Globular clusters in the inner regions of NGC 5128 (centaurus a)

Dante Minniti, M. Victoria Alonso, Paul Goudfroou, Pascale Jablonka, Georges Meylan

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

We have identified 26 new globular cluster candidates in the inner 3 kpc of NGC 5128 (Centaurus A), the nearest known large galaxy that is the probable product of a merger. The clusters are selected on the basis of their structural parameters (observed core diameters and duplicities), as measured from archival Wide Field Planetary Camera (WFPC) Hubble Space Telescope (HST) images. IR photometry obtained with IRAC2B at the ESO/MPI 2.2 m telescope is combined with the optical HST photometry. Most of these clusters have normal colors typical of old globular clusters like those found in the Milky Way and M31. We estimate their metal abundances based on the R-K° color, confirming the existence of a metallicity gradient in the inner regions of NGC 5128. The presence of metal-rich globular clusters suggests that one of the colliding galaxies was a bulge-dominated galaxy (E or early S). A few clusters have colors and magnitudes similar to intermediate-age clusters containing carbon stars in the Magellanic Clouds. If the intermediate-age clusters were formed during a merger, then this episode must have occurred a few gigayears ago. Alternatively, we are looking at the cluster members of one of the colliding galaxies, which would then have been a late-type disk galaxy.

Original languageEnglish
Pages (from-to)221-226
Number of pages6
JournalAstrophysical Journal
Volume467
Issue number1 PART I
Publication statusPublished - 1996

Fingerprint

globular clusters
merger
galaxies
metal
color
Hubble Space Telescope
photometry
carbon stars
disk galaxies
carbon
Magellanic clouds
European Southern Observatory
metals
metallicity
cameras
telescopes
gradients
estimates
products

Keywords

  • Galaxies: abundances
  • Galaxies: individual (NGC 5128)
  • Galaxies: interactions galaxies: star clusters

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Minniti, D., Victoria Alonso, M., Goudfroou, P., Jablonka, P., & Meylan, G. (1996). Globular clusters in the inner regions of NGC 5128 (centaurus a). Astrophysical Journal, 467(1 PART I), 221-226.
Minniti, Dante ; Victoria Alonso, M. ; Goudfroou, Paul ; Jablonka, Pascale ; Meylan, Georges. / Globular clusters in the inner regions of NGC 5128 (centaurus a). In: Astrophysical Journal. 1996 ; Vol. 467, No. 1 PART I. pp. 221-226.
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Minniti, D, Victoria Alonso, M, Goudfroou, P, Jablonka, P & Meylan, G 1996, 'Globular clusters in the inner regions of NGC 5128 (centaurus a)', Astrophysical Journal, vol. 467, no. 1 PART I, pp. 221-226.

Globular clusters in the inner regions of NGC 5128 (centaurus a). / Minniti, Dante; Victoria Alonso, M.; Goudfroou, Paul; Jablonka, Pascale; Meylan, Georges.

In: Astrophysical Journal, Vol. 467, No. 1 PART I, 1996, p. 221-226.

Research output: Contribution to journalArticle

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AU - Meylan, Georges

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AB - We have identified 26 new globular cluster candidates in the inner 3 kpc of NGC 5128 (Centaurus A), the nearest known large galaxy that is the probable product of a merger. The clusters are selected on the basis of their structural parameters (observed core diameters and duplicities), as measured from archival Wide Field Planetary Camera (WFPC) Hubble Space Telescope (HST) images. IR photometry obtained with IRAC2B at the ESO/MPI 2.2 m telescope is combined with the optical HST photometry. Most of these clusters have normal colors typical of old globular clusters like those found in the Milky Way and M31. We estimate their metal abundances based on the R-K° color, confirming the existence of a metallicity gradient in the inner regions of NGC 5128. The presence of metal-rich globular clusters suggests that one of the colliding galaxies was a bulge-dominated galaxy (E or early S). A few clusters have colors and magnitudes similar to intermediate-age clusters containing carbon stars in the Magellanic Clouds. If the intermediate-age clusters were formed during a merger, then this episode must have occurred a few gigayears ago. Alternatively, we are looking at the cluster members of one of the colliding galaxies, which would then have been a late-type disk galaxy.

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Minniti D, Victoria Alonso M, Goudfroou P, Jablonka P, Meylan G. Globular clusters in the inner regions of NGC 5128 (centaurus a). Astrophysical Journal. 1996;467(1 PART I):221-226.