One of the most confusing and delightful objects in our sky is the planetary nebula. When initially discovered by early telescope builders, these often round blobs of light looked like planets but failed to wander relative to the stars the way planets do. As telescopes got better and better over the centuries, new details emerged, making these blobs resolve into still hard-to-see structures that looked like faces or geometric doodling. 

It was eventually understood that these nebulae form in the final stages of a middle-sized star’s life. When stars like our Sun come to an end, they exhale their outer layers and leave behind their core to form a white dwarf star. The shape of the resulting nebula depends on how that star puffs off its layers. Is it a continual process? Does it occur in pulsations? It is also is a function of what is around the star. Is there a neighboring star or surrounding planets to block the path of gas? To put all these pieces together, high-quality data is needed to describe the shape and anything else that can be measured.

One of the original justifications for the Hubble Space Telescope was to image planetary nebulae from above the atmosphere so the smallest possible details could be seen. Over recent decades, Hubble has not disappointed, and its rich catalog of images has brought home to all of us that what is going on is far more complicated than any of us realized from looking with ground-based telescopes.

With high-quality images in hand, folks realized we need more: we needed velocity data to explain to us how every knot and twist of gas is moving. In a paper shared on arXiv while undergoing peer review, researchers present data on planetary nebula NGC 1514 and show that this extraordinarily complex planetary nebula has a binary star system in its center, a morphology that is, so far, unique, and motions they can actually measure! 

By placing a very thin slit into a telescope’s instrumentation, it’s possible to spread the light out into a spectrum that captures the specific motions, temperature, and composition of whatever happens to be located at each point along the slit. By looking at motions at many points throughout the planetary nebula, they were able to piece together this object’s complexity. 

In the data, they found a parallel-like structure, two well-defined rings glowing cooly in infrared, and temperatures that allow argon, neon, and helium to glow brightly like naturally occurring neon signs. More data is still needed to understand what all of this means. More data and also a lot of computer modeling, but this research highlights that there is more than one way to probe planetary nebulae, and even the weirdest looking systems have the possibility to be understood.

More Information

Phys.org article

“The morpho-kinematical structure and chemical abundances of the complex planetary nebula NGC 1514,” Alba Aller et al., to be published in Monthly Notices of the Royal Astronomical Society (preprint on arxiv.org)