## Astronomy C

Magikarpmaster629
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### Re: Astronomy C

```1. What is an H II region?
2. What gives them their name?
3. Which of the DSOs on the list contain an H II region?
4. When we observe H II regions, what color do we see them as?```

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A man passes through this world, leaving behind a name.

Magikarpmaster629
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### Re: Astronomy C

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

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### Re: Astronomy C

Not anymore
```1. a region of ionized hydrogen in space that when recombined with an electron, emits light at 656nm when the electron goes from n = 3 to n = 2 (called H alpha)
2. not sure, but is it because they contain ionized hydrogen, which is called H II?
3. M42
4. red (since they emit light at 656nm which is reddish light)```
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

Magikarpmaster629
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Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
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### Re: Astronomy C

Not anymore
```1. a region of ionized hydrogen in space that when recombined with an electron, emits light at 656nm when the electron goes from n = 3 to n = 2 (called H alpha)
2. not sure, but is it because they contain ionized hydrogen, which is called H II?
3. M42
4. red (since they emit light at 656nm which is reddish light)```
yep

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

Moderator
Posts: 473
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

Not anymore
```1. a region of ionized hydrogen in space that when recombined with an electron, emits light at 656nm when the electron goes from n = 3 to n = 2 (called H alpha)
2. not sure, but is it because they contain ionized hydrogen, which is called H II?
3. M42
4. red (since they emit light at 656nm which is reddish light)```
yep
Do main sequence stars spin faster or slower than protostars of the same final mass? Why?
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

finagle29
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### Re: Astronomy C

`Main sequence stars spin slower than protostars of the same final mass; protostars have a greater radius and therefore greater rotational inertia so by the conservation of angular momentum as a protostar condenses further into a main sequence star it must spin faster.`
Bayard Rustin HS Alum

2013 Events: Thermo, Circuit Lab, Experiment, Robot Arm
2014 Events: Circuit Lab, Experiment, TPS, Mat Sci, Astro
2015 Events: Astro, Chem Lab, Compound Machines, Experiment, Time, TPS
2016 Events: Astro, Cell Bio, Chem Lab, Electric Vehicle, Time, Protein Modeling, Wind Power

Magikarpmaster629
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### Re: Astronomy C

`Main sequence stars spin slower than protostars of the same final mass; protostars have a greater radius and therefore greater rotational inertia so by the conservation of angular momentum as a protostar condenses further into a main sequence star it must spin faster.`
Wouldn't a higher rotational inertia cause them to spin more slowly, given they are the same mass?

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

finagle29
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Joined: January 28th, 2013, 11:37 am
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### Re: Astronomy C

`Main sequence stars spin [b][i][u]faster[/u][/i][/b] than protostars of the same final mass; protostars have a greater radius and therefore greater rotational inertia so by the conservation of angular momentum as a protostar condenses further into a main sequence star it must spin faster.`
Wouldn't a higher rotational inertia cause them to spin more slowly, given they are the same mass?
You're right. I thought one think and typed the other.
Bayard Rustin HS Alum

2013 Events: Thermo, Circuit Lab, Experiment, Robot Arm
2014 Events: Circuit Lab, Experiment, TPS, Mat Sci, Astro
2015 Events: Astro, Chem Lab, Compound Machines, Experiment, Time, TPS
2016 Events: Astro, Cell Bio, Chem Lab, Electric Vehicle, Time, Protein Modeling, Wind Power

Moderator
Posts: 473
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

`Main sequence stars spin [b][i][u]faster[/u][/i][/b] than protostars of the same final mass; protostars have a greater radius and therefore greater rotational inertia so by the conservation of angular momentum as a protostar condenses further into a main sequence star it must spin faster.`
Wouldn't a higher rotational inertia cause them to spin more slowly, given they are the same mass?
You're right. I thought one think and typed the other.
Both of you are (now) right, y'all can choose who asks the next question

University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

Magikarpmaster629
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### Re: Astronomy C

I guess I'll go.

Explain the gravitational instability theory of gas giant formation, and some of its flaws.