25.1 Flashcards
Explain the relationship between color and temperature in stars
Blue = hottest
Red = coldest
What are the main colors of stars? (Hottest to coldest)
Blue (30,000K), yellow (5,000-6,000K), red (5,000K)
How small is 1 second of arc?
1/60^2 • 1 degree
Explain a light year
A vast distance that makes km or AU impractical
How many km does light travel in one year?
9.5 trillion km
What is apparent magnitude?
The brightness of a star when viewed from Earth
What is absolute magnitude?
The apparent brightness of a star when viewed from a distance of 32.6 light years (10 parsecs)
What does a H-R diagram illustrate?
It shows the relationship between absolute magnitude and the temperature of the stars
What is Cepheid variable? What is it used for?
A star whose brightness varies periodically because it expands and contracts.
They pulse. The longer the period of time they pulse between bright periods, the greater the absolute magnitude.
What is a bright emission nebula?
-It has low pressure, so it emits light
-Mostly hydrogen
-Absorbs UV radiation
-Fluorescence
What is a bright reflection nebula?
-Reflects light of bright stars around it
-Larger dust particles
What is a dark nebula?
Matter that is scattered far
-low density
-can be seen blocking densely packed areas in the Milky Way
