00:01
Okay, so in an hr diagram, you have luminosity going up and temperature going to the left.
00:11
And so what happens for a main sequence star, for a solar mass star, so star with a mass of the sun roughly, it's on the main sequence for a bit.
00:24
This is the main sequence.
00:26
And hydrogen is burning in the core.
00:29
So that's the phase the sun is in right now.
00:34
Eventually, it'll leave the main sequence.
00:37
So this is sometimes called the sub -giant branch.
00:43
There's also the horizontal branch, et cetera.
00:46
But essentially, it is starting to burn hydrogen in a shell around the core.
00:54
Okay...