ASTRON 100 Lecture Notes - Flattening, Nuclear Fusion, Main Sequence
21 Jan 2014
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Document Summary
Stars form in dark clouds of dusty gas in interstellar space. The gas between the stars is called the interstellar medium. We can determine the composition of interstellar gas from its absorption lines in the. 70% h, 28% he, 2% heavier regions in our region of the milky way. In general, the gas and dust is too cold to produce visible light. However, the tiny solid particles of interstellar dust block our view of stars in the other. Particles are <1 micrometer in size and made of elements like c, o, si, and fe. Stars viewed through the edges of the cloud look redder because dust blocks (shorter- wavelength) blue light more effectively than (longer-wavelength) red light. Long wavelength infrared light passes through a cloud more easily than visible light. Observations of infrared light reveal stars on the other side of the cloud.
