Massive alien world amazes with shortest day of any planet known
Thursday, May 1, 2014, 4:25 PM -
Astronomers working at the European Southern Observatory (ESO) have hit a new milestone of exoplanet research. For the very first time, they have been able to figure out how long the day is for a distant alien world, and this massive planet is setting records with the shortest day of any planet we know about.
Back in mid-November of 2008, astronomers using the Very Large Telescope, at the ESO in northern Chile, discovered a massive alien world orbiting the bright blue star Beta Pictoris, located roughly 63 light years away from Earth. Studies of this 'exoplanet' - named Beta Pictoris b - have yielded estimates of its size and mass (65 per cent larger than Jupiter and between 4 and 11 times Jupiter's mass), the length of its year (around 20 Earth years), and it was even one of the very first exoplanets that astronomers were able to directly image (as opposed to just seeing indirect evidence of it). One of the latest studies, using the very same Very Large Telescope (VLT) have produced an even more amazing tidbit of information about this world: the length of its day.
If someone were able to stand on the 'surface' of this massive gas-giant planet, they would see Beta Pictoris rise every 8 hours. That means that the planet spins at a dizzying rate of over 100,000 kilometers per hour, which is over twice as fast as Jupiter, and nearly 60 times faster than Earth.
This is an incredible discovery, especially considering how far away this exoplanet is, and it's all due to the innovative techniques used by astronomers.
"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," study lead author Ignas Snellen said in an ESO press release.
The Doppler effect is how the wavelength of light waves changes depending on how the source of the light is moving relative to us. Thus, the radiation from the side of the planet that is rotating towards us will have the wavelengths compressed slightly compared to the radiation being emitted from the side of the planet that is rotating away from us.
"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."
Even more amazing is that this planet appears destined for an even shorter day than it has now. The planets in our solar system are roughly 4.5 billion years old, and it has taken that long for them to 'settle' into the lengths-of-day they have now. Beta Pictoris b is only 20 million years old, so it formed around the time when apes began to roam the surface of the Earth. As Beta Pictoris b ages, it will shrink, and as it shrinks, it will begin to spin faster, simply due to physics.
"It is not known why some planets spin fast and others more slowly," co-author Remco de Kok said in the ESO statement, "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."