Supernova Nebula Cassiopeia A began to move in the opposite direction, and not as usual. This was discovered by astronomers from the University of Amsterdam and Harvard.
Scientists have noticed that on the western side of Cassiopeia A there are inner regions of the nebula, and for some reason they do not expand, but move inward.
Moving backwards can mean two things – either there’s a black hole somewhere, some kind of vacuum, or the nebula has collided with something.
Jakko Wink, researchers from the University of Amsterdam, the Netherlands
Cassiopeia A is the remnant of an exploding star in the constellation Cassiopeia. It is located 11,000 light years from us. The light from the explosion was supposed to reach Earth for the first time around 1670. But there was too much gas and dust around the star for the explosion to be visible to the naked eye or with the simplest telescopes at the time.
The Cassiopeia A Nebula is expanding at an average speed of 4,000 to 6,000 km/s. Its temperature is about 30 million °C. The expansion most likely takes place in gas that was ejected by the star long before the explosion. Cassiopeia A is now about 16 light-years across.
Astronomers observe the unusual movement of the nebula. The authors of the new work said that this happened after the shock wave collided with a shell of gas particles. This shell probably formed when an unexploded star swept away all the gas streams. This happened during the explosion of a star in the constellation Cassiopeia.
Researchers continue to study this phenomenon to find out exactly what caused the nebula to behave this way.