26 terms

Characteristics of Stars

List the 5 Characteristics used to classify stars.
color, temperature, size, composition, and brightness.
What does a star's color reveal?
It's surface temperature.
What are very large stars called?
Super Giants.
What size is our sun?
Medium size star.
What do astronomers use to determine the chemical compositions in stars?
What elements make up most stars?
73% Hydrogen, 25% Helium, and 2% other elements.
The brightness of stars depend on what?
It's size and temperature.
What determines how bright stars are viewed from Earth?
The distance from Earth and how bright it truly is.
Define apparent brightness.
The brightness as seen from Earth.
Why does our sun look so bright?
The sun looks so bright because it is so close to Earth.
Define absolute brightness.
The brightness the star would have if you were at a standard distance from Earth.
What two variables must astronomers have to calculate absolute brightness?
Distance and apparent brightness.
What is a light year?
The distance light travels in a year. 9.5 million million Kilometers.
What is a light year used to measure?
It is used to measure the distance between stars
Is a light year a measurement of distance or time?
It's a measure of distance because it used to show how long light travels in a year.
Define parallax.
The apparent change in position of an object when you look at it in different places.
Astronomers measure...
how much the nearby star appears to move against a background of stars much farther away.
The less the nearby star appears to move, _____________
the further away it is.
What is plotted on the Hertz sprung diagram?
The surface temperature of the stars are plotted on the x axis and the absolute brightness on the y axis. Most stars are are main sequence stars.
As main sequence stars surface temperature increases, what happens to the absolute brightness?
Absolute brightness increases.
Describe Super Giants brightness and surface temperature
very bright, and cooler
Describe Giants brightness and surface temperature.
Not as bright as Super Giants and cool.
Define White Dwarfs brightness and surface temperature.
Hot and dimmer
What kind of star is our sun? What color is it?
Main sequence star. Cooler and not as bright. It is yellow.
What color are cooler stars?
What color are the hottest stars?