Rubidium abundances of galactic disk stars

Takeda, Yoichi

doi:10.1002/asna.202123873

Cited by 7 publications

(3 citation statements)

References 26 publications

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“…Even more recently,Takeda (2021) performed a similar 1D non-LTE study, including for the Sun, where they found a less noticeable non-LTE correction: −0.05 dex. Because they only considered the classicalDrawin (1968) formula with a scaling factor for the inelastic H collisions and no specification is given as to which recipe for the electron collisions is employed, we here give a preference to the results ofKorotin (2020).…”

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confidence: 90%

The chemical make-up of the Sun: A 2020 vision

Asplund

Amarsi

Grevesse

2021

A&A

401

270

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Context. The chemical composition of the Sun is a fundamental yardstick in astronomy, relative to which essentially all cosmic objects are referenced. As such, having accurate knowledge of the solar elemental abundances is crucial for an extremely broad range of topics. Aims. We reassess the solar abundances of all 83 long-lived elements, using highly realistic solar modelling and state-of-the-art spectroscopic analysis techniques coupled with the best available atomic data and observations. Methods. The basis for our solar spectroscopic analysis is a three-dimensional (3D) radiative-hydrodynamical model of the solar surface convection and atmosphere, which reproduces the full arsenal of key observational diagnostics. New complete and comprehensive 3D spectral line formation calculations taking into account of departures from local thermodynamic equilibrium (non-LTE) are presented for Na, Mg, K, Ca, and Fe using comprehensive model atoms with reliable radiative and collisional data. Our newly derived abundances for C, N, and O are based on a 3D non-LTE analysis of permitted and forbidden atomic lines as well as 3D LTE calculations for a total of 879 molecular transitions of CH, C2, CO, NH, CN, and OH. Previous 3D-based calculations for another 50 elements are re-evaluated based on updated atomic data, a stringent selection of lines, improved consideration of blends, and new non-LTE calculations available in the literature. For elements where spectroscopic determinations of the quiet Sun are not possible, the recommended solar abundances are revisited based on complementary methods, including helioseismology (He), solar wind data from the Genesis sample return mission (noble gases), sunspot observations (four elements), and measurements of the most primitive meteorites (15 elements). Results. Our new improved analysis confirms the relatively low solar abundances of C, N, and O obtained in our previous 3D-based studies: log ϵC = 8.46 ± 0.04, log ϵN = 7.83 ± 0.07, and log ϵO = 8.69 ± 0.04. Excellent agreement between all available atomic and molecular indicators is achieved for C and O, but for N the atomic lines imply a lower abundance than for the molecular transitions for unknown reasons. The revised solar abundances for the other elements also typically agree well with our previously recommended values, with only Li, F, Ne, Mg, Cl, Kr, Rb, Rh, Ba, W, Ir, and Pb differing by more than 0.05 dex. The here-advocated present-day photospheric metal mass fraction is only slightly higher than our previous value, mainly due to the revised Ne abundance from Genesis solar wind measurements: Xsurface = 0.7438 ± 0.0054, Ysurface = 0.2423 ± 0.0054, Zsurface = 0.0139 ± 0.0006, and Zsurface/Xsurface = 0.0187 ± 0.0009. Overall, the solar abundances agree well with those of CI chondritic meteorites, but we identify a correlation with condensation temperature such that moderately volatile elements are enhanced by ≈0.04 dex in the CI chondrites and refractory elements possibly depleted by ≈0.02 dex, conflicting with conventional wisdom of the past half-century. Instead, the solar chemical composition more closely resembles that of the fine-grained matrix of CM chondrites with the expected exception of the highly volatile elements. Conclusions. Updated present-day solar photospheric and proto-solar abundances are presented for 83 elements, including for all long-lived isotopes. The so-called solar modelling problem – a persistent discrepancy between helioseismology and solar interior models constructed with a low solar metallicity similar to that advocated here – remains intact with our revised solar abundances, suggesting shortcomings with the computed opacities and/or treatment of mixing below the convection zone in existing standard solar models. The uncovered trend between the solar and CI chondritic abundances with condensation temperature is not yet understood but is likely imprinted by planet formation, especially since a similar trend of opposite sign is observed between the Sun and solar twins.

