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Largest solar system ever known: Planet orbits star 1trn km away
27 January 2016
A new study discovered that a planet previously thought to be a loner actually orbits a star 1 trillion kilometers away from it. It takes a million Earth years to orbit its sun, making it the largest solar system found to date.
“We were very surprised to find such an object so far from its parent star,” said one of the study’s authors, Dr Simon Murphy of The Australian National University.
“We can speculate they formed 10 million to 45 million years ago from a filament of gas that pushed them together in the same direction,” Murphy said.
Knowing the planet’s age allowed the scientists to estimate its size. Age is measured by the amount of lithium in a star’s atmosphere – the more lithium a star has, the younger it is.
From the BBC:
Astronomers discover largest solar system
7 hours ago
Astronomers have discovered the largest known solar system, consisting of a large planet that takes nearly a million years to orbit its star.
The gas giant is one trillion kilometres away, making its orbit 140 times wider than Pluto‘s path around our Sun.
Only a handful of extremely wide pairs of this kind have been found in recent years.
Details appear in the Monthly Notices of the Royal Astronomical Society.
The planet, known as 2MASS J2126-8140, is between 12 and 15 times the mass of Jupiter.
“We were very surprised to find such a low-mass object so far from its parent star,” said Dr Simon Murphy from the Australian National University (ANU).
“There is no way it formed in the same way as our solar system did, from a large disc of dust and gas.”
This system is nearly three times the size of the previous widest star-planet pair.
The star and its planet were found by a survey of young stars and brown dwarfs in Earth’s neighbourhood.
Once team members discovered they were a similar distance from the Earth – about 100 light-years – they compared the motion of the two through space and realised they were moving together.
“We can speculate they formed 10 million to 45 million years ago from a filament of gas that pushed them together in the same direction,” Dr Murphy explained.
“They must not have lived their lives in a very dense environment. They are so tenuously bound together that any nearby star would have disrupted their orbit completely.”
Latest dark matter searches leave scientists empty-handed. Physicists ponder possibilities for bulk of universe’s mass. By Emily Conover, 5:30am, October 25, 2016: here.