Rocky asteroids and planets display nucleosynthetic isotope variations that are attributed to the heterogeneous distribution of stardust from different stellar sources in the solar protoplanetary disk. Here we report new high-precision palladium isotope data for six iron meteorite groups. The palladium data display smaller nucleosynthetic isotope variations than the more refractory neighbouring elements. Based on this observation, we present a model in which thermal destruction of interstellar dust in the inner Solar System results in an enrichment of s-process-dominated stardust in regions closer to the Sun. We propose that stardust is depleted in volatile elements due to incomplete condensation of these elements into dust around asymptotic giant branch stars. This led to the smaller nucleosynthetic variations for Pd reported here and the lack of such variations for more volatile elements. The smaller magnitude variations measured in heavier refractory elements suggest that material from high-metallicity asymptotic giant branch stars is the dominant source of stardust in the Solar System. These stars produce fewer heavy s-process elements (proton number Z ≥ 56) compared with the bulk Solar System composition.
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The authors declare that the original data supporting the findings of this study are available within the paper and its Supplementary Information. Original Pd and Pt data points for individual meteorites are also available from the EarthChem library (https://doi.org/10.1594/IEDA/111416). All other data are available from the corresponding author on reasonable request.
Zhukovska, S., Gail, H.-P. & Trieloff, M. Evolution of interstellar dust and stardust in the solar neighbourhood. Astron. Astrophys. 479, 453–480 (2008).
Hoppe, P., Leitner, J. & Kodolányi, J. The stardust abundance in the local interstellar cloud at the birth of the Solar System. Nat. Astron 1, 617–620 (2017).
Zinner, E. In Treatise on Geochemistry Vol. 1, 2nd edn (eds Holland, H. D. & Turekian, K. K.) 181–213 (Elsevier, 2014).
Qin, L. & Carlson, R. W. Nucleosynthetic isotope anomalies and their cosmochemical significance. Geochem. J. 50, 43–65 (2016).
Regelous, M., Elliott, T. & Coath, C. D. Nickel isotope heterogeneity in the early Solar System. Earth Planet. Sci. Lett. 272, 330–338 (2008).
Dauphas, N. et al. Neutron-rich chromium isotope anomalies in supernova nanoparticles. Astrophys. J. 720, 1577–1591 (2010).
Trinquier, A. et al. Origin of nucleosynthetic isotope heterogeneity in the solar protoplanetary disk. Science 324, 374–376 (2009).
Huss, G. R., Meshik, A. P., Smith, J. B. & Hohenberg, C. M. Presolar diamond, silicon carbide, and graphite in carbonaceous chondrites: implications for thermal processing in the solar nebula. Geochim. Cosmochim. Acta 67, 4823–4848 (2003).
Akram, W., Schönbächler, M., Bisterzo, S. & Gallino, R. Zirconium isotope evidence for the heterogeneous distribution of s-process materials in the solar system. Geochim. Cosmochim. Acta 165, 484–500 (2015).
Yokoyama, T., Alexander, C. M. D. & Walker, R. J. Assessment of nebular versus parent body processes on presolar components present in chondrites: evidence from osmium isotopes. Earth Planet. Sci. Lett. 305, 115–123 (2011).
Poole, G. M., Rehkämper, M., Coles, B. J., Goldberg, T. & Smith, C. L. Nucleosynthetic molybdenum isotope anomalies in iron meteorites—new evidence for thermal processing of solar nebula material. Earth Planet. Sci. Lett. 473, 215–226 (2017).
Dauphas, N., Davis, A. M., Marty, B. & Reisberg, L. The cosmic molybdenum–ruthenium isotope correlation. Earth Planet. Sci. Lett. 226, 465–475 (2004).
Fischer-Gödde, M., Burkhardt, C., Kruijer, T. S. & Kleine, T. Ru isotope heterogeneity in the solar protoplanetary disk. Geochim. Cosmochim. Acta 168, 151–171 (2015).
Burkhardt, C. et al. Molybdenum isotope anomalies in meteorites: constraints on solar nebula evolution and origin of the Earth. Earth Planet. Sci. Lett. 312, 390–400 (2011).
Fischer-Gödde, M. & Kleine, T. Ruthenium isotopic evidence for an inner Solar System origin of the late veneer. Nature 541, 525–527 (2017).
Wombacher, F., Rehkämper, M., Mezger, K., Bischoff, A. & Münker, C. Cadmium stable isotope cosmochemistry. Geochim. Cosmochim. Acta 72, 646–667 (2008).
