Historical Information on Solar Abundances of the Elements

    Noting that the Earth's crust and the Sun's gaseous envelope may not represent the overall compositions of these bodies, Harkins [1] showed in 1917 that 99% of the material in ordinary meteorites consists of seven, even-numbered elements - Fe, O, Ni, Si, Mg, S and Ca.   He concluded that "... in the evolution of elements much more material has gone into the even-numbered elements than into those which are odd ..." (p. 869).   In the 1920s, Payne [2] and Russell [3] showed that the solar atmosphere is mostly H and He, and in 1938 Goldschmidt [4] proposed an abundance table based on stellar spectra for volatile elements and on meteorites for nonvolatile elements.   However, Hoyle [5] and other astronomers continued to believe until the end of World War II that "... the Sun was made mostly of iron ..." (p. 153).   Research on H-fusion at Los Alamos during the War [6] likely aided their conversion.

    Goldschmidt's proposed loss of light, volatile elements from meteorites and rocky planets [4] is reasonable from the view of cosmic evolution, but from the view of nuclear physics the difference between an Fe-rich and a H-rich Sun is drastic.  Iron is an even-numbered element.   It consists mostly of Fe-56, with an ordinary charge density, Z/A = 0.46, and the lowest [7] mass per nucleon, M/A. Hydrogen is an odd-numbered element.   It consists mostly of H-1, with the highest values of Z/A and M/A among stable nuclides [7].   The H-rich Sun thus violates, on a grand scale, Harkins' prediction [1] (p. 859) that "... the more stable atoms should be more abundantly formed ...", but fine structure abundance peaks are still assigned to nuclear stability (e.g., Suess & Urey [8]).   To explain an H-rich Sun, Burbidge et al. [9] and Cameron [10] assumed that the products of nucleosynthesis were mixed back into the interstellar medium before the solar system formed.

    The discovery [11] of radiogenic Xe-129 in meteorites [12] severely constrained the time for mixing.   The mixing time essentially vanished as Reynolds' mass spectrometer [13] and others revealed the decay products of many short-lived nuclides and isotopic anomalies from nucleosynthesis as regular components of meteorites.   As a graduate student, Manuel joined Kuroda's effort to decipher isotope abundances in 1960, and in 2000 he officially retired as Professor and Department Chairman.  The evidence he found for an iron-rich Sun is summarized in Section II, in a 1998 review [14], and in the proceedings of an ACS symposium [15] organized by Seaborg and Manuel in August, 1999.   The conclusion that a hydrogen-filled Sun is obsolete, related observations, and the status of work on remaining issues are given in Section III.

References: [1] Harkins W.D. (1917) J. Am. Chem. Soc. 39, 856-879; [2] Payne, C.H.(1925)Stellar atmospheres (Harvard Observatory Monograph #1, Cambridge, MA, USA) pp.177-189; [3] Russell, H.N. (1929) Ap. J. 70, 11-82; [4] Goldschmidt V.M.(1938) Geochemische Verteilungsgestze der Elemente. IX. Die Mengenverhältnisse der Elemente und der Atom-arten, Skrifter Norske Videnskaps-Akad., Oslo I Math.-Naturv. Klasse, no. 4, 148 pp; [5] Hoyle F. (1994) Home is where the wind blows (University Science Books, Mill Valley, CA, USA) pp. 153-154; [6] Teller E.(1987) Better a shield than a sword (Macmillian, Inc., New York, NY, USA) p. 70; [7] Tuli J.K.: 2000, Nuclear wallet cards (Sixth edition, National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY, USA) 74 pp; [8] Suess H.E. & Urey H.C. (1956) Rev. Mod. Phys. 28, 53-74; [9] Burbidge E.M., Burbidge G.R., Fowler W.A. & Hoyle F. (1957) Rev. Mod. Phys. 29, 547-650; [10] Cameron A.G.W.(1957) Publ. Astron. Soc. Pac. 69, 201-222; [11] Reynolds J.H. (1960) Phys. Rev. Lett. 4, 8-10; [12] Fowler W.A., Greenstein J.L. & Hoyle F. (1961) Am. J. Phys. 29, 393-403; [13] Reynolds J.H. (1956) Rev. Sci. Instruments 27, 928-934; [14] Origin of Elements in the Solar Sysyem: Implications of Post-1957 Observations, Proceedings of the 1999 ACS symposium organized by Glenn T. Seaborg and Oliver K. Manuel (Kluwer Academic/Plenum Publishers, New York, NY, USA, ed., O.K.Manuel, 2000), 646 pp.; [15] Manuel O.K., Lee J.T., Ragland D.E., Macelroy J.M.D., Li, Bin, Brown & W. K. (1998) J. Radioanal. Nucl. Chem. 238, 213-225.