JWST takes incredible pictures of dust pushed by light

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

A binary object called WR 140 is surrounded by a series of nested shells of dust that are slowly pushed into space not only by the stellar wind of charged particles of the binary system, 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.

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

“It’s hard to see starlight. causing acceleration because the force disappears with distance and other forces quickly take over,” says astronomer Yinguo Han from the University of Cambridge.

“In order to observe acceleration at a level that becomes measurable, the material must be close enough to the star, or the source of radiation pressure must be especially strong.

WR 140 is a binary star whose violent radiation field amplifies these effects, making them available to our high-precision data.”

WR 140 lies about 5,600 light-years away in the constellation Cygnus, and is a rarity among rarities. This is what is known as a colliding wind binary, consisting of an extremely rare Wolf-Rayet star and a blue O-type supergiant companion star, another rare object.

As we have explained before, Wolf-Rayet stars are very hot, very bright and very old, they burn out 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.

O-type stars, on the other hand, 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 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 (1,864 miles) 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).

JWST takes incredible pictures of dust pushed by light 2
Animation showing how the WR 140 binary produces dust in the periastron, as if watching the binary from above

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

But you may have noticed that the shape of the shells is peculiar, with one side elongated producing what has been described. in the form of a square. This is difficult to explain by the stellar wind alone.

“In the absence of external forces, each dust spiral should expand at a constant rate,” Khan says.

“We were puzzled at first because we couldn’t get our model to match the 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. The first time I caught it on camera.”

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 light sail 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.

“In a way, we always knew that this must be the reason for the outflow, but I never dreamed that we could see physics in action in this way,” says astrophysicist Peter Tuthill of the University of Sydney in Australia.

“When I look at the data now, I see the WR140 plume unfurling like a giant sail of dust. leap forward.”

The universe is truly full of wonders.


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