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:
“I feel as tall as you.”
—Ellis Meredith, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 14, by Susan B. Anthony and Ida Husted Harper (1902)
“In history the great moment is, when the savage is just ceasing to be a savage, with all his hairy Pelasgic strength directed on his opening sense of beauty;—and you have Pericles and Phidias,—and not yet passed over into the Corinthian civility. Everything good in nature and in the world is in that moment of transition, when the swarthy juices still flow plentifully from nature, but their astrigency or acridity is got out by ethics and humanity.”
—Ralph Waldo Emerson (1803–1882)
“It’s nice to be a part of history but people should get it right. I may not be perfect, but I’m bloody close.”
—John Lydon (formerly Johnny Rotten)