Astronomy 100

Are All Stars the Same?

• Answer Now: Why does the Sun shine? Are all stars the same as our Sun? (How or how not?)

• Goal:– Be able to tell me how stars are born– Know what stars are made of– Know how stars shine– (if we have time) Know how stars die

• Vocabulary: Planck curve, luminosity, H-R Diagram, absolute magnitude, apparent magnitude, fusion, H, He, CNO Cycle, protostar, nebula, protostar, hydrostatic equilibrium, interstellar medium, compression wave,

http://www4.nau.edu/meteorite/Meteorite/Images/PlanckCurve.jpg

Planck Curve - Temperature DIRECTLY related to peak wavelength.

• Luminosity– Apparent magnitude– Absolute magnitude– Luminosity is the total brightness

• Temperature or Type– Can tell temp from color– Can tell type from spectrum, temp or color

• Types: O, B, A, F, G, K, M

http://www.eso.org/gallery/d/4380-2/phot-28c-07.jpg

http://raviramanathan.blogspot.com/2007/05/life-cycle-of-star.html

It all starts with gas

• Interstellar medium• Gas cloud (nebula)• Compression wave• Pockets of compacted gas• Gravity further squeezes gas• PROTOSTAR!• Squished enough (enough energy) fusion begins• STAR!

E=mc2

H+H+H+H+H+H =He + H + H+ energy

Hydrostatic Equilibrium

Energy from fusion

• Compression Wave: http://video.google.com/videoplay?docid=-6732533372822687572&ei=c_iASe30OZ64qAPS-MSVDg&q=slinky+compression&hl=en

http://people.maths.ox.ac.uk/schmitz/Files/starlife.jpg

And in the end…• < 4 Solar Mass – when finished fusing H,

begins to fuse He• Ffffffft (planetary nebula)• White dwarf/black dwarf

• > 4 Solar Mass – when finished fusing H, begins to fuse He – when finished fusing He, begins to fuse C, N, O (shells)

• Kerblewie! (supernova)• Black hole/neutron star

• Review – define 3 of the terms at the beginning of this lecture.

• Quiz Review

“High Mass Stars”

My candle burns at both ends;It will not last the night;

But ah, my foes, and oh, my friends--It gives a lovely light.

Emily Dickinson

• Brownian Motion: http://www.youtube.com/watch?v=43-BKoqQxsM