> Instead, it circles a brown dwarf, an object larger than a planet, that orbits the CD-35 2722 star.
Isn't the dividing line between the largest possible gas giants and the smallest brown dwarfs a bit fuzzy?
> Instead, it circles a brown dwarf, an object larger than a planet, that orbits the CD-35 2722 star.
Isn't the dividing line between the largest possible gas giants and the smallest brown dwarfs a bit fuzzy?
It's fuzzy in terms of mass but not in physical properties. The definition is that a brown dwarf has undergone deuterium fusion.
The fuzziness is only in the mass and composition needed to achieve that. 13 Jupiter masses is generally the line where deuterium fusion starts, but that can vary: a brown dwarf composed of only primordial H and He would need a bit more, while one with some heavier elements from previous generations of stars will be denser and need slightly less.
There is fuzziness in what we can observe, so sometimes we're not sure if an object is a brown dwarf. We may not know its exact mass and composition, and we might not be able to tell if it's radiating energy from deuterium fusion, or just from gravitational compression, or (in a binary system) if it's just reflecting light from its companion star.
The definition of a brown dwarf is that there is enough heat and compression for deuterium and/or lithium fusion, but not protium fusion.
The exact model limit is unclear, but the physics modelling is relatively straightforward.
I had only the vaguest notion up until 15 minutes ago of how these are being categorized, this one is described as either a brown dwarf or giant planet? https://en.wikipedia.org/wiki/CoRoT-3b
see the Classification header of the page