Three-dimensional map of the Ring Nebula reveals its unexpected shape

The Ring Nebula (NGC 6720) is one of the most recognizable objects in the night sky. This planetary nebula is the remnant of a sun-like star and is about 2,000 light-years from Earth. Its characteristic smoke ring-like appearance has long attracted the attention of astronomers. However, the question of whether the nebula is really ring-shaped, or whether it is just an optical illusion, remains open.

In the image taken by the NIRCam camera, the intricate details of the filamentary structure of the inner ring are particularly impressive. Author credit: ESA/Webb, NASA, CSA

Recent studies have shown that the Ring Nebula is more like an elongated barrel through whose poles we observe. “We’re looking right down its barrel, which is an amazing coincidence,” noted Joel Kastner of the Rochester Institute of Technology at an American Astronomical Society press conference.

Formation of planetary nebulae

The discovery contributes to a better understanding of the formation of planetary nebulae, the remnants of sun-like stars that ended their lifetimes thousands of years ago. Although the name “planetary nebulae” is actually a historical mistake: early astronomers, observing them in telescopes, thought these objects looked like planets. 

This illustration shows the geometry and structure of the Ring Nebula as it appears from the side, rather than along the line of sight. The image shows the nebula’s wide halo, inner region, particles of lower density material stretching toward and away from us, and a prominent glowing disk. New data from JWST and the submillimeter array now complement this previous Hubble image.

“Previously, planetary nebulae were thought to have a simple circular shape with a single central star. But how can a spherical star create such complex structures?” – Roger Wesson of Cardiff University explained.

The latest research methods for NGC 6720

To solve the mystery of NGC 6720’s true shape, Kastner’s team used the Submillimeter Array (SMA), a network of radio antennas in Hawaii.The latest methods for studying NGC 6720. Thanks to it, it was able to create a detailed map of the motion of the carbon monoxide molecules that form the nebula. Analyzing the velocities and locations of these molecules allowed us to reconstruct the three-dimensional shape of the object. Even the most powerful telescopes, such as Hubble or James Webb, cannot provide such data from images alone.

The model confirmed that the stellar body at the center, known as a white dwarf, was indeed located exactly at the center of the nebula. “This is not an obvious conclusion, because in many images the white dwarf looks a bit displaced. This is due to the perspective and characteristics of the residual structure,” Kastner noted.

Unexpected discoveries

The James Webb Space Telescope has detected a series of concentric arcs outside the main ring that form every 280 years. Astronomers suggest that these structures may be related to the existence of an invisible companion star that orbits around the white dwarf. Its gravitational influence may have contributed to the formation of the nebula’s complex structure.

This image shows Hubble optical images of the Ring Nebula (left), SMA images of carbon monoxide (middle), and the location of neutral CO in the contours compared to JWST observations of various other features such as neutral H2 and polycyclic aromatic hydrocarbons (right). Author credit: NASA/ESA

Additional observations have revealed “holes” in the nebula that are likely caused by young emissions associated with the influence of this companion star. “The presence of a stellar companion complicates our ideas about the formation of nebulae. A simple one-star scenario no longer explains these processes,” Kastner emphasized.

Studies of the Ring Nebula have revealed new aspects of stellar evolution and the formation of complex structures in the Universe. The study of this object continues to inspire scientists, uncovering new mysteries of the cosmos that require further exploration.

We previously reported on James Webb’s investigation of a “crime scene” in space.

According to Space

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