A new evolutionary pathway for massive stars
has been discovered. The first phase is a
supernova explosion, which leaves behind a
neutron star. The neutron star then undergoes
a second explosion -- the quark nova. This
violent eruption signals the transition from
a neutron star to a quark star.
In the late stages of a massive star's life,
its interior has an onion-like structure with
nuclear burning occuring at different layers.
When nickel and iron are produced in the core,
the nuclear fusion quickly stops, leading
to core collapse. A violent supernova follows.
Out of the ashes is born a neutron star. Its
fast rotation and misaligned magnetic field
creates a lighthouse effect in radio emission.
The predominantly iron crust of the star
encases a dense neutron-rich interior. The
spindown of the neutron star leads to extreme
core densities, liberating quarks from neutrons.
The magnetic field is forced to align with
the axis of rotation, shutting off the lighthouse
effect. This phase transition releases neutrinos
and photons that build up a fireball as the
core collapses. The intense energy blows off
the outer layers of the neutron star as a
quark nova.
If the delay between supernova and quark nova
is on the order of weeks, a violent collision
occurs, re-energizing the supernova remnant,
dramatically announcing the birth of a quark
star.