Toth, E., Schönbächler, M., Friebel, M. & Fehr, M. Search for nucleosynthetic cadmium isotope variations in bulk carbonaceous chondrites. In Proc. 79th Annual Meeting Meteoritical Society 6275 (Lunar and Planetary Science Institute, 2016).
Fehr, M. A. et al. Tellurium isotopic composition of the early solar system—a search for effects resulting from stellar nucleosynthesis, 126Sn decay, and mass-independent fractionation. Geochim. Cosmochim. Acta 69, 5099–5112 (2005).
Mayer, B., Wittig, N., Humayun, M. & Leya, I. Palladium isotopic evidence for nucleosynthetic and cosmogenic isotope anomalies in IVB iron meteorites. Astrophys. J. 809, 180–187 (2015).
Bisterzo, S., Gallino, R., Straniero, O., Cristallo, S. & Käppeler, F. The s-process in low-metallicity stars – II. Interpretation of high-resolution spectroscopic observations with asymptotic giant branch models. Mon. Not. R. Astron. Soc 418, 284–319 (2011).
Pellin, M. et al. Heavy metal isotopic anomalies in supernovae presolar grains. In Proc. 37th Lunar Planetary Science Conference 2041 (Lunar and Planetary Science Institute, 2006).
Savina, M. R. et al. Isotopic composition of molybdenum and barium in single presolar silicon carbide grains of type A+B. In Proc. 34th Lunar Planetary Science Confence 2079 (Lunar and Planetary Science Institute, 2003).
Maas, R. et al. Isotope anomalies in tellurium and palladium from Allende nanodiamonds. Meteorit. Planet. Sci 36, 849–858 (2001).
Ott, U. et al. New attempts to understand nanodiamond stardust. Publ. Astron. Soc. Aust 29, 90–97 (2012).
Wanajo, S. The r-process in proto-neutron-star wind revisited. Astrophys. J. 770, L22 (2013).
Wanajo, S., Janka, H.-T. & Müller, B. Electron-capture supernovae as the origin of elements beyond iron. Astrophys. J. 726, L15 (2011).
Travaglio, C., Rauscher, T., Heger, A., Pignatari, M. & West, C. Role of core-collapse supernovae in explaining solar system abundances of p nuclides. Astrophys. J. 854, 18 (2018).
Côté, B. et al. The origin of r-process elements in the milky way. Astrophys. J. 855, 99 (2018).
Pian, E. et al. Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger. Nature 551, 67–70 (2017).
Nanne, J. A. M., Nimmo, F., Cuzzi, J. N. & Kleine, T. Origin of the non-carbonaceous–carbonaceous meteorite dichotomy. Earth Planet. Sci. Lett. 511, 44–54 (2019).
Van Kooten, E. M. M. E. et al. Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites. Proc. Natl Acad. Sci. USA 113, 2011–2016 (2016).
Leya, I., Schönbächler, M., Wiechert, U., Krähenbühl, U. & Halliday, A. N. Titanium isotopes and the radial heterogeneity of the solar system. Earth Planet. Sci. Lett. 266, 233–244 (2008).
Arlandini, C. et al. Neutron capture in low-mass asymptotic giant branch stars: cross sections and abundance signatures. Astrophys. J. 525, 886–900 (1999).
Lugaro, M. et al. Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17O. Nat. Astron. 1, 0027 (2017).
Travaglio, C. et al. Galactic evolution of Sr, Y, and Zr: a multiplicity of nucleosynthetic processes. Astrophys. J. 601, 864–884 (2004).
Maeder, A., Meynet, G. & Chiappini, C. The first stars: CEMP-no stars and signatures of spinstars. Astron. Astrophys. 576, A56 (2015).
Gail, H.-P., Zhukovska, S., Hoppe, P. & Trieloff, M. Stardust from asymptotic giant branch stars. Astrophys. J. 698, 1136–1154 (2009).
Pignatale, F. C., Charnoz, S., Chaussidon, M. & Jacquet, E. Making the planetary material diversity during the early assembling of the solar system. Astrophys. J. 867, L23 (2018).
Bell, K., Cassen, P., Wasson, J. & Woolum, D. in Protostars and Planets IV (eds Mannings, V. et al.) 897–926 (Univ. Arizona Press, 2000).
