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Brickleberried t1_j9v87uu wrote

Reply to comment by ciarenni in Massive 'forbidden planet' orbits a strangely tiny star only 4 times its size. by Rifletree

A white dwarf is a dead star that lost much of its mass though, so it's not really comparable. Gas giants will never form around a white dwarf, although secondary rocky planets might.

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ciarenni t1_j9wf6oh wrote

Yeah, it wasn't the best example star but my point was that just because it's small doesn't mean anything about how much mass it has, which is the point that I feel like the headline was missing.

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Brickleberried t1_j9zisc7 wrote

Radius of a main sequence star is proportional to the mass of the star. If you know the radius, you can pretty accurately get the mass. (It depends some on age and metallicity too, but not that much, as long as it hasn't evolved to a red giant yet.)

Planets, on the other hand, don't follow the rule nearly as well, especially for gas giants. Jupiter and a brown dwarf 80x the mass of Jupiter both have the same radius.

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