Proximal Planet Formation

Somehow or other (and it’s by no means clear how), some exoplanet gas giants whizz around their stars at great proximity.  The hottest of these objects so far discovered is an exoplanet named Kelt-9b.  It is a sub-brown dwarf of ~3 Jupiter masses.  It’s so close to its parent star that its rotation is tidally locked, and orbits the star in just 36 hours.  The temperature of its ‘dayside’ is over 4000 degrees C.  This remarkably high temperature is likely due to the immense amount of stellar radiation Kelt-9b is subjected to.  This temperature and stellar irradiation is driving off huge amounts of hydrogen from Kelt-9b’s atmosphere, creating an extended envelope of atomic hydrogen gas (1).  Other similar tailed gas giants have been studied before (2,3).  One can only imagine how spectacular this must look – a gas giant ‘comet’ streaming out a tail from near to or even within its parent star’s extended corona.

New analysis of Kelt-9b’s atmosphere has confirmed the presence of iron and titanium atoms within the planet’s atomic chemical soup (4).  It’s known that brown dwarfs can have cloudy atmospheres containing liquid iron rain, as well as other atmospheric dusts (5).  These dusty, cloudy atmospheres tend to form below 2,500 degrees Celsius, and then clear when the brown dwarf drops its temperature below about 1,500 degrees C.  Read More…

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The Most Eccentric Planet Yet

A recent discovery of a new exoplanet has revealed a Jupiter-sized world which whizzes around its parent star as if it were a comet.  The planet, dubbed HD 20782b, is located some 117 light years away, and was discovered initially from the a signal of reflected light as the planet made its closest approach to the star.

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