Scientists are observing a giant planet that is about nine times the mass of Jupiter. The planet was in a very early stage of formation and contradicts current understanding of planet formation. Scientists describe the planet as if it were still in the womb.
The researchers used the Subaru Telescope, located near the summit of a dormant Hawaiian volcano, and the orbiting Hubble Space Telescope to detect and study gas giant planets orbiting very far from their young host stars. Gas giants are planets, like the largest planets in the solar system, namely Jupiter and Saturn, composed mostly of hydrogen and helium, with gas revolving around a smaller solid core.
“We think it’s still very early in the ‘birth’ process,” said astrophysicist Thayne Currie of the Subaru Telescope and NASA-Ames Research Center, lead author of the study published Monday in the journal Nature Astronomy. “The evidence suggests that this is the earliest stage of formation ever observed for a gas giant.”
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The planet sits in a vast disk of gas and dust, carrying the planet-forming material, which surrounds a star called AB Aurigae that lies 508 light-years – the distance light travels in a year or 9.5 trillion km – from Earth.
About 5,000 planets outside our solar system, or exoplanets, have been identified. The newly discovered planet, called AB Aur b, is among the largest. The planet is closer to the maximum size to be classified as a planet rather than the smallest object. The planet is heated by the gases and dust that fall into it.
These planets still in the process of forming – called protoplanets – have been observed only in the vicinity of one other star.
Nearly all known exoplanets have orbits around their stars within the distance that separates our sun from the farthest planet, Neptune. But the planet orbits three times the distance of Neptune from the sun and 93 times the distance of Earth from the sun.
The planet’s birth appears to have followed a different process from the standard planetary formation model.
The star AB Aurigae is about 2.4 times larger than our sun and nearly 60 times brighter. It’s about 2 million years old – a baby by stellar standards – compared to about 4.5 billion years for our middle-aged sun. The sun in its early life was also surrounded by a disk that gave rise to Earth and the other planets.
“New astronomical observations continue to challenge our current theory, ultimately improving our understanding of the universe,” Guyon said. “Planet formation is complex and messy, with many surprises still ahead.” [ah/rs]
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