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Long-period variables in the giant elliptical galaxy NGC 5128:
the Mira P-L relation at 4 Mpc
M. Rejkuba1,2,
D. Minniti2,
D.R. Silva1 and
T.R. Bedding3
1European Southern Observatory, Karl-Schwartzschild-Strasse 2, D-85748
Garching, Germany
2Department of Astronomy, P. Universidad Católica, Casilla 306, Santiago 22, Chile 3School of Physics, University of Sydney 2006, Australia
We have obtained multi-epoch infrared photometry of two fields in the halo of the giant elliptical galaxy NGC~5128 (Cen A). The data were taken in K band over three years with ISAAC on the VLT. We have detected about 1750 red variables, which are mostly identified as Mira and semiregulars. The period-luminosity diagram shows two parallel sequences, corresponding to sequences B and C of Wood (2000), which were derived from MACHO observations of the LMC. Sequence C, which contains the Miras, is the more populated and a comparison with the LMC relation yields a distance modulus for NGC 5128 that is in excellent agreement with that derived from the RGB tip in the same data.
Last changed: 2002/Jun/19
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