Ay, for t’were absurdTo think that nature in the earth bred goldPerfect i’ the instant: Something went before.There must be remote matter.

Ben Jonson, The Alchemist, 1610

Katharina Lodders, Washington University Saint Louis, USA

Stars and the Abundances of the Elements

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

Air Fire

WaterEarth

Aristotle's periodic table of the elements

The periodic table of the elements 2300 years later:

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

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A high-quality version of the movie will be posted on our web-page in the near future

Cosmochemical Periodic Table of the Elements in the Solar System 2.43e10 2.343e9

55.47 0.7374 17.32 7.079e6 1.950e6 1.413e7 841.1 2.148e6

57510 1.020e6 84100 1.000e6 8373 444900 5237 91200

3692 62870 34.20 2422 288.4 12860 9168 838000 2323 47800 527 1226 35.97 120.6 6.089 65.79 11.32 55.15

6.572 23.64 4.608 11.33 0.7554 2.601 1.900 0.3708 1.435 0.4913 1.584 0.1810 3.733 0.3292 4.815 0.9975 5.391

0.3671 4.351 0.4405 0.1699 0.02099 0.1277 0.05254 0.6738 0.6448 1.357 0.1955 0.4128 0.1845 3.258 0.1388

1.169 0.1737 0.8355 0.2542 0.09513 0.3321 0.05907 0.3862 0.08986 0.2554 0.0370 0.2484 0.03572

0.03512 9.31e-3

abund.

H He.

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac Rf 105 106 107 108 109 110 111 112

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No. Lr

EL < 3

1142 s 1452 s 908 s 40 123 180 734 s 9.1

958 s 1336 1653 1310 1229 664 948 s 47

1006 s 1517 1659 s 1582 1429 s 1296 s 1158 s 1334 1352 s 1353 s 1037 s 699 s 980 s 887 s 1065 s 695 s 546 s 52

800 s 1464 s 1659 s 1741 1559 s 1590 s 1551 s 1392 s 1324 s 996 s 652 s 536 s 704 s 979 s 709 s 535 s 68

799 s 1455 s 1578 s 1684 s 1573 s 1789 s 1821 s 1812 s 1603 s 1408 s 1060 s 252 s 532 s 727 s 746 s

1478 s 1582 s 1602 s 1590 s 1356 s 1659 s 1659 s 1659 s 1659 s 1659 s 1659 s 1487 s 1659 s

1659 s 1610 s

Tc (K)...... element symbol...... Si = 1e6 atoms

...... 50% condensationtemperature ......at 1e-4 barbox color:

lithophilechalcophilesiderophileatmophile

refractorycommonvolatile

highly volatiles=solid solution

K. Lodders, 2003, Solar System Abundances and Condensation Temperatures of the Elements,Astrophys. J. 591, 1220-1247

Solar abundances: present-day observable composition of Sun, mainly photosphere; also sunspots, solar flares, solar wind

Solar system abundances: composition at birth of solar systemISM/molecular cloud composition 4.6 billion years agoproto-solar abundancesLi, D, short-lived radioactive nuclides: 26Al, 129I long-lived (still present) radioactive nuclides: 87Rb, 235U, 238U, 232Th

Cosmic abundances: there is no “generic” cosmic compositionavoid 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:

Abundance is a relative quantityMost 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 universeset to H = 1012 atoms

gives the number of atoms of an element per one trillion H atoms

converted to log scale: A(H) = log H = 12abundances are measured relative to H, e.g.,N(Fe)/N(H), so log Fe = log { N(Fe)/N(H) } + 12used for H-rich systems: stars, ISM

Cosmochemical abundance scale:normalized to Si, the most abundant cation in rock, set to N(Si) = 106 atoms

gives the number of atoms of an element per one million Si atomsused for planetary modeling, meteorites

HUGE RANGE IN VALUES

The atomic abundances of the elements in the solar system vary over 12 orders of magnitude

