* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download IB_Op_F_04 - Effectsmeister
Extraterrestrial life wikipedia , lookup
Orion (constellation) wikipedia , lookup
Rare Earth hypothesis wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
Constellation wikipedia , lookup
Observational astronomy wikipedia , lookup
Corona Borealis wikipedia , lookup
Aries (constellation) wikipedia , lookup
Auriga (constellation) wikipedia , lookup
Corona Australis wikipedia , lookup
Cosmic distance ladder wikipedia , lookup
Canis Minor wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
H II region wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Star catalogue wikipedia , lookup
Canis Major wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Stellar evolution wikipedia , lookup
Stellar classification wikipedia , lookup
Stellar kinematics wikipedia , lookup
Page Ver. 0.3.4 Physics Activities Last updated 11.01.02 Activities for Option F.2 Activitities are unassessed short experiments with some problems (pre questions, post questions, and syllabus questions) assigned. These problems will be a starting point for class discussion on the material after the activities. Due to time restrictions some of the problems will be given as homework. Text book reference: Section 14.2, “Types of Stellar Objects” in Chapter 14 - Astrophysics - pp. 559-562 of Gregg Kerr, Nancy Kerr and Paul Ruth, Physics, IBID Press 1999, ISBN 0-958-56867-7 A.1 Binary Stars Aim One aim is to know the difference between visual binaries, eclipsing binaries and spectroscopic binaries. Another one is to understand their different properties by kinesthesic simulation. Syllabus reference F.2.4 Group size Three to four Equipment Two stars (i. e. students) Procedure: 1. Most of the stars in the universe are actually a binary system, i. e. two stars that revolve around their common center of mass. The set of all binary systems are often divided into visual binaries, eclipsing binaries and spectroscopic binaries. Use the book to find the difference between these three cases. 2. Assume that the star 1 and star 2 in the diagram below are visual binaries or eclipsing binaries and that they have equal intensity. Your task is now to find the maximum and minimum intensity as seen from the earth. Let two members of the group simulate (slowly) the rotation of the two stars about a common point and let the other members (the Earth) determine if the intensity will increase or decrease. Make a sketch that shows intensity vs time where the unit along the time axis is a quarter of a period. 170 3. Make a similar sketch if star 1 is much brighter than star 2. Starting with a simulation will probably make the result much clearer. 4. Assume now that the stars are spectroscopic binaries. It is known that if a star is radially approaching the earth the light spectrum will be blueshifted (all wavelengths become smaller) and if a star is moving radially away from the earth, the light spectrum will be redshifted (all wavelengths become larger). Use the four positions in the figure under part 2 to predict which star(s) that are blue/redshifted if a shift appears. A simulation might make the various cases more clear. 5. Several of the star names in the table of Appendix B appear twice followed by an A or a B. These are mostly double stars - two stars which are revolving around each other together in space. They seem to frequently have similar spectral types. Can you guess why they have similar spectral types? A.2 The Hertzsprung-Russell Diagram Aim The aim of this activity is to plot near stars and bright stars on a color magnitude diagram. White stars, red giants, the main sequence and possible variable stars are also identified. Syllabus reference F.2.1 – F.2.3 Group size Two Equipment needed Pencil Paper Procedure 171 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Using the list of bright stars in Appendix A and the list of near stars in appendix B, plot their absolute magnitude vs. spectral class on the attached graph in appendix C. Use different colors for the near stars and for the bright stars. What general trends or concentrations do you see in the data? Are there generalizations you