Bell Ringer Take out your notebook Draw a line under your last bell ringer answers Put today’s date in the left hand margin Complete Day 1 Bell Ringer Questions

Stars Essential Question: How is the Hertzsprung Russell (H-R) Graph used to classify stars? Stars Essential Question: How is our Sun similar or different than other stars? http://viewpure.com/32WyKgdBQgE?start=0&end=0

What is a star? A large spherical body that is composed of gases and emits light.

Characteristics of Stars 1 - Size of stars *Stars are measured in solar radii *The Sun is measured at 1 S.R. (solar radius) http://viewpure.com/_sQQkLUGPmw?start=0&end=0

Size of Stars Star Size (in solar radii) The Sun 1 Polaris 46 Rigel 78 Betelgeuse 1200 (approx) VY Canis Majoris 1,400 (approx) UY Scuti 1,700 (approx)

Size of Stars

Characteristics of Stars 2 – Color and Temperature *The color of a star indicates its temperature *Blue – White – Yellow – Orange – Red (Hottest) (Coolest)

Characteristics of Stars 3 - Magnitude (brightness of stars)

Characteristics of Stars *Apparent Magnitude - How bright a star appears to be from Earth Star Apparent Magnitude The Sun 26.8 Sirius -1.46 Vega +0.03 Betelgeuse +0.5

Characteristics of Stars *Absolute Magnitude How bright a star actually is Star Apparent Mag Absolute Mag The Sun 26.8 +4.8 Sirius -1.46 +1.2 Vega +0.03 +0.6 Rigel +0.12 -8.1 Betelgeuse +0.5 -7.2

Bell Ringer Take out your notebook Draw a line under your last bell ringer answers Put today’s date in the left hand margin Complete Day 2 Bell Ringer Questions

Hertzsprung-Russell Diagram A graph measuring the star's absolute magnitude (brightness) against its temperature (color).