Exoplanetary Scratchpad

[SysBP Img]

Wide binary star consisting of a sun-like primary (A) and a red-dwarf secondary (B) separated by 1,100 AU, 41 light years away. Star A contains five exoplanets, the first system found with this many. It has three tightly packed eccentric planets close in to the star, including planet e (hot Super Earth/Neptunian), b (hot Jupiter), and c (hot Saturn). Planet e was the first Neptunian discovered. It was later found to be the shortest-period planet discovered (18 hours) and to transit. The planet has about half of Neptune's mass, but is Earth-like in size and density (2.17 Earth Radius). It is composed 70% of rock and the outer 30% is likely an ocean of super-critical water (between a gas and liquid state) that is 3000km thick. This is the hottest and densest super-Earth and the is the most watery planet found to date. It likely possesses a thick atmosphere of CO and CO2. The brightness of the star (also closest known to transit and only known naked eye star to do so) makes it more easily studied than other hot super Earths. Planet f is a very eccentric Saturnian in the habitable zone. Planet d is a super jovian at Jupiter-like distances, which was the first found at true Jupiter distances and still the exoplanet discovered with dopplar spectrometry with the largest known semi-major axis. The distant outer star causes planet d's axis to flip on its axis every million years. Planet d in turn causes the other planets to flip, including its star. The axis tilt of transiting planet e should be determined at some point. "Bode's law" predicts four undiscovered planets.

55 Cancri System Web Pages

55 Cancri System In the News

Planet c First Planet in True Jupiter-Like Orbit Found (2002)

Neptunian Planet e Discovered (Aug 2004)

A fourth planet is discovered in the system, making 55 Cancri the first known 4-planet system. The new planet is the second/third Neptunian planet discovered along with Gliese 436 b.

Controversy Over First Neptunian Discovered (Sep 2004)

Models Predict Earthlike Planet Could Form Here (2006)

Planet e Orbit Unstable? (2006)

Saturnian f Discovered in HZ (2007)

Bode's Law Predicts One More Planet

Planet e's Year Shortened to the Smallest Known (2010)

Planet e Transit Detected (2011)

Bode's Law Predicts Four More Planets

Planet e Less Dense Than Thought (Sep 2011)

Planet e Covered in Super-Critical Water (Nov 2011)

Star Causes Outer Planet to Flip on Axis (2011)

55 Cancri System Fun Links

  • article - Is the planet Republican or Democrat?