Cambridge and Sydney astronomers observe for the first time how intense starlight pushes

Astronomers have directly observed for the first time how intense light from stars can ‘push’ matter.

Researchers at the University of Cambridge and University of Sydney tracked a giant plume of dust that was generated by violent interactions between two massive stars.

Infrared images of the binary star system WR140 were taken over 16 years.

And a complementary study using NASA’s James Webb Space Telescope was able to see not just one accelerating dust plume – but almost 20, nested like onion skins.

WR140 feature a huge Wolf-Rayet star and a bigger blue supergiant star, which are gravitationally bound in an eight-year orbit.

It puffs out plumes of dust that stretch thousands of times the distance from the Earth to the Sun, giving researchers a chance to see how starlight can affect matter. Light carries momentum and exerts a push on matter known as radiation pressure.

Yinuo Han, from Cambridge’s Institute of Astronomy, first author of a paper in Nature, said: “It’s hard to see starlight causing acceleration because the force fades with distance, and other forces quickly take over.

“To witness acceleration at the level that it becomes measurable, the material needs to be reasonably close to the star or the source of the radiation pressure needs to be extra strong. WR140 is a binary star whose ferocious radiation field supercharges these effects, placing them within reach of our high-precision data.”

Co-author Prof Peter Tuthill, from the University of Sydney, said: “Like clockwork, this star puffs out sculpted smoke rings every eight years, with all this wonderful physics written then inflated in the wind like a banner for us to read.

“I never dreamed we’d be able to see the physics at work like this. “When I look at the data now, I see WR140’s plume unfurling a like giant sail made of dust. When it catches the photon wind streaming from the star, like a yacht catching a gust, it makes a sudden leap forward.”