Some of the heaviest known stars may be as much as 100 times the mass of our Sun. Our Sun contains 2 x 10^33 grams of matter. That's equal to about 500,000 times the mass of our Earth which is, to us, a big planet. We do not think that stars can get heavier than about 200 times the Sun's mass because the pressure caused by the light they emit into space becomes so enormous that it causes these stars to evaporate, loosing large quantities of their mass back into space in a few thousand years.
The most massive star know is called Eta Carina (above Hubble Space Telescope photo) and has a mass that is estimated to be about 120 times that of the Sun. These stars are so hard for nature to make that there are only one or two of them in an entire galaxy as big as the Milky Way which contains over 200 BILLION stars! Eta Carina is located 2,500 parsecs away or 8200 light years from the Sun. Even now, it is in the process of ejecting gas and may soon go supernova in a few thousand years or so.
Copyright 1997 Dr. Sten Odenwald
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