One of the most famous nebulae in the universe is changing — and scientists don’t know why

The Butterfly Nebula It changes, and astronomers are at a loss as to why these changes occur. Observations of this planetary nebula show dramatic changes in a butterfly’s wings over just 11 years.

“I’ve been comparing Hubble images for years, and I’ve never seen anything quite like it,” said Bruce Palic, professor emeritus of astronomy at the University of Washington.

What are nebulae?

Hubble imaged NGC 6302, better known as the “Butterfly Nebula,” observing it across a fuller spectrum of light, from the near ultraviolet to the near infrared.NASA, ESA, and J. Kastner (RIT)

Planetary nebulae form from an expanding shell of gas around an old red giant star. Most are ring-shaped, but a few have wing-like shapes, such as the Butterfly Nebula. Astronomers believe the rare hourglass shapes are likely the result of a gravitational pull from a second star orbiting the nebula’s parent star, causing matter to stretch out into a pair of wings. While the wings grow over time, the original shape usually does not change.

what’s new – Palek and his former student Lars Borchert, now a graduate student at Aarhus University in Denmark, compared two exposures of the Butterfly Nebula taken by the Hubble Space Telescope in 2009 and 2020. They noticed dramatic changes in the materials inside the wings. Strong winds lead to complex changes in the materials within the nebula’s wings, the researchers said. But that shouldn’t happen, because the red giant star making the flankers must be a “pretty much moribund intermittent star with no remaining fuel,” the researchers said, when reporting their findings at the 241st meeting of the American Astronomical Society this month in Seattle. , Washington.

The team saw that material in the outer parts of the nebula is moving quickly, at about 800 kilometers per second (500 miles per second), while material closer to the hidden central star is expanding much more slowly, at about a tenth of that speed. . The paths of the jets cross each other, forming “chaotic” structures and growth patterns within the wings.

Digging into the details – The rapidly changing internal structure is not easy to explain using current models of how planetary nebulae form and evolve, Palek said. Hidden by dust and debris, the star at the nebula’s center could have merged with a companion star or siphoned off material from a nearby star, creating complex magnetic fields and generating the jets.

“At this point, these are all just hypotheses,” Balik said in a press release.

“What this shows us is that we don’t fully understand the full range of formation processes at work when planetary nebulae form. The next step is to image the center of the nebula with the James Webb Space Telescope where infrared light from the star can penetrate the dust.”

In about 5 billion years, our Sun will expand into a red giant and form a planetary nebula. This will expel carbon and other heavy elements into the interstellar medium to form star systems and planets in the distant future. This researcher said their findings — a kind of “time lapse” analyzes of planetary nebulae — could help explain not only how material for the star systems of tomorrow was formed but also how the building blocks of our oasis were produced and collected billions of years ago.

“It’s a story of creation that happens over and over again in our universe,” Balik said. “Formation processes provide key insight into the history and effects of stellar activity.”

This article was originally published the universe today by Nancy Atkinson. Read the original article here.

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