 A supernova explosion blows away the star 's outer layers , leaving a remnant such as the Crab Nebula . The core is compressed into a neutron star , which sometimes manifests itself as a pulsar or X @-@ ray burster . In the case of the largest stars , the remnant is a black hole greater than 4 M ☉ ) s . In a neutron star the matter is in a state known as neutron @-@ degenerate matter , with a more exotic form of degenerate matter , QCD matter , possibly present in the core . Within a black hole , the matter is in a state that is not currently understood . 
 A supernova explosion <a href='uninflect' title='1'><mark>blows</mark></a> away the star <a href='null_genetive' title='2'><mark>'s</mark></a>outer layers , leaving a remnant such as the Crab Nebula . The core is compressed into a neutron star , which sometimes <a href='uninflect' title='3'><mark>manifests</mark></a> itself as a pulsar or X @-@ ray burster . In the case of the largest stars , the remnant <a href='drop_aux' title='4'><mark>is</mark></a>a black hole greater than 4 M ☉ ) s . In a neutron star the matter is in a state known as neutron @-@ degenerate matter , with a more exotic form of degenerate matter , QCD matter , possibly present in the core . Within a black hole , the matter is in a state <a href='null_relcl' title='5'><mark>that</mark></a>is not currently understood . 
A supernova explosion blow away da star  outer layers , leaving a remnant such as the Crab Nebula . The core is compressed into a neutron star , which sometimes manifest itself as a pulsar or X @-@ ray burster . In the case of tdalargest stars , thdaemnant a black hole greater den 4 M ☉ ) s . In a neutron star the matter is in a state known as neutron @-@ degenerate matter , with a more exotic form of degenerate matter , QCD matter , possibly present in the core . Within a black hole , the matter is in a state ain't currently understood .