Back to my roots

Analysing stars used to be my bread and butter, but it's still an area of great interest.  Therefore when I came across the Open Exoplanet Catalogue and found out it had host star information, I couldn't resist plotting out a Hertzsprung-Russell diagram:

I'm curious about those hot stars (blue cluster), their effective temperatures and luminosities are a bit odd.  I'd love to think they were blue dwarf stars, but as none have been seen before, I doubt it.