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Home Q & A Board Science-Related Homework Help Physics Astronomy
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hannah415 hannah415
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6 years ago
The most effective wavelengths to see through the clouds of Venus to the surface are ________.
 
  Fill in the blank(s) with correct word

Question 2

Explain how forbidden lines appear in spectra of emission nebulae.
 
  What will be an ideal response?

Question 3

Pair production can occur if:
 
  A) the energy of two photons is greater than the combined mass-energy of a particle-anti-particle pair.
  B) only virtual particles are produced.
  C) photons are at the event horizon of a black hole.
  D) one particle is struck by a sufficiently high energy photon that a pair of electrons is formed.
  E) the particle and antiparticle have opposite spins.

Question 4

How do we know that a hot main sequence star (and not some other kind of star) is embedded in a cloud of interstellar gas?
 
  What will be an ideal response?
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Replies
wrote...
#1
6 years ago
Answer to q. 1

radio or radar

Answer to q. 2

These lines correspond to excited states that require a very long time to decay and emit a photon. In Earth labs, the gas density cannot be made low enough to allow this transition before a collision knocks the atom into another state. In the nebula, though, the density is so low that the transition has a chance to proceed.

Answer to q. 3

A

Answer to q. 4

Except for white dwarfs, all hot stars are very luminous. The large amount of ultraviolet light produced by them will ionize any gas in their vicinity and produce an HII region. The visible light from the HII region's emission spectrum tells us of the presence of the gas.
hannah415 Author
wrote...
#2
6 years ago
All correct
wrote...
#3
6 years ago
Happy to help
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