ASTR1020 Exam 3: Astronomy II - Important Questions and University Topics - Prof. Donald G, Exams of Astronomy

Download ASTR1020 Exam 3: Astronomy II - Important Questions and University Topics - Prof. Donald G and more Exams Astronomy in PDF only on Docsity! Astronomy II (ASTR1020) — Exam 3 Test No. 3D 23 October 2001 The answers of this multiple choice exam are to be indicated on the Scantron with a No. 2 pencil. Don’t forget to write your name and the Test No. (e.g., 3D) on the Scantron sheet. You may keep these test questions. There are 32 questions on this exam and you will be graded out of 30 points. As such, 2 of the questions can be considered as extra credit. 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 103 = one thousand 106 = one million 109 = one billion 1012 = one trillion Useful Equations D = αd 206265 e = h 2a = a − b a E = mc2 rp = a(1 − e) ra = a(1 + e) 2a = rp + ra vt = 4.74µd (km/s) vr c = λ − λ◦ λ◦ = ∆λ λ◦ ν = c/λ P 2 = [ 4π 2 G(m1 + m2) ] a 3 F = G ( m1m2 r 2 ) F = σ T 4 L = 4πR 2F = 4πσR 2T 4 L L = ( R R )2 ( T T )4 d = 1/p λmax = 0.0029 m K T E = hν = hc λ P 2yr = a 3 AU m2 − m1 = −2.5 log ( f2 f1 ) m − M = 5 log d − 5 F = ma Mbol − Mbol( ) = −2.5 log ( L L ) M1 + M2 = a 3 P 2 v = √ v 2r + v 2 t tMS = ( M M )3 × 1010 yr vesc = √ 2GM R vr = H◦d z = ∆λ λ◦ = √ 1 + vr/c√ 1 − vr/c − 1 z = ∆λ λ◦ = vr c (vr  c) L L = ( M M )4 T = 1 (km/s/Mpc) H◦ × 1012 yr q◦ = 8πG 3 ρ H 2◦ 9. The triple-alpha process is a) responsible for production of carbon in the Universe. b) how main sequence stars generate energy. c) powered by the weak nuclear force. d) the technique used to apply for Hubble Space Telescope observing time. e) how astronomers determine the distances to stars. 10. Pulsating stars fall on what strip on the H-R Diagram? a) main sequence b) sub dwarf c) Chandrasekhar d) instability e) Eddington 11. When the UV photons from a collapsed core lights up the detached shell of a star’s outer envelope, the shell is called a(n) a) supernova remnant b) reflection nebula c) H II region d) planetary nebula e) none of these 12. Which of the following energy mechanisms does the Sun currently derive its energy? a) coal burning b) photoelectric effect c) fusion with CNO cycle d) fission of uranium e) fusion with proton-proton chain 13. What opacity source causes the kappa effect to function in Miras? a) Balmer lines b) hydrogen ionization c) Lyman lines d) Rayleigh scattering e) electron scattering 3 14. In the Cosmos video that we saw in class, what was the name of the astronomer that narrated the episode? a) Carl Sagan b) Chandrasekhar c) Arthur Eddington d) Albert Einstein e) Issac Asimov 15. Objects that have M < 0.01 M are called a) brown dwarfs b) planets c) black dwarfs d) main sequence stars e) white dwarfs 16. Which of the following is true about main sequence stars with M < 0.4 M ? a) They produce most of their energy via the proton-proton chain. b) They have spectral types of A, F, or G. c) They have radiative cores and convective envelopes. d) These stars do not have chromospheres and coronae. e) They are stable due to electron degeneracy. 17. What happens to stars that ignite carbon in a degenerate core? a) They become completely disrupted through a supernova explosion. b) They collapse to a carbon-rich white dwarf. c) They go through a helium flash. d) They get drunk at the local bar and follow a random walk back to their home like a photon trying to escape the interior of a star. e) They collapse to a black hole. 4 18. Main sequence stars with 4M < M < 8M will a) helium flash and finally end up as a white dwarf. b) supernova via an Fe-core bounce. c) never become red giant stars. d) collapse directly into a black hole. e) supernova via carbon detonation in a degenerate core. 19. Stars that have M > 8M are/will a) go through a helium flash. b) supernova via an iron-core bounce. c) be completely convective their entire lives. d) supernova via carbon detonation. e) not massive enough to support nuclear fusion. 20. When the energy that flows into a layer of gas in a star is balanced by the flow of energy out of that layer, such a layer is said to be in a) dynamic equilibrium b) hydrostatic equilibrium c) momentum equilibrium d) radiative equilibrium e) thermal equilibrium 21. Massive stars end their thermonuclear lives by blowing themselves up. Astronomers call these explosions a) supernova b) nova c) gamma ray bursters d) big bangs e) none of these 5