How do we measure stellar luminosities ?
By the apparent brightness which equals luminosity.
Formula :4pi x distance^2
How do we measure stellar temperatures ?
By looking at the spectra of stars show their surface temperatures. This is usually ranging from more than 40,000K to less than 3000K.
How do we measure stellar masses?
We can find the masses of stars in binary systems if we can measure both their orbital period and separation between them.
What is the hertzsprung Russell diagram?
It is a classification method of stars luminosity and stellar surface temperature.
What is the significance of the main sequence?
The main sequence stars mass determine both its luminosity and surface temperature. Also the more massive stars have much shorter lives because they fuse hydrogen at a much greater rate than then the others.
What are giants, super giants and white dwarfs ?
Giant and super giants are stars that are nearing the ends of their lives. While the
white dwarfs are cooling embers of star that have exhausted their fuel.
What are the two types of star clusters?
Open clusters which contain up to several thousand stars and are found in the disk of the galaxy. Globular clusters contain hundreds of thousands of stars all closely packed together, found mostly in halo of the galaxy.
How do we measure the age of the star clusters?
By finding the main sequence turn off on H-R diagram. The hydrogen core fusion lifetime of the most massive main sequence stars remaining within it.
Do we know any cluster older than 14 billion years old/ how old is our universe?
Unfortunately we do not because that is the age of our universe.
Amber Reed
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