Question: What do you look at in the stars?

Paul Roche answered on 23 Jun 2010:

There are quite a few things we can look at – one of the easiest is changes in brightness, as that is often a sign that the star is doing something interesting (maybe changing in size, or in temperaturem, or maybe theer is another star or a planet passing in front of it). I also look at what we call the spectrum of a star – that is like looking at a rainbow, which is when sunlight is spread out so that you can see the colours thgat make up “white light’.

A spectrum can reveal a huge amount about a star – how hot it is, how big it is, what chemicals are in it’s atmosphere (mostly hydrogen) and whether it is moving (and if it is, how fast).

If I find a binary system (2 stars orbiting each other), I can try and weigh them, although I have to make some assumptions and lots of measurements. We can really only estimate the mass of a star, or a black hole if we find one orbiting (and tearing apart…) a star.

Studying the Sun is a great way to get a close-up look at a pretty average star – but studying the biggest and hottest, and smallest and coolest, stars helps us understand what happens at the extremes. That’s where we can really learn a lot.