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TOPS June 21, 2001 - Origins?
Where did all this stuff come
from?
(What astronomy has to say about it?)
Jeff Kuhn, IfA
[email protected]
Substance?
• Molecules, compounds
• Atoms, elements
• Fundamental atomic constituents
Forces for change
• Thermodynamics
• Chemistry
• Life
Building blocks
Electrons
Elements
Nuclear building blocks and
“patterns”
Cosmic abundances
Solar system abundances
Very local abundances
Most common compound:
Water!
CNO
Fe
Most common elementary particle:
Pb
Neutron, almost same as protons, IDENTICAL
number of electrons
Element origins
• Where does it start (Big Bang?)
• Did it all come from the first 3 minutes?
– Can stars play a role?
A brief history
Epochs
BB works for light elements
• Even oldest generations of stars have a lot
of Helium…
• “Hot soup” model works
Making He in the sun...
Heavy Stars
Evidence of heavy element
production
Heavy elements require more...
• Higher densities and temperatures…
• Above Iron need something special to
happen…
Heaviest elements from cosmic
explosions (Supernovae)
• SN1987A was the first Supernovae in
hundreds of years that was visible by eye
Molecule problems...
• Collisions aren’t frequent enough to get
atoms to stick…Need a way to collect
atoms so they can combine…
• Cosmic dust is the answer...
Molecules and solids?
We see dust/molecules around
giant stars
Dust and gas are always found
together! ISO image of HD97300
Where did we come from then?
Summary
• Light elements formed in the first 3 minutes
• Heavies formed in stars later and now
• Dust (grains) formed in cool parts of giant
stars
• Molecules formed on dust grains
• Planets condensed from stellar environment
• Biological processes differentiated elements
Web resources
–
www.pbs.org/deepspace/timeline/index.html
• Big Bang, classroom activities, screen savers
– howstuffworks.lycos.com/atom.htm
• activities, atoms, general science, *links*
– micro.magnet.fsu.edu
• higher level science, movies, Electricity/Mag
– www.lbl.gov/abc/wallchart/index.html
• Nuclear science intro
–
–
–
–
–
www.iso.vilspa.esa.es/science/
btc.montana.edu/ceres/html/stars1.html#lessonplans
helios.gsfc.nasa.gov/nucleo.html#nucactys
www.ncsa.uiuc.edu/Cyberia/Bima/SolSys.html
www.eng.rpi.edu/~napolj/Origins
– this power point presentation at hubble.ifa.hawaii.edu, anonymous
ftp on directory INCOMING named topsorigins.ppt
Activities
• Concepts
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–
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Atoms as product of matter subdivision
Atoms mostly space, nucleus+electrons
Fission requires high density and temperature
“Cross-section” concept
• protons and neutrons different cross-sections
– Molecules built from atoms
– Local constituents result from “fractionation”
Activities
• Making atoms, 10cm paper strip cut 31
times…
• Make cardboard atom target. Rice grain
nucleus, 3’ diameter circle
• Proton and neutron target practice, making
He
• Atomic differentiation, rice and bb’s for H
and Fe