“Starry Night”, Vincent van
Gogh’s famous painting, is renowned for its
bold whorls of light sweeping across a
raging night sky. Although this image of the
heavens came only from the artist’s restless
imagination, a new picture from the NASA/ESA
Hubble Space Telescope bears remarkable
similarities to the van Gogh work, complete
with never-before-seen spirals of dust
swirling across trillions of kilometres of
interstellar space.

This image, obtained with the Advanced
Camera for Surveys on February 8, 2004, is
Hubble’s latest view of an expanding halo of
light around a distant star, named V838
Monocerotis (V838 Mon). The illumination of
interstellar dust comes from the red
supergiant star at the middle of the image,
which gave off a flashbulb-like pulse of
light two years ago. V838 Mon 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.

Called a light echo, the expanding
illumination of a dusty cloud around the
star has been revealing remarkable
structures ever since the star suddenly
brightened for several weeks in early 2002.
Though Hubble has followed the light echo in
several snapshots, this new image shows
swirls or eddies in the dusty cloud for the
first time. These eddies are probably caused
by turbulence in the dust and gas around the
star as they slowly expand away. The dust
and gas were likely ejected from the star in
a previous explosion, similar to the 2002
event, which occurred some tens of thousands
of years ago. The surrounding dust remained
invisible and unsuspected until suddenly
illuminated by the brilliant explosion of
the central star two years ago.

The Hubble Space Telescope has imaged V838
Mon and its light echo several times since
the star’s outburst in January 2002, in
order to follow the constantly changing
appearance of the dust as the pulse of
illumination continues to expand away from
the star at the speed of light. During the
outburst event, the normally faint star
suddenly brightened, becoming 600,000 times
more luminous than our Sun. It was thus one
of the most luminous stars in the entire
Milky Way, until it faded away again in
April 2002. The star has some similarities
to a class of objects called “novae,” which
suddenly increase in brightness due to
thermonuclear explosions at their surfaces;
however, the detailed behavior of V838 Mon,
in particular its extremely red color, has
been completely different from any
previously known nova.

Nature’s own piece of performance art, this
structure will continue to change its
appearance in coming years as the light from
the stellar outburst continues to propagate
outward and bounce off more distant black
clouds of dust. Astronomers expect the
echoes to remain visible for at least the
rest of the current decade.

The colour image is composed of 3 different
exposures through a blue filter (5250
seconds), a green filter (1050 seconds) and
a near-infrared filter (300 seconds).

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Notes for editors
Animations of the discovery and general
Hubble Space Telescope background footage
are available from:
http://www.spacetelescope.org/bin/videos.pl?&string=heic0405

Image credit: NASA, the Hubble Heritage Team
(AURA/STScI) and ESA

The Hubble Space Telescope is a project of
international cooperation between ESA and
NASA.