Element Abundanceper 1012 H atoms

Num

ber

10-2

10-1

100

101

102

103

104

105

106

107

108

109

1010

1011

1012

1013US Natl debt = 6 T

US deficit = 410B

InBev offer for AB = 52 BNASA budget 2008/9 = 19 B

Shuttle launch (avg.) = 1.5 BOEF+OIF/day = 410 M

WU endowed gifts 2007 = 20 M

Millionaire = 1 M

WU tuition 2008 = 36 K

Gold/oz = 970

Oil/barrel = 140

Fed. min. wage/h = 5.85

Parking meter = 0.25

One penny

One dollar

Carbon 290 M

Hydrogen 1 T

Helium 96 B

Silicon 41 M

Gold 8

Uranium 0.4

Nickel 2 M

Oxygen 580 M

Chlorine 215 K

Fluorine 35 K

Lead 130

t ho

u s

a n

d s

| m

i l l

i o

n s

|

b i l

l i o

n s

| t

r i

l l i

o n

s

Amount US$

Gallium 1480

Where do the abundance numbers come from?

Earth’s crustMeteoritesSolar photospheric spectrumsolar wind, solar energetic particlesOther solar system objects: gas-giant planets, comets, meteors

Spectra of other dwarf stars (B stars)Interstellar mediumPlanetary Nebulae (PN)Galactic Cosmic Rays (GCR)

Also presolar grains found in meteorites

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 1860sMendeleev’s periodic table 1869

There are 16 abundant elements common to different crustal rocks, ore veins, mineral & ocean waters, meteorites, & organic matter:

“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

Extend search for chemical elements to other celestial objects

I.A. Kleiber, 188568 elements are known & periodic table is established

Compare:Earth’s crustMeteoritesCometsMeteorsSunOther stars

Composition of celestial objects is not random

Helium found in 1868 but not plotted,no other noble gases known at the time

Abundances in the Earth’s crust & igneous rocksClarke 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

ph

oto

: K

. Lo

dd

ers

Abundances in igneous rocks

(Table IX, col. II of Harkins 1917)

Atomic Numbers

6 8 10 12 14 16 18 20 22 24 26 28

We

igh

t Pe

rcen

t

0

10

20

30

40

50

C

O

F

Na

Mg

Al

Si

P S Cl

KCa

TiCr

Fe

Ni

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 abundancesas a function of atomic number or mass

Composition of the Earth’s crust

Clarke 1898, Harkins 1917

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 compositionElement fractionations started during formation of planetesimals from molecular cloud material processed in the protoplanetary accretion disk (solar nebula)

Molecular cloud composition 4.6 billion years ago gives the solar system composition

proto-Sun &solar nebula

gas giant protoplanetsbegin to form

evaporation & recondensation

of dust

Before the solar system forms: stars feed gas and dust to a molecular cloud:

Meter to km size planetesimals begin to form mixtures of silicates, metal and sulfides that may have been processed subsequently on their parent asteroids:

primitive planetesimals chondrite parent bodies

recondensedsilicatemetalsulfide

agglomeration

accretion,planetesimalgrowth

preservedpresolar

dust

differentiatedplanetesimals

ironsachondrites

break-up

terrestrialplanets

crust formationbasaltic volcanism

largeimpactsmetallic core

formation duringheating

Planetesimals grow to larger asteroids and planets which experienced melting:

chondrites

achondrites & iron meteorites

redgiants super

novaedust

presolar molecular cloud

differentiatedplanetesimals

ironsachondrites

break-up

terrestrialplanets

crust formationbasaltic volcanism

largeimpactsmetallic core

formation duringheating

Molecular cloud composition 4.6 billion years ago = solar system composition

Earth’s crust today

primitive planetesimals chondrite parent bodies

recondensedsilicatemetalsulfide

agglomeration

accretion,planetesimalgrowth

preservedpresolar

dust

proto-Sun &solar nebula

gas giant protoplanetsbegin to form

evaporation & recondensation

of dust

Earth’s crust:Good place to live, bad place to determine solar system abundances

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 chondrulesChondrite groups: Ordinary chondrites: H, L, LL

