Answers at the end (Just starting work on this...)
51. The spectral class of our sun is
a) S0 L b) K2 Ia c) A0 V d) F5 V e) G2 V
52. The spectral class of Sirius is
a) S0 L b) K2 Ia c) A0 V d) F5 V e) G2 V
53. The (negative of the) distance modulus to our sun is about
a) 8, b) 16, c) 24, d) 32, e) 40.
54. The parallax of alpha Centauri (arcseconds) is about
a) 0.75, b) 1.55, c) 23.5, d) 320, e) 1800.
55. The distance, in parsec, to a star with a parallax of 0.007 arcsec is
a) 143, b) 220, c) 750, d) 12000, e) 22000.
56. Bernard's star moves over ten arcsec (10.25") per year relative to the
background of "fixed stars". This change of direction in the sky is called
a) proper motion, d) dynamical parallax,
b) transverse parallax, e) dynamical motion.
c) apparent drift,
57. The space velocity of the sun (km/s) relative to all stars within a hundred pc is about
a) 235, b) 6000, c) 0.14, d) 55, e) 20.
58. Achernar shines at magnitude 0.5 and beta Gruis shines at magnitude 2.2 so Achernar is brighter than beta Gruis by a factor of
a) 1.1, b) 1.7, c) 4.8, d) 10.2 e) 19.
59. Aldebaran shines at magnitude +0.6 and has a parallax of 0.050 arcsec. The absolute magnitude of Aldebaran must be about
a) -0.9, b) +1.8, c) -1.8, d) +2.1, e) -1.6
60. The colour of Aldebaran is +1.54 so is brighter in the V band than the B band by a factor of about
a) 1.5, b) 4, c) 15, d) 40, e) 6.
61. Aldebaran is spectral class
a) R, b) K, c) A, d) G, e) F.
62. Vega has very strong Balmer lines and is rich in lines of ionized metals so is classified
a) A, b) B, c) O, d) G, e) K
63. Lambda Orionis has lines of ionized helium and is spectral class
a) A, b) B, c) O, d) G, e) K
64. 40 Eridani has a radial velocity of -43 km/s. The 589.0 nm "D" line is blue shifted by
a) 8.44, b) 0.048, c) 4.80, d) 0.48, e) 0.084 nm.
65. The luminosity of a star with the same radius and twice the effective temperature of our sun has a luminosity that is greater than our sun's by a factor of
a) 1.4, b) 2, c) 4, d) 8, e) 16 times.
66. The luminosity of a star with twice the radius and the same effective temperature of our sun has a luminosity that is greater than our sun's by a factor of
a) 1.4, b) 2, c) 4, d) 8, e) 16 times.
67. The period of revolution, in years, of a binary-star system in which each star has the same mass as the Sun and semimajor axis 50 AU is
a) 1.36, b) 62500 c) 250 d) 25 e) 125 y.
68. The distance (pc) at which a binary star system having a semimajor axis of 25 AU would appear to have a separation of one arcsecond is about
a) 25, b) 0.025, c) 4, d) 40 e) 0.04 pc.
69. The true relative orbit of Xi UMa has a semimajor axis of 2.5 arcsec and the parallax of the system is 0.127 arcsec. The period of Xi UMa is 60 years. The total mass of the Xi Uma system is, in solar masses,
a) 3.82, b) 3.14, c) 1.66, d) 2.12, e) 1.21 Msun.
70. A visible-spectroscopic binary with maximum radial velocity of one star with respect to the other of 60 km/s and orbital inclination 30 degrees (sin 30=1/2) has a 22d (0.0602y) period. The total mass of the system in solar masses is
(Recall the earth's orbital speed is 29.78 km/s or 2pi AU/y.)
a) 3.82, b) 3.14, c) 1.66, d) 2.12, e) 1.21 Msun.
71. The figure to the right shows the radial velocity curve of the spectroscopic binary in
problem 70. The mass ratio must be about
a) 4, d) 1.4,
b) 8, e) 2.
c) 3,
72. The figure to the right shows the light curve of an eclipsing binary with exactly central
eclipses, period three days, and separated by 11,460,000 km. The diameter of the
smaller star in millions of km is
a) 4, b) 1, c) 8, d) 0.5, e) 0.25
(million km).
73. Which of the following relates to the statement "A spectral-type A0 star has a colour
index of zero".
a) This is not a surprising observation for population Ia stars.
b) This is surprising for such stars.
c) The absolute magnitude is zero so the colour must be zero,
d) The star appears white.
e) The B and V colours were chosen to make this so.
