Last night I encountered my first O class. An O7 to be exact. It has an AU of 800000 times that of our sun. It was mind boggling how large the system it generated was. I think it had 8 or so primary bodies. The closest to the entry JP was some 2000 days at 2500km/s travel speed. The JP survey points required for each survey location were 2700 points a spot and at 2500 km/s it took about 30 days travel between each of the inner ring of survey locations.
I had to look up an O class. I had never heard of it. And that got me to thinking: there shouldn't be any planets in an O class system if I am understanding wiki right (yeah, I know to take wiki with a grain of salt). Frequency is 1 in 3,000,000 stars is an O and the solar wind being emitted is so strong it causes photoevaporation in nearby systems. The wind blows away the protoplanetary disks (which makes me think it should have blown away it's own disks too)