Astronomers ‘surprised’ by cause of South Rim Nebula’s iconic shape

(ORDO NEWS) — A new study has found that the intricate whorls of the South Rim Nebula, recently famous for being one of the first objects captured by the JWST, are the product of at least four stars.

While studying images from a new space telescope, an international team of astronomers has discovered previously unknown stars in a cloud of glowing gas and plasma.

The presence of these stars explains the structures that are still forming as a nebula. expanding, which is the result of the violent death of a single star at the center of the nebula.

“We were surprised to find the presence of two or three companion stars that likely hastened her death, as well as another ‘innocent bystander’. “a star caught in an interaction,” explains astrophysicist Orsola De Marco of Macquarie University in Australia, who led the study.

Planetary nebulae, such as the South Rim Nebula, form when a star such as the Sun dies. When a star begins to run out of fuel needed for nuclear fusion in its core, it swells hundreds of times, turning into a red giant.

Eventually, the fuel runs out and the star’s outer material is ejected into space and the core collapses into a white dwarf.

The ejected material continues to expand outward and, ionized by radiation from the white dwarf (which will continue to radiate residual heat for potentially trillions of years), glows fluorescently.

These are planetary nebulae, so named because without interference from other objects they tend to be quite spherical, resembling a planet.

But if there is something else near the star and it often is, since many stars are in systems with multiple stars gravitationally bound to each other great structures can form in the nebula as it travels through space.

The South Rim Nebula, officially named NGC 3132 and located about 2,460 light-years away, is the death shroud of a star estimated to be three times the Sun’s lifetime mass.

Now this star is a small dense white dwarf, about half the mass of the Sun, packed into a sphere the size of the Earth.

It is also surrounded by a cloud of cold dust, making it difficult to see. The JWST image, released in July, was the sharpest ever taken: light in the infrared and near-infrared range, in which JWST sees the universe, can penetrate dust more efficiently than other wavelengths.

But there was also a problem. there is much more to see in the picture.

“When we first saw the images, we knew we had to do something, we had to explore!” De Marco says. “The community came together, and in this single image of a randomly selected nebula, we were able to discern much more precise structures than ever before.”

There is a second star close to the center of the nebula. This too was already known, the white dwarf’s double companion.

This star is at an earlier stage in its life and is still on the main sequence, but has not yet begun the series of transformations that will mark the end of its days.

The spiral structures that form arches around the center of the nebula are the product of the orbital dance of these two stars – a dead white dwarf and its living companion.

But when the researchers performed a 3D reconstruction of the nebula, they found pairs of structures that form when objects like stars and black holes spewing jets of plasma from their poles.

This suggests that more stars are present in the intricate starry waltz.

“We first inferred a close companion due to the dusty disk around the central star, a distant companion that created the arches, and a super-long companion that you can see in the image,” explains De Marco.

“Once we saw the jets, we knew that there must be another star or even two in the center, so we believe that there are one or two very close companions, another one at an average distance and one very far away. If this is the case, then there are four or even five objects involved in this dirty death.”

The new images also allowed the researchers to perform a new calculation of the white dwarf’s temperature. It burns at about 110,000 Kelvin (about 109,700 degrees Celsius, or 197,540 degrees Fahrenheit).

Planetary nebulae are relatively short-lived phenomena, fluorescing for only about 10,000 years before dissipating into interstellar space.

So in a way, we’re very lucky to have caught up with this stage in the life cycle of the South Rim Nebula. The team’s results are also important for studying this period of the white dwarf’s life and the interactions that may occur.

And it is interesting that the discovery of several new stars gravitationally bound to each other has implications for gravitational wave astronomy. White dwarfs are in a continuum of dense objects; they have the smallest mass and the smallest density, followed by neutron stars and black holes.

It is possible that “chaotic” systems such as the South Rim Nebula may in the future lead to many successive collisions of dead stars, resulting in objects with a mass that cannot be formed from a single star.

The researchers said studying more of these objects with JWST could help us better understand how they form and inform future observations.


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