Two rare stars whipping around one another in a wide, wild tango give astronomy a unique opportunity to study the gentle slap of light against their dusty skirts
A series of nested shells of dust that are slowly being pushed out into space, not just by the stellar winds of charged particles, but the glow of radiation emitted by the stars themselves, can be seen around the object calledWR 140.
For the first time, scientists have been able to directly observe this radiation pressure in action, using the Keck Observatory to track a giant plume as it expanded out into space over the course of 16 years.
This helps explain what we're seeing in a recent image from the James Webb Space Telescope, the subject of a second paper.
Yinuo Han is an astronomer at Cambridge University.
The material needs to be close to the star or the source of the radiation pressure needs to be stronger. The effects of the radiation field are within reach of our high-precision data.
It's a rare sight to find a rare sight in the constellation of Cygnus. An extremely rare Wolf-Rayet star and a blue O-type supergiant star are two rare objects.
Wolf-Rayet stars are very hot, very bright, and very old at the end of their main-sequence lives. They lose mass at a very high rate due to being rich in hydrogen, nitrogen, and carbon. The carbon in this lost mass absorbs radiation from the stars and re-emits it as light.
O-type stars are among the most massive stars known, and they are also very hot and bright, so their lifespans are very short.
The stars in the system have stellar winds that blow out into space at a rate of around 3,000 kilometers per second. They are losing mass at a rapid rate. This isn't unusual. The stars are in an elliptical shape, which means they don't always circle the same way. They are drawn together for a close approach and then apart again to a distance.
At periastron, the stellar winds create shocks and a giant puffed of dust that expands. Each new shell is created after the last one, which is 7.94 years after the last star. The predictability means that objects like WR 140 are interesting to study.
The shape of the shells is unusual, with one side stretched out, which has been described as a " squircle" shape. It's difficult to explain from just the winds.
Han says that each dust spiral should expand at a constant speed.
We were puzzled at first because we couldn't fit our model to the observations, until we realized that we were seeing something new. The data didn't fit because the expansion speed wasn't constant but it was speeding up. For the first time, we caught that.
Radiation pressure is one of the possible explanations. The transfer of momentum from the photon to the surface of the light causes it to exert a tiny, tiny pressure on anything it slams up against. It's not going to affect your day-to-day life because stars give out a lot of powerful radiation. It can push matter in the air. Lightsail technology is based on this principle.
The strange shape of the shells ballooning around thebinary was reproduced by the team when they included radiation pressure in their models.
"In one sense, we always knew this must be the reason for the outflow, but I never imagined we'd be able to see the physics at work like this."
When I look at the data, I see a huge sail made of dust. It makes a sudden jump forward when it catches the wind from the star.
There are many wonders in the Universe.
The team's research has been published in two different places.
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