Labeled as a “rogue planet” when it was discovered eight
years ago, does the exoplanet 2MASSJ2126-8140 and its parent star TYC9486-927-1
make up the largest solar system discovered so far?
By: Ringo Bones
When it was first discovered and observed by astronomers
eight years ago, the exoplanet 2MASSJ2126-8140 was first thought of as a “rogue
planet” – i.e. a planet ejected away from its parent star and destined to
wander forever across the universe because it doesn’t seem to orbit any star.
But after a few years of careful observation, it was then found out that this
exoplanet is part of the largest solar system discovered so far.
Exoplanet 2MASSJ2126-8140, a gas giant type planet, was recently
found out to lie one million kilometers away from its parent star TYC9486-927-1
which makes its orbit 140 times wider than Pluto’s orbital path around our Sun.
Only a handful of extremely wide pairs of this kind have been found in recent
years. Details were published in the Monthly Notices of the Royal Astronomical
Society back in January 27, 2016.
Exoplanet 2MASSJ2126-8140 has an observed
mass between 12 to 15 times that of the planet Jupiter.
Exoplanet 2MASSJ2126-8140’s distance from its parent star is
around 7,000 times the distance between Earth and the Sun and about 140 times
the distance between Pluto and the Sun. This makes it the widest of any planet
around a star discovered so far by a significant margin – about three times the
width of the previously widest pair discovered. If it orbited around our Sun,
exoplanet 2MASSJ2126-8140 would lie far beyond Pluto – like approximately in
the midst of our Solar System’s Oort Cloud.
That huge gap – which equals to 6,900 Astronomical Units
(AU) – means it would take exoplanet 2MASSJ2126-8140 about 900,000 years to
complete a single orbit around its parent star TYC9486-927-1. By estimating the
parent star’s age using its lithium signature, the researchers say
TYC9486-927-1 is somewhere between 10 million and 45 million years old. This
would mean that exoplanet 2MASSJ2126-8140 has completed less than 50 orbits
around its parent star since coalescing from the primordial gas and dust from
which it first came.