With the help of the James Webb Space Telescope (JWST), a group of international scientists studied a planetary nebula called Messier 57, also recognized as NGC 6720 and often referred to as the Ring Nebula. Their observations revealed that the core star within this nebula is encircled by a dust ring. This discovery was elaborated upon in a research article. published April 1 on the arXiv preprint server.
Planetary nebulae consist of expanding clouds of gas and dust that were expelled from a star as it evolved from a main-sequence star to a red giant or white dwarf. Although they are not common, these structures hold significant value for astronomers investigating the chemical changes in both stars and galaxies.
First identified in 1779, the Ring Nebula is a famous planetary nebula located within the boundaries of the Lyra constellation, approximately 2,570 light years distant from our planet. This celestial body appears as an ellipse-shaped band of gases spanning roughly 1.3 light years across, earning itself the reputation of being one of the quintessential examples of such nebulas.
The main star at the center of the Ring Nebula, which is transitioning into a white dwarf, possesses a mass approximately equal to 0.61 times that of our Sun and has an effective temperature measured at roughly 135,000 Kelvin. This star is largely made up of carbon and oxygen, enveloped by a slim layer of less heavy elements on its exterior.
A team of astronomers headed by Raghvendra Sahai from NASA's Jet Propulsion Laboratory (JPL) conducted fresh observations of the Ring Nebula and its core star using the near-to-mid infrared spectrum. To achieve this, they utilized JWST’s Near-Infrared Camera (NIRCam) along with its Mid-Infrared Instrument (MIRI).
The observations revealed an overabundance of emissions in the spectral energy distribution beyond 5.0 µm along with extended emissions visible in the 7.7, 10, and 11.3 µm images. This data points towards the existence of a dense dust disc circling the central star.
As stated in the document, the dust cloud spans about 2,600 astronomical units and comprises predominantly tiny amorphous silicate particles. The overall mass of this dust was calculated to be roughly equivalent to 0.00000186 times the mass of Earth.
In addition, the findings revealed that the central star of the Ring Nebula exhibits a luminosity equivalent to 310 times that of our Sun, along with an interstellar extinction of 0.15 magnitudes as seen from Earth. The research further indicated notable fluctuations in brightness for this central star. These variations could potentially result from the existence of a nearby main-sequence dwarf companion star whose mass is less than one-tenth that of the Sun.
The researchers behind the study observed that the dust cloud enveloping the central star of the Ring Nebula might be left over from a disk formed due to interactions between binaries during an earlier stage of the star’s evolution, with most of this material having since dispersed nearly entirely.
More information: Raghvendra Sahai along with colleagues examined the Ring Nebula (NGC 6720) using JWST observations: Part three focuses on a dust disk surrounding its central star. arXiv (2025). DOI: 10.48550/arxiv.2504.01188
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