Did you made a mistake? Do you mean red dwarf or red giant;/? Not every dwarfs have to have mass 72 times bigger than Jupiter e.g. OTS 44 has mass 15 times bigger than Jupiter. ;-)
OTS 44 is no verified brown dwarf, but likely a sub-brown dwarf. Brown dwarf is it only, if it would be verified, that stable convection streams take place inside it. The 13 Jupiter masses are a lower limit for observation, to tell, here we can theoretically have already a brown dwarf, 75 Jupiter masses is the upper limit, there you would already get into the main sequence as yellow dwarf star.
Astronomers are currently a bit in a brown dwarf hype to find the smallest object that must be a brown dwarf, but they have still not found a good way to tell reliable between Jupiter or a Star- a brown dwarf with 75 Jupiter masses would be only 10% bigger than Jupiter.
72 Jupiter masses is a good mass definition, because there you would have the convection in any case, masses below are potential convection streams. A 60 MJ object could still already have convection, but the smaller things get, the less likely it is.
Also, a red dwarf is still a small cold star, but much bigger than a brown dwarf, which is a star that failed to enter main sequence at all.
[ame="http://en.wikipedia.org/wiki/Red_dwarf"]Red dwarf - Wikipedia, the free encyclopedia[/ame]