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confidence: 90%

The chemical make-up of the Sun: A 2020 vision

Asplund

Amarsi

Grevesse

2021

A&A

401

270

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“…[Fe/H] Figure 12. Observed [X/Fe] abundance ratios as a function of metallicity for the stars analyzed in this study (black dots with error bars) along with data for field giant stars (grey dots, taken from Gratton & Sneden 1994;Tomkin & Lambert 1999;Burris et al 2000;Mishenina & Kovtyukh 2001;Mishenina et al 2007;Johnson 2002;Luck & Heiter 2007;Zhang et al 2009;For & Sneden 2010;Santrich et al 2013;Hansen et al 2014;Ishigaki et al 2018;Forsberg et al 2019;Abia et al 2021;Takeda 2021) Reyniers et al 2004;De Smedt et al 2012van Aarle et al 2013). Triangles are data for CEMP-𝑠 (cyan), CEMP-𝑟 (magenta), and CEMP-𝑟/𝑠 (purple) stars, taken from Masseron et al (2010) and Karinkuzhi et al (2021).…”

Section: Heavy Elementsmentioning

confidence: 99%

“…Figure12. Observed [X/Fe] abundance ratios as a function of metallicity for the stars analyzed in this study (black dots with error bars) along with data for field giant stars (grey dots, taken fromGratton & Sneden 1994;Tomkin & Lambert 1999;Burris et al 2000;Mishenina & Kovtyukh 2001;Mishenina et al 2007;Johnson 2002;Luck & Heiter 2007;Zhang et al 2009;For & Sneden 2010;Santrich et al 2013;Hansen et al 2014;Ishigaki et al 2018;Forsberg et al 2019;Abia et al 2021;Takeda 2021), barium stars (green dots, taken fromAllen & Barbuy 2006;Allen & Porto de Mello 2007;Karinkuzhi et al 2018;Shejeelammal et al 2020; Roriz et al 2021a,b), CH stars (yellow diamonds, takenfrom Vanture 1992c;Pereira & Drake 2009;Pereira et al 2012;Goswami et al 2016;Purandardas et al 2019), and post-AGB stars (brown squares, taken fromVan Winckel & Reyniers 2000;Reyniers et al 2004; De Smedt et al 2012van Aarle et al 2013). Triangles are data for CEMP-𝑠 (cyan), CEMP-𝑟 (magenta), and CEMP-𝑟/𝑠 (purple) stars, taken fromMasseron et al (2010) andKarinkuzhi et al (2021).…”

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confidence: 99%

High-resolution spectroscopic analysis of four new chemically peculiar stars

Roriz¹,

Pereira²,

Junqueira³

et al. 2022

Preprint

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We present detailed chemical compositions of four stars on the first-ascent red giant branch that are classified as chemically peculiar, but lack comprehensive analyses at high spectral resolution. For BD+03 • 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, we derived metallicities [Fe/H] = −1.21, −0.19, −0.31, and −0.55, respectively, indicating a range in Galactic population membership. In addition to atmospheric parameters, we extracted elemental abundances for 28 elements, including the evolutionary-sensitive CNO group and 12 C/ 13 C ratios. Novel results are also presented for the heavy elements tungsten and thallium. All four stars have very large enhancements of neutron-capture elements, with high [La/Eu] ratios indicating enrichments from the slow neutron capture (𝑠-process). To interpret these abundances, all indicative of [𝑠/Fe] > 1.0, we compared our results with data from literature, as well as with predictions from the Monash and 𝑠-process nucleosynthesis models.

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The Gaia RVS benchmark stars

Caffau

Bonifacio

Коротин

et al. 2021

A&A

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Context. The Radial Velocity Spectrometer (RVS) on board the Gaia satellite is not provided with a wavelength calibration lamp. It uses its observations of stars with known radial velocity to derive the dispersion relation. To derive an accurate radial velocity calibration, a precise knowledge of the line spread function (LSF) of the RVS is necessary. Good-quality ground-based observations in the wavelength range of the RVS are highly desired to determine the LSF. Aims. Several radial velocity standard stars are available to the Gaia community. The highest possible number of calibrators will surely allow us to improve the accuracy of the radial velocity. Because the LSF may vary across the focal plane of the RVS, a large number of high-quality spectra for the LSF calibration may allow us to better sample the properties of the focal plane. Methods. We selected a sample of stars to be observed with UVES at the Very Large Telescope, in a setting including the wavelength range of RVS, that are bright enough to allow obtaining high-quality spectra in a short time. We also selected stars that lack chemical investigation in order to increase the sample of bright, close by stars with a complete chemical inventory. Results. We here present the chemical analysis of the first sample of 80 evolved stars. The quality of the spectra is very good, therefore we were able to derive abundances for 20 elements. The metallicity range spanned by the sample is about 1 dex, from slightly metal-poor to solar metallicity. We derived the Rb abundance for all stars and investigated departures from local thermodynamical equilibrium (NLTE) in the formation of its lines. Conclusions. The sample of spectra is of good quality, which is useful for a Gaia radial velocity calibration. The Rb NLTE effects in this stellar parameters range are small but sometimes non-negligible, especially for spectra of this good quality.

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Rubidium abundances of galactic disk stars

Cited by 7 publications

References 26 publications

The chemical make-up of the Sun: A 2020 vision

The chemical make-up of the Sun: A 2020 vision

High-resolution spectroscopic analysis of four new chemically peculiar stars

The Gaia RVS benchmark stars

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