Luminosity
amount of power a star radiates (does not depend on distance)
apparent brightness
the amount of starlight that reaches earth
Distance
1r:1. , 2r:1/4, 3r:1/9
Magnitude
negative bright positive dark
Absolute magnitude
how bright 0 parsecs away
apparent mag> abs mag
star is farther than 10 parsecs
Apparent < absolute
closer than 10 parsecs
Stellar parallax
star appears at two different positions in the sky during earths different seasons
d=1/p
p in arc seconds, d in parsecs
higher temperature
bluer star
Lower temperature
Redder star
star can have high total luminosity if…
its hot and heavy
main sequence stars
convert h to he in core
low mass stars
white dwarfs
High mass stars
neutron star
Very large
black hole
All stars in star clusters are…
the same age and the same distance from earth
With 10 parsecs…
absolute fainter than apparent