An international team of astronomers used the James Webb Space Telescope (JWST) to observe the planetary nebula NGC 6720, better known as the Ring Nebula. Observation campaign described in the article on the print server arXivrevealed many structural details of this nebula.

Planetary nebulae (PNe) are expanding envelopes of gas and dust released during a star’s evolution from a main sequence star to a red giant or white dwarf. They are relatively rare but important to astronomers studying the chemical evolution of stars and galaxies.

Located about 2,600 light-years from Earth in the constellation of Bush, the Ring Nebula is a well-known PN with a complex morphology. Its star is a white dwarf with a mass of at least 0.58 solar masses, an effective temperature of 135,000 K, and a solar luminosity of 310. Previous observations had shown that the white dwarf is currently in a rapid fading phase and that part of the ionized nebula will likely recombine.

In mid-2022, a team of astronomers led by Roger Wesson of Cardiff University in the United Kingdom observed the Ring Nebula with JWST to learn more about its nature. Observations were carried out as part of the General Observers (GO) program of the 1st cycle.

“Here we report a JWST image of the NGC 6720 Ring Nebula using 13 filters from 1.6 µm to 25 µm,” the researchers wrote in the paper.

The images showed that the Ring Nebula has an inner cavity and crust, where the nearly 20,000 dense clusters contain up to half the total mass. The image also revealed the presence of a thin ring of possible polycyclic aromatic hydrocarbon (PAH) emission and a halo containing about 10 concentric arcs and 400 flares.

Analyzing the resulting images, the astronomers discovered that the central cavity contains highly ionized gas and exhibits two linear structures. In general, the cavity has an approximately circular structure with a radius of about 25 arcseconds. The crust surrounding this cavity is a large area of ​​elliptical shape with a well-defined inner and outer edge.

It turns out that the center of the Ring Nebula has shifted by two arcseconds to the northwest of the central star. Astronomers suggest that this change may be due to primitive mass loss, ionization, and the hot stellar wind.

JWST observations of the central star showed that it was a triple system. Based on the images, the researchers found that the star has a double companion about 35 AU away and a distant self-motion companion believed to be a low-mass M2-M4 parent star about 14,400 AU away. serial star.

According to the paper’s authors, their findings confirm that PNe in general can contain a wide variety of structures and stages, from highly ionized hot gas to dense molecular clusters. Source