Studies have come to think that it is possible that the first stars in the universe 400 to 200,000 time bigger then that width of the sun but did not emit any visible light and were the result of the annihilation of dark matter. It is possible that these stars still exist today because instead of emitting visible light they shoud emit gamma rays, neutrinos and antimatter and would be associated with clouds of cold, molecular hydrogen gas that normally wouldn't harbor such energetic particles.
the concept of dark matter is important because they know it exists based on the fact that galaxies rotate faster than they should with the visible matter within them. Scientists have even come to conclude that the universe is made up of 4% visible matter, 23% dark matter and 73% "dark energy".
The current belief is that dark matter is made up of weakly interacting massive particles WIMPs. the beliefs is that these stars start by the different dark matter neutralinos interacting and destroying one another producing subatomic particles that generate heat that then would keep hydrogen and helium clouds hot and prevent them from shrinking and fusion from igniting a star.
The process of studying this could be very helpful in the exploration and understanding of astrophysics and the search for dark stars could help explain dark matter. It could also help to explain why black wholes formed much earlier in the universe's history than expected.
http://www.astronomy.com/asy/default.aspx?c=a&id=6368