Abundances of Cu and Zn in metal-poor stars: Clues for Galaxy evolution

Mishenina, T. V.; Kovtyukh, V. V.; Soubiran, C.; Travaglio, C.; Busso, M.

doi:10.1051/0004-6361:20021399

Cited by 153 publications

(221 citation statements)

References 37 publications

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“…An inspection of Fig. 6 of Bihain et al (2004) suggests that these measurements substantially agree with those of Mishenina et al (2002), which are essentially based on the measurements of the lines of Mult. 2.…”

Section: Hd 218502supporting

confidence: 59%

“…It was not until the comprehensive study of Sneden et al (1991) that this trend was clearly defined in a robust way, resting on measurements in a large sample of stars. Recent studies of field (Mishenina et al 2002;Bihain et al 2004) and Globular Cluster stars (Shetrone et al 2001(Shetrone et al , 2003Simmerer et al 2003;Yong et al 2005) have confirmed this trend (see Fig. 1 of Bisterzo et al 2004).…”

Section: Introductionmentioning

confidence: 68%

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Cu i resonance lines in turn-off stars of NGC 6752 and NGC 6397

Bonifacio

Caffau

Ludwig

2010

A&A

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Context.Copper is an element whose interesting evolution with metallicity is not fully understood. Observations of copper abundances rely on a very limited number of lines, the strongest are the Cu i lines of Mult. 1 at 324.7 nm and 327.3 nm which can be measured even at extremely low metallicities. Aims. We investigate the quality of these lines as abundance indicators. Methods. We measure these lines in two turn-off (TO) stars in the Globular Cluster NGC 6752 and two TO stars in the Globular Cluster NGC 6397 and derive abundances with 3D hydrodynamical model atmospheres computed with the CO5BOLD code. These abundances are compared to the Cu abundances measured in giant stars of the same clusters, using the lines of Mult. 2 at 510.5 nm and 578.2 nm. Results. The abundances derived from the lines of Mult. 1 in TO stars differ from the abundances of giants of the same clusters. This is true both using CO5BOLD models and using traditional 1D model atmospheres. The LTE 3D corrections for TO stars are large, while they are small for giant stars.Conclusions. The Cu i resonance lines of Mult. 1 are not reliable abundance indicators. It is likely that departures from LTE should be taken into account to properly describe these lines, although it is not clear if these alone can account for the observations. An investigation of these departures is indeed encouraged for both dwarfs and giants. Our recommendation to those interested in the study of the evolution of copper abundances is to rely on the measurements in giants, based on the lines of Mult. 2. We caution, however, that NLTE studies may imply a revision in all the Cu abundances, both in dwarfs and giants.

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Section: Hd 218502supporting

confidence: 59%

Section: Introductionmentioning

confidence: 68%

Cu i resonance lines in turn-off stars of NGC 6752 and NGC 6397

Bonifacio

Caffau

Ludwig

2010

A&A

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“…Relative abundances of metals do not show strong variations in DLAs, despite significant changes of the absolute metallicity Z. The Fe/Zn ratio is very close to solar in metal-poor stars with metallicities typical of DLA systems (Mishenina et al 2002;Gratton et al 2003;Nissen et al 2004;see discussion in Vladilo 2004). Deviations from the solar ratio are measured in stars with extremely low metallicities.…”

Section: Extinction Versus N Zn In Dla Systemsmentioning

confidence: 85%

The dust obscuration bias in damped Lyman αsystems

Vladilo

Péroux

2005

A&A

141

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We present a new study of the effects of quasar obscuration on the statistics of Damped Ly α (DLA) systems. We show that the extinction of any Galactic or extragalactic H i region, A λ , increases linearly with the column density of zinc, with a turning point ∂A λ /∂(log N Zn ) = 1, above which background sources are suddenly obscured. We derive a relation A λ = A λ (N H , Z, z) between the extinction of a DLA system and its H i column density, N H , metallicity, Z, fraction of iron in dust, f Fe (Z), and redshift, z. From this relation we estimate the fraction of DLA systems missed as a consequence of their own extinction in magnitude-limited surveys. We derive a method for recovering the true frequency distributions of N H and Z in DLAs, f N H and f Z , using the biased distributions measured in the redshift range where the observations have sufficient statistics (1.8 ≤ z ≤ 3). By applying our method we find that the well-known empirical thresholds of DLA column densities, N Zn < ∼ 10 13.1 atoms cm −2 and N H i < ∼ 10 22 atoms cm −2 , can be successfully explained in terms of the obscuration effect without tuning of the local dust parameters. The obscuration has a modest effect on the distribution of quasar apparent magnitudes, but plays an important role in shaping the statistical distributions of DLAs. The exact estimate of the bias is still limited by the paucity of the data ( 40 zinc measurements at 1.8 ≤ z ≤ 3). We find that the fraction of DLAs missed as a consequence of obscuration is ∼30% to 50%, consistent with the results of surveys of radio-selected quasars. By modelling the metallicity distribution with a Schechter function we find that the mean metallicity can be ∼5 to 6 times higher than the value commonly reported for DLAs at z ∼ 2.3.

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“…Gratton et al (2003) and Fulbright (2000). Cu field star data are obtained from Mishenina et al (2002) and Co field star data are taken from Johnson (2002). Interestingly, there is a lack of Co data for globular clusters.…”

Section: Discussionmentioning

confidence: 99%

“…The vast majority of the Fe-group members have roughly solar abundance ratios with two exceptions: copper and manganese. The relative abundance of Cu is known to be exceedingly subsolar in metal-poor field stars (at metallicities [Fe/H]< −2, [Cu/Fe] approaches −1; Sneden et al 1991a, Mishenina et al 2002). An analogous deficiency of Cu in globular cluster stars has recently been reported by Simmerer et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Manganese abundances in cluster and field stars

et al. 2005

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We have derived Mn abundances for more than 200 stars in 19 globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field and disk stars possessing an overlapping range of metallicities and stellar parameters. Our primary data set was comprised of high resolution spectra previously acquired at the McDonald, Lick and Keck Observatories. To enlarge our data pool, we acquired globular and open cluster spectra from several other investigators. Data were analyzed using synthetic spectra of the 6000Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that for the metallicity range −0.7>[Fe/H]>−2.7 stars of 19 globular clusters have a a mean relative abundance of <[Mn/Fe]>= −0.37 ± 0.01 (σ = 0.10), a value in agreement with that of the field stars: <[Mn/Fe]>= −0.36 ± 0.01 (σ = 0.08). Despite the 2 orders of magnitude span in metallicity, the <[Mn/Fe]> ratio remains constant in both stellar populations. Our Mn abundance data indicate that there is no appreciable variation in the relative nucleosynthetic contribution from massive stars that undergo core-collapse supernovae and thus, no significant change of the associated initial mass function in the specified metallicity range.

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Abundances of Cu and Zn in metal-poor stars: Clues for Galaxy evolution

Cited by 153 publications

References 37 publications

Cu i resonance lines in turn-off stars of NGC 6752 and NGC 6397

Cu i resonance lines in turn-off stars of NGC 6752 and NGC 6397

The dust obscuration bias in damped Lyman αsystems

Manganese abundances in cluster and field stars

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