Scientific American - USA (2020-12)

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.