wow so nice .. i use the high res pic as my wallpaper
Light Echoes From a Red Supergiant
V838 Monocerotis
This Hubble Space Telescope image of the star V838 Monocerotis
reveals dramatic changes in the illumination of surrounding dusty
cloud structures. The effect, called a light echo, unveiled
never-before-seen dust patterns when the star suddenly brightened
for several weeks in early 2002.
A light echo is light from a stellar explosion echoing off dust
surrounding the star that produces enough energy in a brief flash
to illuminate surrounding dust. The star presumably ejected the
illuminated dust shells in previous outbursts. Light from the
latest outburst travels to the dust and then is reflected to
Earth.
The phenomena is similar to that of a nova. 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 --
exposing a searing stellar core with 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.
V838 Monocerotis is located about 20,000 light-years away from
Earth in the direction of the constellation Monoceros, placing the
star at the outer edge of our Milky Way galaxy.
Image credit: NASA, ESA, and The Hubble Heritage Team
(STScI/AURA)
http://www.nasa.gov/images/content/171965main_image_feature_784_ys_full.jpg
http://www.nasa.gov/multimedia/imagegallery/image_feature_784.html