PSR B1257+12
Star
PSR B1257+12 ('Lich') — not a star but a stellar corpse: a neutron star ~1.4 times the Sun's mass crushed into a sphere only ~24 km across, spinning 161 times a second and sweeping radio beams across space like a lighthouse. Its density is almost unimaginable — a sugar-cube of its matter would weigh billions of tonnes — and it was the first 'sun' ever found to host planets.
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Key facts
Mass
2.78 × 10³⁰ kg
1.4 M☉
Radius
12 km
Spectral type
Neutron star (millisecond pulsar) — a stellar corpse, not a main-sequence star; no spectral class
Science
Physical
- Mass
- 2.78 × 10³⁰ kg · 1.4 M☉
- Radius
- 12 km
- Spectral type
- Neutron star (millisecond pulsar) — a stellar corpse, not a main-sequence star; no spectral class
Composition
- By mass
- Not a star but a stellar corpse: ~1.4 solar masses crushed into a sphere only ~24 km across, spinning 161 times a second and sweeping radio beams across space like a lighthouse. Its density is almost unimaginable — about 10¹⁷ kg/m³, so a sugar-cube of its matter would weigh roughly a billion tonnes; its surface gravity is ~200 billion times Earth's and its escape velocity is a large fraction of the speed of light. Formed in a supernova, it was the first 'sun' ever found to host planets.
Discovery & history
- Method
- Pulsar-timing detection
- Name
- A pulsar catalogue designation (position 12h57m, +12°); nicknamed 'Lich', a name for an undead sorcerer, echoing a world reborn around a dead star (not a formal IAU name).
Formed in a supernova, this pulsar was catalogued for its radio pulses; in 1992 those pulses revealed the first known exoplanets. How planets came to orbit a dead star — survivors, or reborn from the debris of the explosion — is still debated.
Images
Images from open archives · credit shown per image