| Abstract | New observations of the Cepheids in the galactic clusters and external galaxies LMC, NGC 6822, NGC 300, and Sex A in the 1.05 micron wave band (IV) are presented. The slope of the P-L(IV) relation derived from the Cepheids in the LMC agree with that in the SMC and that obtained for Galactic Cepheids. The zero point of the relation has been determined from the distances to the galactic Cepheid clusters obtained through ZAMS fitting and referenced to the Pleiades modulus of 5.57. The bolometric P-L relations derived individually using the data in V, J, K wave bands are found to have the same slope and the zero point as observed in the IV wave band. The comparison of the bolometric P-L relation with that obtained theoretically by Becker, Iben, and Tuggle shows agreement in the value of the slope. But the theoretical magnitudes are brighter by ~ 0.4 mag. The true distance moduli to the LMC, the SMC, NGC 6822, NGC 300, and Sex A have been derived from P-L(IV) data and are found to be as 18.42, 18.83, 23.18, 25.72, and 25.27, respectively. |
