Most of the elements that people enjoy each day—oxygen, carbon,
etc.—did not result from the Big Bang, but rather are originally from
deep in the core
of a star where lighter elements are fused into these heavy stellar
elements. These elements are then ejected into space when the stars die
an explosive death. This means that when you observe a star you should
see the elements that were present at the time the star originally
formed. Stars present at the beginning of the
galaxy—those formed from the primordial material—should not be
composed of heavy elements, since these would have been formed later.
However, to date these types of have not been detected in our galaxy which leaves a
big question: where is the primordial generation of stars in the Milky Way galaxy?
Astronomers have long searched for these primordial stars, but have had
little success. The prevailing theory was that, since the Milky Way was
formed from the inside out, these early stars would be clustered
about the center of the galaxy. This explanation also provided a reason for
why they haven't been directly observed: the center of our galaxy is
full of dust and young stars that obscure our vision when we try to
look into it.
A new set of computer simulations—reported in a December edition of
the Astrophysical Journal—suggest
something completely different.
By simulating both the history of the star's location and the star's
chemical makeup, the research suggests that primordial stars should be
evenly distributed throughout the galaxy. The results from the simulation, illustrated on the right, show that
the earliest primordial stars are at the center of the galaxy (top), but
stars that form later, yet still from the primordial material, are
everywhere (bottom). This would mean that we should be able to
detect stars made up of the primordial elements with current
telescope technology, but to date, astronomers have not. So, where are
they? According to one of the co-authors of the study
It could be that they were all high-mass stars, which would not have
lived long enough to still be around, or there could be another twist
to the story that we haven't yet figured out.
It seems that even with a study that reveals so much information, there is still much
more to be done. This is good news as it shows how science
deals with unexpected results; science will keep going, and people will
keep searching for the answer. In turn, this quest for understanding
will keep researchers like myself employed for a long time to come.