Enstatite chondrites: EH, EL Carbonaceous chondrites: CI, CM, CV, CO, CK, CR, CH

Bjurboele L/LL3 chondrite Chondrules in the Tieschitz ordinary chondrite

Check meteoritic abundance distributions

ABUNDANCE OF THE ELEMENTS

(stony meteorites; Harkins 1917)

Atomic Numbers

6 8 10 12 14 16 18 20 22 24 26 28

We

igh

t P

erc

en

t

0

10

20

30

40

C

O

Na

Mg

Al

Si

P

S

K

Ca

Ti Cr

Fe

Co

Ni

Abundances vs. atomic number:

Harkins 1917

Use average abundances from meteoritesno 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

Ph

oto

: L

e M

usé

um

Na

tion

al d

'His

toire

Na

ture

lle,

Pa

ris

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 type5 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)

mass distribution in thesolar system

mass

%

0.00000001

0.0000001

0.000001

0.00001

0.0001

0.001

0.01

0.1

1

10

100

Su

n

Mercu

ry

MarsV

en

us

Ea

rth

Jup

iter

Uran

us

Ne

ptu

ne

Sa

turn

Plu

to

ErisC

eres

Sun holds more than 99% ofthe 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

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, PbDifficult 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

Good correlation for many heavy elements (1:1 line)

Meteorites depleted in elements that form volatile compounds Noble gases, CO, CH4, N2, H2O

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=106 atoms:

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

nuclear properties control abundances, not chemical (electron shell) properties

Li, Be, Bfragile

Fe-peakmost tightly

bound nuclei

peaks of elements with tightly bound

nuclei

H, He (Li) produced in big-bang

Elements heavier than He produced in starsNucleosynthesis 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)

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

H, He (Li) produced in big-bangElements heavier than He are produced in starsNucleosynthesis 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 yearsOn the red giant branches: He to C for ~110 million yearsNo more nucleosynthesis, white dwarfs

Massive stars above ~ 8 times the Sun’s masse.g., 15 solar-mass star:main sequence: H to He for ~ 8 million yearsRed/blue supergiant stage:He to C and O for ~1.2 million yearsC to Ne and Mg for ~1 thousand yearsO and Ne to Si and S ~0.6-1.3 yearsSi and S to Fe, Ni ~12 daysSupernova: few secondsB2FH 1957, Cameron 1957

Light stars live longer and produce mainly Helium, C and OMassive stars have short lives and produce essentially all the abundant elements up to Fe

“Shells” containing the principal products of the nucleosynthesis stages in massive stars are detected in SN remnants through X ray emissions

Cas-ABroadband, Si, Ca, FeChandra X-ray observatory

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

Legend:

atomic number, Z40 50 60 70 80 90

fra

ctio

n o

f to

tal e

lem

ent

0.0

0.2

0.4

0.6

0.8

1.0 AsSeBr KrRb Sr Y Zr NbMoTcRuRhPdAgCd In SnSbTe I XeCsBaLaCe PrNdPmSmEuGdTbDyHo ErTmYbLu Hf Ta W ReOs Ir Pt AuHg Tl Pb Bi Th U

weak S R processP processmain S

Ba Au PbSr

Low-intermediategiant stars

---------Massive stars ------

Where the heavy elements in our solar system come from

U, Th

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

Composition of the Human Body(mass %)

oxygen 63.4%

carbon 20.5%

hydrogen10%

nitrogen 2.8%calcium 1.5%

phosphorusK, S, Na, Clother elements

< 0.06%

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…

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 seeLodders, 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 workplease visit the Planetary Chemistry laboratory’s webpage at:http://solarsystem.wustl.edu