The Pistol Star is one of the most extreme
stars we known about, both in size,
mass and luminosity.
While only 3 million years old,
the star is 100 times more massive
than our Sun,
(although it used to be 200 times as
massive), and it is approximately
10 million times as bright. In 6 seconds
it has emitted more light than our
Sun will in an entire year, making
it the most luminous star in our
It is located in the constellation
Sagittarius, about 25,000 light years
away. Because of its proximity to
the center of the Milky Way, it
is hidden behind enormous clouds of
dust, which is why it hasn't been
given much attention until recently.
Even the Hubble Space Telescope
has to observe it in the infrared
part of the spectrum, since it
passes through the dust more easily.
The star was recently (a few thousand
years ago) a so-called
LBV (Luminous Blue Variable) star,
and in this phase many stars blow
away large amounts of gases. After
shedding the outer, hydrogen-rich
layers, the extremely hot core of
the star is exposed. The
Pistol Star is probably going
through this phase right now,
having shed a cloud of gas
which we call the Pistol Nebula.
Another indication is
that the star's surface
rapidly rising, perhaps up to
as much as 100,000 degrees.
After completing this transition,
it will have become
a Wolf-Rayet star.