Astronomers discover ‘homeless’ planet

Astrophysicists at the University of Montreal have discovered a “homeless” planet.

By Max Sonnenberg, The Space Reporter
Thursday, November 15, 2012

Astronomers discover ‘homeless’ planet

Astrophysicists at the University of Montreal (UdeM) have discovered a “homeless” planet (i.e., a planet that is not orbiting a star). UdeM along with their European colleagues found the planet using data from the Canada-France-Hawaii Telescope (CFHT) and the European Southern Observatory’s Very Large Telescope (VLT).

“Although theorists had established the existence of this type of very cold and young planet, one had never been observed until today,” said Étienne Artigau, an astrophysicist at the UdeM, in a statement. “This object is also the closest planetary mass to our solar system that has ever been found.”

Astronomers hope that this “homeless” planet will help them understand more about exoplanets that orbit stars.

“Over the past few years, several objects of this type have been identified, but their existence could not be established without scientific confirmation of their age,” said Jonathan Gagné, a doctoral student of physics at UdeM, in a statement. “Astronomers weren’t sure whether to categorize them as planets or as Brown Dwarfs. Brown dwarfs are what we could call failed stars, as they never manage to initiate nuclear reactions in their centers.”

The “homeless” planet has been dubbed CFBDSIR2149. Astronomers believe that the newly-named planet is part of a group of extremely young stars known as the AB Doradus Moving Group.

“This group is unique in that it is made up of around thirty starts that all have the same age, have the same composition and that move together through Space. It’s the link between the planet and AB Doradus that enabled us to deduce its age and classify it as a planet,” said Lison Malo, an astrophysicists with UdeM and the Centre for Research in Astrophysics of Quebec, in a statement.

The astronomers attained a number of infrared images of  CFBDSIR2149 using the CFHT. They then turned to the VLT to measure the planet’s mass, its temperature, and its age. They discovered that the planet is between 50 and 120 million years old, has a temperature of about 400 degree Celsius, and a mass four to seven times that of the planet Jupiter.

The fact that the planet is nomadic is ironic given the history of the word “planet.”

“Planet as a word originates from the Latin word planetus, which originally comes from the Greek words planeta or planêtês, meaning moving or wandering celestial bodies, as opposed to stars which appeared to be in a fixed position in the sky,” said Oliver Hernandez, an astrophysicist at UdeM, in a statement.

Astronomers noted that this is the fist “homeless” planet not connected by gravity to a star that also meets the mass, temperature and age criteria. This finding supports theories that suggest that nomadic planets may be much more numerous than previously thought.

“This object was discovered during a scan that covered the equivalent of 1000 times the surface of the full moon,” Artigau said. “We observed hundreds of millions of stars and planets, but we only found one homeless planet in our neighborhood  Now we will be looking for them amongst an astronomical number of sources further afield. It’s like looking for a single needle in amongst thousands of haystacks.”


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