2006/05/29 by Laura Ferrarese, Jeremy R. Mould, J. R. Mould +6 · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/506612
published as Astrophys.J.654:186-218,2006 · Accepted by the Astrophysical Journal. 40 pages, 17 figures. A version of the paper including full resolution figures can be dowloaded from http://astrowww.phys.uvic.ca/~lff/publications.html
arxiv created 2006/05/29 · openalex publication_date 2006/12/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We discuss a new distance to NGC 5128 (Centaurus A) based on Cepheid variables observed with the Hubble Space Telescope . Twelve F555W ( V ) and six F814W ( I ) epochs of cosmic-ray-split WFPC2 observations were obtained. A total of 56 bona fide Cepheids were discovered, with periods ranging from 5 to ~50 days; five of these are likely Population II Cepheids of the W Virginis class, associated with the bulge or halo of NGC 5128. Based on the period and V - and I -band luminosities of a subsample of 42 classical (Population I) Cepheids, and adopting an LMC distance modulus and extinction of 18.50 ± 0.10 mag and E ( B - V ) = 0.10 mag, respectively, the true reddening-corrected distance modulus to NGC 5128 is μ 0 = 27.67 ± 0.12 (random) ± 0.16 (systematic) mag, corresponding to a distance of 3.42 ± 0.18 (random) ± 0.25 (systematic) Mpc. The random uncertainty in the distance is dominated by the error on the assumed value for the ratio of total to selective absorption, R V , in NGC 5128, and by the possible metallicity dependence of the Cepheid period-luminosity relation at V and I . This represents the first determination of a Cepheid distance to an early-type galaxy.