Can I interact with this creature?

I encountered this creature a couple of times while playing Super Mario Galaxy, but could never get close to it:

So far, I haven't been able to find any information in any walkthroughs, and I'm not sure what it's called, so my searches have come up blank.

Is it possible to catch this creature? If it is possible, what happens when you do catch it?

Solution 1:

Oh, this is a fun little guy. He is, in fact, an enemy, so yes, he is interact-able. If you manage to chase this bugger down (running long jumps help here) and spin/stomp him, he will explode in a shower of ~20 star bits.

They're called "Starbags" according to Super Mario Wiki.

Solution 2:

Yes, you can catch it, it's not particularly easy and it's been a long time since I've played so can't offer any specific advice.

I believe they drop a lot of star bits when you land a successful hit.

I don't know what it's called.

Again, it's been a while since I last played so apologies for being vague -- this will hopefully help until a fuller answer appears.)