X-ray Images of Cassiopeia A
These images from NASA's Chandra X-ray Observatory show the location of different elements in the Cassiopeia A supernova remnant including silicon (red), sulfur (yellow), calcium (green) and iron (purple). Each of these elements produces X-rays within narrow energy ranges, allowing maps of their location to be created. The blue color shows high energy X-ray emission, and the blue outer ring in particular is a representation of the expanding blast wave. Astronomers study supernova remnants to better understand how stars produce and then disseminate many of the elements on Earth and in the cosmos at large.
(Credit: NASA/CXC/SAO )

Origins: SolarSystem Elements
Oxygen is the most abundant element in the human body (about 65% by mass), calcium helps form and maintain healthy bones and teeth, and iron is a vital part of red blood cells that carry oxygen through the body. All of the oxygen in the Solar System comes from exploding massive stars. About half of the calcium and about 40% of the iron also come from these explosions, with the balance of these elements being supplied by explosions of smaller mass, white dwarf stars.
(Credit: NASA/CXC/SAO/K. Divona)

Reference: Science Blog from the SDSS, Origin of the Elements in the Solar System by Jennifer Johnson

Pre-Supernova Star Illustration
As it nears the end of its evolution, heavy elements produced by nuclear fusion inside the star are concentrated toward the center of the star.
(Credit: NASA/CXC/S. Lee)