Details Title: ASTRONOMY CHAPTER 10 Description: from book and outline paper Total Flash Cards: 32 Created: 04/01/2009 20:25:47		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term True or false: the space between stars is empty Definition false Term What is the space between the stars filled with? Definition dilute gas and dust Term What are two reasons to be interested in the interstellar medium? Definition 1. dense interstellar clouds are birthplace of stars 2. dark clouds alter and absorb the light from the stars behind them Term What is an interstellar gas cloud called? Definition nebula Term What is the interstellar medium? Definition the gas and dust between the stars Term What kind of spectra does emission nebulae produce? Definition emission spectra Term What is another name for an emission nebulae? How is it produced? Definition AKA HII region. Produced UV radiation from nearby hot stars ionizes gas Term What do the red, blue and violet Balmer lines blend together to produce? Definition the pink-red color of ionized hydrogen Term What color does reflection nebulae appear? why? Definition blue, because blue light is scattered by larger angles than red light Term How is reflection nebulae produced? Definition by gas and dust illuminated by a star that is not hot enough to ionize the gas Term What is a dark nebulae? Definition a nebula that absorbs the light from stars behind it Term What color does interstellar clouds make background stars appear? Definition red Term How much does the interstellar dust make up of the interstellar medium? Definition roughly 1% Term At what wavelengths does the interstellar medium absorb light more strongly? Definition shorter wavelengths Term three ways the absorption lines of the interstellar medium can be told apart from those of stars? Definition 1. absorption from wrong ionization states 2. small line width 3. multiple components Term What are the two types of interstellar clouds? Definition 1. HI (Hydrogen-one) 2. HII (Hydrogen-two) Term What does HI (hydrogen-one) consist of? Definition cold clouds of neutral hydrogen Term what does HII (hydrogen-two) consist of? Definition hot clouds with ionized hydrogen Term What else does the interstellar medium contain, other than atoms and ions? What does this do? Definition molecules, which stores energies in rotation and vibration Term What do transitions between energy levels typically emit? Definition radio wavelengths Term What are the two easiest molecules to observe in space? What is the most common molecule in space? Definition CO (carbon monoxide) and OH (hydroxyl); most common is hydrogen Term What do we use to trace hydrogen in space? Why? Definition CO (carbon monoxide) because H and CO exist together Term True or false: Molecules are easily destroyed by UV radiation from hot stars? Definition true Term Where do molecules exist on dense molecular clouds? Definition in the center Term A molecular cloud can have a mass of how many times greater than the sun? Definition 1 million times Term What is coronal gas? Definition a component of the interstellar medium that is created from a supernova explosion Term What are four components of the interstellar medium? Definition 1. H-one clouds 2. Intercloud medium 3. coronal gas 4. molecular clouds Term What are the three types of nebulas? Definition 1. emission nebulae 2. reflection nebulae 3. dark nebulae Term what impact does interstellar extinction have? Definition makes distant stars look fainter than they should Term What affect does interstellar reddening have? Definition makes distant stars look redder than they really are Term What are HI clouds seperated by? Definition  intercloud medium Term What do the collision of gas clouds build? Definition massive clouds where stars are born