PCS 181 Lecture Notes - Bok Globule, Outer Space, Main Sequence
17 Mar 2013
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Document Summary
Interstellar space is filled with diffuse gas and dust. 50 pc in diameter and with a million solar masses, are filled with molecules. In these molecular clouds, shock fronts from nearby star formations or a supernova explosion or some other global gravitational disturbance may begin the process of self- gravitational contraction, leading to the formation of new stars. The earliest stages of pre main sequence evolution are not directly observable, becauseprotostars are hidden behind massive amounts of dust. Consequently, no radiation from the forming star is visible. If one could envision a protostar without the obscuring dust, theory suggests that initially a protostar would be very cool but luminous, with convection very efficiently moving gravitational energy that is released in the interior outwards to the exterior. As the object shrank, the surface area would dramatically decrease and the overall luminosity likewise decrease rapidly.
