Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood

Tautvaišienė, G.; Vázquez, C. Viscasillas; Mikolaitis, Š.; Stonkutė, E.; Minkevičiūtė, R.; Drazdauskas, A.; Bagdonas, V.

doi:10.1051/0004-6361/202039979

Cited by 34 publications

(21 citation statements)

References 133 publications

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“…The relation between the abundances of neutron-capture elements and stellar ages has been widely investigated (e.g. D 'Orazi et al 2009;Maiorca et al 2011Maiorca et al , 2012Yong et al 2012;Mishenina et al 2013b,a;Jacobson & Friel 2013;Battistini & Bensby 2016;Marsakov et al 2016;Nissen 2016;Reddy & Lambert 2017;Delgado Mena et al 2017;Spina et al 2018;Magrini et al 2018;Tautvaišienė et al 2021;Casamiquela et al 2021;Baratella et al 2021;Zinn et al 2021;Sales-Silva et al 2021). However, most of the previous works were limited to the solar neighbourhood region, using both solar twins or star clusters.…”

Section: Age Versus [El/fe] Relationsmentioning

confidence: 99%

“…The idea of combining pairs of elements with different origins, particularly s processes and α elements (or odd-Z elements such as Al), has taken shape in the last decade (see, e.g. Jofré et al 2020;Tautvaišienė et al 2021). Here, we aim to extend them in different regions of the Galactic disc using our sample of open clusters.…”

Section: Age Versus [S/α] Relations: Chemical Clocks Across the Discmentioning

confidence: 99%

“…Tucci Maia et al 2016b;Slumstrup et al 2017;Casamiquela et al 2021), metallicity (see, e.g Feltzing et al 2017Delgado Mena et al 2019;Casali et al 2020), and population type (thin disc, thick disc, halo) (see, e.g. Titarenko et al 2019;Nissen et al 2020;Tautvaišienė et al 2021), or even in dwarf galaxies (Skúladóttir et al 2019); ii) to calibrate them with a sample of stars with reliable age determination, which are usually open star clusters (OCs), solar twins, or targets with asteroseismic observations. Finally, it is essential to understand whether these relationships are valid throughout the Galactic disc, or whether they are necessarily position-dependent.…”

Section: Introductionmentioning

confidence: 99%

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The Gaia-ESO survey: Age-chemical-clock relations spatially resolved in the Galactic disc

Vázquez

Magrini

Casali

et al. 2022

A&A

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Context. The last decade has seen a revolution in our knowledge of the Galaxy thanks to the Gaia and asteroseismic space missions and the ground-based spectroscopic surveys. Aims. To complete this picture, it is necessary to map the ages of its stellar populations. During recent years, the dependence on time of abundance ratios involving slow (s) neutron-capture and α elements (called chemical-clocks) has been used to provide estimates of stellar ages, usually in a limited volume close to the Sun. We aim to analyse the relations of chemical clocks in the Galactic disc extending the range to R GC ∼6-20 kpc. Methods. Using the sixth internal data release of the Gaia-ESO survey, we calibrated several relations between stellar ages and abundance ratios [s/α] using a sample of open clusters, the largest one so far used with this aim (62 clusters). Thanks to their wide galactocentric coverage, we investigated the radial variations of the shape of these relations, confirming their non-universality.Results. The multi-variate relations allowed us to infer stellar ages for field stars. We estimated our accuracy (ranging from 0.0 to -0.9 Gyr) and precision (from 0.4 to 2.3 Gyr) in recovering the global ages of open clusters, and the ages of their individual members. We applied the relations with the highest correlation coefficients to the field star population, finding an older population at lower metallicity and higher [α/Fe] in the thin disc, and a younger one at higher [Fe/H] and low [α/Fe], as expected. Conclusions. We confirm that there is no single age-chemical clock relationship valid for the whole disc, but that there is a dependence on the galactocentric position, which is related to the radial variation of the star formation history combined with the non-monotonic dependence on metallicity of the yields of the s-process elements from low-and intermediate-mass stars. Finally, the abundance ratios [Ba/α] are more sensitive to age than those with [Y/α] for young disc stars, and their slopes vary less with galactocentric distance. We remind the reader that the application of such relationships to field stars is only of statistical value.

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Section: Age Versus [El/fe] Relationsmentioning

confidence: 99%

Section: Age Versus [S/α] Relations: Chemical Clocks Across the Discmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Gaia-ESO survey: Age-chemical-clock relations spatially resolved in the Galactic disc

Vázquez

Magrini

Casali

et al. 2022

A&A

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“…Galactic chemical evolution provides an alternative explanation for mild barium stars (with [Ba/Fe] ∼ 0.2−0.3 dex), which represent the upper [Ba/Fe] tail of the Galactic ([Ba/Fe],[Fe/H]) trend (e.g. Edvardsson et al 1993;Tautvaišienė et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Sr and Ba abundances: Comparing machine-learning with star-by-star analyses

