IB PHYSICS Name: DEVIL PHYSICS Period: Date: # Marks: XX Raw Score: IB Curve: BADDEST CLASS ON CAMPUS OPTION E, ASTROPHYSICS TEST REVIEW S1. This question is about the nature of certain stars on the Hertzsprung-Russell diagram and determining stellar distance. The diagram below shows the grid of a Hertzsprung-Russell (H-R) diagram on which the positions of the Sun and four other stars A, B, C and D are shown. 10 6 A B 10 4 10 2 Luminosity ( L) (Sun L = 1) 1 Sun 10 2 C 10 4 D 10 6 State an alternative labelling of the axes, 25000 10000 8000 6000 5000 4000 3000 Surface temperature ( T / K) (i) x-axis... y-axis... Complete the table below. 2011 Option E Test Review.docx Page 1 of 18
(d) (e) Star A B C D Type of star Explain, using information from the H-R diagram, and without making any calculations, how astronomers can deduce that star B is larger than star A. Using the following data and information from the H-R diagram, show that star B is at a distance of about 700 pc from Earth. Apparent visual brightness of the Sun = 1.4 10 3 W m 2 Apparent visual brightness of star B = 7.0 10 8 W m 2 Mean distance of the Sun from Earth = 1.0 AU 1 parsec = 2.1 10 5 AU Explain why the distance of star B from Earth cannot be determined by the method of stellar parallax. (Total 14 marks) S2. This question is about the possible evolution of the Universe. The diagram below is a sketch graph that shows three possible ways in which the size of the Universe might change with time. 2011 Option E Test Review.docx Page 2 of 18
Size of Universe Depending on which way the size of the Universe changes with time, the Universe is referred to either being open or flat or closed. On the diagram, identify each type of Universe. Time Complete the table below to show how the mean density ρ of each type of Universe is related to the critical density ρ 0. Type of Universe Relation between ρ and ρ 0 Open Flat Closed S3. This question is about white dwarfs and neutron stars. State the property that determines whether a star ends its life as a white dwarf or as a neutron star. Define the Chandrasekhar limit and use this concept to explain the difference between a white dwarf and neutron star. State the name given to a rotating neutron star. S4. This question is about galactic redshift, the Hubble constant and the age of the Universe. (Total 6 marks) (Total 5 marks) 2011 Option E Test Review.docx Page 3 of 18
State how the observed redshift of light from many distant galaxies is explained. Using the axes below sketch a graph to show how the recessional speed v between galaxies varies with the distance d between them. (Please note this is a sketch graph; you do not need to add any numerical values.) v (d) 0 State how the Hubble constant is determined from such a graph. A value for the Hubble constant is 100 km s 1 Mpc 1. Use this value to estimate the age of the Universe in years. (1 Mpc 3 10 19 km, 1 year 3 10 7 s) S5. This question is about some facts regarding some of the planets in the Solar system. Four of the planets in the Solar system are Jupiter, Earth, Mars and Pluto. List these four planets in order of increasing distance from the Sun. d (Total 5 marks) nearest increasing distance from Sun List these four planets in order of increasing diameter. furthest 2011 Option E Test Review.docx Page 4 of 18
smallest increasing diameter largest S6. This question is about some of the properties of Barnard s star. Barnard s star, in the constellation Ophiuchus, has a parallax angle of 0.549 arc-second as measured from Earth. With the aid of a suitable diagram, explain what is meant by parallax angle and outline how it is measured. (Total 4 marks) (d) Deduce that the distance of Barnard s star from the Sun is 5.94 ly. The ratio (i) apparent brightness of Barnard's star apparent brightness of the Sun Define the term apparent brightness. is 2.6 10 14. Determine the value of the ratio luminosity of Barnard' s star luminosity of the Sun (1 ly = 6.3 10 4 AU). The surface temperature of Barnard s star is about 3 500 K. Using this information and information about its luminosity, explain why Barnard s star cannot be (6) 2011 Option E Test Review.docx Page 5 of 18
(i) a white dwarf. a red giant. S7. This question is about the evolution of stars. (d) Outline the process that provides the source of energy for stars while on the main sequence. State the conditions required for the above process to take place. State the reason why stars leave the main sequence. Main sequence stars eventually evolve to form red giants. With reference to the Chandrasekhar limit, describe and distinguish between the subsequent evolutionary paths of red giant stars that have evolved from main sequence stars of mass (i) about two times that of the Sun. about ten times that of the Sun. (Total 16 marks) (Total 10 marks) 2011 Option E Test Review.docx Page 6 of 18
