PSR B1620-26 A white dwarf companion in orbit around a millisecond pulsar, (PSR 1620-26) located within the globular clusterM4 (NGC 6121). Measurements using the pulsar timing method indicate that the white dwarf is orbited by three massive planets.1, 2
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Thorsett, S., Arzoumanian, Z., Camilo, F., and Lyne, A. "The Triple Pulsar System PSR B1620-26 in M4," Astrophysical Journal (submitted 1999).