Allamandola, L. J., Bernstein, M. P., Sandford, S. A. & Walker, R. L. In Composition and Origin of Cometary Materials (eds Altwegg, K. et al.) 219–232 (Springer, 1999).
King, A. J., Henkel, T., Rost, D. & Lyon, I. C. Trace element depth profiles in presolar silicon carbide grains. Meteorit. Planet. Sci 47, 1624–1643 (2012).
Yin, Q.-z From dust to planets: the tale told by moderately volatile elements. Astron. Soc. Pac. Conf. Ser. 341, 632–644 (2005).
Davidson, J. et al. Abundances of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS. Geochim. Cosmochim. Acta 139, 248–266 (2014).
Alexander, C. M. O. D. Re-examining the role of chondrules in producing the elemental fractionations in chondrites. Meteorit. Planet. Sci 40, 943–965 (2005).
Savage, B. D. & Sembach, K. R. Interstellar abundances from absorption-line observations with the hubble space telescope. Annu. Rev. Astron. Astrophys. 34, 279–329 (1996).
Lodders, K. & Fegley, B. Complementary trace element abundances in meteoritic SiC grains and carbon star atmospheres. Astrophys. J. Lett. 484, L71 (1997).
Ireland, T. R. et al. Rare earth element abundances in presolar SiC. Geochim. Cosmochim. Acta 221, 200–218 (2018).
Lodders, K. & Fegley, B. Jr The origin of circumstellar silicon carbide grains found in meteorites. Meteorit. Planet. Sci. 30, 661–678 (1995).
Tielens, A. G. G. M. in The Physics and Chemistry of the Interstellar Medium 117–172 (Cambridge Univ. Press, 2005).
Hunt, A. C., Ek, M. & Schönbächler, M. Platinum isotopes in iron meteorites: Galactic cosmic ray effects and nucleosynthetic homogeneity in the p-process isotope 190Pt and the other platinum isotopes. Geochim. Cosmochim. Acta 216, 82–95 (2017).
Cseh, B. et al. The s process in AGB stars as constrained by a large sample of barium stars. Astron. Astrophys. 620, A146 (2018).
Lewis, K. M., Lugaro, M., Gibson, B. K. & Pilkington, K. Decoding the message from meteoritic stardust silicon carbide grains. Astrophys. J. Lett. 768, L19 (2013).
Ferrarotti, A. S. & Gail, H.-P. Composition and quantities of dust produced by AGB-stars and returned to the interstellar medium. Astron. Astrophys. 447, 553–576 (2006).
Lugaro, M., Karakas, A. I., Pető, M. & Plachy, E. Do meteoritic silicon carbide grains originate from asymptotic giant branch stars of super-solar metallicity? Geochim. Cosmochim. Acta 221, 6–20 (2018).
Kruijer, T. S., Burkhardt, C., Budde, G. & Kleine, T. Age of Jupiter inferred from the distinct genetics and formation times of meteorites. Proc. Natl Acad. Sci. USA 114, 6712–6716 (2017).
Alibert, Y. et al. The formation of Jupiter by hybrid pebble–planetesimal accretion. Nat. Astron 2, 873–887 (2018).
Cristallo, S., Piersanti, L. & Straniero, O. The FRUITY database on AGB stars: past, present and future. J. Phys. Conf. Ser. 665, 012019 (2016).
Lodders, K. Solar system abundances and condensation temperatures of the elements. Astrophys. J. 591, 1220–1247 (2003).
Hunt, A. C. et al. Late metal–silicate separation on the IAB parent asteroid: constraints from combined W and Pt isotopes and thermal modelling. Earth Planet. Sci. Lett. 482, 490–500 (2018).
Hunt, A. C., Ek, M. & Schönbächler, M. Separation of platinum from palladium and iridium in iron meteorites and accurate high-precision determination of platinum isotopes by multi-collector ICP-MS. Geostand. Geoanal. Res. 41, 633–647 (2017).
Markowski, A. et al. Correlated helium-3 and tungsten isotopes in iron meteorites: quantitative cosmogenic corrections and planetesimal formation times. Earth Planet. Sci. Lett. 250, 104–115 (2006).
Ek, M., Hunt, A. C. & Schönbächler, M. A new method for high-precision palladium isotope analyses of iron meteorites and other metal samples. J. Anal. At. Spectrom 32, 647–656 (2017).
Kelly, W. & Wasserburg, G. Evidence for the existence of Pd-107 in the early solar system. Geophys. Res. Lett. 5, 1079–1082 (1978).
