Term
| True or false: the space between stars is empty |
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Definition
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Term
| What is the space between the stars filled with? |
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Definition
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Term
| What are two reasons to be interested in the interstellar medium? |
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Definition
1. dense interstellar clouds are birthplace of stars
2. dark clouds alter and absorb the light from the stars behind them |
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Term
| What is an interstellar gas cloud called? |
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Definition
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Term
| What is the interstellar medium? |
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Definition
| the gas and dust between the stars |
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Term
| What kind of spectra does emission nebulae produce? |
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Definition
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Term
| What is another name for an emission nebulae? How is it produced? |
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Definition
| AKA HII region. Produced UV radiation from nearby hot stars ionizes gas |
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Term
| What do the red, blue and violet Balmer lines blend together to produce? |
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Definition
| the pink-red color of ionized hydrogen |
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Term
| What color does reflection nebulae appear? why? |
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Definition
| blue, because blue light is scattered by larger angles than red light |
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Term
| How is reflection nebulae produced? |
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Definition
| by gas and dust illuminated by a star that is not hot enough to ionize the gas |
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Term
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Definition
| a nebula that absorbs the light from stars behind it |
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Term
| What color does interstellar clouds make background stars appear? |
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Definition
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Term
| How much does the interstellar dust make up of the interstellar medium? |
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Definition
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Term
| At what wavelengths does the interstellar medium absorb light more strongly? |
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Definition
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Term
| three ways the absorption lines of the interstellar medium can be told apart from those of stars? |
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Definition
1. absorption from wrong ionization states
2. small line width
3. multiple components |
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Term
| What are the two types of interstellar clouds? |
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Definition
1. HI (Hydrogen-one)
2. HII (Hydrogen-two) |
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Term
| What does HI (hydrogen-one) consist of? |
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Definition
| cold clouds of neutral hydrogen |
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Term
| what does HII (hydrogen-two) consist of? |
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Definition
| hot clouds with ionized hydrogen |
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Term
| What else does the interstellar medium contain, other than atoms and ions? What does this do? |
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Definition
| molecules, which stores energies in rotation and vibration |
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Term
| What do transitions between energy levels typically emit? |
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Definition
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Term
| What are the two easiest molecules to observe in space? What is the most common molecule in space? |
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Definition
| CO (carbon monoxide) and OH (hydroxyl); most common is hydrogen |
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Term
| What do we use to trace hydrogen in space? Why? |
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Definition
| CO (carbon monoxide) because H and CO exist together |
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Term
| True or false: Molecules are easily destroyed by UV radiation from hot stars? |
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Definition
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Term
| Where do molecules exist on dense molecular clouds? |
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Definition
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Term
| A molecular cloud can have a mass of how many times greater than the sun? |
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Definition
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Term
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Definition
| a component of the interstellar medium that is created from a supernova explosion |
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Term
| What are four components of the interstellar medium? |
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Definition
1. H-one clouds
2. Intercloud medium
3. coronal gas
4. molecular clouds |
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Term
| What are the three types of nebulas? |
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Definition
1. emission nebulae
2. reflection nebulae
3. dark nebulae |
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Term
| what impact does interstellar extinction have? |
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Definition
| makes distant stars look fainter than they should |
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Term
| What affect does interstellar reddening have? |
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Definition
| makes distant stars look redder than they really are |
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Term
| What are HI clouds seperated by? |
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Definition
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Term
| What do the collision of gas clouds build? |
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Definition
| massive clouds where stars are born |
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