how am I going to pass?

The Interstellar Medium

• Interstellar Medium 

  • What is it? Dark material consisting of gas & dust detected primarily using the radio part of the E.M. Spectrum. 

  • What is reddening? ∙ Density and Composition of the Interstellar Medium 

•  Interstellar Clouds 

  • Emission nebulas 

  • Reflection nebulas

  • Dark dust clouds 

• What is 21-centimeter radiation and why/how is it used?

• Molecular gas and molecular clouds

Star Formation: Know the main events that occur in the process in each stage of formation

• The role of gravity & heat (“battle” of opposite forces) in starting star formation

• Star Formation – Stages 

  • Stage 1 – An Interstellar Cloud

  • Stage 2 & 3 – A Contracting Cloud Fragment Protostar 

  • Stage 4 & 5 – Protostellar Evolution 

  • Stage 6 & 7 – A Newborn Star 

• Zero-age main sequence – it’s not a place! 

• What’s an Evolutionary Track?

• “Failed” stars that never made the sequence (brown dwarfs) 

• Death of low mass stars, stars like our Sun, and high mass stars 

• Star Clusters 

  • Open / Association / Globular
    
    

H-R Diagram & Stellar Masses

• Hertzsprung-Russell Diagram (H-R) (Know main axes variables for relationship)

• Understand that stars are placed on the diagram based on mass during  their lifetime – it is not a “waystation” (like a train stop) before its death

• Main Sequence of stars in the center of the H-R – Our Sun as reference to  luminosity on y-axis (vertical) set at 1 (all other stars exponentially above are much more luminous or below between 1 & 0 far less luminous) 

• Luminosity vs. Temperature 

• Stars “outside” the Main Sequence – Giants, Supergiants, and Dwarfs

• What does the H-R Diagram really tell us? Why is it important?