1. IT for Astronomy Presentation 2007 Stars Formation and Evolution: Interstellar Medium to Protostar Protostars Main Sequence Stars Giants and Dwarfs Supernova The Cycle restarts

2. IT For Astronomy Presentation 2007 Interstellar Medium to Protostar 1. The ISM consists of gas and dust particles 2. Regions may be viewed as clouds 3. Some give off visible light, others weak radio waves 4. Dense molecular clouds collapse 5. Density is relative – virtual vacuum 6. Colliding clouds can start gravitational compression 7. Collapsing clouds fragment 8. Molecules speed up and heat up 9. Protostar starts to emit Infra Red radiation

3. IT For Astronomy Presentation 2007 Protostars

4. IT For Astronomy Presentation 2007 Main Sequence Stars  The Hertzsprung-Russell diagram is a way of categorising stars  It plots luminosity versus spectral colour which relates to temperature  Main sequence stars with a range of masses occupy a narrow band

5. IT For Astronomy Presentation 2007 Giants and Dwarfs  Hydrogen fuel supply exhausted in center – outer parts expand to form a Red Giant  Eventually outer parts shed to form a planetary nebula and leave a remnant White Dwarf  Larger mass stars can come to a worse end..

6. IT For Astronomy Presentation 2007 Supernova 1. Star explodes in minutes. 2. May be visible to naked eye. 3. Remanant shrinks under own gravity. 4. May form Pulsar or 5. Black Hole.

7. IT For Astronomy Presentation 2007 The Cycle Restarts