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I'm finishing up a piece on this too, Chris. It's a planet as far as I'm concerned. But the nomenclature problem is clearly going to sow confusion for a long while.

The definition of a BD has always been “sub-stellar” - not massive enough to burn hydrogen. It’s a well-defined theoretical boundary (0.08Msun), with directly observable consequences. The boundary between low mass BDs and massive giant planets is somewhat fuzzy. But BDs are definitely not stars.

So what would Pluto be if it were orbiting a brown dwarf?

How do you end up with a Jupiter-mass satellite/planet of a brown dwarf anyway? As I understand it, Jupiters get rarer as the host mass decreases. Capture during whatever process launched the brown dwarf onto an e>0.9 orbit?

It doesn't help that there's also no agreed-on definition of how small something can be and still be labelled a brown dwarf. It gets messy when nature works in a continuum but humans want to sort everything into tidy categories. Guess it's time for another IAU vote. :)

I kinda always saw it as a continuum but like planetoids and planets the properties change sufficiently you can distinguish planets from brown dwarfs (deuterium burning) from main sequence stars (hydrogen burning mass), but somewhere we put lines to put things in boxes for sample selection/analysis

I blame the people who want to label things. We should spend more time asking the Brown Dwarfs about their feelings. Do they want to be known as Dwarfs, or giant Jupiters? What about "Glowing Cloud Stars"? Let's spend some time embracing these objects on their own terms.

Pretty sure I saw Nomenclature Melange at Bluedot Festival a few years back.

With a lot of this I’m feeling we latch on to definitions a bit too much. The description of the system tells us what we need to know, and as long as we put the definitions we use in a paper where they’re relevant that’s all fine. Like, how many definitions have I seen of a red galaxy?

I like to call brown dwarfs "overachieving planets" (because calling them "failed stars" makes me sad), so I'm here for the discourse if it means their planets get a fun new naming scheme

Sometimes I think it should all be divided into "stars" and "leftover debris." "Star" includes everything that forms from a gas/dust cloud (includes brown dwarfs regardless of size/mass). "Leftover debris" = everything that forms from a debris disk around a star or other bit of leftover debris.

I think we need a consult by @davidkipping.bsky.social here. The article acknowledges the nomenclature challenge here, because dynamically it is like a moon. My instinct agrees with yours, though, that it is better thought of as either a planet or a secondary in a brown dwarf binary.

I didn't think brown dwarfs have ever been considered stars or planets.