1994A&A...287..371P

Five Cepheids in Sextans A and three in Sextans B, already discovered and studied by Sandage & Carlson (1982, 1985), have been measured into a new photometric CCD sequence in B. A zero point offset of 0.22 magnitudes has been detected with respect to previous photographic photometry (CCD magnitudes being brighter). Five additional Cepheid candidates in Sextans A and four in Sextans B have been identified and preliminary periods have been proposed. The new Cepheids allow to extend the period-luminosity relation to one magnitude fainter. For all the variables, single epoch V, R, and I magnitudes are derived. Apparent B, V, and I distance moduli relative to the LMC have been calculated. Combining the data at different wavelength and assuming a true distance modulus of 18.5 mag for the LMC, we obtain a true distance modulus, corrected for the effects of interstellar extinction, of (m-M)₀=25.71±0.20 for Sextans A and (m-M)₀=25.63±0.21 for Sextans B. The resulting distances are 20% shorter than previously suggested by Sandage and Carlson. Adopting E(B-V)=0.08 for the LMC, the interstellar reddening for the Cepheids in Sextans A is E(B-V)=0.02, and in Sextans B E(B-V)=0.01. Adopting the above distance moduli and reddening, the absolute magnitudes of the brightest stars are: <M_B(3)≥-7.44 for the three brightest blue and <M_V(3)≥-7.28 for the three brightest red stars in Sextans A; for Sextans B it is <M_B(3)≥-6.39 and <M_V(3)≥-6.43.