SMT 314 - Introduction to Cosmology » Fall 2020 » HW 11

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Question #1
"Absolute magnitude" defines the intensity of a star as measured from _____.
A.   Earth
B.   our Sun
C.   10 parsecs away
D.   one parsec away
E.   that star
Question #2
A candle has a brightness of x at 1 meter. What is the candle's brightness at 4 meters?
A.   x/4
B.   x/16
C.   x/2
D.   x/8
Question #3
Ages of open star clusters can be determined by the length of their Main Sequence stars. If an open cluster has a few blue stars and many white, yellow & red dwarfs, what is the age?
A.   5 billion years
B.   > 10 billion years
C.   young (< millions of years)
Question #4
If you can measure the apparent magnitude of a star and known the absolute magnitude of that type of star (e.g. RR Lyrae or Cepheids), then what can you determine?
A.   radius
B.   distance
C.   temperature
D.   semi-major axis distance
Question #5
In a binary star system, the two stars actually orbit their [a] _____rather than each other.
A.   radius
B.   distance
C.   common center of mass
Question #6
Inverse square law: If Stars Reka and Ivan have the same apparent brightness, but Star Reka is 5 times farther away from Earth than Star Ivan, then Star Reka's luminosity (absolute magnitude) is _________ times the luminosity of Star Ivan. o Earth * Ivan * Reka
A.   25
B.   1
C.   1/25
D.   1/5
E.   5
Question #7
The Hertzsprung-Russell diagram plots star intensity versus the star's __________.
A.   spectral type
B.   diameter
C.   distance
D.   Doppler speed
E.   mass
Question #8
The spectral types, O, B, A, F, G, K, M, L, T, differentiate between stars of different mass, and between stars of different _________.
A.   radial velocity
B.   periods
C.   surface temperature
D.   distance
Question #9
The star Sirius has a brighter apparent magnitude than its absolute magnitude. Which statement is correct?
A.   Sirius is located 10 ps from Earth.
B.   Sirius is located greater then 10 ps from Earth.
C.   This is an impossible situation. The apparent magnitude can't be more than the absolute magnitude.
D.   Sirius is located less than 10 ps from Earth.
Question #10
Which one of the following is a true statement for a globular cluster and a false statement for an open cluster?
A.   There are usually about a few hundred stars loosely held together by gravity.
B.   A temperature-luminosity (H-R) diagram can reveal the cluster's age
C.   All stars in the cluster had approximately the same initial chemical composition.
D.   They are usually found away from the disk and arms of a spiral galaxy.
E.   All stars in the cluster formed at about the same time.

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