Scientists have created the first three-dimensional computer model of the Cat’s Eye Nebula, revealing a pair of symmetrical rings surrounding the outer layer of the cosmic cloud. This symmetry suggests that they were formed by a jet of gas, providing strong evidence for the presence of a binary star at the center of the nebula.
Led by Ryan Claremont, an American high school student with a passion for astronomy, the research has published its results Monthly Notices of the Royal Astronomical Society.
Planetary nebulae are formed by the ejection of the outer layer of gas from dying solar-mass stars, creating a shell-like structure with a distinct color from these objects.
Also known as NGC 6543, the Cat’s Eye Nebula is one of the most complex planetary nebulae known. It is a little more than three thousand light years from Earth, in the constellation Draco.
The nebula was previously photographed by the Hubble Space Telescope in high resolution, revealing a complex structure of knots, spherical shells and arcuate filaments. This mysterious structure puzzled astrophysicists because it could not be explained by previously accepted theories of the formation of planetary nebulae.
Recent research suggests that gas jets are potential modeling mechanisms in complex planetary nebulae such as NGC 6543, but they have not yet been modeled in detail.
Claremont decided to try to determine the detailed 3D structure of the cat’s eye to learn more about the potential mechanism that gave it its complex shape. For this, he sought the advice of Professors Wolfgang Steffen of the National Autonomous University of Mexico and Nico Koning of the University of Calgary.
Conning by site physicalWas responsible for the development of SHAPE, a 3D astrophysical modeling software particularly suited for planetary nebulae.
Hubble data helped create a 3D model of the Cat’s Eye Nebula
To reconstruct the three-dimensional structure of the Cat’s Eye Nebula, the researchers used spectral data from the National Observatory of San Pedro Martir in Mexico, which provided detailed information about the internal motion of matter in the nebula.
Using this data and Hubble images, Claremont built a 3D model and determined that rings of high-density gas wrapped around the outer layer of the cat’s eye.
Because the rings are almost perfectly symmetrical about each other, Claremont thinks they are formed by a jet—a stream of high-density gas ejected in the opposite direction from the nebula’s central star.
The jet precessed, similar to the oscillating motion of a rotating surface. As the jet oscillated (or advanced), it circled and formed rings around the cat’s eye.
However, the data indicate that the rings are only partial, suggesting that the precessional jet never completed a 360-degree rotation and that the emergence of the jets is only a short-lived phenomenon.
The duration of the streams is important information for the theory of planetary nebulae. Given that only binary stars can precess the planetary nebula jet, the team’s findings are strong evidence that such a system exists at the center of the Cat’s Eye.
As the angle and direction of the jet changed over time, it probably formed all the features of the cat’s eye, including jets and nodules. Using the 3D model, the researchers were able to calculate the tilt angle and aperture of the precession jet based on the orientation of the rings.
“When I first saw the Cat’s Eye Nebula, I was struck by its brilliant, perfectly symmetrical structure,” said Claremont, a recent graduate of Stanford University. “I was even more surprised that its 3D structure was not fully understood. »
He said it was very rewarding to be able to do astrophysical research that really has an impact in the field. “Precessional jets in planetary nebulae are relatively rare, so it is important to understand how they contribute to the formation of more complex systems such as the cat’s eye. »
Ultimately, he said, understanding how precessional jets form provides insight into the ultimate fate of our Sun, “which will one day become a planetary nebula.”
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