Exoplanetary Scratchpad

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Ammonia Cloud Jovians and Neptunians are giant planets whose visible cloud decks are dominated by ammonia compound clouds. This is a list of systems containing Ammonia Cloud Jovians (or Jupiter Twins) as identified on Extrasolar Visions. This list may be updated to incorporate new science and discoveries. For a list of those exactly seen on Extrasolar Visions, see EV Ammonia Cloud Giants.

Jupiter Twins

  • Solar System - Home system of Earth, the only confirmed habitable planet. Also has three other terrestrials, two Jovians, two Neptunians, several rocky and icy Dwarf Planets, a asteroid belt, a kuiper belt, and an Oort cloud.
  • HD 70642 System - First Jupiter analog discovered in a system with no giant planets further in, making it the closest solar system analog. Planet is 3.3 AU from an aging yellow dwarf star 90 light years away.
  • HD 128311 System - An orange dwarf star with two jovians (a Jupiter analog detected in 2005 and an eccentric giant in the outer habitable zone) possibly in 1:2 resonance and a dusk disk detected by Spitzer.
  • 47 Ursae Majoris System - One of earliest systems discovered one. Planets b (2.5 MJ, 2.1 AU) and c (0.5 MJ, 3.6 AU) are in circular orbits at asteroid-belt like distances, while planet d (1.6 MJ, 11.6 AU) is in a distant more eccentric orbit. Planet b was the first found to have a circular orbit beyond the habitable zone. The discovery of planet c made the system the first multiplanet system whose planets have circular orbits. Planet d has not yet completed a full year yet since its discovery, but is the furthest out planet discovered with the dopplar spectrometry method. Studies have shown a terrestrial planet could only form in the innermost part of the habitable zone. Several transmissions have been sent to the star system.
  • HD 117207 System - A jupiter analogue 3.8 AU from a yellow dwarf star.

Ammonia Cloud Jovians

  • HD 37124 System - The fourth triple planet system discovered around a normal star, the last one announced with 4 other multiplanet components in 2005. A Sunlike star with Jovian planets that received Venus-like, Mars-like, and Asteroid Belt-like radition from their stars. Simulations showed that no terrestrial planets could form between the Venus-like and Mars-like Jovian planets.
  • Solar System - Home system of Earth, the only confirmed habitable planet. Also has three other terrestrials, two Jovians, two Neptunians, several rocky and icy Dwarf Planets, a asteroid belt, a kuiper belt, and an Oort cloud.

Eccentric Ammonia Cloud Jovians

  • Gliese 777 System - Outer planet of the primary star was initially believed to be a Jupiter analog, but later found to be eccentric (its apastron is at Jupiter-like distance). Its second planet was the fourth Neptunian discovered and was announced with four other "second" planets in 2005.
  • HD 30177 System - An eccentric ammonia cloud jovian orbiting 2.7 to 5.0 AU from a yellow dwarf star.
  • 55 Cancri System - 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.
  • HD 33636 System - One of the six extrasolar systems thought to have planets to be first shown to also have a dust disk by Spitzer. The "planet" was later shown to be a star.
  • Epsilon Eridani System - Nearest single non-red dwarf star to the Sun and the second nearest system with a confirmed planet. The planet is a very elliptical Jupiter-like world. It also has two asteroid belts and a kuiper belt, with evidence of planets in between.
  • Mu Arae System - At first believed to be a system dominated by orbit crossing eccentric Super Jupiters. Instead, three Jovians orbit in roughly circular orbits at Earth-like, Mars-like, and Jupiter-like distances in addition to a Hot Neptune (the first Neptunian announced).
  • 14 Herculis System - Contains the first discovered exoplanet orbiting beyond the habitable zone. An eccentric ammonia cloud giant ranging from 1.9 to 3.7 au from a yellow dwarf star.
  • HD 89307 System - A moderately eccentric ammonia cloud jovian around a yellow dwarf star.

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