Oldest Known Planet 'Methuselah' - Astronomy Facts

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Oldest Known Planet "Methuselah" - Astronomy Facts

PSR B1620-26 b is an extrasolar planet located approximately 12,400 light-years from Earth in the constellation of Scorpius. It bears the unofficial nicknames "Methuselah" and "the Genesis planet" due to its extreme age. The planet is in a circumbinary orbit around the two stars of PSR B1620-26 (which are a pulsar (PSR B1620-26 A) and a white dwarf (WD B1620-26)) and is the first circumbinary planet ever confirmed. It is also the first planet found in a globular cluster. The planet is one of the oldest known extrasolar planets, believed to be about 12.7 billion years old.

Facts about Oldest Known Planet "Methuselah" 

• At an estimated age of 12.7 billion years, the planet is more than twice as old as Earth's 4.5 billion years.
• It formed around a young, sun-like star barely 1 billion years after our universe's birth in the Big Bang.
• The ancient planet orbits a peculiar pair of burned-out stars in the crowded core of a cluster of more than 100,000 stars.
• "Methuselah" is 2.5 times the mass of Jupiter.
• It is the first planet found in a globular cluster, and one of the oldest known extrasolar planets.
• PSR B1620-26 b orbits a pair of stars just outside the core of M4: a pulsar (a rapidly rotating super-dense neutron star) and a white dwarf with a mass of 0.34 solar masses orbiting each other at a distance of 1 AU about once every six months.
• Methuselah  orbits at a distance of 23 AU (3.4 billion km), a little larger than the distance between Uranus and the Sun. Each orbit of the planet takes about 100 years.
• The triple system is just outside the core of the globular cluster Messier 4. The age of the cluster has been estimated to be about 12.7 billion years, and because all stars in a cluster form at about the same time, and planets form together with their host stars, it is likely that PSR B1620-26 b is also about 12.7 billion years old. This is much older than any other known planet, and nearly three times as old as Earth. It has been undergoing many stages through its lifetime.
• PSR B1620-26 b orbitspairstars. The primary star, PSR B1620-26, is a pulsar, a neutron star spinning at 100 revolutions per second
• The name comes from the biblical person Methuselah (who in Christian tradition was the oldest person who ever lived).

Like nearly all extrasolar planets discovered prior to 2008, PSR B1620-26 b was originally detected through the Doppler shifts its orbit induces on radiation from the star it orbits (in this case, changes in the apparent pulsation period of the pulsar). In the early 1990s, a group of astronomers led by Donald Backer, who were studying what they thought was a binary pulsar, determined that a third object was needed to explain the observed Doppler shifts. Within a few years, the gravitational effects of the planet on the orbit of the pulsar and white dwarf had been measured, giving an estimate of the mass of the third object that was too small for it to be a star. The conclusion that the third object was a planet was announced by Stephen Thorsett and his collaborators in 1993.

• Check Out Universe Facts

The evolution of the PSR B1620-26 system.

There are about 150 known globular clusters in the Milky Way. It is thought that globular clusters formed very early in the vast halo surrounding the nascent galaxy before it flattened to form the spiral disc.

"A globular cluster might be the first place in which intelligent life is identified in our galaxy," observed Rosanne DiStefano of the Harvard-Smithsonian Center for Astrophysics (CfA) in January, 2016. Globular star clusters are extraordinary in almost every way. The globulars, which are found in the halo of a galaxy, contain considerably more stars than the less dense galactic, or open clusters, which are found in the disk. They're densely packed, holding a million stars in a ball only about 100 light-years across on average. They're old, dating back almost to the birth of the Milky Way. And according to new research, they also could be extraordinarily good places to look for space-faring civilizations.