Distances and Magnitude Flashcards
What’s it the luminosity of a star?
The total energy it emits in the form of electromagnetic radiation per second
Measured in watts
What is the intensity of an object that we observe?
Power received from it per unit area at earth
What is the effective brightness of an object?
Its intensity
What is apparent magnitude?
How bright the object appears from earth
What does the brightness of a star in the night sky depend on? (ignoring weather and light pollution)
Its luminosity and its distance
What is the scale of apparent magnitude?
1 = brightest 6 = dimest
A magnitude 1 star has an intensity how many times greater than a magnitude 6 star?
100 times
whats the equation for calculating brightness ratio between 2 stars?
I2 / I1 = 2.51^m1-m2
What is a parallax?
The apparent change in position of an object as the observer moves position
Parallax is measured in?
An angle
1 arc second = X degrees?
X = 1/3600
Absolute magnitude is based on what?
Only luminosity
What is absolute magnitude defined as?
what its apparent magnitude would be if it was 10 parsecs away
Why can’t parallax be used to measure the distance to most stars?
They are too far away
What is a standard candle? Whats an example?
An object that you can calculate the luminosity directly e.g. type 1a supernova
