G2C2 - II. Integrated colour-metallicity relations for Galactic globular clusters in SDSS passbands

Joachim Vanderbeke, Michael J. West, Roberto De Propris, Eric W. Peng, John P. Blakeslee, Andreś Jordán, Patrick Ĉoté, Michael Gregg, Laura Ferrarese, Marianne Takamiya, Maarten Baes

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We use our integrated Sloan Digital Sky Survey (SDSS) photometry for 96 globular clusters in g and z, as well as r and i photometry for a subset of 56 clusters, to derive the integrated colour- metallicity relation (CMR) for Galactic globular clusters.We compare this relation to previous work, including extragalactic clusters, and examine the influence of age, present-day mass function variations, structural parameters and the morphology of the horizontal branch on the relation. Moreover, we scrutinize the scatter introduced by foreground extinction (including differential reddening) and show that the scatter in the CMR can be significantly reduced combining two reddening laws from the literature. In all CMRs, we find some low-reddening young GCs that are offset to the CMR. Most of these outliers are associated with the Sagittarius system. Simulations show that this is due to less age than to a different enrichment history. Finally, we introduce CMRs based on the infrared calcium triplet, which are clearly non-linear when compared to (g′ - i′) and (g′ - z′) colours.

Original languageEnglish
Pages (from-to)1734-1749
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume437
Issue number2
DOIs
StatePublished - Nov 2013
Externally publishedYes

Keywords

  • General
  • Globular clusters

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