The Distribution of the Elements in the Galactic Disk

Luck, R. E.; Kovtyukh, V. V.; Andrievsky, S. M.

doi:10.1086/505687

Cited by 139 publications

(171 citation statements)

References 54 publications

(64 reference statements)

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“…However, before a definitive interpretation in terms of models could be given, the data still demand more investigations and analysis. For example, there is still very little information about the possible azimuthal variations of the gradient (e.g., Luck et al 2006;Stanghellini & Haywood 2010).…”

Section: The Inner Gradientmentioning

confidence: 99%

“…This radial region is particularly interesting because from Cepheid metallicities, several authors (e.g., Andrievsky et al 2002;Luck et al 2006;Pedicelli et al 2009) have shown that there is yet another change of slope of the gradient. From ∼4 to ∼7−8 kpc (values vary slightly in different papers) the gradient is much steeper than in the outer regions.…”

Section: Introductionmentioning

confidence: 97%

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Open clusters towards the Galactic centre: chemistry and dynamics

Magrini

Randich

Zoccali

et al. 2010

A&A

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Context. In the framework of the study of the Galactic metallicity gradient and its time evolution, we present new high-resolution spectroscopic observations obtained with FLAMES and the fiber link to UVES at VLT of three open clusters (OCs) located within ∼7 kpc from the Galactic centre (GC): NGC 6192, NGC 6404, NGC 6583. We also present new orbit determination for all OCs with Galactocentric distances (R GC ) ≤ 8 kpc and metallicity from high-resolution spectroscopy. Aims. We aim to investigate the slope of the inner disc metallicity gradient as traced by OCs and to discuss its implication for the chemical evolution of our Galaxy. Methods. We have derived memberships of a group of evolved stars for each clusters, obtaining a sample of 4, 4, and 2 member stars in NGC 6192, NGC 6404, and NGC 6583, respectively. Using standard LTE analysis we derived stellar parameters and abundance ratios for the iron-peak elements Fe, Ni, Cr, and for the α-elements Al, Mg, Si, Ti, Ca. We calculated the orbits of the OCs currently located within 8 kpc from the GC, and discuss their implication on the present-time radial location. Results. The average metallicities of the three clusters are all oversolar: [Fe/H] = +0.12±0.04 (NGC 6192), +0.11±0.04 (NGC 6404), +0.37 ± 0.03 (NGC 6583). They are in qualitative agreement with their Galactocentric distances, because they are all internal OCs, and expected to be more metal rich than the solar neighbourhood. The abundance ratios of the other elements over iron [X/Fe] are consistent with solar values. Conclusions. The clusters we have analysed confirm, together with other OC and Cepheid data, a steep gradient in the inner disc, a signature of an evolutionary rate that is different from the one in the outer disc.

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Section: The Inner Gradientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Open clusters towards the Galactic centre: chemistry and dynamics

Magrini

Randich

Zoccali

et al. 2010

A&A

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“…For the solar neighbourhood, the data were compiled from several authors (Bensby & Feltzing 2006;Ecuvillon et al 2004;Fabbian et al 2009a;Gratton et al 2000;Gustafsson et al 1999, Jonsell et al 2005, Spite et al 2005, while the Cepheid abundances in Fig. 7 were taken from the works by Andrievski et al (2002aAndrievski et al ( ,b,c, 2004 and Luck et al (2003Luck et al ( , 2006. The observed G-dwarf distributions used in this paper were taken from Edvardsson et al (1993) and Wyse & Gilmore (1995).…”

Section: Abundance Datamentioning

confidence: 99%

The origin of carbon: Low-mass stars and an evolving, initially top-heavy IMF?

