Five colour photometry of the RRd star V372 Serpentis
Aims: The first U-band and new BV(RI)C photometry of the RRdstar V372 Ser is presented to determine someparameters of the star. Methods: In April, May 2007, 2812U,B,V,R_C,IC frames were obtained at Konkoly and TeideObservatories and 1508 V observations were collected from theliterature. Fourier fitted light curves were derived in all bands. Results: The non-linearly coupled frequencies f_0=(2.121840±.000001)~cycles~day-1, f_1=(2.851188±.000001)~c~d-1, i.e. periods P_0=0.4712891± .0000002days, P_1=0.3507310± .0000001 d, P_1/P_0=0.7441950, amplitudesA_0(V)=0.15399 mag, A_1(V)=0.20591 mag, and phaseshave been found. A_1/A_0=1.319± .008 has been found fromaveraging the amplitude ratio in the different bands i.e. the firstovertone is the dominant pulsation mode. From the V observations, upperlimits are given for secular change of the Fourier parameters. Theperiod ratio and period put V372 Ser among the RRd stars of the globularclusters M3 and IC 4499; mass, luminosity, and metallicity estimates aregiven.Photometric data are only available in electronic form at CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/497/481
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