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Astronomy > Galaxies and Big Bang Theory > Flashcards

Galaxies and Big Bang Theory Flashcards

1
Q

What is a galaxy?

A

A gravitationally bound system consisting of stars and stellar remnants.

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2
Q

Describe a spiral galaxy?

A

Spiral galaxies have a central, dense bulge of stars with curving outward arms.

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3
Q

Describe a barred-spiral galaxy?

A

Barred-spiral galaxies have elongated central bulges (bar) with curving arms at the ends

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4
Q

Describe an elliptical galaxy?

A

A spherical to flattened-spherical shape with no spiral arms.

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5
Q

What is the name of the galaxy type that does not fit into the Hubble Classifications?

A

An irregular galaxy

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6
Q

What is a globular cluster?

A

A large, symmetrical group of stars located in the halo of a galaxy?

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7
Q

What is the halo of a galaxy?

A

An area in the outer part of a galaxy consisting of the oldest stars and probably dark matter.

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8
Q

What is a rich cluster?

A

A gravitationally bound group of many galaxies.

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9
Q

What is a poor cluster?

A

A gravitationally bound group of just a few galaxies.

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10
Q

What is dark matter?

A

A theoretical source of mass that has a gravitational influence on galaxies.

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11
Q

What is a galactic core?

A

A dense group of stars located in the center of a galaxy.

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12
Q

Why do scientists theorize the presence of black holes in the center of many galaxies?

A

Their evidence is the behavior of stars in the central core and x-ray emissions.

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13
Q

In which galaxy is Earth’s Sun found?

A

The Milky Way Galaxy

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14
Q

In which group is the Milky Way found?

A

The Local Group

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15
Q

What type of galaxy do scientists believe the Milky Way is?

A

A barred-spiral galaxy

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16
Q

Approximately how many stars are in the Milky Way galaxy?

A

Scientists believe the Milky Way contains 100 to 400 billion stars.

17
Q

Why is it hard for scientists to determine the size of the Milky Way?

A

The gas and dust scatter visible light.

18
Q

How do scientists know about some of the structures in the galactic core of the Milky Way?

A

They use telescopes that collect radio, infrared and x-ray radiation.

19
Q

Why do scientists think there is a black hole in the center of the Milky Way Galaxy?

A

The stars that form Sagittarius A are a massive source of radio waves.

20
Q

How old do scientists believe the Milky Way is?

A

13.6 billion years old

21
Q

What are the members of the Local Group?

A

The Local Group consists of about 30 galaxies including the Milky Way galaxy, the Andromeda galaxy, and the Large and Small Magellenic Clouds.

22
Q

What is a singularity?

A

Matter and energy under extreme pressure that is infinitely dense.

23
Q

Describe the Big Bang Theory

A

The universe started from a singularity approximately 13.7 billion years ago. The singularity rapidly expanded.

24
Q

What elements formed shortly after the Big Bang expansion?

A

Hydrogen, some helium, and trace amounts of Lithium

25
Q

What evidence, first discovered by Hubble, supports the Big Bang Theory?

A

Hubble’s Law, a mathematical relationship of the distance between galaxies and the speed at which they are moving away from each other.

26
Q

What is a red shift?

A

A change in the location of absorption spectral lines towards the red end of the spectrum that indicates objects are moving away from each other.

27
Q

What is a blue shift?

A

A change in the location of absorption spectral lines towards the blue end of the spectrum that indicates objects are moving towards each other.

28
Q

What is Cosmic Microwave Background Radiation?

A

Low level of energy at approximately 3 Kelvin that is found throughout the universe and is remnant energy from the Big Bang.

29
Q

According to the Big Bang Theory, how are most galaxies moving in relation to each other?

A

The galaxies are moving away from each other, which indicates that the universe is expanding.

30
Q

What is nucleosynthesis?

A

Nucleosynthesis is the formation of elements beyond iron during a supernova explosion.

31
Q

Why do scientists believe there is no center of the universe?

A

Hubble’s Law showing galaxies moving away from each other at a rate based on separation distance is observed everywhere in the universe.

Astronomy (8 decks)

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