tops june 21, 2001 - origins?. where did all this stuff come from? (what astronomy has to say about...
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Where did all this stuff come from?
(What astronomy has to say about it?)
Jeff Kuhn, IfA
Very local abundances
CNO
PbFe
Most common compound: Water!
Most common elementary particle: 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?
BB works for light elements
• Even oldest generations of stars have a lot of Helium…
• “Hot soup” model works
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...
We see dust/molecules around giant stars
Dust and gas are always foundtogether! ISO image of HD97300
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– 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