The <i>Gaia</i> RVS benchmark stars

Caffau, E.; Bonifacio, P.; Коротин, С. А.; François, P.; Lallement, R.; Pinto, A. M. Matas; Matteo, P. Di; Steffen, M.; Mucciarelli, A.; Katz, David; Haywood, M.; Chemin, L.; Sartoretti, Paola; Sbordone, L.; Andrievsky, S. M.; Kovtyukh, V. V.; Spite, M.; Spite, F.; Panuzzo, P.; Royer, F.; Thévenin, F.; Ludwig, H.‐G.; Marchal, Olivier; Plum, G.

doi:10.1051/0004-6361/202140808

Cited by 5 publications

(2 citation statements)

References 52 publications

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“…It is worth recalling however that the chemical and geometrical separations give rise to rather different groups(Minchev et al 2019, see alsoCaffau et al 2021;Romano et al 2021). Therefore, from now on we refer only to the high-α and low-α sequences.…”

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confidence: 99%

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

Palla

Santos-Peral

Recio–Blanco

et al. 2022

A&A

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Context. The [Mg/Fe] abundance ratios are a fundamental fossil signature used to trace the chemical evolution of the disc and to divide it into low-α and high-α populations. Despite the huge observational and theoretical efforts, discrepancies between models and data are still present and several explanations have been put forward to explain the [α/Fe] bimodality. Aims. In this work we take advantage of a new AMBRE:HARPS dataset, which provides new more precise [Mg/Fe] estimations and reliable stellar ages for a subsample of stars, to study the [α/Fe] bimodality and the evolution of the solar neighbourhood. Methods. The data are compared with detailed chemical evolution models for the Milky Way, exploring the most used prescriptions for stellar yields and different formation scenarios for the Galactic disc (i.e. the delayed two-infall and the parallel models), including prescriptions for stellar radial migration. Results. We see that most of the stellar yield prescriptions struggle to reproduce the observed trend of the data and that semi-empirical yields describe best the [Mg/Fe] evolution in the thick and thin discs. In particular, most of the yields still predict a steeper decrease of the [Mg/Fe] ratio at high metallicity than shown by the data. The bulk of the data are well reproduced by the parallel and two-infall scenarios, but both scenarios have problems in explaining the most metal-rich and metal-poor tails of the low-α data. These tails can be explained in light of radial migration from the inner and outer disc regions, respectively. Conclusions. Despite the evidence of stellar migration, it is difficult to estimate the actual contribution of stars from other parts of the disc to the solar vicinity in the data we adopt. However, the comparison between data and models suggests that peculiar histories of star formation, such as that of the two-infall model, are still needed to reproduce the observed distribution of stars.

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confidence: 99%

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

Palla

Santos-Peral

Recio–Blanco

et al. 2022

A&A

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“…The use of SYNTHE to derive the abundances of the heavy elements would imply the use of older partition functions. On the one hand the SYNTHE grids are already available and we have invested considerable time to develop these grids (see e.g., Caffau et al 2021). On the other hand, the use of Turbospectrum to compute complete grids of synthetic spectra would be much more time consuming than with SYNTHE.…”

Section: Abundance Determinationmentioning

confidence: 99%

Detailed investigation of two high‐speed evolved Galactic stars

et al. 2021

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The study of metal poor stars provides clarification and knowledge about the primordial Universe. Specially, halo stars provide explanations of the nature of the first generations of stars and the nucleosynthesis in the metal‐poor regime. We present a detailed chemical analysis and determination of the kinematic and orbital properties of two stars characterized by high speed with respect to the Sun. We analyzed two high‐resolution Subaru spectra employing the MyGIsFOS code, which allows to derive the detailed chemical abundances for 28 elements (C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, and Eu), and abundance from two ionization states in the case of four elements (Ti, Cr, Fe, and Zr). TYC 622–742–1 and TYC 1193–1918–1 are metal‐poor stars ([Fe/H] of −2.37 and −1.60), they are similar in the chemical pattern with respect to Fe, they are α enhanced and show a slight excess in Eu abundance. Both giant stars are poor in C and rich in N, as expected for evolved stars, and this fact is supported by the low 12Cfalse/13C isotopic ratio in TYC 1193–1918–1. Nevertheless, the C abundance of TYC 622–742–1 is particularly low. TYC 622–742–1 and TYC 1193–1918–1 have a similar chemical composition to the other Galactic halo stars of comparable metallicity. According to their kinematics, both stars belong to the Galactic halo, but they are not a part of the Gaia‐Sausage‐Enceladus structure.

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The Gaia RVS benchmark stars

Caffau,

Katz,

Gómez

et al. 2024

A&A

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The Gaia satellite has already provided the astronomical community with three data releases, and the Radial Velocity Spectrometer (RVS) on board Gaia has provided the radial velocity for 33 million stars. When deriving the radial velocity from the RVS spectra, several stars are measured to have large values. To verify the credibility of these measurements, we selected some bright stars with the modulus of radial velocity in excess of 500\ to be observed with SOPHIE at OHP and UVES at VLT. This paper is devoted to investigating the chemical composition of the stars observed with UVES. We derived atmospheric parameters using Gaia photometry and parallaxes, and we performed a chemical analysis using the code. We find that the sample consists of metal-poor stars, although none have extremely low metallicities. The abundance patterns match what has been found in other samples of metal-poor stars selected irrespective of their radial velocities. We highlight the presence of three stars with low Cu and Zn abundances that are likely descendants of pair-instability supernovae. Two stars are apparently younger than 1\,Ga, and their masses exceed twice the turn-off mass of metal-poor populations. This makes it unlikely that they are blue stragglers because it would imply they formed from triple or multiple systems. We suggest instead that they are young metal-poor stars accreted from a dwarf galaxy. Finally, we find that the star RVS721 is associated with the Gjoll stream, which itself is associated with the Globular Cluster NGC\,3201.

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The Gaia RVS benchmark stars

Cited by 5 publications

References 52 publications

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

Detailed investigation of two high‐speed evolved Galactic stars

The Gaia RVS benchmark stars

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