Star (outer space)
From the Super Mario Wiki
A Star is a very massive astronomical body which fuses atoms of Hydrogen and Helium to create heavy elements. In fact, almost every atom in the universe that is not a hydrogen or helium atom was created inside a star. Stars are made from a substance known as plasma. Their internal fusion reactions produce heat and radiation.
In the Mario series, Mario must often collect artifacts resembling stars on his journeys. However, true stars don't come into prominence until Super Mario Galaxy. Here, it is revealed that they are actually mature Lumas. Bowser utilizes the power of the stars to create a giant reactor, with which he tries to crate his own Galaxy and conquer the universe. However, his efforts are thwarted by Mario and Rosalina.
In Galaxy, Rosalina states that when stars die, they turn to star dust and scatter across the universe. This is actually true, as the cast off material of a supernova can eventually condense to form new stars.
