HR 8799 System

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Exoplanetary Scratchpad

[SysBP Img]

Hot young star system which is the only imaged and wide multiplanetary system. The 30 MY old star is the only known Gamma Doradus variable that is also a Vega-like star. The innermost is e (14.5 AU, 10 MJ), followed by d (24 AU, 10 MJ), c (38 AU, 10 MJ), and b (68 AU, 7 MJ). Inside the inner planet's orbit is an asteroid belt, while outside of the outer planet is a cometary belt (including a clump at 1:2 resonance with the outermost planet), while further yet is a huge halo extending to 2000 AU. The outer three are planets are 2-2.5 times as far as Saturn, Uranus, and Neptune are respectively, but receive similar radiation. The large planets would likely pull the system apart, leading scientists to believe the inner three planets are probably locked in a 1:2:4 orbital resonance in order to maintain stability. An inner planet is at Saturn-to-Uranus-like distances and challenges planetary formation models. Fomalhaut is the only other system where interaction between planets and dust belts can be observed. They are near the upper limits of mass to be classified as planets and could be Brown Dwarves. All three planets were later found in archived Hubble images. The middle planet became the first to have its spectrum directly measured. The spectrum confused scientists and didn't fit current formation theories. They contain carbon monoxide and are depleted in methane, which suggests they were formed in part by absorbing comets in the system. The outermost planet b has unusually thick dust clouds.

HR 8799 System Web Pages

HR 8799 System Artwork

Template:HR 8799 Gallery

HR 8799 System In the News

Three Planets Imaged (2008)

Outermost Planet Found in Hubble Archive Photos (2009)

Asteroid and Kuiper Belt Found (2009)

Link Between Planets and Halo (2009)

Are Planets Brown Dwarves Instead? (2009)

First Direct Planetary Spectrum Obtained (2010)

Extrasolar Visions Thread

Detected With Smaller Ground Telescopes (2010)

Planet b Has Unusually Thick Clouds of Dust (2010)

Mentioned when 500th Planet Discovered (Nov 2010)

Planet d Discovered, Challenges Both Formation Models (Dec 2010)

Clump in Resonance Detected (Apr 2011)

Feature Article on Imaged Planets (2011)

See Imaged Exoplanets for more systems

Outer Two Planets Found in Old Hubble Photos (Oct 2011)

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