Long Period Variables in NGC 5128: II. Near-IR properties

Abstract

Long Period Variable stars are ubiquitous among the bright red giant branch stars in NGC 5128. Mostly they are found to be brighter than the tip of the first ascent giant branch with magnitudes ranging from about K=19 to K=21.5. They have periods between 155 and 1000 days and K-band amplitudes between 0.1 and 2 mag, characteristic of semi-regular and Mira variables. We compare the colors, periods and amplitudes of these variables with those found in old stellar populations like Galactic globular clusters and Galactic bulge as well as with intermediate-age Magellanic Cloud long period variables. The population of stars above the tip of the red giant branch (RGB) amounts to 2176 stars in the outer halo field (Field 1) and 6072 stars in the inner halo field (Field 2). The comparison of the luminosity functions of the Galactic bulge, M31 bulge and NGC 5128 halo fields shows an excess of bright AGB stars extending to M_K ~ -8.65. The large majority of these sources belong to the asymptotic giant branch (AGB) population in NGC 5128. Subtracting the foreground Galactic stars and probable blends, at least 26% and 70% of AGB stars are variable in Fields 1 and 2, respectively. The average period of NGC 5128 LPVs is 395 days and the average amplitude 0.77 mag. Many more short period Miras are present in Field 2 than in Field 1 indicating a difference in the stellar populations between the two fields. Period and amplitude distributions and near-IR colors of the majority of LPVs in NGC 5128 are similar to the Galactic bulge variables. However, some ~10% of LPVs have periods longer than 500 days and thus probably more massive, hence younger, progenitor stars. A few carbon star candidates are identified based on their red J-H and H-K colors.

11 pages, 10 figures; accepted for publication in A&A; for high resolution version see: http://www.eso.org/~mrejkuba/cenA_LPVs_IRprop.ps The catalogue (Paper I) can be downloaded from http://www.eso.org/~mrejkuba/cenA_LPVs_cat.ps

References in corpus (23)

• Age and Metallicity Distribution of the Galactic Bulge from Extensive Optical and Near-IR Stellar Photometry
• Obscured Asymptotic Giant Branch Variables in the Large Magellanic Cloud and the Period-Luminosity Relation
• The Metallicity Distribution in the Halo Stars of NGC 5128: Implications for Galaxy Formation
• Infrared stellar populations in the central parts of the Milky Way galaxy
• Hubble Space Telescope Observations of M32: The Color-Magnitude Diagram
• Towards the absolute planes: a new calibration of the Bolometric Corrections and Temperature scales for Population II Giants
• AGB stars in the Magellanic Clouds. I. The C/M ratio
• A Galactic Bar to Beyond the Solar Circle and its Relevance for Microlensing
• Variability and spectral classification of LMC giants: results from DENIS and EROS
• The red tail of carbon stars in the LMC: Models meet 2MASS and DENIS observations
• Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge
• The Stellar Populations of Pixels and Frames
• Stellar populations in NGC 5128 with the VLT: evidence for recent star formation
• Globular Clusters and the Mira Period-Luminosity Relation
• The Stellar Content of M31's Bulge
• Pulsation at the tip of the first giant branch?
• The Nature of the Halo Population of NGC 5128 Resolved with NICMOS on the Hubble Space Telescope
• V, J, H and K Imaging of the Metal Rich Globular Cluster NGC 6528
• Long Period Variables in NGC 5128: II. Near-IR properties
• Long Period Variables in Globular Clusters and the Galactic Bulge: Their Dependence on Metallicity
• Long Period Variable Stars: galactic populations and infrared luminosity calibrations
• Long Period Variables in NGC 5128: I. Catalogue
• M giants in Macho, DENIS and Isogal

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