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The central region of the Virgo cluster of galaxies contains thousands of globular clusters (GCs), an order of magnitude more than the numbers found in the Local Group. Relics of early star formation epochs in the universe, these GCs also…

The spectroscopic and photometric signals of the star-to-star abundance variations found in globular clusters seem to be correlated with global parameters like the cluster's metallicity, mass and age. Understanding this behaviour could…

We have performed a spectroscopic study of globular clusters (GCs) in the giant elliptical NGC 5128 using the 2dF facility at the Anglo-Australian telescope. We obtained integrated optical spectra for a total of 254 GCs, 79 of which are…

We present the results from spectroscopic and photometric analysis of 17 globular cluster (GC) candidates in the Irr II galaxy NGC 3077. The GC candidates were selected on the Hubble Space Telescope (HST) images and were cleaned of…

We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in: M33 (15 objects), M31 (3), IC10 (4), UGCA86 (4), HolmbergIX (1),…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Margarita E. Sharina , Rupali Chandar , Thomas H. Puzia , Paul Goudfrooij , Emmanuel Davoust

We present accurate relative ages for a sample of 55 Galactic globular clusters. The ages have been obtained by measuring the difference between the horizontal branch and the turnoff in two, internally photometrically homogeneous databases.…

Astrophysics · Physics 2009-07-28 F. De Angeli , G. Piotto , S. Cassisi , G. Busso , A. Recio-Blanco , M. Salaris , A. Aparicio , A. Rosenberg

Aims.We study the photometric and structural properties of the star cluster system in the late type Sc spiral NGC 3370. Methods. BVI observations from the Advanced Camera for Surveys on board of HST are used to analyse in detail the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Michele Cantiello , Enzo Brocato , John P. Blakeslee

The turnover, or peak, magnitude in a galaxy's globular cluster luminosity function (GCLF) may provide a standard candle for an independent distance estimator. Here we examine the GCLF of the giant elliptical NGC 4365 using photometry of ~…

Astrophysics · Physics 2009-10-28 Duncan A. Forbes

We present measurements of ages, metallicities, and [alpha/Fe] ratios for 16 globular clusters (GC) in NGC 147, NGC 185, and NGC 205 and of the central regions of the diffuse galaxy light in NGC 185, and NGC 205. Our results are based on…

Astrophysics · Physics 2009-11-11 M. E. Sharina , V. L. Afanasiev , T. H. Puzia

The WFPC2 Camera on board HST has been used to obtain high-resolution images of NGC 3610, a dynamically young elliptical galaxy. These observations supersede shorter, undithered HST observations where an intermediate-age population of…

Astrophysics · Physics 2009-11-07 B. C. Whitmore , F. Schweizer , A. Kundu , B. W. Miller

We have identified 26 new globular cluster candidates in the inner 3 kpc of NGC 5128 (Cen A), the nearest known large galaxy being the probable product of a merger. The clusters are selected on the basis of their structural parameters…

Astrophysics · Physics 2009-10-28 D. Minniti , M. V. Alonso , P. Goudfrooij , P. Jablonka , G. Meylan

We have investigated the formation of globular cluster (GC) systems in the fiducial semi-analytic galaxy formation model of Cole et al. We assume that GCs are formed at high-redshift (z > 5) in proto-galactic fragments, and during the…

Astrophysics · Physics 2009-11-07 M. A. Beasley , C. M. Baugh , Duncan A. Forbes , R. M. Sharples , C. S. Frenk

Ages have been derived for 55 globular clusters (GCs) from overlays of isochrones onto the turnoff photometry, assuming distances based on fits of zero-age horizontal branch (ZAHB) models to the lower bound of the observed distributions of…

Astrophysics of Galaxies · Physics 2013-10-14 Don A. Vandenberg , Karsten Brogaard , Ryan Leaman , Luca Casagrande

Shells in Elliptical Galaxies are faint, sharp-edged features, believed to provide evidence of a recent ($\sim 0.5 - 2 \times 10^9$ years ago) merger event. We analyse the Globular Cluster (GC) systems of six shell elliptical galaxies, to…

Astrophysics · Physics 2009-11-11 G. Sikkema , R. F. Peletier , D. Carter , E. A. Valentijn , M. Balcells

We present g and z photometry and size estimates for globular clusters (GCs) in the massive Virgo elliptical NGC 4649 (M60) using a five-pointing Hubble Space Telescope/Advanced Camera for Surveys mosaic. The metal-poor GCs show a monotonic…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Jay Strader , Giuseppina Fabbiano , Bin Luo , Dong-Woo Kim , Jean P. Brodie , Tassos Fragos , John S. Gallagher , Vassiliki Kalogera , Andrew King , Andreas Zezas

An excellent candidate for a young elliptical, or `protoelliptical' galaxy is NGC 1700. Here we present new B, V and I band imaging using the Keck telescope and reanalyse existing V and I band images from the Hubble Space Telescope. After…

Astrophysics · Physics 2009-10-31 Richard J. N. Brown , Duncan A. Forbes , Markus Kissler-Patig , Jean P. Brodie

We present an analysis of compact star clusters in deep HST/WFPC2 images of NGC 1275. B and R band photometry of roughly 3000 clusters shows a bimodality in the B-R colors, suggesting that distinct old and young cluster populations are…

Globular Cluster (GC) systems of most early-type galaxies show bimodal optical color distributions, yet their Luminosity Functions (LFs) look like simple Gaussians with turn-over magnitudes used for determination of distances and the Hubble…

Astrophysics · Physics 2009-11-10 Uta Fritze -- v. Alvensleben

The presence of two globular cluster subpopulations in early-type galaxies is now the norm rather than the exception. Here we present two more examples for which the host galaxy appears to have undergone a recent merger. Using multi-colour…

Astrophysics · Physics 2009-11-06 Duncan A. Forbes , Antonis E. Georgakakis , Jean P. Brodie

The discovery of star-to-star abundance variations (a.k.a. multiple populations - MPs) within globular clusters (GCs), which are generally not found in the field or in lower mass open clusters, has led to a search for the unique property of…