Webb Telescope photographed how the light of stars moves huge clouds of dust

(ORDO NEWS) — Two rare stars circling each other in a wild tango have given astronomers a unique opportunity to study the gentle touch of light on their dusty skirts.

The binary object, called WR 140, is surrounded by a series of dust shells that are being slowly pushed into space not only by a stellar wind of charged particles, but also by the glow of radiation emitted by the stars themselves.

For the first time, scientists have been able to directly observe this radiation pressure in action, using infrared observations from the Keck Observatory to track the giant plume as it expanded into space for 16 years.

That helps explain what we’re seeing in a recent James Webb Space Telescope (JWST) image, the subject of a second article , showing a blazing binary nestled among many glowing dust shells.

“It is difficult to see how starlight causes acceleration because this force weakens with distance, and other forces quickly take over.

To notice the acceleration at a level at which it can be measured, the material must be close enough to the star, or the source of radiation pressure must be very strong. them within range of our highly accurate data,” explained astronomer Yinguo Han from the University of Cambridge.

Star tango

Object WR 140 is located at a distance of about 5600 light years in the constellation Cygnus and is a rarity among rarities. It is a colliding wind binary consisting of an extremely rare Wolf-Rayet star and a blue O-type supergiant companion, another rare object.

Wolf-Rayet stars are very hot, very bright and very old, they burn up at the end of their lives on the main sequence.

They are significantly depleted in hydrogen, rich in nitrogen or carbon, and lose mass very quickly.

This lost mass also contains a large amount of carbon, which absorbs the star’s radiation and re-radiates it as infrared light.

On the other hand, O-type stars are among the most massive stars known, and are also very hot and bright; because they are so massive, their lifespan is incredibly short and it disappears after only a few million years.

Both stars in the WR 140 system have fast stellar winds blowing into space at about 3,000 kilometers per second. Therefore, both lose mass at a rather frantic rate. This is actually quite normal.

But the stars revolve around each other in an elliptical or oval shape, which means they rotate unevenly. They approach for a close approach (periastre) and again diverge at a great distance (apastron).

At periastron, their powerful stellar winds collide, creating shocks and a giant layer of dust that expands outward, creating a dust shell.

The stars revolve around each other once every 7.94 years, which means that each new shell is created 7.94 years after the previous one.

This predictability means that objects such as the WR 140 are interesting targets for studying dust generation and acceleration.

Not only the wind

Webb Telescope photographed how the light of stars moves huge clouds of dust 2
Animation showing how the WR 140 twin produces dust in the periastron, as if watching the twin from above

But you may have noticed that the shape of the shells is peculiar: one side is elongated, giving what has been described as a “square” shape. This is difficult to explain with stellar winds alone.

“In the absence of external forces, each dust spiral should expand at a constant rate. At first we were puzzled because we couldn’t get our model to match our observations, until we finally realized we were seeing something new.

The data did not match because the rate of expansion was not constant, but rather accelerated. This is the first time we have filmed this on camera,” the scientists admit.

But there is another explanation: radiation pressure. Electromagnetic radiation – light – exerts a tiny, tiny pressure on whatever it bumps into due to the transfer of momentum from the photon to the surface.

Photons are so small and massless that they won’t affect your daily life, but stars emit a lot of powerful radiation. Unfiltered and in the vacuum of space, it can actually push matter. This is the principle of Lightsail technology.

When the team incorporated radiation pressure into their WR 140 models, they were able to reproduce the peculiar shape of the shells swelling around the binary system.

“When I look at the data now, I see the WR140 plume unfurling like a giant sail of dust. When it catches the photon wind from the star, like a yacht catching a gust of wind, it makes a sudden leap forward,” said astrophysicist Peter Tuthill from the University of Sydney in Australia.

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