Massive stellar explosions eject large amouts of heavy elements

Dec 21, 2007 08:12 GMT  ·  By

Now, we mostly know what nuclear reactions take place in the cores of the stars to create heavy elements that are spread into space following the supernovae explosions, but what types of supernovae are necessary for this process has been, so far, mostly unknown, considering the fact that stars like our own are relatively stable over tens of billions of years.

Heavy elements are critical for the formation of rocky planets similar to Earth. However, stars like the Sun are thought to be too long-lived to provide with enough material for the formation of such structures. Now astronomers think that, instead, massive stars could be responsible for this process, since they are mostly gassy, burn up their fuel relatively fast, meaning about a few million years, while our Sun has been around for more than 4.7 billion years, thus they are short-lived and provide with massive amounts of heavy elements.

This may also be the case of the Cassiopeia A supernova remnant, which exploded more than 11,300 years ago. Analysis of the light coming from it reveals that the supernova, visible from Earth 325 years ago, could have ejected 10,000 times more heavy material than the mass of the entire Earth, such as silicate, carbon, aluminum oxides and other heavy elements.

Astronomers believe that these remnants ejected by the supernova are the ingredients which would have eventually formed planets similar to Earth, in the past. Also, it seems that the heavy elements spewed by the explosion usually originate in the stellar core and are processed into dust clouds well after the supernova event, as the remnant material cools down. This could also be used to explain the large proportion of dusty gas present all over the universe.

An alternative theory takes into consideration the fact that a similar heavy element processing might take place in the near vicinity of active black holes, the so-called quasars, thus the ESA will launch in 2008 the Herschel spacecraft to explore this possibility, suggested by most of the X-ray observations concentrated on studying hyperactive black holes.