Using ESO’s Very Large Telescope (VLT), astronomers have produced the first detailed optical maps of the gas and dust distributed throughout the spectacular planetary nebula NGC 7009, also known as the Saturn Nebula.
This colorful image of the Saturn Nebula was captured by the MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the gas and dust inside the nebula. Image credit: J. Walsh / ESO.
The Saturn Nebula is located 4,322 light-years away in the constellation of Aquarius.
Its name derives from its odd shape, which resembles everyone’s favorite ringed planet seen edge-on. But in fact, planetary nebulae have nothing to do with planets.
The Saturn Nebula was originally a low-mass star, which expanded into a red giant at the end of its life and began to shed its outer layers. This material was blown out by strong stellar winds and energized by UV radiation from the hot stellar core left behind, creating a circumstellar nebula of dust and brightly-colored hot gas. At the heart of the nebula lies the doomed star, visible in this image.
The nebula will last only a few tens of thousands of years before expanding and cooling to such an extent that it becomes invisible to us. Its central star will then fade as it becomes a hot white dwarf.
An annotated version of the above image labels the features of the Saturn Nebula. Image credit: J. Walsh / ESO.
In order to better understand how planetary nebulae are molded into such odd shapes, ESO astronomer Dr. Jeremy Walsh and colleagues used VLT’s Multi Unit Spectroscopic Explorer (MUSE) instrument to peer inside the dusty veils of the Saturn Nebula.
The resulting maps of the nebula reveal many intricate structures, including an elliptical inner shell, an outer shell, a halo, and two previously imaged streams extending from either end of the nebula’s long axis, ending in bright ansae.
Intriguingly, Dr. Walsh and co-authors also found a wave-like feature in the dust, which is not yet fully understood.
“Dust is distributed throughout the Saturn Nebula, but there is a significant drop in the amount of dust at the rim of the inner shell, where it seems that it is being destroyed,” the astronomers said.
“There are several potential mechanisms for this destruction. The inner shell is essentially an expanding shock wave, so it may be smashing into the dust grains and obliterating them, or producing an extra heating effect that evaporates the dust.”
