Hubble Heritage Archive: V838 Monocerotis

The text and images in this article were originally published on March 4, 2003, and reflect information about V838 Monocerotis available at that time.

Space Phenomenon Imitates Art in Universe’s Version of Van Gogh Painting

“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 NASA’s Hubble Space Telescope bears remarkable similarities to the van Gogh work, complete with never-before-seen spirals of dust swirling across trillions of miles 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 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 brightest 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.

Image Credit: NASA and The Hubble Heritage Team (AURA/STScI)

Fast Facts about V838 Monocerotis

About this Object

Object Name: V838 Monocerotis
Object Description: Nova-like variable star and surrounding light echo
Position: R.A. 07h 04m 04.8s
Dec. –03° 50′ 50″
Constellation: Monoceros
Distance: The star is ~20,000 light-years (~6 kiloparsecs) away.
Dimensions: This image is 2.4 arcminutes (13.6 light-years or 4.2 parsecs) wide.

About this Data

Data Description: These data are from the HST program 10089: K. Noll, H. Bond, C. Christian, L. Frattare, F. Hamilton, Z. Levay, M. Mutchler, and T. Royle (STScI).
Instrument: ACS/WFC
Exposure Date: February 8, 2004
Exposure Time 1.8 hours
Filters: F435W (B), F606W (V), F814W (I)

About this Image

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Release Date: March 4, 2003

The Light Echo Around V838 Mon

Images taken in May, September, October, and December 2002 (four panels on left) show the early stages of the forming light 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.

Additional Images:

Light Echo V838 Mon* HST * ACS/WFC

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