James Webb unravels the mystery of a nebula around a dying star

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James Webb unravels the mystery of a nebula around a dying star

The Southern Ring Nebula

It is one of the first discoveries of the space telescope James Webb: Two hitherto hidden stars have emerged from the Southern Ring Nebula that surrounds a dying star, thanks to observations of unrivaled accuracy.

This strange nebula located in the Milky Way, about 2000 light years from the solar system, is a gigantic cloud of gas and dust produced by a star which, as it dies, expels some of its material – a lot of gas and a little of dust.

In the center, there remains the core of this star, called a white dwarf: a very hot and very small star, difficult to see directly, but whose presence can be guessed by the orange rings all around, traces of the material it contains. ejected. Within a few billion years, our Sun should experience roughly the same fate, as the vast majority of stars.

Comparison showing Webb telescope observations of the Southern Ring Nebula in the near-infrared, left, and in the mid-infrared, right.

Except that unlike the Sun, which will die alone, the white dwarf at the heart of the Southern Ring Nebula is accompanied. We knew so far a companion star, easier to observe than the white dwarf, because it is still in the prime of life. It is this companion star that appears brightest in the center of the dusty disk, in photos taken by the James Webb Telescope, which has been operating since this summer 1.5 million kilometers from Earth.

< p class="e-p">But this duo operation, fairly classic in the Milky Way, did not explain the atypical structure of the nebula, explains to AFP Philippe Amram, from the Marseille astrophysics laboratory, the x27;one of the authors of the study published Thursday in Nature Astronomy, which dissects the recent observations of the telescope.

Since its discovery by astronomer John Herschel (in 1835), we wonder why the Austral Ring nebula has such a bizarre shape, not really spherical, rather elongated, continues this CNRS researcher.

Observations from the James Webb Telescope come to clear up the mystery: thanks to their vision in the infrared, a wavelength invisible to the human eye, the instruments telescope unearthed evidence of at least two other stars within the nebula.

These discovered stars are located in the center of the nebula, which is x27; spans a diameter equivalent to 1500 times the distance from the Sun to Pluto. They are farther from the white dwarf than the companion star, but overall the four stars are close enough together to interact.

There Energy exchanges then occur between this group of stars which will shape the structure of the nebula in their wake, according to the astrophysicist. Which would finally explain its unique appearance.

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