Long period variables in NGC 5128 - I. Catalogue

The first variable star catalogue in a giant elliptical galaxy NGC 5128 (Centaurus A) is presented. Using multi-epoch observations with ISAAC at the VLT we have detected 1504 red variables in two halo fields covering 10.46 arcmin square. For the variables with at least 10 good measurements, periods and amplitudes were determined using Fourier analysis and non-linear sine-curve fitting algorithms. The final catalogue contains 1146 long period variables with well established light curve parameters. Periods, amplitudes, $J_{\rm s}HK_{\rm s}$ photometry as well as individual K s -band magnitudes are provided for all the variables. The distribution of amplitudes ranges from 0.3 to a few magnitudes in the K s -band, with a median value around 0.7 mag. The amplitudes, mean magnitudes and periods indicate that the majority of variables belong to the class of long period variables with semiregular and Mira variables. Exhaustive simulations were performed in order to assess the completeness of our catalogue and the accuracy of the derived periods.

[1]  N. Lomb.  Least-squares frequency analysis of unequally spaced data , 1976 .

[2]  M. Feast,et al.  The infrared properties of mira-type variables and other cool stars as determined from JHKL photometry. , 1982 .

[3]  P. Quinn,et al.  Shell structure in NGC 5128. , 1983 .

[4]  M. Bessell,et al.  Long-period variables in the Magellanic Clouds: Supergiants, AGB stars, supernova precursors, planetary nebula precursors, and enrichment of the interstellar medium , 1983 .

[5]  P. Stetson.  DAOPHOT: A COMPUTER PROGRAM FOR CROWDED-FIELD STELLAR PHOTOMETRY , 1987 .

[6]  J. Frogel,et al.  M giants in Baade's window: infrared colors, luminosities, and implications for the stellar content of E and S0 galaxies , 1987 .

[7]  J. Elias,et al.  Red Variables in Globular Clusters: Their Classification and Evidence for Mass Loss , 1988 .

[8]  John L. Tonry,et al.  A new technique for measuring extragalactic distances , 1988 .

[9]  P. Schechter,et al.  The surface-brightness fluctuation distance of NGC 5128 , 1990 .

[10]  J. G. Hoessel,et al.  RR Lyrae stars in local group galaxies. II. NGC 147 , 1990 .

[11]  Peter B. Stetson,et al.  Robust variable star detection techniques suitable for automated searches: new results for NGC 1866 , 1993 .

[12]  Peter B. Stetson,et al.  THE CENTER OF THE CORE-CUSP GLOBULAR CLUSTER M15: CFHT AND HST OBSERVATIONS, ALLFRAME REDUCTIONS , 1994 .

[13]  M. Dickinson,et al.  Evolution of Infrared-selected Galaxies in Z approximately 0.4 Clusters , 1995, astro-ph/9504007.

[14]  Stefano Casertano,et al.  Detection of the Tip of the Red Giant Branch in NGC 5128 , 1996 .

[15]  Peter B. Stetson,et al.  ON THE AUTOMATIC DETERMINATION OF LIGHT-CURVE PARAMETERS FOR CEPHEID VARIABLES , 1996 .

[16]  H. J. Habing,et al.  Circumstellar envelopes and Asymptotic Giant Branch stars , 1996 .

[17]  Sergio Ortolani,et al.  On Calibrating Brightest Asymptotic Giant Branch Stars as Age Indicators: The Bulge Globular Cluster NGC 6553 and the Age of M32 , 1997 .

[18]  S. E. Persson,et al.  A New System of Faint Near-Infrared Standard Stars , 1998 .

[19]  P. Whitelock,et al.  Luminous Long-Period Variables in Globular Clusters and the Galactic Bulge: Their Dependence on Metallicity , 1997, astro-ph/9712191.

[20]  STAR FORMATION IN GALAXIES ALONG THE HUBBLE SEQUENCE , 1998, astro-ph/9807187.

[21]  Gregory B. Poole,et al.  The Metallicity Distribution in the Halo Stars of Ngc 5128: Implications for Galaxy Formation , 1998 .

[22]  M. Feast,et al.  Infrared colours for Mira-like long-period variables found in the Catalogue , 2000 .

[23]  James R. Graham,et al.  The Nature of the Halo Population of NGC 5128 Resolved with NICMOS on the Hubble Space Telescope , 2000 .

[24]  C. Fassett,et al.  Age, Evolution, and Dispersion of the Loose Groups of Blue Stars in the Northeast Radio Lobe of Centaurus A , 2000 .

[25]  D. Calzetti,et al.  Jet-induced Star Formation in Centaurus A , 2000 .

[26]  Michael C. Liu,et al.  SURFACE BRIGHTNESS FLUCTUATIONS OF FORNAX CLUSTER GALAXIES : CALIBRATION OF INFRARED SBFS AND EVIDENCE FOR RECENT STAR FORMATION , 2001 .

[27]  M. Rejkuba,et al.  Stellar populations in NGC 5128 with the VLT: Evidence for recent star formation , 2001, astro-ph/0109406.

[28]  Samus,et al.  General catalogue variable stars , 2001 .

[29]  D. Bersier,et al.  Variable Stars in the Fornax Dwarf Galaxy , 2001, astro-ph/0110555.

[30]  Anomalous surface brightness fluctuations in NGC 4489 , 2000, astro-ph/0011276.

[31]  M. Rejkuba.  Deep VLT search for globular clusters in NGC 5128: Color-magnitude diagrams and globular cluster luminosity function , 2001 .

[32]  M. Rejkuba,et al.  Radio-Optical Alignment and Recent Star Formation Associated with Ionized Filaments in the Halo of NGC 5128 (Centaurus A) , 2001, astro-ph/0109407.

[33]  Michael C. Liu,et al.  Surface Brightness Fluctuations of Fornax Cluster Galaxies: Calibration of Infrared Surface Brightness Fluctuations and Evidence for Recent Star Formation , 2001, astro-ph/0107357.