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Astronomy > Chapter 15 > Flashcards

Chapter 15 Flashcards

1
Q

What is the gas and dust that fill the space between the stars within a galaxy?

A

Interstellar medium

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2
Q

The evolution of a star depends on what?

A

Mass

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3
Q

What are small particles or grains of matter distributed throughout interstellar space?

A

Interstellar dust

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4
Q

What is the dimming of visible and ultraviolet light by interstellar dust?

A

Interstellar extinction

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5
Q

What is the effect by which stars and other objects, when viewed through interstellar dust, appear redder than they actually are?

A

Interstellar reddening

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6
Q

What is a discrete, high-density region of the interstellar medium made up mostly of atomic or molecular hydrogen and dust?

A

Interstellar cloud

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7
Q

What is a low-density region of the interstellar medium that fills the space between interstellar clouds?

A

Intercloud gas

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8
Q

What are the four components of the interstellar medium?

A
  1. Hot intercloud gas
  2. Warm intercloud gas
  3. Cold intercloud gas
  4. Interstellar gas
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9
Q

What is a nebula?

A

It is any interstellar cloud of gas & dust

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10
Q

Do long wavelengths or short wavelengths penetrate interstellar dust?

A

Long wavelengths

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11
Q

What is an interstellar cloud composed primarily of molecular hydrogen?

A

Molecular cloud

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12
Q

What is a very young object that is still contracting before becoming a true star?

A

Protostar

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13
Q

What is a reflection nebula?

A

Its the scattered light that shows a blue color around bright stars

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14
Q

What is an emission nebula?

A

Its a cloud of interstellar gas and dust that emits lights in different colors

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15
Q

What is a cold dark nebula?

A

Its a nebula that it blocks visible light that is emitted from stars behind it

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16
Q

What are planetary nebula?

A

They are the ejected envelopes from dying stars

17
Q

What is meant by the term - ZAMS?

A

Zero-Age Main Sequence

18
Q

What is the Zero-Age Main Sequence?

A

It is where stars start hydrogen fusion

19
Q

What is a star cluster?

A

It’s a group of stars that all formed at the same time and in the same general location

20
Q

Why is understanding the interstellar medium important?

A

It helps us to understand the creation of the universe

21
Q

What is a proto-planetary disk?

A

It’s a rotating ring-shaped disk of dense gas and dust that surrounds a newly formed star
(It look like Target’s logo)

22
Q

What does the H-R diagram for a young star cluster look like?

A

A lot of the stars are still forming, so only a few are on the main sequence while the rest are below it
(Look at Chapter 15 slide 58 for visual)

23
Q

What does the H-R diagram for a middle-aged star cluster look like?

A

All the low mass stars have become main sequence stars, so the majority of them are on the main sequence while a few are above it
(Look at Chapter 15 slide 59 for visual)

24
Q

What does the H-R diagram for an old star cluster look like?

A

A lot of the stars have stopped producing hydrogen in their core, so the majority of them have become red giants/supergiants and are above the main sequence. Only a few remain on the main sequence
(Look at Chapter 15 slide 60 for visual)

25
Q

How does the pre-main sequence evolutionary track of a low-mass star differ from the track of a high-mass star?

A

Since a high-mass star is massive it won’t take long for it’s core to start burning hydrogen. This means that it’s evolutionary track will look like a horizontal line at the top of the diagram. It takes a while for a low-mass star to burn hydrogen, so it will go down until it starts to burn hydrogen. Once that happens it will stop going down and it will move to the left until it reaches the main sequence.
(Look at Chapter 15 slide 52 fro visual)

26
Q

An H I region is a region of what?

A

Atomic hydrogen

proton + electron

27
Q

An H II region is a region of what?

A

Ionized hydrogen

just proton, no electron

28
Q

An H2 region is a region of what?

A

Molecular hydrogen

two atoms of hydrogen

29
Q

What are the pre-main sequence stages to form a star?

A
  1. A molecular cloud loses its equilibrium
  2. The denser regions in the cloud start to collapse
  3. As it’s collapsing the regions are becoming hotter and smaller
  4. They then turn into dense, star-forming cores
30
Q

What causes a cloud to lose its equilibrium and start to contract?

A

Gravity

31
Q

True or False:

Some regions inside a molecular cloud are denser than others

A

True

Astronomy (10 decks)

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