Term
| How much of the visible mass of the Milky Way Galaxy is int the form of gas and dust spread out between the stars? |
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Definition
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Term
| How is gas distributed in interstellar space? |
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Definition
| in clumps, concentrated in interstellar clouds |
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Term
| Images of the Milky Way have large dark regions because |
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Definition
| dark dust clouds block the light of stars behind them |
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Term
| What is the characteristic color of a reflection nebula? |
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Definition
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Term
| What causes the characteristic blue color of a reflection nebula? |
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Definition
| scattering of starlight from dust grains in the nebula |
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Term
| The spectrum of light coming from a reflection nebula would look like |
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Definition
| the spectrum of the star illuminating the nebula |
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Term
| What is an emission nebula? |
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Definition
| a glowing region of ionized hydrogen around one or more hot O- and B- type stars |
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Term
| The bright stars at the center of an emission nebula ( H II region) are |
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Definition
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Term
| An emission nebula is formed near a star that emits large amounts of |
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Definition
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Term
| A reflection nebula's color |
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Definition
| is blue because dust clouds reflect blue most effectively |
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Term
| Emission nebulae are important because |
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Definition
| they are regions of very active star formation |
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Term
| Most emission nebulae that we can see |
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Definition
| form on the edge of dense molecular clouds |
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Term
| In which type of nebula would you expect to find stars forming? |
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Definition
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Term
| Which type of nebula can be studied most easily to gain the most information about the composition of the interstellar medium? |
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Definition
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Term
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Definition
| large interstellar gas and dust cloud containing young stars |
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Term
| A bright nebula surrounding a class F star would have to be a (n) |
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Definition
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Term
| New stars are formed from |
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Definition
| huge, cool dust and gas clouds |
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Term
| There are several mechanisms that can trigger star formation in a cold, dark nebula. In each mechanism, the key to star formation is |
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Definition
| compressing the gas and dust so that gravitation will overcome the gas pressure |
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Term
| All of these are common ways of causing star formation EXCEPT |
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Definition
| a small cluster of brown dwarf stars collide and form new stars |
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Term
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Definition
| sphere of gas after collapse from an interstellar cloud belt before nuclear reactions have begun |
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Term
| Where in the universe would you look for a protostar? |
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Definition
| in dense dust and gas clouds |
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Term
| Which of the following is closest to the amount of time it takes a cloud of gas and dust to collapse and form a new star? |
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Definition
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Term
| A star's protostellar evolution is finished when the core temperature reaches |
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Definition
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Term
| A protostellar nebula starts in the upper right corner of an H-R diagram. As the protostar collapses, it becomes |
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Definition
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Term
| The position that a star will take on the Zero-Age Main Sequence depends mostly on the ___ of the cloud that forms the protostar |
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Definition
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Term
| If a collapsing cloud fragment is too small, it will not form a star, but will instead form a |
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Definition
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Term
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Definition
| Young G, K, or M star that is ejecting gas |
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Term
| Herbig-Haro and T-Tauri objects |
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Definition
| are short, violent stages in the final part of a protostar's evolutionary track |
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Term
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Definition
| star of mass less then 0.08 solar mass whose core temperature is too low to initiate hydrogen fusion |
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Term
| The definition of a main-sequence star is a star |
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Definition
| in which nuclear fusion reactions generate sufficient energy to oppose further condensation of the star. |
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Term
| Clusters of stars which formed at the same time in the same place are |
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Definition
| common, because most cloud fragments as they collapse |
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Term
| Star clusters are particularly interesting to astronomer because |
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Definition
| The formed at the same place and time, so they shoe the effect of stellar evolution |
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Term
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Definition
| could not create an emission nebula because it is too cool |
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Term
| A large molecular cloud complex can contain enough mass to form ___ stars like our sun |
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Definition
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