I-band Cepheid Distance to NGC 6822

Extract

NGC 6822 was the first galaxy outside the Galaxy where the Cepheid period-luminosity relation was applied as a distance indicator (Hubble 1925, ApJ, 62, 409). Later, thirteen Cepheids in this galaxy were studied by Kayser (1967, AJ, 72, 134) using BV photographic photometry. We have obtained BVRI CCD photometry of stars in two 2.2' X 3.5' fields of NGC 6822. Field 3) using Figure 1 shows an I – (V – I) diagram of ∼ 6,400 measured stars in NGC 6822 including seven known Cepheids. The reddening is estimated to E(B – V) = 0.28 ± 0.03 from the (B – V)-(V – I) diagram of the stars with V < 20 mag. The distance to NGC 6822 has been estimated using the random-phase I band photometry of seven Cepheids (V7(I=16.31), V5(I=18.97), V6(I=18.44), V3(I=17.88), V1(I=18.05), V28(I=17.61), and V2(I=17.29)) combined with their periods given by Kayser.