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GEARS Workshop Tuesday

GEARS Workshop Tuesday. 2011. Warm Up. Good morning! Complete form online Complete paper evaluation up to activities completed Create a code name to add to top of sheet so you can get the same one back each day – OR keep yours safe all week to turn in on Friday. Flux Simulator.

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GEARS Workshop Tuesday

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  1. GEARS Workshop Tuesday 2011

  2. Warm Up Good morning! Complete form online Complete paper evaluation up to activities completed Create a code name to add to top of sheet so you can get the same one back each day – OR keep yours safe all week to turn in on Friday.

  3. Flux Simulator Flux Simulator for Fluxiness we found

  4. So for same bulb

  5. Engage: Flux Lab How can we use the inverse square law of light to find out how luminous the sun is? Think for a few minutes in groups of 4 or 5. Brainstorming.

  6. Flux Lab – groups of 3-4 • Demonstrate the concept in the room with 2 light bulbs. • Explain that there are 2 measurements to make • distance to bulb for equal brightness wax – each person decides • Color of wax on each side when equal brightness

  7. Photometer Lab Equation One of these items is the light bulb One of these items is the Sun L is the power

  8. For same fluxiness Where the d represents distance to the wax from sun or bulb

  9. Discussion % error Color – each person better have something written down Sources of error: Brainstorm

  10. % error Used when know actual value and you are doing a verification lab. Provides a measure of the accuracy of your results (hint – see characteristics of science)

  11. % difference Used when you don’t know the answer. Provides a measure of the precision of your results. Helps identify outliers.

  12. Accuracy & Precision

  13. Wien’s Law – Color and Temperature Wavelength in meters from this formula 1 nanometer = 10-9 meter 1 meter = 109 nanometer

  14. Find Temperature of the Sun You need the radius of sun from the pinhole camera experiment. Prize to the group with the closest measurement if your workshop facilitator thinks it is OK

  15. Find color of the Sun http://eosweb.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html Compare with what you saw.

  16. Explain: Flux Lab We used inverse square law model & known source We assumed Sun was blackbody (known from other observations) We used Stefan-Boltzmann model and pinhole camera radius (from geometry and knowing distance) to get temperature of the sun as blackbody We used Wien’s Law model for peak wavelength of blackbody emitter using the temperature

  17. Models Models (aka theories, math equations, previously tested ideas) help extend our knowledge of the world around us Why can’t we just go measure the temperature of the Sun? How do we measure anything in astronomy?

  18. Sun • Insert advertisement here • Fall workshop • Resource Teachers • GEARS wiki • Sun & Space Weather Introduction

  19. Elaborate: Intrinsic Properties of Stars Let’s think back to initial categories made of star image Having made a few measurements now – let’s list the intrinsic properties of stars on the board together

  20. Organizing Stars Astronomers want nothing more than to classify and categorize – just like every other scientist First thing we do is try to plot things on graphs to see if there is a pattern Let’s plot two intrinsic properties against one another.

  21. This is on board – not in powerpoint Start with axes only Point out logarithmic scaling Point out backwards temperature Add main sequence – units of solar lum – what that mean Test for understanding – ask where blue stars Ask where red stars Ask where luminous, cold, hot, less luminous

  22. Add white dwarfs Ask for understanding – hot cold dim not Add supergiants Add giants

  23. Hey.. You know – dwarfs, giants.. Seems to imply something about radius Blackbodies follow Stefan-Boltzmann relation Luminosity and temperature and radius all related.

  24. Radius on HR diagram

  25. WOW! What a great diagram – 3 intrinsic properties in one graph!

  26. Mass? Yes indeedy… mass for main sequence is on this diagram too. Luminosity – Mass Relation

  27. Age on diagram? Sort of – if high mass main sequence star – know something. As they fuse such a short time But what about if it is a G star, like the Sun? Need groups of stars and use a model

  28. Composition? No… but hey Luminosity, Mass, temperature, radius, and age… on one graph! Models of blackbodies allow us to know more about stars than we can get from observations alone.

  29. Elaborate more: Create a diagram If time – if not, assign for HW. Nearby Stars Bright Stars Cluster 1 Cluster 2 Put all on same axes! See today’s online agenda for a data file.

  30. Your Graphs Did all the graphs look the same?

  31. Stellar Evolution Engage: What are some questions you have about stars right now? Brainstorm a list on your whiteboards.

  32. Explore: Stellar Evolution Simulators – as on agenda. Is the main sequence for stars on the L-T diagram a sequence of age?

  33. Explain Stars are simply balance (or imbalance) of forces – in vs. out. Formation – gravity stronger than gas pressure force Main sequence – gravity in balance with gas pressure force (btw – fusion!) Unbalance signals end of main sequence –exciting things happen Then back in balance for end state

  34. Star Formation What are some of the things you notice about places where we find young stars?

  35. Star Formation

  36. M16 – X-ray stars

  37. Star Formation • Accompanied by dust! • Collapse requires cold – think ideal gas law • “Dust” protects from light from nearby stars that might heat gas • Wispy gas – the future fuel for the star • And some very powerful stars that are very high temperature – emitting lots of light at X-ray and UV- the signatures of young stars

  38. Explain: Do all stars evolve the same way? Do all stars take the same amount of time to evolve? What is your evidence to support your claim?

  39. Summary: Really high mass High mass The Sun and the lower mass stars http://cheller.phy.georgiasouthern.edu/gears/Units/2-StellarEvolution/2Stars_7.html Compare main sequence lifetimes, end states.

  40. End of Stars Main sequence is the stage of existence where stars are fusing hydrogen to helium Spend largest fraction of their existence doing this More massive stars – short lived Low mass stars – long lived Range – 100,000 years – 100 billion years!

  41. BPPSC – Red Giant – on left. Artist conception - right

  42. Planetary Nebula

  43. White dwarf – Artist impression

  44. Supergiant to Supernova

  45. Crab SNR + Pulsar

  46. Black Holes http://hubblesite.org/explore_astronomy/black_holes/

  47. Black Hole G1915+105. 14 solar masses.

  48. Patterns + models = stellar evolution theory Along with physical models of gravity, gas pressure, electrostatic repulsion, nuclear physics Plus some nice spectral line measurements Get a beautiful scenario of stellar evolution Imagine the Universe powerpoint

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