1. Distances -- stellar parallax

2. Distances
Parsec -- distance at which a star has a parallax of one second of arc (pc)
kiloparsec (kpc) , megaparsec (mpc)
Light year – distance light travels in 1 year (lyr)
1 pc ~ 3.3 lyr

3. Motions --- along the line of sight
Doppler Effect
Change in l or n divided by rest l 0 or n 0
Equals velocity (v) of approach or recession divided by c
l - l 0 = v
l c
Longer l, redshift , away, vel is +
Shorter l, blueshift , toward, vel is -
Radial Velocity

4. Motions -- across the line of sight
Proper Motion -- angular motion
Plus distance – transverse velocity

5. “APPARENT VISUAL MAGNITUDES”
Sun: m =
Moon:
Venus:
Mars:
Sirius:
Vega:
Antares:
Polaris:

6. “APPARENT VISUAL MAGNITUDES”
BRIGHTEST STAR (SIRIUS): m =
20th BRIGHTEST STAR:
FAINTEST VISIBLE: about 6.5
WITH BINOCULARS: about 8
6-INCH TELESCOPE: about 12
PLUTO:
LIMIT WITH MODERN DETECTORS
ON BIG TELESCOPES:

7. Atomic Spectra – spectra of the elements

8. Kirchoff’s Laws

9. The Spectra of the Stars and Spectral Classification
Early classification – the Harvard system
OBAFGKM -- a temperature sequence – decreasing

11. Binary Stars – Weighing and Measuring the Stars
> 50% of all stars are multiple

12. Three Types Visual Eclipsing – light curve
Spectroscopic – velocity curve

13. The HR Diagram
Fundamental diagram of stellar astrophysics

15. HR Diagram for solar neighborhood

17. Relative Sizes

19. The Largest Stars – Red Supergiants