Chapter 16 in 4th Edition of Bennett et al.
Star Birth

 

Interstellar Medium (ISM)

            Some parts are hot, some cold
            Examples of cold, dust-rich clouds: Barnard 86
           Dust in plane of spiral galaxy            Dust Lane in Cygnus/Aquila
           

 

Birth

            Out of the gas and dust come stars

            Example stellar nursery  Orion, viewed in IR wavelengths

            Requirements: cold 10-30K and "dense" (105 atoms/cm3)

            Cloud fragmenting into protostars (drawing)       Thackeray's Globules (astronomical image)

 

Protostar

         Conservation of angular momentum causes the collapsing cloud to spin faster ->
         protostar + protostellar disk

         Energy source is gravity

         Disks cartoon photo with shadowed disk photo

         Jets T Tauri stars and Herbig-Haro Objects

         Winds clear out dust

 

Evolutionary tracks
         details for low mass star evolutionary track
         low, intermediate and high mass stars

 

Statistics

Many more low mass stars are born than high mass stars

No stars "weigh" more than 100MSun

Brown Dwarfs  < .08MSun