Thursday, January 28, 2016

Astronomers Discover Largest Solar System

False colour infrared image of TYC 9486-927-1 and 2MASS J2126-8140, with arrows showing their motion on the sky over the next 1,000 years. The scale is given in Astronomical Units (AU), the average Earth-Sun distance. For comparison, Pluto has an average distance of only 39 AU. Credit: Two Micron All Sky Survey (2MASS)/Simon Murphy (ANU)

Astronomers studying a lonely planet drifting through space have found its mum; a star a trillion kilometers away. The planet, known as 2MASS J2126−8140, has an orbit around its host star that takes nearly a million Earth years and is more than 140 times wider than Pluto's. This makes it easily the largest solar system ever found. "We were very surprised to find such a low-mass object so far from its parent star," said Simon Murphy of ANU Research School of Astronomy and Astrophysics. "There is no way it formed in the same way as our solar system did, from a large disc of dust and gas."

Only a handful of extremely wide pairs of this kind have been found in recent years. The distance between the new pair is 6,900 Astronomical Units (AU) - 1,000,000,000,000 kilometers or 0.1 light years - nearly three times the previous widest pair, which is 2,500 AU (370,000,000,000 km).

2MASS J2126−8140's parent is a red dwarf star called TYC 9486-927-1. At that distance, it would appear as only a moderately bright star in the sky, and light would take about a month to reach the planet.

Murphy is part of an international team of scientists that studied 2MASS J2126−8140, a gas giant planet around 12 to 15 times the mass of Jupiter, as part of a survey of several thousand young stars and brown dwarfs close to our solar system.

Once they realized 2MASS J2126−8140 and TYC 9486-927-1 were a similar distance from the Earth - about 100 light years - they compared the motion of the two through space and realized 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," Murphy said.

"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."

The research, which will be published in the Monthly Notices of The Royal Astronomical Society, was led by Niall Deacon from University of Hertfordshire and included Joshua Schlieder from the NASA Ames Research Center.

Credit: anu.edu.au

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