Answers and **NEW** result histogram at end of exam...
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 How many magnitudes fainter would the sun appear to an observer
located in the epsilon Eri system (parallax=0.303 arcsec).
a) 22.2, b) 49.2, c) 17.185, d) 122, e) 29.2 magnitudes.
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 Most nearby stars (<10 pc) appear on the H-R diagram
*a) along the lower main seq., d) along the subdwarf (sd) sequence,
b) on the giant branch, e) uniformly spaced along the main sequence.
c) to the right of the "forbidden zone",
66 A number of nearby stars (<10 pc) lie
a) well above the giant branch, d) well below the main sequence,
b) in the instability strip, e) along the subdwarf (sd) sequence.
c) to the left of the instability strip,
67 If the nearby stars are a good sample, our sun is
a) relatively faint, d) unique in having a planetary system,
b) an average star, e) relatively old.
c) relatively massive,
68 If you observe the spectrum of an M5 Ib star you can estimate its
distance via
a) cluster parallax, d) trigonometric parallax,
b) dynamic parallax, e) statistical parallax.
c) spectroscopic parallax,
69 The K line of ionized calcium lies at 3933.68A. If the feature is seen
in the spectrum of a star shifted to 3934.07A,
its radial velocity [km/s] is
a) +28, b) -30, c) +3.8, d) -68, e) +7 km/s.
70 Eclipsing binary stars are particularly useful since they provide stellar
a)distances, b)luminosities, c)parallaxes, d)rotation rates, e)radii.
Star m M
a 1.5 5.0
b 8.4 7.7
c 13.9 15.0
d 3.7 3.7
e 16.7 -7.0
Which of the above stars
71 is nearest,
72 is most distant,
73 is 10 pc away,
74 appears brightest,
75 appears faintest,
76 is intrinsically brightest,
77 is intrinsically least luminous,
78 is most like the sun?
-----------------------------------------------
79 The second most common constituent of cosmic rays is
a) H I, b) H II, c) deuterium, d) tritium, e) He II
80. The tangential velocity [km/s] of a star having proper motion
1.5 arcsec per year and distance 20pc is
a) 14, b) 142, c) 1420, d) 14200, e) 142000 km/s.
81. The tangential velocity [km/s] of a star having proper motion
0.01 arcsec per year and parallax one milliarcsec is about
a) 5, b) 50, c) 500, d) 5000, e) 50000 km/s.
82. A star has a proper motion of 3 arcsec per year, a parallax
of 0.474 arcsec, a tangential velocity of 30 km/s and a
radial velocity of 40 km/s. The space motion [km/s] of the star is
a) 5, b) 50, c) 500, d) 5000, e) 50000 km/s.
83. The Solar spectrum has many lines of neutral iron and no lines of helium.
Rigel has no neutral iron lines but strong helium lines. Hence,
a) The Sun is a normal star, Rigel is a supergiant.
b) The surface gravity of the Sun is much greater than Rigel's.
c) Rigel has a much higher helium abundance than the Sun.
d) Rigel is much hotter than the sun,
e) Rigel is a "helium star".
84. The color of a star with B=12 and V=10.5 is
a) +1.26, b) +1.14, c) +1.5, d) +4, e) +126.
85. The spectral class of a star with B=12 and V=10.5 is
a) G, b) B, c) A d) M, e) K.
86. The coolest of the following spectral classes is
a) G, b) B, c) A d) M, e) K.
87. The hottest of the following spectral classes is
a) G, b) B, c) A d) M, e) K.
88. The most likely spectral class of a star picked at random in any
given volume of space is
a) G, b) B, c) A d) M, e) K.
89. Our closest neighbor Proxima Centauri is spectral class
a) G, b) B, c) A d) M, e) K.
90. Tonight at 8PM you can "see" Proxima Centauri (with a telescope)
a) Rising in the east. d) In the southwest.
b) Setting in the west. e) Well up in the southeast.
c) Close to the zenith.
91. Tonight at 8PM you can see Canopus
a) Rising in the east. d) In the southwest.
b) Setting in the west. e) Well up in the southeast.
c) Close to the zenith.
92. Tonight at 8PM you can see Orion
a) Rising in the east. d) In the southwest.
b) Setting in the west. e) Well up in the southeast.
c) Close to the zenith.
Binary star class
a visual
b spectroscopic
c spectrum
d eclipsing
e dynamical
Which of the above binary star classifications
93 applies to alpha Centauri,
94 originally applied to Sirius,
95 gives stellar radii as well as masses,
96 requires a knowledge of distance (parallax) to give mass,
97 yields a "mass function",
98 has a nearly "edge on" orbit,
99 has the shortest period,
100 has the longest period?
=====================Some answers...let me know if there are errors...
51) e 52) c
53) 2.5log((206265/0.303)^2)=29.2 magnitudes
(The sun would be 1/.303 pc or 206265/.303 times farther away)
54) a....no star has a parallax > 1" (closer than 1pc)!!!!!
55) a,a,e,c,a,b
61) Must be very red and luminous -- K giant? -- other classes no good.
62) a,c,e,a* -- 64 had a boo-boo in it so all got credit.
66) d,c,c,a,e
71) a,e,d,a,e,e,c,a OK OK, I know there is no such star as (a).
79) e,b,b,b,d,c
85) d but I accepted e since early M is close to late K.
86) d,b,d,d
90) e (alpha Cen A&B & Proxima are at alt=30, az=147 so e is best)
91) d,b
93) a,e,d,a,b,d,d,a
