Astronomers record rotation of cloudy super Jupiter

​Washington: In a maiden attempt to decode the rotation of a massive exoplanet, astronomers using Hubble Space Telescope have measured the rotation rate of a cloudy "super-Jupiter" by observing the varied brightness in its atmosphere.

The planet called 2M1207b is about four times more massive than Jupiter. It is a companion to a failed star known as a brown dwarf, orbiting the object at a distance of five billion miles. By contrast, Jupiter is approximately 500 million miles from the Sun. The brown dwarf is known as 2M1207. The system resides 170 light-years away from Earth.

“The result is very exciting. It gives us a unique technique to explore the atmospheres of exoplanets and to measure their rotation rates,” said Daniel Apai from University of Arizona in Tucson.The researchers attribute the brightness variation to complex cloud patterns in the planet's atmosphere.

The new Hubble measurements not only verify the presence of these clouds but also show that the cloud layers are patchy and colorless. The observations revealed that the exoplanet's atmosphere is hot enough to have "rain" clouds made of silicates - vaporised rock that cools down to form tiny particles with sizes similar to those in cigarette smoke.

Deeper into the atmosphere, iron droplets are forming and falling like rain, eventually evaporating as they enter the lower levels of the atmosphere. The “super-Jupiter” is so hot that it appears brightest in infrared light. The planet is hot because it is only about 10 million years old and is still contracting and cooling.