NASA (Exoplanet Catalog artwork)PSR B1257+12 b
also named DraugrThe smallest known exoplanet, twice the mass of the Moon, circling a dead star
Overview
PSR B1257+12 b, alternatively designated PSR B1257+12 A, also named Draugr, is an extrasolar planet approximately 2,300 light-years (710 pc) away in the constellation of Virgo. The planet is the innermost object orbiting the pulsar Lich, making it a pulsar planet in the dead stellar system. It is about twice as massive as the Moon, and is listed as the least massive planet known, including among the planets in the Solar System.
Source: Wikipedia
NASA: PSR B1257+12 b is a terrestrial exoplanet that orbits a Pulsar-type star. Its mass is 0.02 Earths, it takes 25.3 days to complete one orbit of its star, and is 0.19 AU from its star. Its discovery was announced in 1994.
Why it matters
- Orbits the millisecond pulsar Lich, detected through tiny timing variations in its radio pulses.
- At roughly 0.02 Earth masses it remains the least massive exoplanet confirmed.
- Its siblings Poltergeist and Phobetor were the first exoplanets ever confirmed, in 1992.
NASA puts it this way: “PSR B1257+12 b, along with fellow doomed worlds, were among the first and creepiest to be discovered as they orbit an undead star known as a pulsar. Pulsar planets like Poltergeist and its neighboring worlds, Phobetor and Draugr, are consumed with constant radiation from the star’s core. ”
Discovery & system
- Discovered
- 1994 · Pulsar Timing · Arecibo Observatory
- Discovery paper
- Wolszczan 1994
- Discoverers
- Aleksander Wolszczan, Maciej Konacki
- Host star
- PSR B1257+12 · 1.4 M☉
- System
- 3 known planets
- Siblings
- PSR B1257+12 c, PSR B1257+12 d
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| PSR B1257+12 b | 25.3 d | 0.19 AU | 0.34 R⊕ | 0.02 M⊕ | — |
| PSR B1257+12 c | 66.5 d | 0.36 AU | 1.91 R⊕ | 4.3 M⊕ | — |
| PSR B1257+12 d | 98.2 d | 0.46 AU | 1.8 R⊕ | 3.9 M⊕ | — |
By the numbers
- Radius
- 0.34 R⊕2,153 km
- Mass
- 0.02 M⊕0.12 ×10²⁴ kg
- Orbital period
- 25.3 d0.07 yr
- Distance from star
- 0.19 AU28 million km
- Eccentricity
- 0nearly circular
- Distance from Earth
- 1,957 ly600 pc
- Density
- 2.85 g/cm³0.52 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.