Chapter 16 Questions

Chapter 16 Questions - Questions for Chapter 16 1 2 What is...

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Questions for Chapter 16 1. What is this ? 2. What is the interstellar medium? What is its chemical composition, and how do we measure it? It is the gas and dust that fills up the spaces between the stars within a galaxy. The gas between the stars is composed mostly of hydrogen and helium. We use spectroscopy to measure the abundances of elements but the most common method is to observe the spectrum of a star to determine the chemical composition of the interstellar medium. 3. What is a molecular cloud? How do a molecular cloud's temperature and density compare with the rest of the interstellar medium? These are clouds that are particularly cold and dense in which stars are born. It is called a molecular cloud because they are cold and dense enough to allow atoms to combine together into molecules. Interstellar mediums are almost a trillion times less dense than the air at sea level on Earth. Molecular clouds have high density regions of about hundreds of denser than average density. The temperature in the cloud is about 10-30K. 4. What is interstellar dust? How does it interact with visible light? What are the consequences for our view of the heavens, and how is that view different in infrared light? It is tiny, solid microscopic dust made from elements heavier than helium. It scatters and absorbs light that enters a molecular cloud. Also, stars appear redder than similar stars outside the cloud, known as interstellar reddening. Interstellar dust blocks all forms of red light so the observed color of a star is different than the star’s actual spectral type. Infrared allow us to see directly through molecular clouds to stars lying at much greater distances. It reveals new stars embedded within the clouds, which are in the act of birth. 5. D
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This note was uploaded on 02/12/2012 for the course ASTR 1110 taught by Professor Jpc during the Spring '08 term at UGA.

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Chapter 16 Questions - Questions for Chapter 16 1 2 What is...

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