S8. This question is about Cepheid variables. Define (i) luminosity. apparent brightness. State the mechanism for the variation in the luminosity of the Cepheid variable. The variation with time t, of the apparent brightness b, of a Cepheid variable is shown below. 10 2 b / 10 W m 1.3 A 1.2 1.1 1.0 0.9 B 0.8 0 1 2 3 4 5 6 7 8 9 10 Time / days Two points in the cycle of the star have been marked A and B. (i) Assuming that the surface temperature of the star stays constant, deduce whether the star has a larger radius after two days or after six days. Explain the importance of Cepheid variables for estimating distances to galaxies. (d) (i) The maximum luminosity of this Cepheid variable is 7.2 10 29 W. Use data from the graph to determine the distance of the Cepheid variable. 2011 Option E Test Review.docx Page 7 of 18
Cepheids are sometimes referred to as standard candles. Explain what is meant by this. S9. This question is about the Big Bang model. (d) Describe what is meant by cosmic background radiation. Explain how cosmic background radiation is evidence in support of the Big Bang model of the universe. State one other piece of evidence in support of the Big Bang model. A student makes the statement that as a result of the Big Bang, the universe is expanding into a vacuum. Discuss whether the student s statement is correct. S10. This question is about galaxies. (Total 13 marks) (Total 7 marks) Draw a sketch showing the basic structure of the Milky Way galaxy. Mark the approximate position of the solar system. 2011 Option E Test Review.docx Page 8 of 18
A particular spectral line of light from a laboratory source has a wavelength of 658 nm. The wavelength of this line of light from a distant galaxy is 670 nm. Calculate the recessional speed of the galaxy. (i) Draw a sketch graph to show how the recessional speed of galaxies varies with distance from Earth. (This is a sketch graph; you do not need to put any values on the axes.) v (0,0) d Deduce how 1 H 0 may be used to estimate the age of the universe. (iii) Outline how Hubble s constant, H o is determined from your graph. (Total 10 marks) S11. This question is about various bodies in the universe. Briefly describe the nature of a star. 2011 Option E Test Review.docx Page 9 of 18
Distinguish between a constellation and a galaxy. Constellation:...... Galaxy:...... S16. This question is about the properties of the star Arcturus. The following data is for the star Arcturus. Distance from Earth / m Apparent magnitude Absolute magnitude Spectral type Luminosity / W 3.39 10 17 0.1 0.3 K 3.8 10 28 Explain the difference between apparent magnitude and absolute magnitude. State and explain, with reference to the data, whether Arcturus would be visible without the aid of a telescope on a clear night. Techniques for determining stellar distances include the use of stellar parallax, spectroscopic parallax and Cepheid variables. (i) Calculate the distance, in pc, of Arcturus from the Earth. (d) (iii) State and explain which technique would be most suitable for determining the distance to Arcturus. Outline the method you have chosen in your answer to. State how it may be deduced from the data that the surface temperature of Arcturus is lower than that (Total 6 marks) 2011 Option E Test Review.docx Page 10 of 18
of the Sun. The temperature of Arcturus is 4000 K. (e) (f) Calculate (i) (iii) the surface area of Arcturus. the radius of Arcturus. the wavelength at which the light from Arcturus has its maximum intensity. Using your answers to (e) deduce the stellar type to which Arcturus belongs. (Total 20 marks) S17. One of the most intense sources known to radio astronomers is the Galaxy NGC5128. Long exposure photographs show it to be a giant elliptical galaxy crossed by a band of dark dust. It lies about 1.5 10 7 light years away from Earth. Describe any differences between this galaxy and the Milky Way. Hubble s law predicts that NGC5128 is moving away from Earth. (i) State Hubble s law. State and explain what experimental measurements need to be taken in order to determine the Hubble constant. 2011 Option E Test Review.docx Page 11 of 18
A possible value for the Hubble constant is 60 km s 1 Mpc 1. Use this value to estimate (i) the recession speed of NGC5128. the age of the universe. (Total 10 marks) S18. This question is about eclipsing binary stars. In a particular binary star system, star A has apparent brightness 8.0 10 13 W m 2 and star B has apparent brightness 2.0 10 14 W m 2. (i) Explain how it is possible to deduce that star A has a higher luminosity than star B. The surface area of star B is 10 000 times smaller than that of star A. Calculate the ratio surface temperatur e of star B surface temperatur e of star A The graph below shows the variation with time of the intensity of light received on Earth from the two stars. 2011 Option E Test Review.docx Page 12 of 18
