Four planets star system - exact opposite of TRAPPIST-1 system
Last week NASA's presentation of TRAPPIST-1 star system with 7 earth-like planets became kind of sensation. Meanwile, three weeks before, another news about star system with 4 planets went almost unnoticed. The video below is just several second long, but it is direct imaging of moving exoplanets in HR 8799 system, compiled from Keck observatory images, taken since 2009 to 2016. The black circle in the image center is telescope protection, shading the parent star to make planets visible.
Young Star HR 8799 is 129 light years away, in the constellation of Pegasus. Its mass is 1,5 Sun masses and luminosity 4,9 times higher. Its age is about 30 million years. There are four planets - gas giants, with orbits distances 15, 24, 38, 68 a.u. (1 a.u.=149,6 million kilometers=distance Sun - Earth=8,2 light minutes). Its masses are in the range 4 - 7 Jupiter masses each. With high probability, all four are in 8-4-2- orbital resonance. This means that while first planet closes 8 orbits, second does 4, then 2 and 1.
Image: ManyWorlds Blog
The closest to the star planet e orbit takes 45 - 50 years, the farthest b planet makes one loop in about 400 years. All orbits are almost circular.
The same researchers from Berkeley NExSS group also published direct image of planet, orbiting giant star Fomalhaut.
