NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida) An image of the Hubble Space Telescope's Cat's Eye Nebula
Researchers have made the first computer-generated three-dimensional model of the Cat's Eye Nebula, revealing a pair of symmetric rings around the nebula's outer shell. The rings' symmetry suggests they were formed by a precessing jet originating from the nebula's central star. This provides strong evidence for a binary star at the center of the nebula.
The Cat's Eye Nebula is one of the most unusual planetary nebulae known, being surrounded by a dying star's outer layer of gas, which results in a colorful, shell-like structure similar to planetary nebulae. It is situated just over 3,000 light years away from Earth, and can be seen in the constellation Draco with the Hubble Space Telescope, which has also shown the Cat's Eye Nebula's complex structure.
Ryan Clairmont, NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) (right) (CC BY-NC-SA 4.0).
Astrophysicists questioned whether the nebula's mysterious structure was possible due to previously accepted theories for planetary nebula formation. More recent research demonstrated that precessing jets were potential shaping mechanisms in complex planetary nebulae such as NGC 6543, but there was no detailed model available.
Clairmont, an astronomy enthusiast, decided to recreate the Cat's Eye's intricate 3D structure in order to investigate its possible origins. Dr. Wolfgang Steffen of The National Autonomous University of Mexico and Nico Koning of the University of Calgary have developed SHAPE, a 3D astrophysical modeling software specially suitable for planetary nebulae.
Clairmont used spectral data from the San Pedro Martir National Observatory in Mexico to reconstruct the nebula's three-dimensional structure. These provide information on the nebula's internal motion, suggesting that the rings were formed by a jet ejected in opposite directions from the nebula's central star.
The jet's precession was similar to a spinning top's wobbling motion. The result indicates that the precessing jet never completed a full 360-degree rotation, and that the jet's emergence was only a short-lived event.
The researchers were able to deduce the precessing jet's tilt and opening angle based on the rings' orientation.
Ryan Clairmont, the lead author of the paper and a prospective Stanford University graduate, said, "It was astounding when I first saw the Cat's Eye Nebula." I was even more surprised that its 3D structure was not fully understood."
"It was very satisfying to be able to do my own astrophysical study that actually has an impact on the field." It's important to understand how they interact with more complex systems like the Cat's Eye, because they will ultimately be a part of our solar system, which will one day become a planetary nebula.
Ryan Clairmont, Wolfgang Steffen, and Nico Koning, in Monthly Notices of the Royal Astronomical Society, 15 September 2022. DOI: 10.1093/mnras/stac2375