Stars

Well more massive stars have more hydrogen fuel, so you're correct there, hence they are hotter stars, because they are fusing more hydrogen nuclei, this means that they use all of their hydrogen nuclei up faster

This doesn't follow - why should they use their hydrogen nuclei up faster? They have much more hydrogen present to begin with. Your argument states that "a car with a larger tank will run out of fuel faster", which is in general false.

This doesn't follow - why should they use their hydrogen nuclei up faster? They have much more hydrogen present to begin with. Your argument states that "a car with a larger tank will run out of fuel faster", which is in general false.

Well more massive stars have more hydrogen fuel, so you're correct there, hence they are hotter stars, because they are fusing more hydrogen nuclei, this means that they use all of their hydrogen nuclei up faster, so they have a significantly shorter life as a main sequence star, so an older cluster will have a lot less massive stars as all of the massive stars will have ran out of hydrogen nuclei and turned into super red giants. I hope this answers your question

In general it might be. But the exception that larger stars have shorter lives is GCSE (and I assume A level) knowledge. Presumably a good mathematical reason would involve the rate of hydrogen fusion increasing faster than the mas of the star. But someone else can go do the maths.

The star is hotter, so more of the hydrogen nuclei have enough kinetic energy to overcome the electrostatic repulsion between them, hence the rate of hydrogen nuclei fusion is greater, this outweighs the fact there is more fuel, so it uses the fuel up faster than in a less massive star.

I genuinely thought that it was just:

a) Smaller stars just "died" out a while back.
c) + d) Older cluster, more time passed, therefore main sequence phase is over.

Compared to the young cluster, the old cluster will have fewer main sequence stars because that phase in their life ended.

Yeah, the physics I'm using is pretty sketchy so I wouldn't take my reasoning on a piece of paper ...

Forgive me if I'm wrong. But don't say I didn't warn you.

Ah, if it's quotable that "this outweights the fact that there is more fuel", then go ahead and quote it

Brill! Thanks a lot!

Please check if i m wrong here

a) The star starts its life as main sequence star and can be either massive or with a low mass.
But generally, this is the time when they have the largest mass compared to the next following stages right?
Well, they ll keep fusing hydrogen until it ceases and then they ll contract and their mass decrease and their temperature, but their luminosity increases. Now they are in the red giant stage, so they ll fuse helium and as that also finishes, they ll further decrease in mass and become dimmer and dimmer and their size will decrease. Also, their surface temperature will drop. This is the white dwarf stage. As time passes, they die.
b) what a standard candle exactly is? I read a lot about it but still not getting it. Please write for me some bullet points or whatever, coz my exam is tomo

Millions of thanks to you!

a) you seem correct there

b) sorrry I'm not particularly confident with the standard candle, I've studied it a little, but not enough to explain it, you might stand a better chance looking around at online articles or youtube videos or something

This doesn't follow - why should they use their hydrogen nuclei up faster? They have much more hydrogen present to begin with. Your argument states that "a car with a larger tank will run out of fuel faster", which is in general false.