The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. VI. The Cepheids in NGC 925
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L.; Ford, Holland; Stetson, Peter B.; Bresolin, Fabio; Ferrarese, Laura; Saha, Abhijit; Graham, John A.; Mould, Jeremy R.; Hoessel, John G.; Hughes, Shaun M. G.; Sakai, Shoko; Silbermann, N. A.; Huchra, John; Harding, Paul; Han, Mingsheng; Hill, Robert J.; Kennicutt, Robert C., Jr.; Phelps, Randy; Turner, Anne
Abstract
We report the detection of Cepheid variable stars in the barred spiral galaxy NGC 925, using the Hubble Space Telescope (HST) Wide-Field and Planetary Camera 2 (WFPC2). Twelve V (F555W) and four I (F814W) epochs of cosmic-ray split observations were obtained. Eighty Cepheids were discovered, with periods from 6 to ~80 days. Light curves of the Cepheids are presented, and their corresponding period-luminosity diagrams are discussed. Using a distance modulus for the Large Magellanic Cloud Cepheids of 18.50 mag and an extinction of E(V - I) = 0.13 mag, the measured distance modulus to NGC 925 is 29.84 +/- 0.16 mag, corresponding to a distance of 9.29 +/- 0.69 Mpc. A mean reddening of E(V-I) = 0.17 mag is found for the Cepheids in this region of NGC 925.