Chapter 30.1: Characteristics of Stars . Star: ball of gas that gives off a tremendous amount of energy in the form of heat and light. Our own ‘ Sun’ is considered an average star!. Characteristics:. Starlight- light given off by stars. Composition- what elements make up the stars.
Star: ball of gas that gives off a tremendous amount of energy in the form of heat and light.
Our own ‘Sun’ is considered an average star!
-by analyzing the light stars emit, we can determine the star’s composition (elements present) and temperature.
-Star composition is determined by analyzing the light being emitted. Equipment is called a spectrometer.
-Since different elements absorb different wavelengths of light, elements can be determined.
-Stars are made up of gas elements. (Hydrogen is the most common!)
-temperature is determined by the star’s color.
-temp.’s range from
2,800 to 50,000 oC.
-Some dwarf stars are as small
as the Earth.
-Our sun is a medium size star (1,390,000 km).
-Some stars are 1,000 times larger than our sun.
-Density affects mass…no relationship between size and mass.
Example: a star can be smaller than our sun, but have a greater mass…meaning it is more dense!
1. Actual motion- what we see with telescopes.
2. Apparent motion- This is motion visible to the unaided eye in a dark sky; due to movement of Earth.
Stars have three actual motions:
3. move toward (blue shift) or away (red shift)
-Light Year = 9.5x1012km; Distance that light travels in one year.
Example: light from the sun takes 8 mins.
to reach the Earth
-Astronomical Unit (AU) - A unit of length used to measure distances in solar system.
Example: Sun to Earth = 1 A.U.
-Absolute Magnitude: true brightness
-Apparent Magnitude: brightness of a star as it
appears to us on Earth.