Homework Three Questions Unsolved - Astronomy II | ASTR 1020, Assignments of Astronomy

Download Homework Three Questions Unsolved - Astronomy II | ASTR 1020 and more Assignments Astronomy in PDF only on Docsity! Astronomy II (ASTR-1020) — Homework 3 Due: 3 March 2009 The answers of this multiple choice homework are to be indicated on a Scantron sheet (either Form # 822 N-E or Ref # ABF-882) which you are to buy at the bookstore. Remember to use a No. 2 pencil on these Scantron sheets. Don’t forget to write your name and the Homework No. (e.g., 2) on the Scantron sheet. You are to turn in this Scantron at the beginning of class on the date indicated above. There are 20 questions on this homework assignment. Useful Constants G = 6.673 × 10−11 m3/s2/kg g = 9.80 m/s2 c = 3.00 × 105 km/s h = 6.626 × 10−34 J s k = 1.38 × 10−23 J/K H◦ = 50 km/sec/Mpc Mmoon = 7.35 × 1022 kg M = 1.99 × 1030 kg M⊕ = 5.98 × 1024 kg R⊕ = 6.38 × 106 m R = 6.96 × 108 m T = 5800 K 1 AU = 1.50 × 1011 m L = 3.90 × 1026 W e = 1.60 × 10−19 C σ = 5.67 × 10−8 W/m2/K4 me = 9.11 × 1031 kg mp = 1.67 × 10−27 kg 1 ly = 9.46 × 1015 m 1 pc = 3.09 × 1016 m 1 km = 103 m 1 hr = 3600 s 1 mi = 5280 ft 1 mi = 1.609 km 1 day = 24 hrs 1 yr = 365.24 days 1 Å = 10−10 m 1 nm = 10−9 m 1. Objects that have M < 0.01 M are called a) white dwarfs b) black dwarfs c) planets d) main sequence stars e) brown dwarfs 2. When the internal pressure of a layer of gas in a star is balanced by the weight of material on top of that layer, such a layer is said to be in a) radiative equilibrium b) thermal equilibrium c) hydrostatic equilibrium d) momentum equilibrium e) thermodynamic equilibrium 3. Which of the following best describes a red giant clump star? a) hydrogen core burner b) helium core burner c) helium shell burner d) collapsing protostar e) hydrogen shell burner 4. Which one of the following is a law of stellar structure? a) A star’s magnetic field lines must remain constant through the interior of the star. b) The internal magnetic pressure is balanced by the weight of the star. c) The luminosity of a star is balanced by the nuclear energy generation in the core. d) The mass flowing in one shell must be balanced by the mass flowing into an adjacent shell. e) None of the above. 1 14. We observe emission lines from highly-ionized metals in a stellar spectrum. What must be true about this star based on this observational fact? a) It has a chromosphere. b) It has a planetary system. c) It is a binary star. d) It is a variable star. e) It has a corona. 15. The Russell-Vogt theorem states that a) almost all properties of a stars are determined by its magnetic field and rotation rate. b) 90% of all stars lie on the main sequence. c) white dwarfs must be much smaller than main sequence stars. d) stars shine due to thermonuclear reactions. e) almost all properties of a stars are determined by its mass and composition. 16. How are the stellar winds of an O main sequence star and an M giant star similar? a) They are thermally driven from the star’s hot corona. b) They are driven by conductive transport. c) They are driven by radiation pressure. d) They are driven by a Honda Accord. e) They are driven by convection transport. 17. The resistance to the flow of radiation through gas is referred to as what of the gas? a) opacity b) inertia c) ohmage d) wattage e) transparency 4 18. We know the age of star clusters by a) counting tree rings. b) the number of stars in the cluster. c) radioactive dating. d) asking them. e) the main sequence turn-off. 19. The statement that two electrons cannot exist in the same quantum state at the same time is better known as the a) Hertzsprung Criterion b) Pauli Exclusion Principle c) Dirac Notation d) Bohr Model e) Russell Diagram 20. Why don’t we see chromospheres and coronae in massive stars (i.e., O & B types)? a) They don’t have convective envelopes. b) Because of their strong magnetic fields. c) They spin too slow. d) They don’t have planetary systems. e) They don’t have radiative envelopes. 5