Lecture 10 Flashcards
(7 cards)
1
Q
Stars
A
- how bright are they (luminosity)
- how far away are they (distance)
- how hot are they (surface temp)
- how big are they (mass and size)
2
Q
Stellar Luminosity (brightness)
A
- radiated power=(energy/sec = watt)
- luminosity = B(4PIr^2)
- Only need to know either distance or brightness and can find the other one
3
Q
apparent brightness
A
- how bright stars appear to us
- -apparent brightness decreases with distance
4
Q
Luminosity measurements
A
-Stars range from 10^6 Sun – 10^-4
5
Q
Stellar temperatures
A
- hotter object = more light with higher average energy
- bigger average energy = lower average wavelength
- hotter objects are brighter
- spectral absorption lines tell us about a stars composition
6
Q
weighing a star
A
-find a binary star system: orbital period, star separation, and orbital velocity can tell use a stars weight
7
Q
Binary Star system
A
3 ways to tell if there is a binary star system:
- visual: can see the difference between stars
- Eclipsing: measure the change in brightness
- spectroscopic: measure red line/blue line shift
