Old stellar populations. II - an analysis of K-giant spectra

Faber, S. M.; Friel, E. D.; Burstein, David; Gaskell, C. M.

doi:10.1086/191024

Cited by 316 publications

(349 citation statements)

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“…Coupling the measurements of both the line-strength indices of the Lick system (Faber et al 1985) and other systems with higher spectral resolution (Johansson et al 2010; Vazdekis et al 2010) with the predictions of single stellar population (SSPs) mod- Table 1. Properties of the sample galaxies.…”

Section: Introductionmentioning

confidence: 99%

Study of the stellar population properties in the discs of ten spiral galaxies

Morelli¹,

Corsini²,

Pizzella³

et al. 2015

Mon. Not. R. Astron. Soc.

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We investigated the properties of the stellar populations in the discs of a sample of ten spiral galaxies. Our analysis focused on the galaxy region where the disc contributes more than 95 per cent of total surface brightness in order to minimise the contamination of the bulge and bar.The luminosity-weighted age and metallicity were obtained by fitting the galaxy spectra with a linear combination of stellar population synthesis models, while the total overabundance of α-elements over iron was derived by measuring the line-strength indices.Most of the sample discs display a bimodal age distribution and they are characterised by a total [α/Fe] enhancement ranging from solar and supersolar. We interpreted the age bimodality as due to the simultaneous presence of both a young (Age 4 Gyr) and an old (Age > 4 Gyr) stellar population. The old stellar component usually dominates the disc surface brightness and its light contribution is almost constant within the observed radial range. For this reason, no age gradient is observed in half of the sample galaxies. The old component is slightly more metal poor than the young one. The metallicity gradient is negative and slightly positive in the old and young components, respectively.These results are in agreement with an inside-out scenario of disc formation and suggest a reduced impact of the radial migration on the stellar populations of the disc. The young component could be the result of a second burst of star formation in gas captured from the environment.

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Section: Introductionmentioning

confidence: 99%

Study of the stellar population properties in the discs of ten spiral galaxies

Morelli¹,

Corsini²,

Pizzella³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…As a consequence, our overall characterization of the GC system of that galaxy mainly relies on the analysis of integrated colors and spectra (see Galleti et al 2004;Puzia et al 2005;Caldwell et al 2009, 2011, andreferences therein). A widely used technique is based on Lick spectral indices Faber et al 1985;Worthey 1994). Typically, indices that are mainly sensitive to age (H β , H γ ) are used in combination with others that are more sensitive to metallicity (Mgb, [MgFe]), attempting to break the well-known age-metallicity degeneracy.…”

Section: Introductionmentioning

confidence: 99%

HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters

Perina¹,

Galleti²,

Pecci³

et al. 2011

A&A

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We present deep (V 28.0) BV photometry obtained with the wide field channel of the Advanced Camera for Surveys on board HST for four M 31 globular clusters that were identified as candidate intermediate-age (age ∼ 1−9 Gyr) by various authors, based on their integrated spectra and/or broad/intermediate-band colors. Two of them (B292 and B350) display an obvious blue horizontal branch, indicating that they are as old as the oldest Galactic globulars. On the other hand, for the other two (B058 and B337), which display red horizontal branches, it was not possible either to confirm or disconfirm the age estimate from integrated spectra. The analysis of the distribution in the spectral indices Mg2 and Hβ of the M 31 and Milky Way clusters whose horizontal branch can be classified as red or blue based on existing CMDs, strongly suggests that classical age diagnostics from integrated spectra may be significantly influenced by the HB morphology of the clusters and can lead to erroneous age-classifications. We also provide the CMD for another two clusters that fall into the field of the main targets, B336, an old and metal-poor globular with a significant population of RR Lyrae variables, and the newly discovered B531, a cluster with a very red red giant branch.

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“…For this purpose we analyse line-strength gradients in Mg2 (Faber et al 1985) and the λ4000-Å break (D4000, definition in Bruzual 1983) in a sample of 11 brightest cluster galaxies. This paper is an extension of a previous work presented in CGA95 after the inclusion of extensive new spectroscopic data.…”

Section: Introductionmentioning

confidence: 99%

Spectral gradients in central cluster galaxies: further evidence of star formation in cooling flows

Cardiel

Gorgas

Aragón-Salamanca

1998

Monthly Notices RAS

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We have obtained radial gradients in the spectral features λ4000-Å break (D 4000 ) and Mg 2 for a sample of 11 central cluster galaxies (CCGs): 8 in clusters with cooling flows and 3 in clusters without. After careful removal of the emission lines found within the D 4000 and the Mg 2 bandpasses for some objects, the new data strongly confirm the correlations between line-strength indices and the cooling flow phenomenon found in our earlier study (Cardiel, Gorgas & Aragón-Salamanca 1995). We find that such correlations depend on the presence and characteristics of emission lines in the inner regions of the CCGs. The nuclear indices are correlated with the mass deposition rate (Ṁ ) only when emission lines are found in the central regions of the galaxies. The central D 4000 and Mg 2 indices in cooling flow galaxies without emission lines are completely consistent with the indices measured in CCGs in clusters without cooling flows. CCGs in cooling flow clusters exhibit a clear sequence in the D 4000 -Mg 2 plane, with a neat segregation depending on emission-line types (Heckman et al. 1989) and blue morphology (McNamara 1997). This sequence can be modelled, using stellar population models with a normal IMF, by a recent (∼ 0.1 Gyr old) burst of star formation, although model uncertainties do not allow us to completely discard a continuous star formation or a series of bursts over the last few Gyr. In CCGs with emission lines, the gradients in the spectral indices are flat or positive inside the emission-line regions, suggesting the presence of young stars. Outside the emission-line regions, and in cooling flow galaxies without emission lines, gradients are negative and consistent with those measured in CCGs in clusters without cooling flows and giant elliptical galaxies. Index gradients measured exclusively in the emission-line region correlate withṀ . Using the same population models we have estimated the radial profiles of the mass transformed into new stars. The derived profiles are remarkably parallel to the expected radial behaviour of the mass deposition rate derived from X-ray observations. Moreover, a large fraction (probably most ) of the cooling flow gas accreted into the emission-line region is converted into stars. In the light of this new data, we discuss the evolutionary sequence suggested by McNamara (1997), in which radio triggered star formation bursts take place several times during the lifetime of the cooling flow. We conclude that this scenario is consistent with the available observations.

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Old stellar populations. II - an analysis of K-giant spectra

Cited by 316 publications

References 0 publications

Study of the stellar population properties in the discs of ten spiral galaxies

Study of the stellar population properties in the discs of ten spiral galaxies

HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters

Spectral gradients in central cluster galaxies: further evidence of star formation in cooling flows

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