Astronomy: Chapter 10 Flashcards Preview

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Flashcards in Astronomy: Chapter 10 Deck (14)
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1
Q

What is the observational evidence that some so-called “nebulae” are actually entire galaxies far outside our own galaxy?

A

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2
Q

Describe the chief method for determining the masses of the galaxies, and what does this tell us about dark matter?

A
  • Rotation Curve Method: Requires
    • The true size of the orbits of stars or gas clouds within a galaxy, which in turn requires knowing the distance of that galaxy.
    • the orbital speeds of the stars or gas clouds, measured from the doppler shifts of their spectral lines.
  • Using keplers third law, we can find the mass of the part of the galaxy contained within the star orbit with measured size and speed.
  • 95% of matter is dark matter.
3
Q

Describe the factors involved in galactic formation, including the role of collisions between galaxies.

A
  • Elliptical galaxies appear to be the product of galaxy mergers, which triggered star formation that used gas and dust.
  • in the beginning, there were proto-galaxies. These proto-galaxies collided to create spiral galaxies. spiral galaxies collided to create elliptical galaxies.
  • galaxies collide frequently. When they collide, gases compress with each other to form new gasses.
4
Q

Be able to identify a galaxy by its shape, according to the Hubble telescope.

A

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5
Q

Describe the observational evidence for the “dark matter” and discuss the most likely candidates for what it consists of.

A

The measured masses of galaxies amount to 10-100 times more mass than we can see. evidence indicates that there is 10-100 times more dark matter than visible matter in galaxies. Dark matter remains to be unresolved. Observations of galaxies and clusters of galaxies reveal that 90-95 percent of dark matter in the universe is dark matter.

6
Q

State in your own words what the Hubble law really says and what its implications are concerning the expansion of the universe.

A

Hubble law: velocity of a galaxy is proportional to its distance.
Farther = faster.

7
Q

Compare and contrast elliptical galaxies and spiral galaxies.

A
  • Elliptical
    • More common
    • few young stars.
    • most luminous stars are red giants.
    • no blue giants.
    • Red tint
    • no visible gas or dust.
  • Spiral
    • spiral and flat
    • smaller range of size.
    • ancient red dwarf and blue giants
    • hot bright stars, constantly luminous, easy to see.
    • blue tint.
    • contains gas and dust.
8
Q

Describe the different types of active galaxies, and the mechanisms proposed to explain their energy output and other characteristics.

A
  • Active galaxy: a galaxy whose center emits large amounts of excess energy, often in the form of radio emission. active galaxies have massive black holes in their centers into which matter is flowing.
  • Radio Galaxy: a galaxy that is a strong source of radio waves.
  • Seyfert Galaxies: an other wise normal spiral galaxy with an unusually bright, small core that fluctuates in brightness and a dim disk.
8
Q

Briefly relate the story of the discovery of quasars.

A

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9
Q

Discuss the controversy that originally surrounded quasars.

A

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10
Q

Describe the current explanation of quasars and their energy sources.

A

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11
Q

Briefly relate the story of the discovery of quasars.

A

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12
Q

Discuss the controversy that originally surrounded quasars.

A

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13
Q

Describe the current explanation of quasars and their energy sources.

A

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