Kruijer, T. S. et al. Neutron capture on Pt isotopes in iron meteorites and the Hf–W chronology of core formation in planetesimals. Earth Planet. Sci. Lett. 361, 162–172 (2013).
Steele, R. C. J., Coath, C. D., Regelous, M., Russell, S. & Elliott, T. Neutron-poor nickel isotope anomalies in meteorites. Astrophys. J. 758, 59–80 (2012).
Fischer-Gödde, M., Becker, H. & Wombacher, F. Rhodium, gold and other highly siderophile element abundances in chondritic meteorites. Geochim. Cosmochim. Acta 74, 356–379 (2010).
Hoashi, M., Brooks, R. R. & Reeves, R. D. Palladium, platinum and ruthenium in iron meteorites and their taxonomic significance. Chem. Geol. 106, 207–218 (1993).
Ryan, D. E., Holzbecher, J. & Brooks, R. R. Rhodium and osmium in iron meteorites. Chem. Geol. 85, 295–303 (1990).
Walker, R. J. et al. Modeling fractional crystallization of group IVB iron meteorites. Geochim. Cosmochim. Acta 72, 2198–2216 (2008).
Bigeleisen, J. Nuclear size and shape effects in chemical reactions. Isotope chemistry of the heavy elements. J. Am. Chem. Soc. 118, 3676–3680 (1996).
Fujii, T., Moynier, F. & Albarède, F. Nuclear field vs. nucleosynthetic effects as cause of isotopic anomalies in the early Solar System. Earth Planet. Sci. Lett. 247, 1–9 (2006).
Leya, I. & Masarik, J. Thermal neutron capture effects in radioactive and stable nuclide systems. Meteorit. Planet. Sci 48, 665–685 (2013).
Wittig, N., Humayun, M., Brandon, A. D., Huang, S. & Leya, I. Coupled W–Os–Pt isotope systematics in IVB iron meteorites: in situ neutron dosimetry for W isotope chronology. Earth Planet. Sci. Lett. 361, 152–161 (2013).
Worsham, E. A., Bermingham, K. R. & Walker, R. J. Characterizing cosmochemical materials with genetic affinities to the Earth: genetic and chronological diversity within the IAB iron meteorite complex. Earth Planet. Sci. Lett. 467, 157–166 (2017).
Pignatari, M. et al. The weak s-process in massive stars and its dependence on the neutron capture cross sections. Astrophys. J. 710, 1557–1577 (2010).
Gallino, R. et al. Evolution and nucleosynthesis in low-mass asymptotic giant branch stars. II. neutron capture and the s-process. Astrophys. J. 497, 388–403 (1998).
García-Hernández, D. A. et al. Rubidium-rich asymptotic giant branch stars. Science 314, 1751–1754 (2006).
García-Hernández, D. A. et al. Hot bottom burning and s-process nucleosynthesis in massive AGB stars at the beginning of the thermally-pulsing phase. Astron. Astrophys 555, L3 (2013).
Travaglio, C. et al. Galactic chemical evolution of heavy elements: from barium to europium. Astrophys. J. 521, 691 (1999).
Käppeler, F., Gallino, R., Bisterzo, S. & Aoki, W. The s process: nuclear physics, stellar models, and observations. Rev. Mod. Phys. 83, 157–193 (2011).
Karakas, A. I. & Lugaro, M. Stellar yields from metal-rich asymptotic giant branch models. Astrophys. J. 825, 26 (2016).
Cristallo, S., Abia, C., Straniero, O. & Piersanti, L. On the need for the light elements primary process (LEPP). Astrophys. J. 801, 53 (2015).
Pignatari, M. et al. The s-process in massive stars at low metallicity: the effect of primary 14N from fast rotating stars. Astrophys. J. 687, L95–L98 (2008).
Frischknecht, U. et al. s-process production in rotating massive stars at solar and low metallicities. Mon. Not. R. Astron. Soc. 456, 1803–1825 (2016).
Choplin, A. et al. Non-standard s-process in massive rotating stars. Astron. Astrophys. 618, A133 (2018).
Prantzos, N., Abia, C., Limongi, M., Chieffi, A. & Cristallo, S. Chemical evolution with rotating massive star yields – I. The solar neighbourhood and the s-process elements. Mon. Not. R. Astron. Soc. 476, 3432–3459 (2018).
