Astronomers have been able to spot an amazing structure ejected from a supernova nucleus collapse, exploding in space at a speed of 4,000 km/s, by taking pictures of it over a period of 14 years.
The supernova remnant and blast wave – called MSH 15-52 – penetrate a cloud of gas called RCW 89, causing shocks and knots in the material, thus slowing the expanding supernova.
MSH 15-52 is located 17,000 light-years from Earth and appears to be one of the smallest known supernova remnants in the Milky Way. The light from the stellar explosion reached Earth about 1,700 years ago, as the predecessor star ran out of fuel to support the fusion, exploding its outer material in space, and the collapse of its core.
(NASA / CXC / SAO / P. Slane, et al.)
This collapsed core turned into a type of “dead” star called a pulsar, an extremely dense object containing neutrons tightly packed so that they take on some of the properties of an atomic nucleus, as light pulses from their poles as they spin at high speed.
This spin also helps form the X-ray nebula of ejected stellar material that is expanding into space.
(NASA/SAO/NCSU/Borkowski et al.)
Exactly how fast they are expanding is detailed in a new study, which uses images from 2004, 2008 and 2017-2018 to monitor changes in RCW 89 as the supernova remnants sink into it.
By calculating the distance these features travel over time, we have a better understanding of the shock wave velocity, and the knots of ejected stellar material at MSH 15-52.
The blast wave is an advantage where MSH 15-52 meets RCW 89 which is moving at 4,000 km/sec, but some material knots are moving faster, up to 5,000 km/sec.
These nodes are thought to be clumps of magnesium and neon that formed in the star before the supernova exploded, and are moving at different speeds.
However, these features are slowed down as they interact with the materials in RCW 89.
The researchers confirmed that the material passed through a cavity or a relatively low-density bubble of gas around the exploding star before it encountered RCW 89. This is consistent with the basic collapse model of a supernova.
When the progenitor star reached the end of the main sequence lifetime, powerful stellar winds had blown into the space around it, stripping the star of hydrogen, creating a giant hole. Then, when the star’s core finally collapsed into a supernova, the explosion ejected the remaining stellar material into this relatively empty region of space.
Supernova ejectors in the higher velocity range have also been observed in the Cassiopeia A supernova remnant, located 11,000 light-years away. This is also believed to be a supernova explosion, as the light from the explosion reached Earth only 350 years ago.
The research was published in a journal Astrophysical Journal Letters.
Source: Science Alert