74. If a spectral-type A0 star is observed to have B=+11.6 and V=+10.8 the color excess is
a) 2.4, b) 2.1, c) 0.8, d) 1.07, e) 7%.
75. If a spectral-type A0 star is observed to have B=+11.6 and V=+10.8 the unreddened V
magnitude is most likely
a) +9.73, b) +10, c) +12.9, d) +6.0, e) +8.4
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Which of the below,
a) neutron, b) proton, c) neutrino, d) deuteron, e) aplha particle,
76. is most associated with energy production on the main sequence,
77. provides energy on the AGB but not on the main sequence,
78. was a major constituent of the universe at t=100s but is now rarely seen,
79. is responsible for the * in Q*, the average energy release,
80. might or might not be a major component of "dark matter"?
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81. Giant branch stars often exhibit the results of the fusion process because of
a) surface fusion, d) helium flash,
b) dredge-up, e) core collapse.
c) mass transfer from novae,
82. A main-sequence star that is ten times as massive as the sun might have a luminosity
that is greater than the sun by a factor of
a) 8000, b) 3, c) 100000, d) 3ú106, e) 31623
83. Given the mass and chemical composition the position of a star on the ZAMS is
uniquely determined, an important result known as the
a) boundary limit, d) virial theorem,
b) polytropic solution, e) Russell-Vogt theorem.
c) Lane-Emden solution,
84. Associated with protostars is/are
a) a rapid infall of interstellar gas and dust,
b) strong stellar winds,
c) planetary nebulae,
d) H II regions,
e) globular clusters.
85. The lower limit to the ZAMS is, in solar masses, about
a) 0.0008, b) 0.14, c) 0.07, d) 0.007, e) 0.707 Msun.
86. The upper limit to the ZAMS is, in solar masses, about
a) 10, b) 280, c) 80, d) 8, e) 800 Msun.
87. An OB association is or is related to
a) a loose group of extremely young stars,
b) the slope of the H-R diagram for early stars,
c) globular clusters,
d) highly evolved galactic clusters,
e) the formation of protoplanetary systems.
In the H-R diagram to the right, the sun is located at coordinates 4-?. The answer would be
"d", the sun is located at 4-d. In a similar vein,
88. The most luminous main sequence star is located at 1-?
89. Flare stars are found at 5-?
90. Luminous AGB stars are found at 4-?
91. Sirius is found at 2-?
92. The companion of Sirius is found at 2-?
I will be lenient on this one, don't worry.
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93. The age of a star cluster can be determined from the
a) main sequence turn-off, d) metallicity,
b) nova rate, e) gas and dust density.
c) total number of blue-stragglers,
94. A main-sequence star of color index zero has absolute magnitude +1. In the color-magnitude diagram of a certain cluster known to be free of reddening the stars of color index zero appear at magnitude +9. The distance to the cluster (pc) is
a) 1584, b) 39.8, c) 64, d) 100, e) 398 pc.
95. A star like our sun will eventually exhaust its core hydrogen and then
a) begin burning hydrogen in a shell about the core,
b) begin burning helium in the core,
c) fade away as a white dwarf,
d) eventually nova, then fade into insignificance as a white dwarf,
e) expand to about the size of earth's orbit, then fade into insignificance as a white dwarf, possibly with the ejection of a planetary nebula.
96. The central star of a PN is 16 times as luminous and twenty times hotter than our sun. The diameter, in terms of the sun's diameter, is
a) 1.25, b) 12.8, c) 0.04, d) 0.00013, e) 0.01 Dsun.
Which of the following bodies,
a) Carbon-oxygen core, no nuclear reactions,
b) Uniform composition throughout, no nuclear reactions in the core,
c) energy generated in the core by PP I/II reactions,
d) energy generated in the core by triple-alpha process,
e) no energy generated in the core but CNO process in a shell,
97. is in the latest stage of stellar evolution,
98. is in the earliest stage of stellar evolution,
99. is a massive star on the giant branch for the first time,
100. is a K2 V star,
101. is a white dwarf?
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102. The distance to the center of the Milky Way galaxy (pc) is about
a) 220, b) 22500, c) 8500, d) 20000, e) 1000 pc.
103. The orbital period (millions of years) of the sun about the Milky Way centre is about
a) 220, b) 22500, c) 8500, d) 20000, e) 1000 Myr.
104. The mass of the Milky Way (solar masses) is about
a) 3E9, b) 2E14, c) 1.6E10, d) 2E11, e) 9E13 Msun.
