Re: A pair of brown dwarfs found around a star, that they shouldn't be around

Andrew Usher wrote:
Yousuf Khan wrote:
planets according to the normal theories. I don't know what to make of
this; but the paper that value comes from finds that planet-hosting
giants have _lower_ metallicity than non-planet-hosts, contrary to
what's observed for dwarfs, so maybe it's a little dubious - is there
some reason spec. metallicity estimates should be worse for giants?
That's entirely reasonable, as a previous study had found that stars
(like our Sun) which have low lithium counts are more likely to have
planets.

As that article makes clear, lithium doesn't behave like the ordinary
metals (carbon and heavier); instead it must be that the existence of
planets has somehow disturbed the outer layers of the star to allow
more lithium to burn up.

My question, too, was why we observe _different_ behavior in giants
compared to dwarfs.


Sorry, I'm not clear about what "different" behaviour we're talking about? You said that the size of the most massive planets are related to how massive their stars are. So a really massive star may produce things as big as brown dwarf stars, but something smaller would produce smaller gas giant planets. Isn't that just expected?

Actually it's looking like our Sun is a bit of an odd-ball. Shouldn't we have something much larger than Jupiter as our largest planet, according to our star's size?

Yousuf Khan
.

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