Researchers Konstantin Batygin and Mike Brown say have not yet observed the object directly

Researchers say they found planet through mathematical modeling and computer simulations

The event took place in the Saudi capital on the second day of Xi's first visit to the region

Sixth seed Kvitova sent crashing out by local hope Gavrilova

Five-time major champion to team up with Spieth, Fowler

Visitors stay in T20 series after defeating Bangladesh by 31 runs

Nils D., a 25-year-old German national, had travelled to Syria in October 2013

The loud explosion sent a plume of smoke rising in the sky, with ambulances and fire-fighters rushing to the scene

The powerful bombing heard across the city also left 24 people wounded

The meeting hosted by US and France was attended by Australian, British, Dutch, German and Italian defence ministers