Supernova Cassiopeia A is one of thebest - study supernova remnantsin the Milky Way . From our point of view , the racing shell of blood plasma has been expanding for 350 years at an ordinary rate of between 4,000 and 6,000 km per second . But not all of it . An area of the supernova looks like going backwards .
The breakthrough , accepted for publication in the Astrophysical Journal and available as a preprint on theArXiv , is based on 19 years ’ worth of data that suggests that the western part of the remnant has bang into something . An alternative account is that there is a hole in the shell , but models favor the collision scenario .
" The backward crusade in the west can mean two matter , " lead author Jacco Vink , from the University of Amsterdam , said in astatement . " Either there is a hole somewhere , a kind of vacuum , in the supernova material , causing the hot shell to abruptly move inwards topically . Or the nebula has collided with something . "
The observation were conducted using NASA ’s Chandra X - ray observation tower . The researchers measured the speedup ( or retardation ) of the inner and outer shell of the supernova . When Vink first reported these findings in 2019 at a medical specialist league , it attracted the attention of an Italian group of astronomers . Intrigued they set out to simulate what might be happening in the event of a collision .
As a virtuoso gets into there ergocalciferol giantphase and subsequently in its super red elephantine form , it boast a lot of material away . These whiz are enormous and their outer layers are loosely bound . Once the star croak supernova — the cataclysmic explosion at the last of its life — the material is thrown at mellow - upper and it can catch up with material previously kick out .
According to the Italian group , the scenario between the collision and the shield having a hole can be distinguished . After a collision , the shock wave first decreases but then it accelerates . This is precisely what has been found by Vink in the observance .
" When we recently found an quickening and they forecast just that in their models , the puzzler pieces fall into billet , " read Vink .
Cassiopea A is locate 11,000 light - years away in the eponymous constellation . The brightness level of the supernova would have first arrive to Earth in 1670 , but between intervene dust and special scope capacity , nobody back then was able to see it .
Since then we have caught up with multiple observations , and now it is afavorite targetfor many observatories . NASA ’s latest X - ray lookout IXPE release itsfirst image last monthand opt the supernova remnant as its subject area . Excitingly , the JWST will study it in infrared radiation later this year .
