Protostars are difficult to observe because
a. the protostar stage is very short.
b. they are surrounded by cocoons of gas and dust.
c. they radiate mainly in the infrared.
d. all of the above
e. they are all so far away that the light hasn't reached us yet.
D
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As shown in the diagram, you've just shined a flash light toward Al, so from your point of view the light is moving to the right at speed c. Al is moving away from you to the right at speed 0.9c. According to Al, what is the light doing?
A) moving to the right at speed c B) gradually catching up to him at speed 0.1c C) moving to the right at speed 1.9c D) moving to the left at 0.1c
How does the traditional theory of the formation of the galaxy explain the origin of globular clusters?
a. They formed in the disk and later were ejected to the halo. b. They formed in other galaxies and were captured by close interactions. c. They build over time from the collision of stars in the halo. d. They formed early on during the free-fall collapse of the proto-galactic material.
Red giants are huge because their outer layers have expanded to a very low-density tenuous atmosphere.
Answer the following statement true (T) or false (F)
A 60.0 cm long organ pipe is filled with air and is open at both ends. The velocity of sound in air at 0
is 331 m/s. What is the wavelength of the fundamental mode?
A. 115 cm B. 120 cm C. 131 cm D. 142 cm E. 167 cm