Astro 101 Chapter 16.1 1. Stars only form in clouds that are unusually cold and dense. 2. Average 2-3 stars born in the Milky Way each year. 3. Interstellar medium is gas and dust that fill the spaces between stars a. Mostly hydrogen and helium b. Use spectroscopy to measure abundance of new elements 4. Molecular clouds give birth to stars because they are cold and dense to allow atoms to combine to molecules a. Temperature of 10-30 K b. Density is about 300 molecules per cubic centimeter c. CO is most abundant, it produces radio emission lines that allow to map the structures of molecular clouds 5. Interstellar dust are solid grains, which makes about 1% of the cloud 6. interstellar reddening – stars seen near the edges of molecular cloud appear redder than similar stars outside the cloud a. dust grains block shorter wavelength so red gets through more easily b. allows us to measure how much dusty gas lies between Earth and distant star c. infrared observations allow us to see directly through molecular clouds to
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 04/05/2009 for the course ASTRO 101 taught by Professor Lloyd during the Spring '08 term at Cornell University (Engineering School).