History
It is theorized that originally PSR B1620−26 A had another, lower mass white dwarf companion, which was ejected when the current PSR B1620−26 B interacted with the original binary system. At that time, PSR B1620−26 B was still a main sequence star, with its planet. Whereupon, the planet settled into orbit around both stars.
The triple system is just outside the core of the globular cluster. The age of the cluster has been estimated to be about 12.2 billion years. Hence this is the age estimate for the birth of the planet, and two stars.
There is a minor dispute about the proper nomenclature rules to use for this unusual star system. One side regards the A/B convention of naming binary stars as having priority, so that the pulsar is PSR B1620-26 A, the white dwarf companion is PSR B1620-26 B and the planet is PSR B1620-26 c. The other side considers PSR to only apply to stars which are pulsars, not their companions, so the white dwarf should be named using the WD convention, making the pulsar PSR B1620-26, the white dwarf "WD J1623-266", and the planet "PSR B1620-26 b." Early articles used the first convention, but star catalogs have been using the second. In practice, context makes it clear whether the pulsar, the white dwarf, the planet, or the system as a whole is being referred to.
Read more about this topic: PSR B1620-26
Famous quotes containing the word history:
“The true theater of history is therefore the temperate zone.”
—Georg Wilhelm Friedrich Hegel (1770–1831)
“There has never been in history another such culture as the Western civilization M a culture which has practiced the belief that the physical and social environment of man is subject to rational manipulation and that history is subject to the will and action of man; whereas central to the traditional cultures of the rivals of Western civilization, those of Africa and Asia, is a belief that it is environment that dominates man.”
—Ishmael Reed (b. 1938)
“We don’t know when our name came into being or how some distant ancestor acquired it. We don’t understand our name at all, we don’t know its history and yet we bear it with exalted fidelity, we merge with it, we like it, we are ridiculously proud of it as if we had thought it up ourselves in a moment of brilliant inspiration.”
—Milan Kundera (b. 1929)