Hi Board

Kmann posted this one on the other board and i thought it was worth discussing here...

http://www.astronomy.com/Content/Dynamic/Articles/000/000/000/497ysisu.asp

that's such a ridiculously long URL, but anyway... the basic idea is that protoplanetary disks get blasted away by hyperactive O and B stars in star-forming nebula. Only 1/10 survive to form planets - or so one theory goes.

But it's only accretion models of big planet formation that have problems with disk destruction. Gravitational instabilities might also form big planets within a few centuries rather than millions of years.

The authors also speculate that gravitational interactions between protostars disrupt their disks and abort planet forming.

However Michael Woolfson, and his team, have an alternative theory which involves planets being formed via that very mechanism - interactions between relatively diffuse protostars... so I will remain skeptical of naysayers who say planets are rare. We need a broad statistical survey like Kepler before we can tell with any degree of certainty.

Adam