Integrated-light spectroscopy of globular clusters at the infrared CA II lines

Armandroff, T. E.; Zinn, R.

doi:10.1086/114792

Cited by 262 publications

(368 citation statements)

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“…Earlier less precise values, e.g. −30 km s −1 (Armandroff & Zinn 1988), −28 km s −1 (Zinn & West 1984) and −38 km s −1 (Hesser 1986, hereafter HSM86) are not inconsistent with the Dubath et al (1997) value. This suggests that our NGC 5824 velocities might be all systematically ∼15-20 km s −1 too high.…”

Section: Comparison With Harris Catalog Valuesmentioning

confidence: 86%

“…After NGC 2419 for which M V = −9.4 and R G = 90 kpc, NGC 5824 is the next most luminous distant globular cluster in the outer halo -M 54, the nuclear star cluster of the Sgr dwarf galaxy has (M V , R G ) of (−9.98, 18.8) while NGC 5024 has (−8.71, 18.4) using the data tabulated by H10. The only previous spectroscopic abundance determination for this cluster is based on an integrated spectrum at the CaT obtained by Armandroff & Zinn (1988). This is the source of the abundances of [Fe/H] = −1.91 (weight 4) and [Fe/H] = −1.94 ± 0.14 listed by H10 and C09, respectively.…”

Section: An Abundance Spread In Ngc 5824mentioning

confidence: 99%

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Homogeneous metallicities and radial velocities for Galactic globular clusters

Saviane

Costa

Held

et al. 2012

A&A

203

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Well determined radial velocities and abundances are essential for analyzing the properties of the globular cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this context, this work provides new radial velocities and abundances for twenty Milky Way globular clusters which lack or have poorly known values for these quantities. The radial velocities and abundances are derived from spectra obtained at the Ca ii triplet using the FORS2 imager and spectrograph at the VLT, calibrated with spectra of red giants in a number of clusters with well determined abundances. For about half of the clusters in our sample we present significant revisions of the existing velocities or abundances, or both. We also confirm the existence of a sizable abundance spread in the globular cluster M 54, which lies at the center of the Sagittarius dwarf galaxy. In addition evidence is provided for the existence of a small intrinsic internal abundance spread (σ[Fe/H] int ≈ 0.11−0.14 dex, similar to that of M 54) in the luminous distant globular cluster NGC 5824. This cluster thus joins the small number of Galactic globular clusters known to possess internal metallicity ([Fe/H]) spreads.

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Section: Comparison With Harris Catalog Valuesmentioning

confidence: 86%

Section: An Abundance Spread In Ngc 5824mentioning

confidence: 99%

Homogeneous metallicities and radial velocities for Galactic globular clusters

Saviane

Costa

Held

et al. 2012

A&A

203

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“…In globular clusters, this reduced equivalent width W was found to be well correlated with metallicity (Armandroff & Zinn 1988;Armandroff & Da Costa 1991;Rutledge et al 1997b). This provides the empirical basis for the validity of the CaT method.…”

Section: Reduced Ewmentioning

confidence: 90%

New constraints on the chemical evolution of the dwarf spheroidal galaxy Leo I from VLT spectroscopy

Gullieuszik

Held

Saviane

et al. 2009

A&A

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We present the spectroscopy of red giant stars in the dwarf spheroidal galaxy Leo I, aimed at further constraining its chemical enrichment history. Intermediate-resolution spectroscopy in the Ca ii triplet spectral region was obtained for 54 stars in Leo I using FORS2 at the ESO Very Large Telescope. The equivalent widths of Ca ii triplet lines were used to derive the metallicities of the target stars We find a few metal-poor stars (whose metallicity values depend on the adopted extrapolation of the existing calibrations), but in no case are stars more metal-poor than [Fe/H] = −2.6. Our measurements provide a hint of a shallow metallicity gradient of −0.27 dex Kpc −1 among Leo I red giants. The gradient disappears if our data are combined with previous spectroscopic datasets in the literature, so that any firm conclusions about its presence must await new data, particularly in the outer regions. By combining the metallicities of the target stars with their photometric data, we provide age estimates and an age-metallicity relation for a subset of red giant stars in Leo I. Our age estimates indicate a rapid initial enrichment, a slowly rising metal abundance -consistent with the narrowness of the metallicity distribution -and an increase of ∼0.2 dex in the last few Gyr. The estimated ages also suggest a radial age gradient in the RGB stellar populations, which agrees with the conclusions of a parallel study of asymptotic giant branch stars in Leo I from near-infrared photometry. Together, these studies provide the first evidence of stellar population gradients in Leo I.

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“…All the metallicity values for MW GCs adopted here were taken from ZW84 and Armandroff & Zinn (1988). It is clear that the choice of the calibrators implies that the scale is only valid for old populations having a similar degree of enhancement in the abundance of α-elements with respect to the Sun (see Pritzl et al 2005).…”

Section: The Calibratorsmentioning

confidence: 99%

An updated survey of globular clusters in M 31

Galleti

Bellazzini

Buzzoni

et al. 2009

A&A

110

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Aims. We present a new homogeneous set of metallicity estimates based on Lick indices for the old globular clusters of the M 31 galaxy. The final aim is to add homogeneous spectroscopic metallicities to as many entries as possible of the Revised Bologna Catalog of M 31 clusters , by reporting Lick index measurements from any source (literature, new observations, etc.) on the same scale. Simple parametric statistical tests suggest that the distribution is probably not unimodal. The strong correlation between metallicity and kinematics found in previous studies is confirmed. The most metal-rich GCs tend to be packed into the center of the system and to cluster tightly around the galactic rotation curve defined by the HI disk, while the velocity dispersion about the curve increases with decreasing metallicity. However, also the clusters with [Fe/H] < −1.0 display a clear rotation pattern, at odds with their Milky Way counterparts.

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Integrated-light spectroscopy of globular clusters at the infrared CA II lines

Cited by 262 publications

References 0 publications

Homogeneous metallicities and radial velocities for Galactic globular clusters

Homogeneous metallicities and radial velocities for Galactic globular clusters

New constraints on the chemical evolution of the dwarf spheroidal galaxy Leo I from VLT spectroscopy

An updated survey of globular clusters in M 31

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