Researchers have determined the rotation rate of an exoplanet for the first time in history.
The research team used the European Southern Observatory's (ESO's) Very Large Telescope (VLT) to discover the planet, dubbed Beta Pictoris b, has a rotation that lasts only a few hours, an ESO news release reported.
This rotation is much faster than anything found in our own solar system; Beta Pictoris b's equator moves at a rate of 100,000 kilometers per hour. Jupiter's equator moves at only 47,000 km per hour while Earth's moves at only 1,700.
The researchers hope to use similar techniques in the future to map out other exoplanets using the European Extremely Large Telescope (E-ELT).
The planet is about 63 light-years away from earth in the constellation of Pictor. It was discovered about six years ago and was one of the first exoplanets to be directly imaged. It's also the closest planet to its host star to ever be imaged directly.
"It is not known why some planets spin fast and others more slowly," co-author Remco de Kok, said in the news release. "But this first measurement of an exoplanet's rotation shows that the trend seen in the Solar System, where the more massive planets spin faster, also holds true for exoplanets. This must be some universal consequence of the way planets form."
Beta Pictoris B is believed to be a relatively young planet; it is only about 20 million years old. In the future it is expected to shrink, which would make it spin even faster.
The team used a technique called high-dispersion spectroscopy to split light into its structural colors. The principle of the Doppler effect allowed them to see how the wavelengths changed which revealed which parts of the planet was moving and how fast.
"We have measured the wavelengths of radiation emitted by the planet to a precision of one part in a hundred thousand, which makes the measurements sensitive to the Doppler effects that can reveal the velocity of emitting objects," lead author Ignas Snellen said in the news release. "Using this technique we find that different parts of the planet's surface are moving towards or away from us at different speeds, which can only mean that the planet is rotating around its axis."
The technique closely resembled Doppler imaging, which is used to map the surface of stars.
"This technique can be used on a much larger sample of exoplanets with the superb resolution and sensitivity of the E-ELT and an imaging high-dispersion spectrograph. With the planned Mid-infrared E-ELT Imager and Spectrograph (METIS) we will be able to make global maps of exoplanets and characterise much smaller planets than Beta Pictoris b with this technique", METIS principal investigator and co-author of the new paper, Bernhard Brandl, said in the news release.
