A protostar is a star the is developing as is on the way to starting nuclear fusion. A brown dwarf is a failed star, one that failed to gather enough mass to start fusion.
A brown dwarf.A brown dwarf.A brown dwarf.A brown dwarf.
A protostar; also a brown dwarf.
A protostar is a young star in the early stages of formation, where nuclear fusion has not yet begun. A white dwarf is a small, dense star that is the remnant core of a low to medium mass star after it has exhausted its nuclear fuel.
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A protostar is a star that is still forming and has not yet started a sustained fusion reaction. All the heat is the result of gasses being compressed. A white dwarf is the remnant of a dead star that has exhausted its fuel and is much smaller and denser than a protostar.
If a protostar does not undergo nuclear fusion, it will not become a star. Instead, it will either become a brown dwarf, which is a failed star that lacks the mass to sustain nuclear fusion, or it will simply cool down into a cold, dense object known as a sub-stellar object.
Nebula protostar mid sized star red giant nova white dwarf black dwarf:)
The hobbit is much shorter than a dwarf. Hobbits do not have beards.
Sometimes. If the total mass is high enough, and if the cloud of dust and gas collapse to reach a high enough density and pressure, nuclear fusion can begin in the core and it will become a star. If the total mass is not high enough, it may collapse into a "brown dwarf".
size and color
their colour is one thing but a black dwarf originates from a white dwarf
A brown dwarf will never become a black dwarf. A black dwarf is what becomes of a white dwarf. This process takes hundreds of trillions of years.