Methuselah Star (HD 140283) in Libra
A very old Star
I got impatient last night waiting for the new predicted meteor shower (never
materialized) and turned to the telescope to help pass the hours until dawn.   The
Methuselah Star was on my list of objects I wished to see.  As you can see I made
a drawing.  Like much in astronomy, the image invokes a cerebral response more
than a visual one.  At 14.46 billion years of age the Methuselah Star (HD 140283)
is the oldest star known.  This star has been shinning three-times as long as our sun
has.  When the first stars were formed in the universe they were composed of
hydrogen and helium only.  These were the Population III stars. No Population III
stars have ever been seen.  They completed their short lives (only a few million
years) producing heavier elements at their cores.  These heavier elements were
then expelled from these stars into interstellar space during massive supernova
explosions. When the second generation of stars formed (Population II stars) they
were made mostly of hydrogen and helium but did contain some of the heavier
elements from the first generation of stars.  These Population II stars, for the most
part, have lived out their lives as well and, like the Population III stars, ended by
expelling an even richer array of heavier elements into interstellar space.  The
Methuselah Star is one of the few remaining Population II stars. Our sun and all the
stars you see when you look up at night are Population 1 stars that consolidated
out of gas enriched with heavier elements from the earlier generations of stars.  All
of the heavier elements beyond hydrogen and helium that make up our planet,
including us, were forged in the cores of these old stars – Methuselah Star’s
siblings.