Stellar Properties

1
Stellar Properties

• Distance
• Stellar Parallax
• Earths orbit baseline
• The parsec
• Used to explore our solar neighborhood
• Stellar Motion
• Radial velocity
• The Doppler effect
• Transverse velocity
• Proper motion distance

2

• Luminosity
• An intrinsic property
• Apparent Brightness
• Proportional to Luminosity
• Inversely proportional to distance
• Magnitude scale
• Large magnitude gt FAINT!!!
• Change of 5 in magnitude change of 100 in
  brightness
• Apparent magnitude vs. absolute magnitude
• Stellar Temperatures
• Apparent brightness BB curve
• B V intensities
• Color index

3

• Stellar Temperatures
• Stellar spectra
• Temperature affects line strength
• Hot stellar spectra vs. cold stellar spectra
• Hydrogen lines
• Spectral classification
• OBAFGKM
• Numerical subdivisions
• Stellar Radii
• Direct measurement
• Radius-luminosity-temperature relationship
• Ex. Giants Dwarfs

4

• Hertzsprung-Russell Diagram
• Luminosity vs. temperature plots
• The Main Sequence
• Hot, bright stars to cold, faint stars
• Lines of constant radius
• Blue Giants Red Dwarfs
• White Dwarfs Red Giants
• 90 of all stars are MS!
• Stellar Masses
• Binary Stars
• Visual
• If distance is known
• Spectroscopic
• double and single line
• Doppler shifts
• Lower limits only

5

• Stellar Masses
• Eclipsing
• Light curves
• Orbital inclination is known
• Masses on the Main Sequence
• Mass Radius relationship
• Mass Luminosity relationship
• Stellar lifetime
• High mass stars are young low mass are old
• Distances (again!)
• Spectroscopic Parallax
• Spectral type apparent magnitude yields
  distance information
• Distances out to 10,000 pc
• Assumption of similarity

6

• Luminosity Class
• Based on line width
• Determines type of object