Karinkuzhi

Eck

Jorissen

et al. 2021

A&A

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Context. A new large sample of 895 s-process-rich candidates out of 454 180 giant stars surveyed by LAMOST at a low spectral resolution (R ~ 1800) has been reported by Norfolk et al. (2019, MNRAS, 490, 2219; hereafter N19). Aims. This study is aimed at confirming the s-process enrichment at the higher resolution (R ~ 86 000) offered by the HERMES-Mercator spectrograph for the 15 brightest targets of the N19 sample, which consists of 13 Sr-only stars and two Ba-only stars (designating stars with only the Sr or only Ba lines strengthened). Methods. Abundances were derived for elements Li, C (including the 12C/13C isotopic ratio), N, O, Na, Mg, Fe, Rb, Sr, Y, Zr, Nb, Ba, La, and Ce, using the TURBOSPECTRUM radiative transfer LTE code with MARCS model atmospheres. Binarity has been tested by comparing the Gaia DR2 radial velocity (epoch 2015.5) with the HERMES velocity obtained 1600–1800 days (about 4.5 yr) later. Results. Among the 15 programme stars, 4 show no s-process overabundances ([X/Fe] < 0.2 dex), 8 show mild s-process overabundances (at least three heavy elements with 0.2 < [X∕Fe] < 0.8), and 3 have strong overabundances (at least three heavy elements with [X/Fe] ≥ 0.8). Among the 13 stars classified as Sr-only by the previous investigation, 4 have no s-process overabundances, 8 are mild barium stars, and 1 is a strong barium star. The two Ba-only stars turn out to be both strong barium stars. Especially noteworthy is the fact that these two are actually dwarf barium stars. Two among the three strong barium stars show clear evidence in support of their binary character, as expected for objects produced through mass-transfer. The results for the no s-process and mild barium stars are more surprising; namely, among the no-s stars, there are two binaries out of four, whereas only one out the eight diagnosed mild barium stars shows a clear signature of radial-velocity variations. Conclusions. Blending effects and saturated lines have to be considered very carefully when using machine-learning techniques, especially when applied to low-resolution spectra. Among the Sr-only stars from the previous study sample, about 60% (8/13) of them can be expected to be true mild barium stars and about 8% to be strong barium stars; this fraction is likely close to 100% for the N19 Ba-only stars (2/2). Therefore, we recommend to limit the sample to N19 Ba-only stars when one needs an unpolluted sample of mass-transfer (i.e., extrinsic) objects.

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“…The abundance of s-process elements in the Galactic disk has been the subject of intense study in recent years (e.g., using open clusters: D 'Orazi et al (2009); Maiorca et al (2011); Yong et al (2012); Magrini et al (2018); Spina et al (2021); as well as field stars: Battistini & Bensby (2016); Spina et al (2018); Tautvaišienė et al (2021) among others); the relationship between abundance and age may not be the same for all s-process elements (Yong et al 2012;Jacobson & Friel 2013). Some studies found an increase of the [X/Fe] abundance ratio of s-process elements, mainly Ba, with decreasing age of the open clusters and field disk stars (D'Orazi et al 2009;Maiorca et al 2012;Spina et al 2018Spina et al , 2021.…”

Section: Introductionmentioning

confidence: 99%

Exploring the s-process history in the Galactic disk: Cerium abundances and gradients in Open Clusters from the OCCAM/APOGEE sample

Sales-Silva,

Daflon,

Cunha

et al. 2021

Preprint

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The APOGEE Open Cluster Chemical Abundances and Mapping (OCCAM) survey is used to probe the chemical evolution of the s-process element cerium in the Galactic disk. Cerium abundances were derived from measurements of Ce II lines in the APOGEE spectra using the Brussels Automatic Code for Characterizing High Accuracy Spectra (BACCHUS) in 218 stars belonging to 42 open clusters. Our results indicate that, in general, for Ages < 4 Gyr, younger open clusters have higher [Ce/Fe] and [Ce/α-element] ratios than older clusters. In addition, metallicity segregates open clusters in the [Ce/X]-Age plane (where X can be H, Fe, and the α-elements O, Mg, Si, or Ca). These metallicitydependant relations result in [Ce/Fe] and [Ce/α] ratios with age that are not universal clocks. Radial gradients of [Ce/H] and [Ce/Fe] ratios in open clusters, binned by age, were derived for the first time, with d[Ce/H]dR GC being negative, while d[Ce/Fe]/dR GC is positive. [Ce/H] and [Ce/Fe] gradients are approximately constant over time, with the [Ce/Fe] gradient becoming slightly steeper, changing by ∼+0.009 dex-kpc −1 -Gyr −1 . Both the [Ce/H] and [Ce/Fe] gradients are shifted to lower values of

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Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood

Cited by 34 publications

References 133 publications

The Gaia-ESO survey: Age-chemical-clock relations spatially resolved in the Galactic disc

The Gaia-ESO survey: Age-chemical-clock relations spatially resolved in the Galactic disc

Sr and Ba abundances: Comparing machine-learning with star-by-star analyses

Exploring the s-process history in the Galactic disk: Cerium abundances and gradients in Open Clusters from the OCCAM/APOGEE sample

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