RCW 86 is a large supernova remnant in the southern Milky Way, the likely relic of the earliest supernova on record, a guest star noted by Chinese astronomers.
At a glance
| type | supernova remnant |
|---|---|
| distance from the Sun | 8,150 light-years (2.5 kpc) |
| its light left it | 8,150 years ago |
| size in the piece | about 98 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About RCW 86 (SN 185)
Chinese court astronomers recorded a guest star, SN 185, near Alpha Centauri, and RCW 86 lies in that part of the sky. If the identification is right, it is the remnant of the oldest supernova known from written records. Its name comes from a catalogue of glowing hydrogen regions in the southern sky.
It is unusually large for its supposed age. The likely explanation is that the white dwarf that exploded sat inside a cavity blown by winds in its system, so the blast expanded quickly through thin gas before meeting the cavity wall. Its X-ray spectrum, rich in iron, supports a thermonuclear origin.
Like SN 1006, parts of its rim glow in X-rays from particles accelerated to high energies by the shock.
What you see in the piece
It is drawn as a wide, hollow shell of shocked gas, faint in visible light and easier to find in the radio band, where supernova shells shine.
Measured or modelled
The link between RCW 86 and the recorded guest star is widely accepted but not certain. The drawn extent is modelled.
Questions
Is RCW 86 the oldest recorded supernova?
It is thought to be the remnant of the guest star recorded by Chinese astronomers, the earliest supernova known from written records, though the link is not certain.
How far away is RCW 86?
RCW 86 is about 8,150 light-years (2.5 kpc) from the Sun.