Liquid water on a planet revolving around a brown dwarf?
Well, it is possible. If it orbits close enough, it can be warm enough to exist in a liquid form. The close orbiting planet, at first would be too warm to sustain life, but as the star cools, it becomes more habitable, and in theory might be a better place for life than our own Earth.
Because a planet in the hypothetical habitable zone would have to be very close in, it would suffer very strong tides. These would have multiple effects. In chronological order::
1 the planet would suffer tidal (frictional) heating, just as Io does as the result of tides as it moves round Jupiter. These would probably lead to vulcanism, and the outgassing of all sorts of stuff, in a Venus-like way.
2 the tidal friction would slow the rotation of the planet (i.e. make its days longer), until its periods of rotation and revolution were locked together, probably leading to a moon-like situation, with one face permanently towards the brown dwarf, as you suggest. That would reduce habitability, because all the water would eventually freeze out on the dark side, along with other volatiles. In other words, within these particular circumstances, it seems very unlikely that liquid water would be able to effect the heat transfer you need. (I don't think you can mean 'to counteract' the heat transfer.)
For these reasons, it seems unlikely that a remotely earth-like environment could result, don't you think?
How large does a gas giant have to be to to become a brown dwarf?
First a gass giant is a planet while a brown dwarf is not real it's a white dwarf. White dawfs are small. They apear when a star looses most of it's energy. It shrinks down to a white dwarf, this does not happen for larger stars. And finally stars don't ignite. This is a cool field of science, as are all sciences, and I hope that you will look into it more.
Patches (For the black and white one)
Lady Rabbitus Hopitus Furritus the Third
Cottontail* (the three starred names are Peter Rabbit's
Thumper (Bambi's friend)
Bunny Foo Foo
I hope these names help!!
The gas giant planet Jupiter is almost big enough to have become a brown dwarf star.
There is no reason a brown dwarf star could not enter our solar system, but there are no stars (dwarf or otherwise) closer than Proxima Centauri, which is about 4.5 light years (25,000,000,000,000 miles) away and not heading this way.
How does a Main Sequence star turn into a Brown Dwarf?
As far as I know, a main sequence star never becomes a brown dwarf. A brown dwarf is a "failed" star since it never gained enough mass during its formation to fuse hydrogen into helium at its core.
I suppose in a binary star system where a small main sequence star is losing mass to a companion white dwarf, then perhaps the main sequence star could lose enough mass where the hydrogen fusion would stop. This is just me speculating, I'm really not sure.
Is the brown dwarf discovered in april 2010 Nibiru?
No. Nibiru is supposedly a planet in our Solar System, and this brown dwarf is well outside our Solar System. Even if it were travelling at the speed of light (which it isn't), it would take ten years to reach us.
What color would a planet's sky be if they are orbiting a brown dwarf stars?
A brown dwarf is a star that is no longer actively fusing elements, all of the EM radiation emitted is due to residual heat. While the majority of the radiation will be in the infrared spectrum, black body radiation is composed of all wavelengths. A very low amount of the radiation from the brown dwarf will be in the visible range with the peak (of visible light) just above infrared.
If the brown dwarf is fairly young and still hot enough, a planet could receive enough light in the red portion of the spectrum. The planets sky could be a very, very dim reddish color.