Kevin Luhman, Penn State’s Associate Professor of Astronomy and Astrophysics classifies this object as a “brown dwarf” ?" an object that formed just like a star out of a massive cloud of duct and gas, but the mass that it accumulates is not enough to ignite thermonuclear reactions in its core, resulting in a failed star that is very cool.
“This planet-like companion is the coldest object ever directly photographed outside our solar system,” Luhman said.
“Its mass is about the same as many of the known extra-solar planets -- about six to nine times the mass of Jupiter -- but in other ways it is more like a star. Essentially, what we have found is a very small star with an atmospheric temperature about as cool as the Earth’s,” he said.
In the case of the new brown dwarf, the scientists have estimated the temperature of its surface to be between 80 and 160 degrees Fahrenheit, which is possibly as cool as a human.
Astronomers have named the brown dwarf “WD 0806-661 B” because it is the orbiting companion of an object named “WD 0806-661”, which is the “white dwarf” core of a star that was like the Sun until its outer layers were expelled into space during the final phase of its evolution.
Luhman and his colleagues searched through infrared images of over six hundred stars near our solar system to make this discovery and compared images of nearby stars taken a few years apart, searching for any faint points of light that showed the same motion across the sky as the targeted star.
“Objects with cool temperatures like the Earth are brightest at infrared wavelengths,” Luhman said.
“We used NASA’s Spitzer Space Telescope because it is the most sensitive infrared telescope available,” he added.
The study will be published in the Astrophysical Journal.