PSR B1620−26
A binary pulsar-white dwarf system with a confirmed exoplanet.
PSR B1620−26 is a binary star system located in the globular cluster Messier 4 in the constellation Scorpius, about 3,800 parsecs from Earth. It consists of a pulsar and a white dwarf star, and as of 2000 it is confirmed to host an exoplanet orbiting both stars.
Quick Facts
- Distance
- 3,800 parsecs (12,400 light-years)
- Constellation
- Scorpius
- Host cluster
- Messier 4 (M4, NGC 6121)
- Components
- PSR B1620−26 A (pulsar), WD B1620−26 (white dwarf)
- Exoplanet
- PSR B1620−26 b
- Cluster age
- about 12.2 billion years
Facts from the source article.
History
The triple system lies just outside the core of the globular cluster, whose age is estimated at about 12.2 billion years, giving the same age for the stars and planet. There is a minor dispute over nomenclature: one convention names the pulsar PSR B1620−26 A, the white dwarf PSR B1620−26 B, and the planet PSR B1620−26 c; another assigns the pulsar as PSR B1620−26, the white dwarf as WD J1623−266, and the planet as PSR B1620−26 b. A more recent proposal uses PSR B1620−26 (AB)b. In practice, context clarifies which component is meant.
Planetary system
PSR B1620−26 b was detected via Doppler shifts in the pulsar's signals. In the early 1990s, Donald Backer's group, studying what was thought to be a binary pulsar, found a third object was needed to explain the shifts. Gravitational effects later gave a mass too small for a star, and Stephen Thorsett and collaborators announced the planet in 1993.
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