An international team of researchers has snapped a picture of a cosmic serpent, a swirling structure of gas and dust around a massive three-star system. Beautiful as it is, the system will not last long. A dramatic and catastrophic future awaits it.
Two of the three stars are Wolf-Rayet stars, extremely hot objects at the end of their lives. These stars are shedding their outer layers in powerful winds while spinning very fast. These factors and the interaction between the two stars have created this stunning coiling sight. As reported in Nature Astronomy, the winds are moving at 12 million kilometers (7.5 million miles) per hour.
The object has been nicknamed Apep after the Egyptian serpentine deity that embodied chaos. Astronomers’ interest in these stars is related to their spectacular deaths. Models suggest that fast-rotating Wolf-Rayet stars like these going supernova are behind long-duration gamma-ray bursts, which are among the most energetic explosions in the universe. To have finally found a progenitor in our galaxy opens up a new avenue for studying these events.
“This is the first such system to be discovered in our own galaxy,” lead author Joseph Callingham, of the Netherlands Institute for Radio Astronomy (ASTRON), said in a statement. “We never expected to find such a system in our own backyard.”
The observations were possible thanks to the Very Large Telescope, one of the many facilities of the European Southern Observatory. The team was able to measure that the dust at the edge of the system is moving at the slower pace of 2 million kilometers (1.2 million miles) per hour. This peculiarity hints at intrinsic differences between the two Wolf-Rayet stars.
“The only way we get such a system to work is if the Wolf-Rayet star is spewing out gas at several speeds,” co-author Benjamin Pope, from New York University, stated. “One way for such different winds to happen is via critical rotation. One of the stars in Apep is rotating so fast that it is nearly ripping itself apart. On its equator, the rotational forces make the gas basically weightless, so it slowly floats off the equator.”
The team couldn’t get an extremely precise distance estimate due to the dustiness of the system. They think it is roughly 8,000 light-years away and definitely no further than 15,000. A safe distance. Gamma-ray bursts are collimated (parallel) so you need to be very unlucky to have a nearby one pointing at your planet. Still, Earth might have experienced one already. The Ordovician–Silurian extinction events are consistent with a nearby gamma-ray burst although no unambiguous evidence has been found.