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and the Origin of the Elements • Nucleosynthesis = mainly H and He • = elements up to Fe formed within = produces heaviest elements and disseminates all

http://hubblesite.org/gallery/album/pr2001009b/

1 2 = mainly H and He

+

10-32 sec 14 sec 40 min 7.0 x 105 years

Time 

+ + quarks H (75%) + etc. He (25%) + + trace 2H, 3He, + and 5Li

3 x 109 3000

(K)

Stellar Nucleosynthesis - Elemental Abundances in the

Big Bang Stellar Nucleo. Supernova

12 H 10 He 8 Fe 6

4

2

0

Logarithm of Abundance B Sc -2 Li Be -4

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81

Mass-5 (Be) and mass-8 (O) “bottleneck”

3 Number of Stable as a function of Even vs. Odd

Number of A Z stable nuclides

Even Even 157

Even Odd 4

Odd Even 53

Odd Odd 50

264 total

Stellar Nucleosynthesis - The Origin of the Elements

H-burning unburned H H-burning H He C Ne O

Si

unburned H unburned He He-burning

Name of Process Fuel Products Temperature (K) Lifetime Remaining 1. H-burning H He 60 x 106 10,000,000 years 2. He-burning He C, O 200 x 106 1,000,000 years 3. C-burning C O, Ne, Na, Mg 800 x 106 1,000 years 4. Ne-burning Ne O, Mg 1500 x 106 10 years 5. O-burning O Mg to S 2000 x 106 1 year 6. Si-burning Mg to S Elements near Fe 3000 x 106 1 day 7. Rapid Elements after Fe supernova 1 sec

4 1. Burning to form He

1. Two H-nuclei () react to form a 1 1 2 0  nucleus (1 proton and 1 neutron) 1H1H1D 1e

3 2. The deuterium captures a proton to form 2 He 2 1 3 (2 protons and 1 neutron) 1D1H2 He

4 3. Two nuclei combine to form 2 He 3 3 4 1 (2 protons and 2 neutrons) plus the release of 2He2He2 He21H two protons 4. is released in each step in the form of gamma rays, , etc – heats up

+ + + + + + + + + + + + + + + neutron + + proton

Helium can also be Produced via the CNO Cycle

12 1 13 1. 6 C1H 7 N

2. 13 13 0  1. start 7N 6 C 1e

3. 13 1 14 6 C1H 7 N

14 1 15 4. 7N1H 8 O

15 15 0  5. 8 O 7 N 1e

15 1 12 4 6. 7N1H 6 C2He

http://upload.wikimedia.org/wikipedia/commons/0/06/CNO_Cycle.png

5 2. Burning to form C and O

A. triple- to form C the key to all the syntheses needed to form elements beyond He H He C 4 4 8 Very unstable – Ne He He Be decays in only O 2 2 4 10-16 sec Si 8 4 12 4 Be2He 6 C

B. alpha process to form O

12 4 16 6C2He 8 O

3. Burning to form O, Ne, Na, Mg

12 12 16 4 6C 6C 8 O 22 He H He C 12 12 20 4 Ne 6C 6C10Ne2He O

Si 12 12 23 1 6C 6C11Na1H

12 12 23 1 6C 6C12Mg 0n

6 4. Burning to form and

20 16 4 H 10Ne    8 O2He He C Ne 20 4 24 O 10Ne2He12Mg   Si

5. Oxygen Burning to form Magnesium 

16 16 24 4 8O 8O12Mg 22 He H He C Ne 16 16 28 4 O 8O 8O14Si 2He Si 16 16 31 1 8O 8O15P1H

16 16 31 1 8O 8O16S0n

7 6. Burning to form Elements Near Fe

Successive alpha processes -

H 28 4 32 He 14Si 2He16S C Ne O 32 4 36 16S2He18Ar Si

36 4 40 18Ar 2He20Ca    48 4 52 24Cr2He26Fe

7. Rapid Neutron Capture* - Heavy Elements After Fe e.g. s-process, r-process

*there is also a p-process where protons are added

8 Formation of The Solar System

http://ircamera.as.arizona.edu/NatSci102/Na tSci102/lectures/solarsysform.htm

9 Elemental Composition of the The Inner Planets

Elemental Composition of the Planets The Gas Giants

10 Structure and Composition of the Earth

Mohorovicic Discontinuity Silicate minerals Plastic flow

Liquid outer core

Solid inner core

Al Fe Si K

Na

O other

11 12