Science Imitates Art
An artistic comparison
is made of Vincent van Gogh's "Starry
Night" dust swirls and bloated stars
with
the stellar and dust features in the region
surrounding V838 Mon.
The Light Echo Around V838 Mon
Images
taken in May, September, October,
and December 2002 (four-panel on
left) show the early stages of the
forming ligh echo. This latest image
(on right) taken in February 2004
by the Hubble Heritage team shows
another epoch of how the light has
spread through the dusty remains
of the exploded star.
Visit
the HST Release STScI-2003-10:
Hubble Watches Light from Mysterious
Erupting Star Reverberate Through
Space
|
In January 2002, a faint
star in an obscure constellation suddenly
became 600,000 times more luminous than
our Sun, temporarily making it one of
the brightest stars in our Milky Way galaxy.
Although back to a more normal brightness,
the mysterious star, called V838 Monocerotis,
has continued to illuminate the dusty
environs in which it lives, uncovering
remarkable new features. The phenomenon,
known as a "light echo," is
providing astronomers with a CAT-scan-like
probe of the three-dimensional structure
of shells of dust surrounding an aging
star.
Astronomers
do not fully understand the star's original
outburst. It was somewhat similar to that
of a nova, a more common stellar outburst.
A typical nova is a normal star that dumps
hydrogen onto a compact white-dwarf companion
star. The hydrogen piles up until it spontaneously
explodes by nuclear fusion -- like a titanic
hydrogen bomb. This exposes a searing
stellar core, which has a temperature
of hundreds of thousands of degrees Fahrenheit.
By contrast, V838 Monocerotis
did not expel its outer layers. Instead,
it grew enormously in size. Its surface
temperature dropped to
temperatures that were not much hotter
than a light bulb. This behavior
of ballooning to an immense size, but
not losing its outer layers, is
very unusual and completely unlike an
ordinary nova explosion.
The outburst may represent
a transitory stage in a star's evolution
that is rarely seen. The star has some
similarities to highly unstable aging
stars called eruptive variables, which
suddenly and unpredictably increase in
brightness.
