1. Ay, for t’were absurd To think that nature in the earth bred gold Perfect i’ the instant: Something went before. There must be remote matter. Ben Jonson, The Alchemist, 1610

2. Katharina Lodders, Washington University Saint Louis, USA Stars and the Abundances of the Elements

3. Why are we interested in the abundances and the distribution of the elements? It’s the stuff we are made of Constitution of (baryonic) matter, numbers and amounts of stable elements/isotopes Composition and formation of the solar system, planetary compositions; other solar systems Origin of the elements in stars, element abundance distributions are critical tests for nucleosynthesis models Clues about the basic make-up and origins of matter

4. AirFire WaterEarth Aristotle's periodic table of the elements

5. The periodic table of the elements 2300 years later:

6. 11 chemical elements known in antiquity Fe, Cu, Ag, Au, Hg, C, Sn, Pb, As, Sb, S

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9. Solar abundances: present-day observable composition of Sun, mainly photosphere; also sunspots, solar flares, solar wind Solar system abundances: composition at birth of solar system ISM/molecular cloud composition 4.6 billion years ago proto-solar abundances Li, D, short-lived radioactive nuclides: 26Al, 129I long-lived (still present) radioactive nuclides: 87Rb, 235U, 238U, 232Th Cosmic abundances: there is no “generic” cosmic composition avoid use of “cosmic abundances” many dwarfs stars are similar in composition as Sun, but amount of elements heavier than He (=metallicity) changes with time and varies across Milky Way Galaxy, & other galaxies What is meant by abundance:

10. Abundance is a relative quantity Most commonly used abundance scales compare the number of atoms of an element to a fixed (normalized) number of atoms of a reference element, (H or Si) Astronomical abundance scale: normalized to H, the most-abundant element in the universe set to  H = 10 12 atoms gives the number of atoms of an element per one trillion H atoms converted to log scale: A(H) = log  H = 12 abundances are measured relative to H, e.g., N(Fe)/N(H), so log  Fe = log { N(Fe)/N(H) } + 12 used for H-rich systems: stars, ISM Cosmochemical abundance scale: normalized to Si, the most abundant cation in rock, set to N(Si) = 10 6 atoms gives the number of atoms of an element per one million Si atoms used for planetary modeling, meteorites

11. HUGE RANGE IN VALUES The atomic abundances of the elements in the solar system vary over 12 orders of magnitude

12. Where do the abundance numbers come from? Earth’s crust Meteorites Solar photospheric spectrum solar wind, solar energetic particles Other solar system objects: gas-giant planets, comets, meteors Spectra of other dwarf stars (B stars) Interstellar medium Planetary Nebulae (PN) Galactic Cosmic Rays (GCR) Also presolar grains found in meteorites

13. Elie de Beaumont, 1847: ~59 out of 83 stable & long-lived elements are known 16 abundant elements common to different crustal rocks, ore veins, mineral & ocean waters, meteorites, & organic matter: H, Na, K, Mg, Ca, Al, C, Si, N, P, O, S, F, Cl, Mn, Fe only later: spectral analysis invented 1860s Mendeleev’s periodic table 1869 Gluconium=Be, Didymium=Nd+Pr, Columbium=Nb

14. There are 16 abundant elements common to different crustal rocks, ore veins, mineral & ocean waters, meteorites, & organic matter: Gluconium=Be, Didymium=Nd+Pr, Columbium=Nb “This identity shows that the surface of the Earth encloses in all its parts everything that is essential for the existence of organized beings...... one sees that nature has provided not only a settlement but also the conservation of this indispensable harmony. The aging Earth will never cease to furnish all the elements to the organized beings necessary for their existence” Elie de Beaumont, 1847

15. Extend search for chemical elements to other celestial objects I.A. Kleiber, 1885 68 elements are known & periodic table is established Compare: Earth’s crust Meteorites Comets Meteors Sun Other stars Composition of celestial objects is not random Helium found in 1868 but not plotted, no other noble gases known at the time

16. Abundances in the Earth’s crust & igneous rocks Clarke 1898, Harkins 1917 Quantitative analyses limited to abundant Elements (wet.chem) Light elements with atomic numbers up to that of Fe (26) are abundant, heavier elements are rare Notable exceptions: light elements Li, Be, B (3-5) are also quite rare 3-3.6 billion year old crust in Bangalore, India photo: K. Lodders

