Rogue Planet finds its home in the largest solar system ever seen

A huge alien world orbits 600 billion miles (1,000 billion kilometers) from its host star, making its solar system the largest known, according to a new study.

Astronomers have found the parent star of a gas giant exoplanet named 2MASS J2126, which was previously thought to be a ‘rogue’ world fly freely in space. The planet and its star are separated by about 7,000 astronomical units (AU), meaning the alien world orbits roughly every 900,000 years, the researchers said. (One AU is the average distance between the Earth and the Sun, approximately 93 million miles or 150 million km).

For comparison, Neptune is about 30 AU from the sun, Pluto averages about 40 AU from Earth’s star, and scientists believe the new hypothesis”planet nine“never strays more than 600 to 1200 AU from the sun. [The Strangest Alien Planets (Gallery)]

“The planet is not as lonely as we initially thought, but it is certainly in a very long distance relationship,” said study lead author Niall Deacon, from the University of Hertfordshire in England. , in a press release.

The previous record for the most distant planet and star was 2,500 AU, researchers said.

Deacon and his colleagues analyzed databases of rogue planets, young stars, and brown dwarfs– strange objects larger than planets, but too small to trigger the internal fusion reactions that power stars – to see if they could link them together.

The team discovered that 2MASS J2126, discovered eight years ago, and a red dwarf star called TYC 9486-927-1 are moving together in space about 104 light years from Earth, strongly implying that they are part of the same system.

False color infrared image of star TYC 9486-927-1 and planet 2MASS J2126; the arrows show their movement projected over 1,000 years. The scale indicates a distance of 4,000 astronomical units (AU), where 1 AU is the average distance between the Earth and the sun (about 93 million miles or 150 million kilometers).
Credit: 2MASS/S. Murphy/UNA

The researchers were able to infer an approximate age for TYC 9486-927-1 and 2MASS J2126, based on the lithium signature in the star’s spectrum: between 10 million and 45 million years old. (Lithium is destroyed relatively early in a star’s life, so the more lithium a star has, the younger it is.)

2MASS J2126 has therefore performed a maximum of 50 orbits around the star so far.

Knowing the age of the planet allowed the researchers to calculate a mass for the planet: around 12 to 15 times that of Jupiter. Previous studies had estimated the temperature of 2MASS J2126 at around 2,730 degrees Fahrenheit (1,500 degrees Celsius). The planet appears to be broadly similar in these characteristics to the extraterrestrial world Beta Pictoris b, but 2MASS J2126 orbits more than 700 times farther from its star than Beta Pictoris b, the team members said.

The chances that life could exist on 2MASS J2126 are very low, the researchers said. But a hypothetical observer on the gas giant would see its sun as just a bright star in the sky, and might not even realize the planet and star were connected, they added. (It takes a month for light from TYC 9486-927-1 to reach the planet; sunlight takes about 8 minutes to reach Earth.)

The exotic planetary system likely did not form from a large spinning disc of dust and gas, as Earth’s solar system did, study team members said. But exactly how it took shape remains a mystery.

“How such a large planetary system forms and survives remains an open question,” said co-author Simon Murphy, from the Australian National University in Canberra, in the same statement.

The new study has just been published in the Monthly Notices of the Royal Astronomical Society.

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Arline J. Mercier