Astronomy and Astrophysics, volume 287, 371-386 (1994/7-2)
On the Cepheid variables of nearby galaxies II. Sextans A and Sextans B.
PIOTTO G., CAPACCIOLI M. and PELLEGRINI C.
Abstract (from CDS):
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: <MB(3)≥-7.44 for the three brightest blue and <MV(3)≥-7.28 for the three brightest red stars in Sextans A; for Sextans B it is <MB(3)≥-6.39 and <MV(3)≥-6.43.
Cepheids - Galaxies: distances - distance scale - Stars: supergiants - galaxies: individual: Sextans A, Sextans B
Table 7: [PCP94] Sex A PNN (Nos P5, P10, P15, P25). Table 9: [PCP94] Sex B PNN (Nos P8, P10, P13, P17)
Stars 'VNN' and 'NN' in Sextans A are: '[SC82] VNN' and 'NN'. Stars 'VNN' and 'NN' in Sextans B are: '[SC85] VNN' and 'NN'.
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