Question about galaxies

[Cloengaa]

Hey all.

I have been wondering about something for a little while now.

When looking at pictures taken of galaxies the cores are always brighter than the stars in the spiral lanes. Why is that ?

Is the stars at the center of the galaxy outputting more effect ? are they bigger, more luminous than the stars in the spiral arms?

Or is it the fact that alot of stars are packed in a (small) area at the center of the galaxy that gives the brightness ?

[ronin]

The last one, simply more stars in a smaller volume, so it is brighter.

Core stars are also usually older and redder, the stellar nursery's are usually in the spiral arm's

[Matt Scunthorpe]

Yeah as Ronin put it, there are more stars in the centre of a galaxy, so it looks to be brighter. Similar to some globular clusters, they are brighter in the middle than around the edges.

Matt.

[Cloengaa]

Thanks alot for the responses