A university student has precisely modelled one of the most extreme and rare types of stars known to science in unprecedented detail, all while stuck in Covid-19 lockdown.
University of Sydney student Yinuo Han and his colleagues applied high-resolution imaging techniques to surveys of the Apep star system snapped by the European Southern Observatory’s Very Large Telescope in Chile.
Han compared the level of magnification required to “seeing a chickpea on a table 50 kilometers away.”
The Apep system – named after the Egyptian god of chaos – consists of not one but two Wolf-Rayet stars, extremely rare suns of which very few have ever been observed.
Only one in a hundred million stars meets the criteria to be considered a Wolf-Rayet: a large, extremely bright star on the verge of collapse, after which it leaves behind either a black hole or a neutron star.
Both stars in the binary are 10 to 15 times as massive as the sun and burn over 100,000 times brighter and five times hotter, at a whopping 25,000 degrees Celsius.
The pair orbit each other every 125 years or so, at a distance roughly equivalent to the entire length of our solar system.
Rarer still is the fact that this binary Wolf-Rayet pair pumps out huge amounts of stellar dust, forming a glowing tail that wraps around them as they spin ever faster.
This newest member to join the ranks of the stellar special forces appears to break all the rules and has baffled researchers since it was first discovered two years ago.
“The dust seems to have a mind of its own, floating along much slower than the extreme stellar winds that should be driving it,” Han says of the star system, located just 8,000 light years from Earth with some truly bizarre physics taking place around it.
Han and his colleagues created a model that accurately explains the intricate and unusual spiral tail, shedding light on these extreme stellar structures’ unusual behavior.
The tail is expanding four times slower than the stellar winds blowing in the vicinity, which initially didn’t make sense, as they haven’t yet been observed behaving in this fashion anywhere else in the universe.
The solar winds emitted by the pair travel at about 12 million km/h – roughly one percent of the speed of light – but the dust they give off is travelling at just a quarter of this speed.
The researchers now suspect that the speed at which the stars are rotating accounts for this oddity, as the dust is being sent out in all directions, creating different types of sub currents from the ones witnessed in the stellar winds, causing the dust currents to slow dramatically.
Han and his team also point out that Apep may one day produce a gamma-ray burst when it finally explodes, something never before witnessed in the Milky Way galaxy.
Apep is already rotating extremely quickly, meaning it has all of the ingredients necessary to produce a long gamma ray burst, one of the most energetic – and potentially deadly – events in the universe.
Such gamma ray bursts are powerful enough to tear away entire atmospheres from planets and have been linked with mass extinction events here on Earth in the past.
Thankfully, Apep poses no risk to the Earth, as it rotates away from our planet. Thanks to the ongoing work of researchers like Han and his team, though, humanity may one day witness one of the most powerful events the universe has to offer.
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