VLT spectroscopy of globular cluster systems

Free access article

Issue		A&A Volume 415, Number 1, February III 2004


Page(s)		123 - 143
Section		Galactic structure, stellar clusters and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20031448

A&A 415, 123-143 (2004)
DOI: 10.1051/0004-6361:20031448

I. The photometric and spectroscopic data set

T. H. Puzia¹, M. Kissler-Patig², D. Thomas³, C. Maraston³, R. P. Saglia¹, R. Bender^{1, 3}, T. Richtler⁴, P. Goudfrooij⁵ and M. Hempel²

¹ Sternwarte der Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany
    e-mail: saglia@usm.uni-muenchen.de
² European Southern Observatory, 85749 Garching bei München, Germany
    e-mail: mkissler@eso.org
³ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching bei München, Germany
    e-mail: bender, maraston, dthomas@mpe.mpg.de
⁴ Grupo de Astronomía, Departamento de Física, Casilla 160-C, Universidad de Concepción, Concepción, Chile
    e-mail: tom@coma.cfm.udec.cl
⁵ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
    e-mail: goudfroo@stsci.edu

(Received 14 May 2003 / Accepted 11 September 2003 )

Abstract
We present Lick line-index measurements of extragalactic globular clusters in seven early-type galaxies (NGC 1380, 2434, 3115, 3379, 3585, 5846, and 7192) with different morphological types (E-S0) located in field and group/cluster environments. High-quality spectra were taken with the FORS2 instrument at ESO's Very Large Telescope. ~ 50% of our data allows an age resolution $\Delta t/t\approx0.3$ and a metallicity resolution ~ 0.25-0.4 dex, depending on the absolute metallicity. Globular cluster candidates are selected from deep B, V, R, I, K FORS2/ISAAC photometry with 80-100% success rate inside one effective radius. Using combined optical/near-infrared colour-colour diagrams we present a method to efficiently reduce fore-/background contamination down to $\la$ 10%. We find clear signs for bi-modality in the globular cluster colour distributions of NGC 1380, 3115, and 3585. The colour distributions of globular clusters in NGC 2434, 3379, 5846, and 7192 are consistent with a broad single-peak distribution. For the analysed globular cluster systems the slopes of projected radial surface density profiles, of the form $\Sigma(R)\sim R\,^{-\Gamma}$ , vary between ~ 0.8 and 2.6. Blue and red globular cluster sub-populations show similar slopes in the clearly bi-modal systems. For galaxies with single-peak globular cluster colour distributions, there is a hint that the blue cluster system seems to have a more extended radial distribution than the red one. Using globular clusters as a tracer population we determine total dynamical masses of host galaxies out to large radii (~ $1.6{-}4.8\, R_{\rm eff}$ ). For the sample we find masses in the range ~ $8.8\times10^{10}~M_\odot$ up to ~ $1.2\times10^{12}~M_\odot$ . The line index data presented here will be used in accompanying papers of this series to derive ages, metallicities and abundance ratios. A compilation of currently available high-quality Lick index measurements for globular clusters in elliptical, lenticular, and late-type galaxies is provided and will serve to augment the current data set.

Key words: galaxies: star clusters -- galaxies: general

Offprint request: T. H. Puzia, puzia@usm.uni-muenchen.de

SIMBAD Objects
Tables at the CDS

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.