Elusive brown dwarfs

The Sun and Jupiter are similar in several respects. Both are self-gravitating ‘gas spheres’ that are composed primarily of hydrogen. However, the mass of Jupiter is only about 1/1000 that of the Sun. Now let us suppose that Jupiter's mass was actually ten times larger and the Sun's mass was decreased by a factor of ten. Would we still refer to Jupiter as a planet and to the Sun as a star? To resolve this question it has become necessary to consider a relatively new class of astronomical objects called brown dwarfs. In essence, brown dwarfs bridge the gap between giant planets and stars.