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Author Question: What is the Hubble constant essentially a measure of? a. the number of galaxies in the universe ... (Read 33 times)

ec501234

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on: Jul 27, 2018
What is the Hubble constant essentially a measure of?
 
  a. the number of galaxies in the universe
  b. the expansion of the universe
  c. the age of the Milky Way galaxy
  d. the amount of dark matter in an average galaxy

Question 2

Why are interstellar absorption lines so narrow compared to the width of lines which originate in the photospheres of stars?
 
  What will be an ideal response?


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juiceman1987

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Reply #1 on: Jul 27, 2018
Answer to Question 1

b

Answer to Question 2

Much of the interstellar gas is cold, and its density is very low. Because atoms in the ISM move slowly and collide only rarely, interstellar absorption lines are extremely narrow.


ec501234

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Reply 2 on: Jul 27, 2018
Great answer, keep it coming :)

abro1885

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Reply 3 on: Yesterday
Excellent

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