Bliss, J., Arcones, A. & Qian, Y. Z. Production of Mo and Ru isotopes in neutrino-driven winds: implications for solar abundances and presolar grains. Astrophys. J. 866, 105 (2018).
Thielemann, F. K. et al. What are the astrophysical sites for the r-process and the production of heavy elements? Prog. Part. Nucl. Phys. 66, 346–353 (2011).
Fujii, T., Moynier, F. & Albarède, F. The nuclear field shift effect in chemical exchange reactions. Chem. Geol. 267, 139–156 (2009).
Angeli, I. & Marinova, K. P. Table of experimental nuclear ground state charge radii: an update. At. Data Nucl. Data Tables 99, 69–95 (2013).
York, D., Evensen, N. M., Martı́nez, M. L. & De Basabe Delgado, J. Unified equations for the slope, intercept, and standard errors of the best straight line. Am. J. Phys 72, 367––3375 (2004).
de Castro, D. B. et al. Chemical abundances and kinematics of barium stars. Mon. Not. R. Astron. Soc. 459, 4299–4324 (2016).
Cristallo, S., Straniero, O., Piersanti, L. & Gobrecht, D. Evolution, nucleosynthesis, and yields of AGB stars at different metallicities. III. Intermediate-mass models, revised low-mass models, and the ph-FRUITY interface. Astrophys. J. Suppl. Ser. 219, 40 (2015).
Cristallo, S. et al. Evolution, nucleosynthesis, and yields of low-mass asymptotic giant branch stars at different metallicities. II. the FRUITY database. Astrophys. J. Suppl. Ser. 197, 17 (2011).
Cristallo, S. et al. Evolution, nucleosynthesis, and yields of low-mass asymptotic giant branch stars at different metallicities. Astrophys. J. 696, 797–820 (2009).
Karakas, A. I. et al. Heavy-element yields and abundances of asymptotic giant branch models with a small magellanic cloud metallicity. Mon. Not. R. Astron. Soc. 477, 421–437 (2018).
Fishlock, C. K., Karakas, A. I., Lugaro, M. & Yong, D. Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity. Astrophys. J. 797, 44 (2014).
Lugaro, M., Karakas, A. I., Stancliffe, R. J. & Rijs, C. The s-process in asymptotic giant branch stars of low metallicity and the composition of carbon-enhanced metal-poor stars. Astrophys. J. 747, 2 (2012).
Battino, U. et al. Application of a theory and simulation-based convective boundary mixing model for AGB star evolution and nucleosynthesis. Astrophys. J. 827, 30 (2016).
This work was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement no. 279779 awarded to M.S. and by the Lendület grant (LP17-2014) of the Hungarian Academy of Sciences awarded to M.L. The authors acknowledge funding from ETH, the National Center for Competence in Research ‘PlanetS’, supported by the Swiss National Science Foundation (SNSF) and project funding from the SNSF (200020_179129). We are grateful to D. Farsky and D. Cook for their assistance in acquiring the Rh/Pd ratios used in this study. We thank C. Smith and D. Cassey (Natural History Museum, London), J. Hoskin (Smithsonian Institute) and P. Heck (Field Museum) for the loan of meteorite materials used in this study. Comments from M. Rehkämper helped improve an early version of this manuscript.
The authors declare no competing interests.
Peer review information Nature Astronomy thanks Camilla Hansen, Trevor Ireland and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended Data Fig. 1 Palladium isotope composition of iron meteorites from the IAB, IIAB, IID, IIIAB, IVA and IVB groups.
All epsilon values are reported relative to 105Pd and internally normalised to 108Pd/105Pd. Uncertainties on data points reflects the 2 standard error of the mean.
(a) The Pd isotope pattern produced by nuclear field shift effects, internally normalised to 108Pd/105Pd (short dashed line) and 108Pd/106Pd (solid line), calculated using the equations from Ref. 89 and the charge radii from Ref. 90. (b) ε105Pd against ε110Pd (internally normalised to 108Pd/106Pd; Supplementary Table 1) for five individually processed aliquots of Toluca (IAB), Odessa (IAB), the other IAB meteorites, Rodeo (IID) and four aliquots of Carbo (IID) sampled at different locations within the meteorite. The solid line shows the nuclear field shift trend, internally normalised to 108Pd/106Pd, and the dashed line shows an s-process deficit/excess trend calculated using the s-process yields of Ref. 20. Uncertainties are shown as the 2 standard error of the mean.
