Apep's Extreme Colliding wind system

 Wolf-Rayet stars (WR stars) is a  heterogeneous set of stars whose spectra indicates that their surface is rich in heavy metals, strong solar winds, and also high surface temperature that ranges from 30000K to 210000K. These stars are evolved massive stars that have completely lost their outer hydrogen and are fusing hydrogen to heavier elements. Wolf- Rayet stars embody the final stage of most massive star just before their evolution is terminated by a supernova explosion and finally ending into a black hole or neutron star.

If WR stars form a binary system, they can pump out huge amounts of Carbon dust driven by the stellar winds. As the stars orbit one another, the dust gets wrapped and forms a beautiful glowing tail. Just a handful of these glows have been observed by the astronomers. In a recent study (Han et al. 2020) they have considered one such system, but it has been found to break the rules of all previous observations.

This WR binary system is named ‘Apep’ (2XMM J160050.7–514245), which is around 8000 light-years from Earth (Stars in the binary are each about 10 to 15 times more massive than the Sun and more than 100,000 times brighter),  was discovered two years ago. It was found by these researchers that the spiral plumes from this system are found to expand in such a way that it feels as if they have brains!. The team led by Hans, confirmed that the dust spiral is expanding four times slower than the measured stellar winds, something strange compared to other systems, and also found that the main star in the binary is rotating rapidly (12 million kilometers an hour, i.e. 1 percent the speed of light) and it could have all the ingredients to detonate a gamma-ray burst when it goes into a supernova. The authors explain this anomaly by saying, the stellar winds are launched in different directions at different speeds. The dust expansion that we measure is driven by solar winds launched from the star’s equator. The researchers are studying more on this observed strangeness and also to explain the physics behind the stellar rotation.

 

References

Y Han, P G Tuthill, R M Lau, A Soulain, J R Callingham, P M Williams, P A Crowther, B J S Pope, B Marcote. The extreme colliding-wind system Apep: resolved imagery of the central binary and dust plume in the infrared. Monthly Notices of the Royal Astronomical Society, 2020; 498 (4): 5604 DOI: 10.1093/mnras/staa2349