17. Crust: no discernable trends of abundance with atomic number or atomic weight  Abundances were modified from the initial solar system element mixture during Earth’s formation and differentiation What controls the abundances of the elements? Check abundances as a function of atomic number or mass Composition of the Earth’s crust Clarke 1898, Harkins 1917

18. Earth’s crust abundances: available material that can be analyzed in the lab but not representative for composition of entire Earth Earth materials are distributed between core, silicate mantle and crust elements follow geochemical affinities: metallic elements Fe, Ni, Co, Au, Ir,… move into the core oxide and silicate rock-forming elements go into silicate mantle and crust Mg, Si, Al, Ca, Ti, REE… Crust has elements with large ionic radii that enter silicate melts and are incompatible in silicate mantle minerals olivine, pyroxene Si, Al, Ca, K, Na, REE, U, Th … Earth is also not representative for solar system composition Element fractionations started during formation of planetesimals from molecular cloud material processed in the protoplanetary accretion disk (solar nebula) 

19. Molecular cloud composition 4.6 billion years ago gives the solar system composition Before the solar system forms: stars feed gas and dust to a molecular cloud:

20. Meter to km size planetesimals begin to form mixtures of silicates, metal and sulfides that may have been processed subsequently on their parent asteroids: Planetesimals grow to larger asteroids and planets which experienced melting: chondrites achondrites & iron meteorites

21. Molecular cloud composition 4.6 billion years ago = solar system composition Earth’s crust today Earth’s crust: Good place to live, bad place to determine solar system abundances

22. Chondritic Meteorites Chondrites: contain mineral phases that most closely resemble the original solids that were present in the solar nebula – TRY THESE FOR ABUNDANCES of non-volatile elements Many types of chondrites contain round silicate spheres called chondrules Chondrite groups: Ordinary chondrites: H, L, LL Enstatite chondrites: EH, EL Carbonaceous chondrites: CI, CM, CV, CO, CK, CR, CH Bjurboele L/LL3 chondriteChondrules in the Tieschitz ordinary chondrite Check meteoritic abundance distributions

23. Abundances vs. atomic number: Harkins 1917 Use average abundances from meteorites no photospheric abundances yet Even-numbered elements are more abundant than their odd-numbered neighbors Li, B, Be (3-5) are below scale, C (6) low because of volatility, but still more abundant than odd numbered neighbors B (5) or N (7) Abundances peak again at Fe (26) Abundances of elements heavier than Fe (26) are quite low Harkins’ discovery graph of the odd-even effect in elemental abundances

24. Photo: Le Muséum National d'Histoire Naturelle, Paris Elemental abundances of CI chondrites match those in the Sun (exceptions volatile elements H, C, N, O, noble gases) Orgueil meteorite “CI” stands for carbonaceous chondrite of Ivuna type 5 observed CI chondrite falls: Alais 1806 (6 kg), Ivuna 1938 (0.7 kg), Orgueil 1864 (14 kg), Revelstoke 1965 (1 g), Tonk 1911 (10 g)

25. Sun holds more than 99% of the solar system’s mass Composition of Sun should be good approximation for solar system as a whole First done by H.N Russell in 1929

26. Element determinations in the Sun ~66 elements out of 83 naturally occurring elements identified in the photosphere all stable elements up to atomic number 83 (Bi) plus radioactive Th and U ~30 – 35 elements well determined in photosphere Determined in photosphere with larger uncertainties: > 0.10 dex: (factor 1.3) Li, Be, B, N, Sc, Cr, Ni, Zn, Ga, Rh, Cd, In, Nd, Tb, Ho, Tm, Yb, Lu, Os, Pt > 0.05 dex: (factor 1.12) Mg, Al, Si, Ti, Fe, Co, Nb, Ru, Ba, Ce, Pr, Dy, Er, Hf, Pb Difficult to determine (line blends, low abundance) Ag, In, Sn, Sb, W, Au, Th, U; As, Se, Br, Te I, Cs, Ta, Re, Hg, Bi He detected but difficult to quantify from spectra He, Ne, Ar, Kr, Xe found in solar wind Determined from Sun-spot spectra, relatively uncertain: F, Cl, Tl

