The discovery of Cepheids and a distance to NGC 5128

被引:94
作者
Ferrarese, Laura
Mould, Jeremy R.
Stetson, Peter B.
Tonry, John L.
Blakeslee, John P.
Ajhar, Edward A.
机构
[1] Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada
[2] Natl Opt Astron Observ, Tucson, AZ 85726 USA
[3] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA
[4] Washington State Univ, Dept Phys & Astron, Pullman, WA 99164 USA
[5] St Thomas Univ, Dept Nat Sci Math & Comp Sci, Miami Gardens, FL 33054 USA
关键词
Cepheids; distance scale; galaxies : distances and redshifts; galaxies : individual (NGC 5128);
D O I
10.1086/506612
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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 similar 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 mu(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.
引用
收藏
页码:186 / 218
页数:33
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