105. The mass of an individual galaxy such as our Milky Way galaxy is determined by
a) the rotation curve, d) the frequency of certain supernovae,
b) the mass/luminosity relation, e) detached eclipsing binaries.
c) the mass to light ratio,
106. The cosmic distance scale ladder depends critically on
a) the theory of (planetary nebulae and) H II regions,
b) an accurate calibration of the H-R diagram,
c) the mass-luminosity relation for long period (Mira) variables,
d) a determination of the distance of the Magelleanic clouds,
e) the theoretical calibration of type Ia supernovae.
107. A tightly wound spiral galaxy might be classified (Hubble scheme)
a) Sa b) SBb c) E0, d) E5, e) Sb.
108. The Milky Way galaxy is generally classified (at least by astronomers that do not think
there is a bar in the center...) as
a) Sa b) SBb c) E0, d) E5, e) Sb.
109. The Andromeda galaxy is classified
a) Sa b) SBb c) E0, d) E5, e) Sb.
110. A galaxy with an elliptical image with major axis twice the minor axis is classified
a) Sa b) SBb c) E0, d) E5, e) Sb.
111. Some galaxies look just like a globular cluster and are classified
a) Sa b) SBb c) E0, d) E5, e) Sb.
112. A feature that distinguishes a star from a quasar is
a) presence of emission lines, d) gravitational lensing,
b) brightness change, e) extreme reddening.
c) large red shift,
113. Assume type Ia supernovae peak at absolute magnitude -19. If one appears in a galaxy
at apparent magnitude +16, the distance, in megaparsec (Mpc), is
a) 2000, b) 100, c) 57, d) 3.57, e) 2.5 Mpc
114. If a type Ia supernova is seen at apparent magnitude +16 it must have occured
a) 8.1, b) 185, c) 31, d) 330, e) 1000
million years ago (see problem 113).
115. Suppose the rotation curve of a galaxy rises from zero to Vo at distance Ro from the center of the galaxy then remains essentially flat.
This indicates (assume spherical symmetry)
a) the total mass is just twice the mass within Ro,
b) an essentially point concentration of mass at the center of the galaxy suggesting the presence of a black hole,
c) the majority of the mass is nonbaryonic,
d) an essentially uniform density as a function of R, ?(R)=constant,
e) each incriment DR adds the same mass increment DM resulting in a substantial mass beyond Ro.
116. The Milky Way galaxy is a member of
a) the Local Group, d) the Coma cluster,
b) the Andromeda cluster, e) the Local Supercluster.
c) the Virgo cluster,
===============
Just starting to put answers up...NO GURANTEES HERE!
51... e,c,5log(20626500)=31.57=d,a,1/.007=143pc
56... a,e,10^0.4(2.2-5)=4.79=c
59... dm=5log(r/10)=5log(2)=1.5 so M=0.6-1.5=-0.9=a
60... b,b,a,c
64... dw=vw/c=43*589/300000=0.0844=e
65... L=r^2T^4=1^2*2^4=16=e
66... c,c,a,m=19.7^3/60^2=2.4=d (???)
70... v=2*60=120km/s=120/4.74au/y, a=v*p/2pi=0.24au, m1+m2=0.24^3/0.0602^2=3.8=a
71...72...
73...e,c,e,b,e,a,c,c
81...b,e,e,b,c,c,a
88..89...90...91...92(white dwarf)
93...a
94...the dm=9-1=8=5log(r/10) so r=398=e
95...a
96...16=r^2*20^4 so r=.01=e (r^2 or d^2...its a ratio!)
97...a,b or c,e,c,a
102...c,a, 2E12?
105...a,d (most of rest of exam not relevant to PH227...
****Hey, an old master key for the 1999 exam: (Warn, not checked!)
51...e,c,d,a,a, 56...a,e,c,a,b, 61...b,a,c,e,e, 66...c,c,a,d,a
71...e,b,e,c,e, 76...b,e,a,c,c, 81...b,a,e,ab,c 86...c,a,a,e,a
91...b,de,a,e,ae 96..e,a,bc,d,c 101...a,c,a,d,a, 106...de,a,e,e,d
111..c,c,b,d,e, 116..a,c,a,c,b, 121...c,d,b,e,b, 126...b,d,b,a,c
131..b,c,a,a,e, 136..d,a,d,a,b, 141...d,b,c,b,a, 146...c,d,e,c,a
========That's all, folks!