can make about bright stars? Any generalizations about near stars? This diagram was first published by Henry Norris Russell and Ejnar Hertzsprung in the early 1900's. It is sometimes called a color - magnitude diagram. Why is this ( or why is this not) an appropriate name for a plot of magnitude versus spectral class? Our star, the Sun, is a G2 spectral class star with an absolute magnitude of 4.8 . How does it compare to the locations of the near stars on the diagram? How does it compare to the locations of the bright stars on the diagram? Which spectral class is most common? Which spectral class is the least common? In general, what is the relationship between the temperature of a star and its brightness? Most of the stars seem to be along a line from the upper left corner to the lower right corner of the HR Diagram. Stars which fall into this category of stars are called main sequence stars . Does our Sun fit into this category? White dwarfs are hot dim stars while red giants are bright cool stars. Where (i.e. in which regions) should these two types of stars be in the diagram? Identify at least one red giant and one white dwarf.have low surface temperature and large negative absolute magnitude. A bit above the middle of the main sequence are the variable stars, called so since they have a time variation of their magnitude. Identify from your diagram at least one candidate for a variable star. The book identifies three groups of variable stars. Write down their names and their characteristics. Stars which are "on the main sequence" are generally very stable stars which are combining their hydrogen atoms into larger helium atoms (this reaction is called fusion and gives off energy). Where in the star do you think that this fusion reaction is most likely occurring? Why? Main sequence stars which are very bright are fusing hydrogen atoms into helium atoms at an enormous rate. Do you think that these bright stars will burn forever? How long do you think these stars will shine compared to the dimmer main sequence stars? Why is it that black holes do not appear on the HR Diagram? Acknowledgements Thanks to Dr. Tim Slater1 for using a modified version of his activity for the HertzsprungRussell diagram at http://solar.physics.montana.edu/tslater/plunger/hr_diag.htm. 1 Research associate professor of physics in the Department of Physics at Montana State University. 172 Appendix A - Stars which appear very bright from the Earth Star Name Spectral Absolute Star Name Class Magnitude Spectral Class Absolute Magnitude 1. Sirius A A1 +1.4 19. Aldebaran A K5 -0.2 2. Sirius B B8 +11.5 20. Aldebaran B M2 +12 3. Canopus F0 -3.1 21. Crucis A B1 -4.0 4. Centaurus A G2 +4.4 22. Crucis B B3 -3.5 5. Centaurus B K5 +5.8 23. Antares A M1 -4.5 6. Arcturus K2 -0.3 24. Antares B B4 -0.3 7. Vega A0 +0.5 25. Spica B1 -3.6 8. Capella A G0 -0.7 26. Pollux K0 +.08 9. Capella B M0 +9.5 27. Fomalhaut A A3 +2.0 10. Capella C M5 +13.0 28. Fomalhaut B K4 +7.3 11. Rigel A B8 -6.8 29. Deneb A2 -6.9 12. Rigel B B9 -0.4 30. Beta Crucis B0 -4.6 13. Procyon A F5 +2.7 31. Regulus B7 -0.7 14. Procyon B F0 +13.0 32. Adhara B2 -5.0 15. Achernar B5 -1.0 33. Castor A A1 +2.1 16. Beta Centari B1 -4.1 34. Castor B A5 +2.9 17. Betelgeuse M2 -5.5 35. Castor C K6 +8.8 18. Altair A7 +2.2 36. Shaula B1 -3.3 - - 37. Bellatrix B2 -4.2 - 173 Appendix B - Stars which are close to the Earth Star Name Spectral Absolute Star Name Class Magnitude Spectral Absolute Class Magnitude 1. Sun G2 +4.8 16. Procyon A F5 +2.7 2. Centari A G2 +4.4 17. Procyon B F0 +13.0 3. Centari B K5 +5.8 18. Struve 2398 M4 +11.1 4. Centari C M5 +15.0 19. Struve 23948 M5 +11.9 5. Lalande 21185 M2 +10.5 20. Groom 34 A M1 +10.5 6. Sirius A A1 +1.4 21. Groom 34 B M6 +13.2 7. Sirius B B8 +11.5 22. Lacaille 9352 M2 +9.6 8. Ross 154 M4 +13.3 23. Tau Ceti G8 +5.7 9. Ross 248 M5 +14.7 24. BD +5 1668 M4 +11.9 10 Epsilon Eridani K2 +6.1 25. Lacaille 8760 M0 +8.7 11. Luyten M5 +14.7 26. Kapteyn's Star M0 +8.7 12. Ross 128 M5 +13.8 27. Krueger 60 A M3 +11.8 13. 61 Cygnus A K5 +7.5 28. Krueger 60 B M4 +13.4 15 61 Cygnus B K7 +8.3 29. Ross 614 M5 +13.1 15. Epsilon Indi K5 +7.0 30. BD -12 4523 M4 +12.0 174 Appendix C – Millimeter sheet 175