{"id":7570,"date":"2014-04-30T13:00:07","date_gmt":"2014-04-30T13:00:07","guid":{"rendered":"http:\/\/hobbyspace.com\/Blog\/?p=7570"},"modified":"2014-04-30T12:33:08","modified_gmt":"2014-04-30T16:33:08","slug":"an-exoplanets-day-measured-for-first-time","status":"publish","type":"post","link":"https:\/\/hobbyspace.com\/Blog\/?p=7570","title":{"rendered":"An Exoplanet’s day measured for first time"},"content":{"rendered":"

An announcement from the European Southern Observatory (ESO<\/a>):<\/p>\n

Length of Exoplanet Day Measured for First Time
\n<\/a><\/strong>VLT measures the spin of Beta Pictoris b<\/em><\/p>\n

Observations from ESO\u2019s Very Large Telescope (VLT) have, for the first time, determined the rotation rate of an exoplanet. Beta Pictoris b has been found to have a day that lasts only eight hours. This is much quicker than any planet in the Solar System \u2014 its equator is moving at almost 100 000 kilometres per hour. This new result extends the relation between mass and rotation seen in the Solar System to exoplanets. Similar techniques will allow astronomers to map exoplanets in detail in the future with the European Extremely Large Telescope (E-ELT).<\/p>\n

\"eso1414a_BetaPictorisB\"
\n<\/a>Artist\u2019s impression of the planet Beta Pictoris b<\/a><\/em><\/p>\n

Exoplanet\u00a0Beta Pictoris b<\/a>\u00a0orbits the naked-eye star\u00a0Beta Pictoris<\/a>\u00a0[1]<\/a>,\u00a0[2]<\/a>, which lies about 63 light-years from Earth in the southern constellation of\u00a0Pictor\u00a0<\/a>(The Painter\u2019s Easel). This planet was discovered nearly six years ago and was one of the\u00a0first exoplanets to be directly imaged<\/a>. It orbits its host star at a distance of only eight times the Earth-Sun distance (eso1024<\/a>) \u2014 making it the closest exoplanet to its star ever to be directly imaged\u00a0[3]<\/a>.<\/p>\n

\"eso1414b\"<\/a>This graphic<\/a> shows the rotation speeds of several of the planets<\/em>
\n in the Solar System along with the recently measured spin rate <\/em>
\nof the planet Beta Pictoris b<\/em><\/p>\n

Using the CRIRES instrument on the\u00a0VLT<\/a>, a team of Dutch astronomers from\u00a0Leiden University<\/a>\u00a0and the\u00a0Netherlands Institute for Space Research<\/a>\u00a0(SRON) have now found that the equatorial rotation velocity of exoplanet Beta Pictoris b is almost 100 000 kilometres per hour. By comparison, Jupiter\u2019s equator has a velocity of about 47 000 km per hour\u00a0[4]<\/a>, while the Earth\u2019s travels at only 1700 km per hour\u00a0[5]<\/a>. Beta Pictoris b is more than 16 times larger and 3000 times more massive than the Earth, yet a day on the planet only lasts 8 hours.<\/p>\n

\u201cIt is not known why some planets spin fast and others more slowly,<\/em>\u201d says co-author Remco de Kok, \u201cbut this first measurement of an exoplanet\u2019s 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.<\/em>\u201d<\/p>\n

Beta Pictoris b is a very young planet, only about 20 million years old (compared to 4.5 billion years for the Earth)\u00a0[6]<\/a>. Over time, the exoplanet is expected to cool and shrink, which will make it spin even faster\u00a0[7]<\/a>. On the other hand, other processes might be at play that change the spin of the planet. For instance, the\u00a0spin of the Earth<\/a>\u00a0is slowing down over time due to the tidal interactions with our Moon.<\/p>\n

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