intensity 5 10 15 time / years (i) The diagrams below each show the orbits of the two stars. Star A is in the inner orbit. Annotate the diagrams to show the relative positions of stars A and B as seen from Earth, that correspond to the intensity-time graph above at times of 5 and 10 years. Diagram at 5 years Diagram at 10 years line of sight from Earth line of sight from Earth (iii) State the period of this binary star system. State what can be deduced from knowing the period of the binary and the separation of the stars. S23. The question is about stellar radiation and the star Betelgeuse. Explain the term black-body radiation. The diagram below is a sketch graph of the black-body radiation spectrum of a certain star. (Total 10 marks) 2011 Option E Test Review.docx Page 13 of 18
intensity Label the x-axis of the graph. On the graph, sketch the black-body radiation spectrum of a star that has a lower surface temperature and lower apparent brightness than this star. The star Betelgeuse in the Orion constellation emits black-body radiation that has a maximum intensity at a wavelength of 0.97 μm. (d) Deduce that the surface temperature of Betelgeuse is about 3000 K. S24. This question is about Olbers paradox. Newton made three assumptions about the nature of the universe. One of these assumptions is that the universe is static. State the other two assumptions. Explain, using a quantitative argument, how these assumptions led to Olbers paradox. Describe one piece of evidence that suggests that the universe is not static. (Total 5 marks) 2011 Option E Test Review.docx Page 14 of 18
S25. This question is about the evolution of stars. The diagram below shows a grid on which a Hertzsprung-Russell diagram could be drawn. The present positions of the Sun and another Main Sequence star A are shown. (Total 8 marks) 10 6 10 4 A 10 2 Luminosity (L) (Sun L = 1) 1 Sun 10 2 10 4 10 6 40 000 10 000 6 000 4 000 3 000 surface temperature (T/K) The mass of star A is about 15 times the mass of the Sun. On the diagram above, draw the evolutionary path of the Sun and the evolutionary path of star A as both stars leave the Main Sequence. When stars with masses of about eight times that of the Sun leave the Main Sequence, they may end up in the same region of the Hertzsprung-Russell diagram as the Sun when it leaves the Main Sequence. Explain, with reference to the Chandrasekhar limit, why this is so. 2011 Option E Test Review.docx Page 15 of 18
State two main changes that take place in nucleosynthesis when a star of about eight times the solar mass leaves the Main Sequence. S26. This question is about the solar system. State the name of the planet in the solar system that has (i) the greatest mass; an orbit around the Sun between that of Saturn and of Neptune. State where, in the solar system, the asteroid belt is found.... State two features of the orbits of comets. 1. 2. S27. This question is about stellar spectra. Stars may be described in terms of their spectral classes. (i) Describe the colour of a B star. Identify the class of the Sun. Discuss two different ways in which atomic spectra can be used to deduce physical data for stars. 1. (Total 10 marks) (Total 5 marks) 2011 Option E Test Review.docx Page 16 of 18
2. S29. This question is about stars. Describe the final nuclear reaction in the core, and the final evolutionary state, of a low-mass star (of the order of 1 solar mass); nuclear reaction:...... evolutionary state:...... a high-mass star (of approximately 15 solar masses). nuclear reaction:...... evolutionary state:...... S35. This question is about stars. Stars are very massive. State why stable stars are not crushed inwards under gravitational pressure.......... State the difference between a visual binary star and a spectroscopic binary star. Visual binary:...... Spectroscopic binary:...... S36. This question is about the star Antares. The following are some data concerning the star Antares. The parallax angle is measured from an ideal position where no atmospheric turbulence affects measurements. Spectral class Parallax angle 5.0 10 3 arcsecond Apparent brightness 1.6 10 8 W m 2 M (Total 6 marks) (Total 4 marks) (Total 4 marks) Wavelength of the maximum intensity of light emitted max 935 nm State the colour of Antares.... 2011 Option E Test Review.docx Page 17 of 18
Deduce that the distance of Antares from Earth is 6.2 10 18 m.......... Calculate (i) the luminosity of Antares; the surface temperature of Antares. (d) The radius R of the Sun is 7.0 10 8 m. Use your answers in to deduce that the radius of Antares is about 500 R............. S37. This question is about Olbers paradox. (Total 11 marks) Newton proposed a model of the universe that is infinite in extent and in which the stars are uniformly distributed. Olbers suggested that, if this model were correct, then the sky would never be dark. Explain how Olbers reached this conclusion............. Suggest two reasons how the Big Bang model of the universe accounts for the night sky being dark. 1. 2. (Total 5 marks) 2011 Option E Test Review.docx Page 18 of 18