On Giant Exoplanet, Days Last Just Eight Hours

By Bill Andrews | April 30, 2014 12:21 pm
Artist's conception of the dust and gas disk surrounding the star Beta Pictoris. Credit: NASA/FUSE/Lynette Cook

Artist’s conception of the dust and gas disk surrounding the star Beta Pictoris. Credit: NASA/FUSE/Lynette Cook

Slowly but surely, astronomers have been making huge strides in understanding planets around other stars. From just proving they existed about 20 years ago, we’re now at the point where they can determine the composition of an exoplanet, its weather patterns and — as of this week — even the length of its day.

Researchers announced today that they’ve calculated the spin of gigantic planet β Pictoris b, about 63 light-years away. A day on the planet lasts just eight hours — confirmation of astronomers’ current models that indicate that larger worlds should spin more quickly.

The Full β Picture

Scientists have known of the gas giant β Pictoris b for almost 6 years, and have been studying it ever since. It was one of the first exoplanets to be observed directly, meaning you can actually see it in pictures (as opposed to just seeing a host star dim when the planet passes in front). The world orbits the star β Pictoris, a bright young star, approximately every 21 years.

Researchers had already managed to learn all this about the system. But using the ESO’s Very large Telescope to observe the light from β Pictoris b, they got precise enough data to figure out just how fast the exoplanet spun on its axis.

They did this by using the Doppler effect, which shifts an object’s light spectrum depending on its velocity. Since half the planet was rotating towards us, its light was blueshifted, and the half rotating away from us was redshifted. That was enough for the researchers to calculate the exoplanet’s equatorial rotation rate of 25 km/s. Since they knew the world’s size, about 1.65 times as big as Jupiter, they could quickly calculate the eight-hour day. The details appear in this week’s edition of Nature.

Astronomers have learned the exoplanet β Pictoris b spins faster than any in the solar system, in line with the trend of bigger worlds rotating more quickly.

Astronomers have learned the exoplanet β Pictoris b spins faster than any in the solar system, in line with the trend of bigger worlds rotating more quickly.

Exoplanet Spin Cycle

As it turns out, β Pictoris b’s spin rate puts it squarely in line with a trend established in our solar system: the bigger a planet is, the faster it spins. (This excludes Mercury and Venus, though, since the sun is so close by it interferes with their rotation.) Actually, for β Pictoris b to fit in perfectly with the trend, it should’ve been spinning about twice as fast, but the researchers chalk that up to its young age of only about 20 million years. When it’s closer to our 4.5 billion years, it should have cooled and shrunk, increasing its spin.

This is actually a fairly significant development for scientists, in addition to being just conceptually neat. Knowing its spin rate will allow scientists to better model β Pictoris b’s weather systems and atmospheric dynamics. Plus, they should be able to apply this technique to figure out the same about lots of other exoplanets as well. This will help them better understand planetary dynamics in general, shedding light on just what determines a planet’s rotation rate to begin with, and learning a little something about how all planets formed.

 

CATEGORIZED UNDER: Space & Physics, top posts
MORE ABOUT: exoplanets
  • http://www.ustechrepair.com John Wolfgang

    Wow, 8 hour days! I wonder what the working hours would be?

    • Trae Michael

      Like 2.5 hours would be pushing it lol

      • http://www.ustechrepair.com John Wolfgang

        That sounds about right :)

    • eirikr1

      3 days to every 24hr shift, and each shift would automatically rotate between days and nights to be fair without adjustment. What a country! I mean planet!

  • Rosa Carrillo

    En espanish pleace tenks for ms

  • luke101

    I wonder if that would lower the sensible gravity because of centrifugal force….

    • Ferdinand Marcos 2.0

      Yes, but the centripetal acceleration at the equator is only part of it. The rotation also causes the equator to bulge, with the result being that the poles are closer to the center and feel more gravitational acceleration.

  • http://blogs.discovermagazine.com Jonathan Tracey

    “What should we use to represent β Pictoris b in our mass scale comparison with solar planets?”
    “Just reuse your picture of Jupiter and make it red. And make sure the eye is clearly visible.”

  • Todd Winiarz

    Would taking a “HIT” of LSD expand this time frame?

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

D-brief

Briefing you on the must-know news and trending topics in science and technology today.
ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »