Five star system

Interesting... that's had me scurrying for my books, as I didn't think that these types of systems were that rare.

The one that immediately came to mind was Castor (Alpha Geminorum), which is a sextuplet system - six stars in three binary groups. Castor A and B are easy to see telescopically, and each of these is a spectroscopic binary. Castor C (another spectroscopic binary) is more difficult to see at about magnitude 9.

But, of course, this is a six-star system... is the report suggesting that five-star systems are rare, or that systems with five or more stars are rare? I'm not sure.