Chapter_16_Star_birth_summary - dust grains emit longer...

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Chapter Summaries Chapter 16: Star Birth 1. General Properties of Stars Stars form in molecular clouds in the Interstellar Medium (ISM) Molecular Clouds consist of gas and dust (note: molecules form in molecular clouds) ISM in the Milky Way: 70% H, 28% He, 2% heavy elements Temperature in molecular clouds: 10 – 30 K Molecular clouds are observed in the radio part of the electromagnetic spectrum CO (carbon monoxide) is the main molecule observed Interstellar dust (made of Carbon, Oxygen, Silicon, and Iron) Dust is observed in the Infrared part of the electromagnetic spectrum Interstellar Reddening dust grains block out shorter wavelengths (bluer photons)
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Unformatted text preview: dust grains emit longer wavelengths (redder photons) Gravity starts contraction Gravity and thermal pressure (tug of war) Mass of molecular clouds are about 100 solar masses to be able to form stars Magnetic Fields, rotation, and turbulence can keep star from contracting Molecular clouds are a place where stars form in multiples Molecular cloud must be very dense to create a single star First Stars: contained only H and He no CO (that would cool collapsing molecular cloud) warmer environment that present epoch of clouds huge stars formed (greater than 30 solar masses)...
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This note was uploaded on 09/08/2010 for the course ASTR 101 at San Jose State.

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