27. Good correlation for many heavy elements (1:1 line) Meteorites depleted in elements that form volatile compounds Noble gases, CO, CH 4, N 2, H 2 O Photosphere depleted in Li Abundances of “missing” rock-forming elements in photosphere can be derived from CI-chondrites Comparison of photospheric and CI chondritic abundances (both scales normalized to Si=10 6 atoms:

28. Lodders 2003 The state of solar system elemental abundances as of 2003

29. nuclear properties control abundances, not chemical (electron shell) properties Li, Be, B fragile Fe-peak most tightly bound nuclei peaks of elements with tightly bound nuclei

30. H, He (Li) produced in big-bang Elements heavier than He produced in stars Nucleosynthesis in the stellar core depends on a star’s initial mass: Low-mass stars with masses less than ~8 times the Sun’s mass: dwarf stars, Sun: main-sequence: H to He for ~ 11 billion years (Bethe, Weizaecker 1930s) On the red giant branches: He to C,O for ~110 million years (AGB, carbon stars; Merrill 1952, Tc) No more nucleosynthesis, white dwarfs Light stars live long and produce mainly Helium, C and O, but also Li, F, and several elements heavier than iron (e.g., Sr, Ba)

31. Nucleosynthesis models for red giant stars have become testable through the analysis of presolar grains found in meteorites. These dust grains captured the star’s nucleosynthesis products when they formed in the stellar winds

32. H, He (Li) produced in big-bang Elements heavier than He are produced in stars Nucleosynthesis in the stellar core depends on a star’s initial mass: Low-mass stars like the Sun (less than ~ 8 times the Sun’s mass) dwarf star Sun, main-sequence: H to He for ~ 11 billion years On the red giant branches: He to C for ~110 million years No more nucleosynthesis, white dwarfs Massive stars above ~ 8 times the Sun’s mass e.g., 15 solar-mass star: main sequence: H to He for ~ 8 million years Red/blue supergiant stage: He to C and O for ~1.2 million years C to Ne and Mg for ~1 thousand years O and Ne to Si and S ~0.6-1.3 years Si and S to Fe, Ni ~12 days Supernova: few seconds B 2 FH 1957, Cameron 1957 Light stars live longer and produce mainly Helium, C and O Massive stars have short lives and produce essentially all the abundant elements up to Fe

33. “Shells” containing the principal products of the nucleosynthesis stages in massive stars are detected in SN remnants through X ray emissions Cas-A Broadband, Si, Ca, Fe Chandra X-ray observatory

34. The elements heavier than iron: e.g., Sr, Ba, Au, Pb, U Production of elements heavier than iron requires input of energy, no more fusion reactions of lighter elements The heavy elements are built-up by neutron capture on pre-existing nuclides such as iron 2 different possibilities: Slow neutron capture during alternate H shell and He-shell burning in red giant stars “slow” compared to the beta-decay rates of the interim produced radioactive nuclides. These decay to a stable atom before another neutron is captured Rapid neutron capture during supernova explosions “rapid” compared to the beta decay rates of the interim produced radioactive nuclides Different isotopes of the heavy elements are preferentially made by either the S or R process  contribution of SN and giant stars to solar system element mixture

35. BaAu PbSr Low-intermediate giant stars ---------Massive stars ------ Where the heavy elements in our solar system come from U, Th

36. Supernovae produce most of the abundant elements heavier than He: C, N, O, Mg, Si, Fe, … R – rated = R process… SN also contribute to elements heavier than iron

37. H from big bang, maybe up to half of all C and N from giant stars, all other major elements made in massive stars going supernova…

39. for solar abundances see: Lodders 2003, Astrophysical Journal 591(2) 1220-1247, Solar system abundances and condensation temperatures of the elements. for a compilation of various physical and chemical data on solar system objects see: Lodders, K. & Fegley, B. 1998, The Planetary Scientist's Companion, Oxford Univ. Press, pp. 384 for a less technical description see Lodders, K. & Fegley, B., 2008/2009, Chemistry of the Solar System, Royal Society of Chemistry, coming soon to a bookstore near you For more information and reprints of our work please visit the Planetary Chemistry laboratory’s webpage at: http://solarsystem.wustl.edu