The SLUGGS survey: Calcium triplet-based spectroscopic metallicities for over 900 globular clusters

Christopher Usher; Duncan A. Forbes; Jean P. Brodie; Caroline Foster; Lee R. Spitler; Jacob A. Arnold; Aaron J. Romanowsky; Jay Strader; Vincenzo Pota

doi:10.1111/j.1365-2966.2012.21801.x

The SLUGGS survey: Calcium triplet-based spectroscopic metallicities for over 900 globular clusters

Christopher Usher^*, Duncan A. Forbes, Jean P. Brodie, Caroline Foster, Lee R. Spitler, Jacob A. Arnold, Aaron J. Romanowsky, Jay Strader, Vincenzo Pota

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

104 Citations (Scopus)

Abstract

Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index-metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In six of the eight galaxies with sufficient numbers of high-quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that most massive early-type galaxies have bimodal metallicity as well as colour distributions. This bimodality suggests that most massive early-type galaxies experienced two periods of star formation.

Original language	English
Pages (from-to)	1475-1495
Number of pages	21
Journal	Monthly Notices of the Royal Astronomical Society
Volume	426
Issue number	2
DOIs	https://doi.org/10.1111/j.1365-2966.2012.21801.x
Publication status	Published - 21 Oct 2012
Externally published	Yes

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title = "The SLUGGS survey: Calcium triplet-based spectroscopic metallicities for over 900 globular clusters",

abstract = "Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index-metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In six of the eight galaxies with sufficient numbers of high-quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that most massive early-type galaxies have bimodal metallicity as well as colour distributions. This bimodality suggests that most massive early-type galaxies experienced two periods of star formation.",

author = "Christopher Usher and Forbes, {Duncan A.} and Brodie, {Jean P.} and Caroline Foster and Spitler, {Lee R.} and Arnold, {Jacob A.} and Romanowsky, {Aaron J.} and Jay Strader and Vincenzo Pota",

year = "2012",

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doi = "10.1111/j.1365-2966.2012.21801.x",

language = "English",

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pages = "1475--1495",

journal = "Monthly Notices of the Royal Astronomical Society",

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T2 - Calcium triplet-based spectroscopic metallicities for over 900 globular clusters

AU - Usher, Christopher

AU - Forbes, Duncan A.

AU - Brodie, Jean P.

AU - Foster, Caroline

AU - Spitler, Lee R.

AU - Arnold, Jacob A.

AU - Romanowsky, Aaron J.

AU - Strader, Jay

AU - Pota, Vincenzo

PY - 2012/10/21

Y1 - 2012/10/21

N2 - Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index-metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In six of the eight galaxies with sufficient numbers of high-quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that most massive early-type galaxies have bimodal metallicity as well as colour distributions. This bimodality suggests that most massive early-type galaxies experienced two periods of star formation.

AB - Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index-metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In six of the eight galaxies with sufficient numbers of high-quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that most massive early-type galaxies have bimodal metallicity as well as colour distributions. This bimodality suggests that most massive early-type galaxies experienced two periods of star formation.

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The SLUGGS survey: Calcium triplet-based spectroscopic metallicities for over 900 globular clusters

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