Mattsson

2010

A&A

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Multi-zone chemical evolution models (CEMs), differing in the nucleosynthesis prescriptions (yields) and prescriptions of star formation, have been computed for the Milky Way. All models fit the observed O/H and Fe/H gradients well and reproduce the main characteristics of the gas distribution, but they are also designed to do so. For the C/H gradient the results are inconclusive with regards to yields and star formation. The C/Fe and O/Fe vs. Fe/H, as well as C/O vs. O/H trends predicted by the models for the solar neighbourhood zone were compared with stellar abundances from the literature. For O/Fe vs. Fe/H all models fit the data, but for C/O vs. O/H, only models with increased carbon yields for zero-metallicity stars or an evolving initial mass function provide good fits. Furthermore, a steep star formation threshold in the disc can be ruled out since it predicts a steep fall-off in all abundance gradients beyond a certain galactocentric distance (∼13 kpc) and cannot explain the possible flattening of the C/H and Fe/H gradients in the outer disc seen in observations. Since in the best-fit models the enrichment scenario is such that carbon is primarily produced in low-mass stars, it is suggested that in every environment where the peak of star formation happened a few Gyr back in time, winds of carbon-stars are responsible for most of the carbon enrichment. However, a significant contribution by zero-metallicity stars, especially at very early stages, and by winds of high-mass stars, which are increasing in strength with metallicity, cannot be ruled out by the CEMs presented here. In the solar neighbourhood, as much as 80%, or as little as 40% of the carbon may have been injected to the interstellar medium by low-and intermediate-mass stars. The stellar origin of carbon remains an open question, although production in low-and intermediate-mass stars appears to be the simplest explanation of observed carbon abundance trends.

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“…The [Fe/H] values obtained by others were transformed to this modified Andrievsky scale based on common Cepheids in the respective projects, Fry & Carney (1997), Lemasle et al (2007), Mottini (2006), and Romaniello et al (2005). The transformation of [Fe/H] values obtained by Yong et al (2006) to the common scale was taken from Luck et al (2006) Giridhar (1983) could not be transformed because of insufficient common stars.…”

Section: Pulsation Amplitudesmentioning

confidence: 99%

Observational studies of Cepheid amplitudes

Klagyivik

Szabados

2009

A&A

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Context. The dependence of amplitude on the pulsation period differs from other Cepheid-related relationships. Aims. We attempt to revise the period-amplitude (P-A) relationship of Galactic Cepheids based on multi-colour photometric and radial velocity data. Reliable P-A graphs for Galactic Cepheids constructed for the U, B, V, R C , and I C photometric bands and pulsational radial velocity variations facilitate investigations of previously poorly studied interrelations between observable amplitudes. The effects of both binarity and metallicity on the observed amplitude, and the dichotomy between short-and long-period Cepheids can both be studied. Methods. A homogeneous data set was created that contains basic physical and phenomenological properties of 369 Galactic Cepheids. Pulsation periods were revised and amplitudes were determined by the Fourier method. P-A graphs were constructed and an upper envelope to the data points was determined in each graph. Correlations between various amplitudes and amplitude-related parameters were searched for, using Cepheids without known companions. Results. Large amplitude Cepheids with companions exhibit smaller photometric amplitudes on average than solitary ones, as expected, while s-Cepheids pulsate with an arbitrary (although small) amplitude. The ratio of the observed radial velocity to blue photometric amplitudes, A V RAD /A B , is not as good an indicator of the pulsation mode as predicted theoretically. This may be caused by an incorrect mode assignment to a number of small amplitude Cepheids, which are not necessarily first overtone pulsators. The dependence of the pulsation amplitudes on wavelength is used to identify duplicity of Cepheids. More than twenty stars previously classified as solitary Cepheids are now suspected to have a companion. The ratio of photometric amplitudes observed in various bands confirms the existence of a dichotomy among normal amplitude Cepheids. The limiting period separating short-and long-period Cepheids is 10.47 days. Conclusions. Interdependences of pulsational amplitudes, the period dependence of the amplitude parameters, and the dichotomy have to be taken into account as constraints in modelling the structure and pulsation of Cepheids. Studies of the P-L relationship must comply with the break at 10. d 47 instead of the currently used "convenient" value of 10 days.

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The Distribution of the Elements in the Galactic Disk

Cited by 139 publications

References 54 publications

Open clusters towards the Galactic centre: chemistry and dynamics

Open clusters towards the Galactic centre: chemistry and dynamics

The origin of carbon: Low-mass stars and an evolving, initially top-heavy IMF?

Observational studies of Cepheid amplitudes

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