Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)

We present Sloan g and i imaging from the Gemini Multi-object Spectrograph (GMOS) instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of about 90 square arcmin. We de...

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Autores principales: Forbes, Duncan A., Faifer, Favio Raúl, Forte, Juan Carlos, Bridges, Terry, Beasley, Michael A., Gebhardt, Karl, Hanes, David A., Sharples, Ray, Zepf, Stephen E.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2004
Materias:
Ciencias Astronómicas
Galaxies: individual: NGC 4649
Galaxies: Star clusters
Globular clusters: general
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84879
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84879
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
Galaxies: individual: NGC 4649
Galaxies: Star clusters
Globular clusters: general
spellingShingle Ciencias Astronómicas
Galaxies: individual: NGC 4649
Galaxies: Star clusters
Globular clusters: general
Forbes, Duncan A.
Faifer, Favio Raúl
Forte, Juan Carlos
Bridges, Terry
Beasley, Michael A.
Gebhardt, Karl
Hanes, David A.
Sharples, Ray
Zepf, Stephen E.
Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
topic_facet Ciencias Astronómicas
Galaxies: individual: NGC 4649
Galaxies: Star clusters
Globular clusters: general
description We present Sloan g and i imaging from the Gemini Multi-object Spectrograph (GMOS) instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of about 90 square arcmin. We detect 2151 unresolved sources. Applying colour and magnitude selection criteria to this source list gives 995 candidate GCs. Our source list is greater than 90 per cent complete to a magnitude of i = 23.6, and has little contamination from background galaxies. We find fewer than half a dozen potential ultracompact dwarf galaxies around NGC 4649. Foreground extinction from the nearby spiral NGC 4647 is limited to be A<SUB>V</SUB> < 0.1. We confirm the bimodality in the GC colour distribution found by earlier work using <i>Hubble Space Telescope</i>/WFPC2 imaging. As is commonly seen in other galaxies, the red GCs are concentrated towards the centre of the galaxy, having a steeper number density profile than the blue GC subpopulation. The varying ratio of red-to-blue GCs with radius can largely explain the overall GC system colour gradient. The underlying galaxy starlight has a similar density profile slope and colour to the red GCs. This suggests a direct connection between the galaxy field stars and the red GC subpopulation. We estimate a total GC population of 3700 ± 900, with the uncertainty dominated by the extrapolation to larger radii than observed. This total number corresponds to a specific frequency S<SUB>N</SUB> = 4.1 ± 1.0. Future work will present properties derived from GMOS spectra of the NGC 4649 GCs.
format Articulo
Articulo
author Forbes, Duncan A.
Faifer, Favio Raúl
Forte, Juan Carlos
Bridges, Terry
Beasley, Michael A.
Gebhardt, Karl
Hanes, David A.
Sharples, Ray
Zepf, Stephen E.
author_facet Forbes, Duncan A.
Faifer, Favio Raúl
Forte, Juan Carlos
Bridges, Terry
Beasley, Michael A.
Gebhardt, Karl
Hanes, David A.
Sharples, Ray
Zepf, Stephen E.
author_sort Forbes, Duncan A.
title Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
title_short Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
title_full Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
title_fullStr Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
title_full_unstemmed Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)
title_sort gemini/gmos imaging of globular clusters in the virgo galaxy ngc 4649 (m60)
publishDate 2004
url http://sedici.unlp.edu.ar/handle/10915/84879
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