Abnormally Large Exoplanet 11 Times Mass of Jupiter but Mystifies Scientists by its Extraordinary Distance from Host Star
ByAn international team of astronomers discovered an exoplanet orbiting its host star at a distance greater than any known today and it also measures at 11 times the mass of Jupiter.
Accoridng to a press release, the planet orbits its star at 65 times the distance Earth does to the sun, changing some theories on planet formation. Previous research has suggested a planet that far from its host star would develop too slowly to ever grow that big.
"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said study lead author Vanessa Bailey, a fifth-year graduate student in the University Arizona's Department of Astronomy.
The researchers' work was published in the Astrophysical Journal.
"A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit," Bailey explained. "It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet's progenitor clump was starved for material and never grew large enough to ignite and become a star."
A binary star system is a possible hypothesis for the strange case of the giant exoplanet, HD 106906, but Bailey said the mass ratio in that case is often no larger than 10-to-1.
"In our case, the mass ratio is more than 100-to-1," she said. "This extreme mass ratio is not predicted from binary star formation theories - just like planet formation theory predicts that we cannot form planets so far from the host star."
The 13-million-year-old planet is also still glowing from residual heat left over from its formation. It is relatively young, considering Earth is some 350 times older. At 2,700 degrees Fahrenheit, it is much cooler than its host star and it emits mostly infrared energy instead of visible light.
"Systems like this one, where we have additional information about the environment in which the planet resides, have the potential to help us disentangle the various formation models," Bailey added. "Future observations of the planet's orbital motion and the primary star's debris disk may help answer that question."