The Characteristics of Stars (Text Ref. Page 370-373)

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

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

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

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

Apparent and Absolute Magnitude

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

Star Color & Temperature

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

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

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

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

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