Sagan (etal) have noted it might be the universe it set up (so to speak) such that spectral type A, B, and O stars don't produce planets during their formation.
They didn't have a specific mechanism in mind, they were just noting some trends in spectral type vs angular momentum and postulating once a forming star gets in the size range of A or larger, planet formation doesn't seem to occur.
I don't think any Kepler findings specifically relate to this prediction in regards ot A, B, and O stars. I suppose at some point somebody will 'data mine' the Kepler data and look for correlations between angular momentum and spectral type and maybe with the new understanding of the variety of ways planets can form, the angular momentum thing isn't as important or strongly correlated.
They didn't have a specific mechanism in mind, they were just noting some trends in spectral type vs angular momentum and postulating once a forming star gets in the size range of A or larger, planet formation doesn't seem to occur.
I don't think any Kepler findings specifically relate to this prediction in regards ot A, B, and O stars. I suppose at some point somebody will 'data mine' the Kepler data and look for correlations between angular momentum and spectral type and maybe with the new understanding of the variety of ways planets can form, the angular momentum thing isn't as important or strongly correlated.
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