Although the Saturn Nebula may be misleading, it has nothing to do with the ringed planet. In fact, planetary nebulae have nothing to do with planets. It is a structure that is located five thousand light years from us, in the constellation of Aquarius, and that owes its name to the jewel of the Solar System, Saturn, due to its similarity to it seen from the front.
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. It has a strange shape, which has no explanation for astronomers. For this reason, and in order to better understand how planetary nebulae are molded into such strange shapes , an international team of astronomers has used a new and powerful telescope to look inside the dusty veils of the Saturn Nebula, to create the first detailed optical map of one of these structures.
It is the Multiple Unit Spectroscopic Explorer, also called MUSE for its acronym in English. It is so powerful that it not only creates an image, but also gathers information about the spectrum or color gamut of the object’s light at each point in the image. It is installed in one of the four Unit Telescopes of the Very Large Telescope at ESO’s Paranal Observatory in Chile.
And what have astronomers observed?
The material that forms the Saturn Nebula expands thanks to strong stellar winds and ultraviolet radiation from the hot stellar core that it leaves behind, creating a nebula of brightly colored hot gas and dust. At the heart of the Saturn Nebula is a star turning into a white dwarf .
Well, the team used MUSE to produce the first detailed optical maps of the gas and dust distributed throughout the planetary nebula. The resulting image of the Saturn Nebula reveals many intricate structures , including an elliptical inner shell, an outer shell, and a halo. It also shows two previously imaged streams extending from either end of the nebula’s long axis.
But most intriguing to the scientists was a characteristic ripple in the dust, which is not yet fully understood. The dust is distributed throughout the nebula, but there is a significant decrease in the amount of dust at the edge of the inner layer, where it appears that it is being destroyed.
There are several possible mechanisms that cause this destruction: the inner envelope is essentially an expanding shock wave, so it can break into the dust grains and erase them ; or produce an additional heating effect that evaporates the powder.
Mapping the gas and dust structures within planetary nebulae will help understand their role in the life and death of low-mass stars and will also help astronomers understand how planetary nebulae take on their strange and complex shapes.
But MUSE’s capabilities extend far beyond planetary nebulae. This sensitive instrument can also study the formation of stars and galaxies in the early Universe, as well as map the distribution of dark matter in galaxy clusters in the nearby Universe. MUSE has also created the first 3D map of the Pillars of Creation in the Eagle Nebula.
Image: ESO / J. Walsh
