1. The Characteristics of Stars
(Text Ref. Page )

2. Learning goals We are learning the characteristics of stars.
We are learning to determine star composition.

3. 1. Star Brightness depends on: Luminosity
the total amount of energy produced by a star per second
Distance
The closer the luminous object is, the brighter it appears to be

4. Apparent Magnitude the brightness of a star as it appears from Earth
on the apparent magnitude scale, brighter stars have a lower apparent magnitude value and dimmer stars have a higher value

5. Absolute Magnitude
the apparent magnitude the object would have if it were 33 ly from the observer
allows you to compare stars as if they were the same distance away,
gives you a much better idea of the actual luminosity of a celestial object

6. Apparent and Absolute Magnitude

7. 2. Star Color & Temperature
the color of a star indicates its temperature (a hot star appears bluish and a cool star appears reddish)

8. Star Color & Temperature

9. 3. The Composition of Stars
determined using a spectrograph which splits light energy into patterns of color
compare the stars spectra with the known spectrum of the elements
can tell us which elements make up the star

10. 4. The Mass of a Star solar mass: the mass of the Sun = 2 x 1030 kg)
solar mass is the standard to which all other stars are compared

11. Learning goals We are learning the characteristics of stars.
We are learning to determine star composition.

12. Activity: Looking at a Star Spectrum
complete the handout to determine the composition of the stars

13. Homework
Page 373 questions 2, 5, 6, 7, 9, 10