In the eye of a star cyclone | DE24 News

“The fact that this relatively simple model can reproduce the spiral geometry to this level of detail is just beautiful,” said Professor Tuthill.

However, not all of physics is simple. Mr. Han’s team confirmed that the dust spiral expands four times slower than the measured stellar winds, which is unknown in other systems.

The leading theory to explain this bizarre behavior makes Apep a strong contender for generating a gamma-ray burst when it eventually explodes, something that has never been seen before in the Milky Way.

Dr. Joe Callingham, co-author of the study at the University of Leiden in the Netherlands, said: “Wolf-Rayet star systems have been studied extensively: these are really the peacocks of the star world. Discoveries of these elegantly beautiful but potentially dangerous objects are causing quite a stir in astronomy. ”

He said this paper was one of three to be released on the Apep system this year alone.

Recently, the team showed that Apep is not just one Wolf-Rayet star, but actually two. And colleagues from the Institute of Space and Astronautics in Japan will shortly publish a paper on another system, Wolf-Rayet 112. The lead author of that paper, Ryan Lau, was co-author of this paper with Mr. Han.

Time bombs

Wolf-Rayet stars are massive stars that have reached their final stable phase before going into supernova and collapsing to form compact remnants like black holes or neutron stars.

“They’re ticking time bombs,” said Professor Tuthill.

“Apep’s main star not only shows the usual extreme behavior of Wolf-Rayets, but also appears to be spinning quickly. This means it could have all the ingredients to detonate a long burst of gamma rays when it goes into the supernova. ”

Gamma ray explosions are among the most energetic events in the universe. And they are potentially fatal. If a blast of gamma rays hit Earth, it could clear the planet of its precious ozone layer and expose us all to the sun’s ultraviolet radiation. Fortunately, Apep’s axis of rotation means it poses no threat to Earth.

,Incredible’

The numbers show Apep’s extreme nature. The two stars are each about 10 to 15 times more massive than the Sun and more than 100,000 times brighter. When the surface of our home star is around 5500 degrees, Wolf-Rayet stars are typically 25,000 degrees or more.

According to the team’s latest findings, the massive stars in the Apep binary orbit each other approximately every 125 years at a distance comparable to the size of our solar system.

“The speeds of the stellar winds generated are just mind-blowing,” said Han. “They spin about 12 million kilometers per hour from the stars. that’s 1 percent of the speed of light.

“The dust generated by this system, however, expands much more slowly, at about a quarter of the stellar wind speed.”

Mr. Han said the best explanation for this is the rapidly rotating nature of the stars.

“It probably means that stellar winds are launched at different speeds in different directions. The amount of dust we’re measuring is driven by slower winds that are triggered near the stellar equator, ”he said.

“Our model now fits the observed data quite well, but we haven’t fully explained the physics of star rotation yet.”

Mr. Han will continue his astronomical studies at Cambridge University when he begins his PhD later this year.

Explanation

This work was done in part on behalf of the Jet Propulsion Laboratory, which was funded by NASA under the Sagan Fellowship Program of the NASA Exoplanet Science Institute. Further funds from the Nederlandse Organizatie voor Wetenschappelijk.