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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
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
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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:
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