TOPS June 21, 2001 - Origins?. Where did all this stuff come from? (What astronomy has to say about...
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Transcript of TOPS June 21, 2001 - Origins?. Where did all this stuff come from? (What astronomy has to say about...
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