Distance to NGC 0247

TL;DR

This paper presents VRI CCD observations of nine Cepheids in NGC 0247, deriving a precise distance of approximately 3.36 Mpc and analyzing period changes over 20 years.

Contribution

It provides new multi-wavelength Cepheid data and refines the distance measurement to NGC 0247, confirming previous estimates with improved accuracy.

Findings

Distance modulus of 27.81 +/- 0.10 mag (3.36 Mpc)

Cepheid period decrease and brightness change over 20 years

Agreement with recent Cepheid and TRGB distance measurements

Abstract

We report VRI CCD observations of nine Cepheids in the South Polar (Sculptor) Group spiral galaxy NGC 0247. Periods of these Cepheids range from 20 to 70 days. Over the past 20 years the very brightest Cepheid in our sample, NGC 0247:[MF09] C1, has decreased its period by 6%, faded by 0.8 mag in the V band, and become bluer by 0.23 mag in (V-I). A multi-wavelength analysis of the Cepheid data yields a true distance modulus of mod = 27.81 +/- 0.10 mag (3.36 +/- 0.16 Mpc) with a total line-of-sight reddening of E(V-I) = 0.07 +/-0.04 mag, after adopting an LMC true distance modulus of 18.5 mag and reddening of E(B-V) = 0.10 mag. These results are in excellent agreement with other very recently published (Cepheid and TRGB) distances to NGC 0247. Combining both Cepheid datasets gives mod_o = 27.85 +/-0.09 mag (3.72 +/- 0.15 Mpc) with E(V-I) = 0.11 +/- 0.03 mag.