30 Scientific American, December 2020
Mass of star (relative to the sun)
8–10× Electron-capture supernova Neutron star
10–20× Type-II core-collapse supernova Neutron star
20–40× Type-II core-collapse supernova Black hole
40–100× Type-Ibc core-collapse supernova Black hole
Greater than 260× Black hole
100–260× Pair-instability supernova Nothing
Death progression Corpse (remnant)
?
Dense shell
of gas
and dust made
of carbon
and oxygen
Star
Gamma-ray burst
(black hole launches a fast jet)
or dirty fireball (black hole launches a slow jet)
Rapidly spinning black hole
Stellar remnant material
Jet
Superluminous supernova
(neutron star launches a wind)
Neutron star with strong
magnetic field (magnetar)
Wind
Stellar remnant/
material
Slow jet launched by
a black hole
or maybe a magnetar
driving a wind
AT2018cow
A dense torus of
gas and dust that
presumably used
to be part of
the star and
was recently shed
Jets stifled inside
recently shed material
Jet
Jet cocoon
Spinning
black hole
Neutron star
(likely)
SN2018gep Explosion debris hits shell
Illustration by Ron Miller
Surprising Supernovae
For a long time the story of stellar death was simple: the life and fate of a star were thought to depend almost exclusively on its mass ●A.
But discoveries of strange supernovae in the past decade, and especially the past few years, have shown that the story is much more compli-
cated than that. Sometimes the core of a dying star becomes an engine that launches a powerful jet or a wind that explodes the star with
extra energy ●B. Other times stars cast off material before they die, exhibiting death omens that foretell the coming explosion ●C.
A ● CLASSIC MODEL
Traditionally a star’s mass was thought to dictate its death. Different types of supernova explosions should occur for different ranges of stellar
mass, leading to various remnant end products. Although this story is still largely true, sometimes the usual process goes off the rails, and
different endings ensue (shown in green, orange, blue and yellow circles).
●C^ ODDITY: DEATH OMENS
Astronomers have found that some massive stars
shed a significant portion of their atmospheres in
the final days to weeks of their lives. =hen the
star finally explodes, the debris from the blast
collides with the recently shed material, producing
a brilliant display. =hy some stars do this and
others do not is unknown. Perhaps it is the result
of rapid rotation or interaction with another starÖ
Perhaps it happens because of changes deep
within the star that occur during the final stages
of nuclear burningÖ 'ne example, based on the
recently observed supernova 3N÷01~gep, is
shown here Êcircled in blueË.