 .008 3 988.4519 6.029 .012 6 988.4527 6.171 .016 5 988.4531 0.066 .008 6 993.3788 6.035 .010 9 993.3841 6.173 .005 8 993.3802 0.071 .005 4 1008.5005 6.029 .010 10 1008.4905 6.165 .009 9 1008.4998 0.060 .008 9 1008.5261 6.033 .005 5 1008.5277 6.177 .006 5 1035.3710 6.037 .006 12 1035.3710 6.169 .010 12 1035.3710 0.058 .010 12 1048.3600 6.037 .011 7 1048.3609 6.185 .011 7 1048.3614 0.071 .009 7 1048.3457 6.020 .009 8 1048.3457 6.178 .017 8 1060.3710 6.034 .013 7 1060.3719 6.169 .011 7 0.073 .007 7 1061.3557 6.023 .020 8 1061.3567 6.175 .026 8 1061.3572 0.066 .008 8 1062.3424 6.022 .009 9 1062.3433 6.165 .014 9 1062.3437 0.071 .009 9 1063.3346 6.033 .022 8 1063.3357 6.174 .024 8 1063.3361 0.075 .011 8 1363.2979 6.025 .004 9 1363.2938 6.159 .006 8 1364.2778 6.026 .013 4 1364.2799 6.153 .032 4 1392.2574 6.023 .014 6 1392.2539 6.177 .012 9 1398.3548 6.032 .015 24 1398.3548 6.181 .016 24 1399.3566 6.026 .012 26 1399.3566 6.181 .014 26 1401.3993 6.038 .014 17 1401.4023 6.188 .025 16 1402.3528 6.036 .010 16 1402.3538 6.175 .013 16 1414.3483 6.032 .013 18 1414.3495 6.176 .008 18 1415.3568 6.026 .013 12 1415.3579 6.177 .018 12 1417.3519 6.030 .008 14 1417.3527 6.180 .005 14 1648.5015 6.022 .004 11 1648.5024 5.171 .005 11 2120.4281 6.032 .009 16 2120.4281 6.168 .013 16 2120.4281 0.073 .005 16 ------------------------------------------------------------------------------------------------------- Data (together with their standard deviation) of the five comparison stars adopted are given in Table 1. No variability of these stars has been detected within the errors. The normal points of the photoelectric data of 53 Cam together with their standard deviation Q and the number N of observations are listed in Table 2. The character of brightness variations is noticeably less remarkable in U light than in B and V, since U data are affected by considerable observational errors. The observational scatter along with the small amplitude of light variations makes it impossible to determine with precision the shapes of the B and V lightcurves. A rough analysis of our data reveals that brightness variations fit two different periods, a longer one of about 8.0 days and a shorter one of about 1.14 days; this latter period may be an effect due to aliasing. Acknowledgement : We are indebted to Dr. U. Flora and Dr. M. Pucillo who generously provided a part of the observational data. M. MEZZETTI, B. CESTER, G. GIURICIN, F. MARDIROSSIAN Osservatorio Astronomico di Trieste Trieste, Italy References: Bidelman, W.P., Bohm, K.H., 1955, Publ.Astron.Soc.Pacific 67, 179 [BIBCODE 1955PASP...67..179B ] Faraggiana, R., 1973, Astron. and Astrophys. 22, 265 [BIBCODE 1973A&A....22..265F ] Jarzebowski, T., 1960a, Acta Astronom. 10, 31 [BIBCODE 1960AcA....10...31J ] Jarzebowski, T., 1960b, Acta Astronom. 10, 273 [BIBCODE 1960AcA....10..237J ] Preston, G. and Stepien, K., 1968, Astrophys.J. 151, 563 [BIBCODE 1968ApJ...151..577P ] Rakos, K.D., 1962, Lowell Bull. 5, 227 [BIBCODE 1962LowOB...5..227R ] Rakos, K.D., 1968, Publ. Astron. Soc. Pacific 80, 563 [BIBCODE 1968PASP...80..563R ] Schonech, W. and Hildebrandt, G., 1976, Astron.Nachr.297, 39 [BIBCODE 1976AN....297...39S ] Wolff, S.C. and Wolff, R., 1971, Astron.J. 76, 422 [BIBCODE 1971AJ.....76..422W ]