Regressions of (a) ε102Pd, (c) ε106Pd, and (d) ε110Pd against ε196Pt for the IAB, IID and IVB groups. Panel (b) shows regressions of ε104Pd versus ε196Pt multiplied by the Rh/Pd ratio of the sample, to account for varied CRE contributions from 103Rh(n,β)104Pd, for the same three groups. Individual samples and the slope of the regression are normalised to the intercept for each isotope/group such that the slopes can be compared directly. The black line shows the modelled CRE trend for each isotope, taken from Ref. 72. The slope of the regressions for ε102Pd, ε104Pd, ε106Pd and ε110Pd overlap for all three groups and agree well with the modelled slope. Uncertainties on individual data points given as the 2 standard error of the mean. Uncertainty envelope around regressions represents the 2 standard deviations of the regression calculated using the equation from Ref. 91.
Extended Data Fig. 4 Isotopic dichotomy between carbonaceous (CC) and non-carbonaceous (NC) meteorites in ε100Mo-ε92Mo and ε110Pd-ε102Pd.
(a) The dichotomy reported in Mo is characterised by an enrichment in ε92Mo for the CC meteorites (blue) relative to the NC group (grey). A small addition of supernova derived material to the stardust and/or ISM dust fraction coupled with thermal processing of ISM dust mantles can explain this offset. (b) Only the IVB irons of the two analysed CC-type iron meteorite groups (IID and IVB) show the negative shift in ε102Pd predicted by the isotopic dichotomy. Given the typical uncertainty on ε102Pd for individual meteorites (~ 1 ε; Supplementary Table 1) due to the large Ru correction on 102Pd (Ref. 62), it is barely possible to resolve the expected effect. The dashed lines indicate a mixing line between an s-process endmember33 and the terrestrial composition. The blue dashed line represents a mixing line between an s-process endmember33 and the terrestrial composition with a 0.008% enrichment in the residual r-process component, estimated based on the Mo data. Mo data from Ref. 11,14 and Pd data from Table 1. Uncertainties on Pd data points reflect either the 2 standard error of the mean or the 2 standard deviation of the x-axis intercept of a regression against ε196Pt (See Table 1). Uncertainties on Mo data points reflect either the 2 standard error of the mean (data from Ref. 11) or the 95 % confidence interval (data from Ref. 14).
Extended Data Fig. 5 Elemental ratios as a function of metallicity for FRUITY, Monash and NuGrid s-process models for AGB stars with an initial mass between 1.5 – 4 Mʘ.
The relative proportion of light s-process elements (Y, Zr, Mo, Ru, Pd and Cd) vary little with different metallicities and are independent of the initial stellar mass and nucleosynthetic model. All models show a clear trend with the yield of heavy s-process elements (Ba, Ce, Nd, Hf, W, Pt, Os) decreasing, relative to the light s-process elements, as the metallicity increases. Shown in panel Ce/Y are the observational data for Ba stars51,92 in grey. These also indicate a decrease in the Ce/Y ratio as a function of increasing metallicity51. FRUITY data93,94,95 correspond to the total yield for non-rotating stars with a metallicity of 0.006, 0.08, 0.010, 0.014 and 0.020 and mass of 1.5, 2.0, 2.5, 3.0 and 4.0 Mʘ. Monash data81,96,97,98 depict the yields of stars with a metallicity of 0.007, 0.014 and 0.030 and mass of 1.5, 2.5, 3.0, 3.5 and 4.0 Mʘ computed with a mass extension of the mixing leading to the formation of the main neutron source 13C of 2 × 10−3 (Mʘ ≤ 3) and 1 × 10−3 (Mʘ > 3). NuGrid data99 represent the final surface composition for stars with a metallicity of 0.01 and 0.02 and mass of 2.0 and 3.0 Mʘ. Elemental ratios are shown in standard spectroscopic notation where [Elx/Ely] = log(Elx/Ely)*-log(Elx/Ely)ʘ, where Elx and Ely are abundances by number.
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Ek, M., Hunt, A.C., Lugaro, M. et al. The origin of s-process isotope heterogeneity in the solar protoplanetary disk. Nat Astron 4, 273–281 (2020). https://doi.org/10.1038/s41550-019-0948-z
Earth and Planetary Science Letters (2021)
Nature Communications (2021)
Astronomy & Astrophysics (2020)
Astronomy & Astrophysics (2020)